Inspection and Preventive Maintenance Procedures

IPM Procedures

Inspection and Preventive Maintenance Procedures Procedure Anesthesia Unit Vaporizers . . . . Anesthesia Unit Ventilators . . . . Anesthesia Units . . . . . . . . . . Apnea Monitors . . . . . . . . . . . Argon Surgical Lasers . . . . . . . Aspirators . . . . . . . . . . . . . . Autotransfusion Units . . . . . . . Beds, Electric . . . . . . . . . . . . Blood Pressure Monitors, Electronic Indirect . . . . . . . . . . . . . . Blood Pressure Monitors, Invasive Blood/Solution Warmers . . . . . . Capnometers and Multiple Medical Gas Monitors . . . . . . . . . . . Carbon Dioxide Surgical Lasers . . Cardiac Resuscitators . . . . . . . Centrifuges . . . . . . . . . . . . . Circulating-Fluid Pumps . . . . . . Conductive Furniture and Floors . Critical Care Ventilators . . . . . . Cryosurgical Units . . . . . . . . . Defibrillator/Monitors . . . . . . . Defibrillators . . . . . . . . . . . . ECG Monitors . . . . . . . . . . . . Electrical Receptacles . . . . . . . Electrocardiographs . . . . . . . . Electrosurgical Units . . . . . . . . Frequency-Doubled Nd:YAG Surgical Lasers . . . . . . . . . General Devices . . . . . . . . . . . Heart-Lung Bypass Units . . . . . Heated Humidifiers . . . . . . . . . Hemodialysis Units . . . . . . . . . Ho:YAG Surgical Lasers . . . . . . Hypo/Hyperthermia Units . . . . .

257941 456-0595 A NONPROFIT AGENCY

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No.

Procedure

436-0595 461-0595 400-0595 420-0595 462-0595 433-0595 449-0595 402-0595

Infant Incubators . . . . . . . . . . . Infusion Devices . . . . . . . . . . . Intra-Aortic Balloon Pumps . . . . . Isolated Power Systems . . . . . . . Laparoscopic Insufflators . . . . . . . Mammography Units . . . . . . . . . Medical Gas/Vacuum Systems . . . . Mobile C-arms . . . . . . . . . . . . Mobile X-ray Units . . . . . . . . . . Nd:YAG Surgical Lasers . . . . . . . Oxygen-Air Proportioners . . . . . . Oxygen Analyzers . . . . . . . . . . . Pacemakers, External Invasive . . . Pacemakers, External Noninvasive . Peritoneal Dialysis Units . . . . . . . Phototherapy Units . . . . . . . . . . Physical Therapy Ultrasound Units . Pneumatic Tourniquets . . . . . . . . Portable Ventilators . . . . . . . . . Pressure Transducers . . . . . . . . Pulmonary Resuscitators, Gas-Powered . . . . . . . . . . . . Pulmonary Resuscitators, Manual . . Pulse Oximeters . . . . . . . . . . . Radiant Warmers . . . . . . . . . . . Radiographic Units, General-Purpose Radiographic/Fluoroscopic Units, General-Purpose . . . . . . . . . . Smoke Evacuators . . . . . . . . . . Sphygmomanometers . . . . . . . . . Suction Regulators . . . . . . . . . . Temperature Monitors . . . . . . . . Traction Units . . . . . . . . . . . . . Transcutaneous O2/CO2 Monitors . . Ultrasound Scanners . . . . . . . . .

. . . 454-0595 . . . 434-0595 . . . 445-0595 . . . . . . . . . . . . . . . . . . . . .

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450-0595 446-0595 421-0595 456-0595 412-0595 441-0595 458-0595 457-0595 408-0595 407-0595 409-0595 437-0595 410-0595 411-0595 464-0595 438-0595 430-0595 431-0595 413-0595 465-0595 414-0595

5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275

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E-mail [email protected]

No. . . . . . . . . . . . . . . . . . . . .

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415-0595 416-0595 432-0595 439-0595 466-0595 467-0595 440-0595 463-0595 468-0595 447-0595 444-0595 417-0595 418-0595 460-0595 455-0595 469-0595 470-0595 443-0595 471-0595 435-0595

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448-0595 422-0595 451-0595 419-0595 472-0595

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473-0595 452-0595 424-0595 459-0595 425-0595 427-0595 453-0595 474-0595

Procedure/Checklist 436-0595

Anesthesia Unit Vaporizers Used For: Anesthesia Unit Vaporizers [10-144]

Also Called: By trade names (e.g., Fluotec 5, Vapor 19.1, Tec 6), which are registered trademarks and should be used only when referring to the specific devices Commonly Used In: Operating rooms, emergency rooms, delivery rooms, trauma rooms, and any areas requiring the administration of an inhalation agent (with anesthesia units) Scope: Applies to the various anesthesia vaporizers used to deliver a known concentration of vaporized liquid anesthetic Risk Level: ECRI Recommended, High; Hospital Assessment, Type

ECRI-Recommended Interval*

Interval Used By Hospital

Major

6 months

months

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hours

Minor

NA

months

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hours

Time Required

* Additional periodic calibration and preventive maintenance is normally required annually or biannually (see manufacturer’s recommendation). Only qualified personnel trained and experienced in this function should perform this additional servicing.

Overview An anesthesia unit vaporizer is used to vaporize a liquid anesthetic agent and deliver a controlled amount to the patient. According to the American Society for Testing and Materials (ASTM) standard ASTM F1161-88, anesthetic agent vaporizers are required to be concentration calibrated (i.e., a calibrated knob controls the output concentration). Older vaporizers, such as the Copper Kettle and the Vernitrol, do not have a single control for selecting the concentration of anesthetic vapor. Where possible, these units should be removed from service. Contemporary concentration-calibrated vaporizers are of two types: variable bypass and heated blender. Conventional (variable-bypass) vaporizers. In a variable-bypass vaporizer, the total background gas flow that enters the unit is split into two streams. The


smaller stream, which acts as the carrier gas, passes through the vaporizing chamber containing the anesthetic agent and becomes saturated with agent vapor; the remainder of the gas bypasses this chamber. A wick may be used in the vaporizing chamber to provide increased surface area for efficient evaporation of the drug and saturation of the carrier gas. The saturated carrier gas leaves the chamber and mixes with the bypass gas. One adjustment is made to set the desired concentration. This adjustment simultaneously balances the carrier and bypass flows to produce the blend required for the set concentration. The mixture exits the vaporizer and is delivered from the anesthesia machine as the fresh gas to be inspired by the patient. Evaporation of the liquid agent contained in the chamber is driven by heat absorbed from the walls of the vaporizer; consequently, when evaporation is occurring, the vaporizer and its contents cool. Because the equilibrium vapor pressure of an agent changes


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Inspection and Preventive Maintenance System pass vaporizer. As a result, the variable-bypass design was abandoned for desflurane, and Ohmeda developed a new vaporizer, the Tec 6, based on a heated-blender design. Figure 2 shows a schematic of this vaporizer. A version of the Tec 6 (also manufactured by Ohmeda) has been adapted for Drager machines and is compatible with the Drager triple-exclusion interlock system. As of this writing, neither Drager nor Siemens has developed its own desflurane vaporizer.

Figure 1. Schematic illustrating the basic elements of a vaiable-bypass vaporizer with temperature, a temperature-sensitive mechanism is used to automatically adjust the carrier and bypass flows to compensate for temperature changes. Figure 1 presents a schematic of a variable-bypass vaporizer. Desflurane (heated-blender) vaporizers. Desflurane, a volatile inhalation anesthetic marketed by Ohmeda Pharmaceutical Products Division under the trade name Suprane, has characteristics that differ markedly from those currently in use — enflurane, halothane, and isoflurane; for example, its low solubility allows rapid induction of and emergence from anesthesia. Thus, by increasing the speed of recovery, desflurane has the potential to shorten hospital stays (although this has not yet been consistently demonstrated). The boiling point of desflurane — 22.9°C at 760 mm Hg — is just above room temperature; therefore, small increases in ambient temperature or decreases in atmospheric pressure can cause it to boil. Also, because of desflurane’s high minimum alveolar concentration, or MAC (i.e., its low potency), evaporation of sufficient agent to achieve a given anesthetic effect would require much more heat absorption from the vaporizer than occurs with other agents. Furthermore, the change in vapor pressure of desflurane per change in temperature is as much as three times that for the other volatile agents at sea-level atmospheric pressure. These profound effects of temperature and ambient pressure on the vapor pressure of desflurane make stabilizing the delivered concentration at a set point extremely difficult in a passive mechanical system, such as a variable-by-

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A desflurane vaporizer requires electrical power to heat the agent to a thermostatically controlled 39°C, producing a stable, saturated vapor pressure of 1,500 mm Hg. No wick is used, and no carrier gas enters the sump chamber. Instead, a stream of vapor under pressure flows out of the sump; this stream blends with the background gas stream, which originates from the anesthesia machine’s flowmeters, to achieve the desired concentration. The background gas stream passes through a fixedflow resistor, producing a back pressure upstream of this resistor that is proportional to the background gas flow. The desired desflurane concentration is set on the dial of the adjustable metering valve in the vapor stream; this setting produces a predetermined aperture. The pressure in the vapor upstream of the aperture and the back pressure in the background gas stream are continually sensed by a differential pressure transducer. The transducer controls a pressureregulating valve in the vapor stream between the sump

Figure 2. Schematic illustrating the basic elements of the Ohmeda Tec 6 vaporizer

Inspection and Preventive Maintenance System ©1995 ECRI. All Rights Reserved.

Anesthesia Unit Vaporizers and the adjustable metering valve. The pressure-regulating valve permits only that flow from the sump necessary to cause the pressure upstream of the adjustable metering valve to equal the back pressure in the background gas stream. In this way, the ratio of the adjustable metering valve’s resistance to the resistance of the fixed-flow resistor determines the ratio of the flows in each stream, and therefore, the concentration of vapor in the blended output. If the flow from the anesthesia machine’s flowmeters through the vaporizer is altered, the flow of vapor from the sump is automatically adjusted so that the pressures at the two monitored points remain equal, the flow ratio does not change, and the output concentration continues to match its setting. The control circuits and heating elements in the vaporizer are turned on by the act of connecting the vaporizer to electrical power. The unit then heats to and remains at operating temperature as long as it receives power, whether it is delivering agent or is in the standby mode. Consequently, it is warm to the touch while plugged into a live socket.

Citations from Health Devices Avoiding anesthesia mishaps through pre-use checks, 1982 May; 11:210-3. Water in halothane vaporizers [Hazard], 1985 Aug; 14:326. Anesthesia units with a flowmeter-controlled vaporizer [Hazard], 1986 Dec; 15:336.

Do not fill a vaporizer with an inhalation agent unless you are qualified to do so. Always use a scavenging system or appropriate ventilation when inspecting vaporizers. For personal safety, when inspecting vaporizers alone, notify other personnel of your location. Be sure that filler ports are tightly capped before passing gas through the vaporizer.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Note: This procedure should be done simultaneously with Anesthesia Units Procedure/Checklist 400, where leak testing of the vaporizer has been included with the anesthesia unit. Each vaporizer should have a separate control number. Inspection documentation for up to three vaporizers (on one anesthesia unit) can be included on one inspection form (record each control number), but some hospitals may prefer to use a separate form for each vaporizer. Be sure that the anesthesia system is level and secure. Check that all hoses and fittings are tight.

1. Qualitative tests 1.1

Pre-use anesthesia check fails to find faults [Hazard], 1988 Sep; 17:274-6.

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that housings are intact, that all assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse.

1.2

Desflurane (Suprane): Considerations for introducing the new inhalation anesthetic agent into clinical practice [Guidance article], 1994 Apr; 23:131-42.

Mount/Fasteners. Check security of mounts or support mechanisms. Verify that the vaporizer is firmly mounted on the anesthesia unit.

1.4

AC Plug. If the unit is so equipped, examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord, if so equipped, for signs of damage. If damaged, replace the entire cord, or if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one.

Vaporizer leak with Mapleson breathing circuits [Hazard], 1986 Dec; 15:344-5. Concentration calibrated vaporizers [Hazard], 1987 Mar-Apr; 16:112-3.

Test apparatus and supplies Halogenated anesthetics analyzer Hoses and adapters

Special precautions As a general precaution, a vaporizer containing an anesthetic agent should not be tipped. If such tipping occurs, notify the user and follow the manufacturer’s recommended procedures for airing or drying the unit.


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Inspection and Preventive Maintenance System 1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord, if so equipped. Be sure that they hold the cord securely.

1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare fuse is provided.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not cracked, kinked, or dirty.

1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors for general condition. Be sure all fittings are tight. 1.13 Controls. Before moving any controls, check their positions. If any of them appear inordinate or are left in the on position, consider the possibility of inappropriate clinical use or of incipient device failure. Examine all controls for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control performs its proper function. Return all controls to the off position following the test. 1.16 Fluid Levels. Check all fluid levels. If the fluid level is zero, we recommend that you have a qualified user fill the sump with anesthetic agent to continue the inspection. 1.17 Battery. Inspect the physical condition of the battery and battery connectors, if so equipped and readily accessible. Operate the battery-powered functions of the unit for several minutes to check that the battery has an adequate charge. Check remaining battery capacity by activating the battery test function or measuring the output voltage. If it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all indicators and visual displays on the unit, if so equipped. 1.20 Alarms/Interlocks. Operate the device in such a way as to activate each audible and visual alarm, if so equipped. If the device has an alarmsilence feature, check the method of reset (i.e.,

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manual or automatic) against the manufacturer’s specifications. Check that the vaporizer interlock allows activation of only one vaporizer at a time. 1.21 Audible Signals. Operate the device in such a way as to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.24 Site Glass, O-Rings, Keyed Filler Mechanism. Examine the physical condition of the site glass, O-rings, and keyed filler mechanism, if so equipped.

2. Quantitative tests 2.1

Grounding Resistance. If the unit is electrically powered, use an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms to measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal of the chassis. We recommend a maximum of 0.5 Ω

2.2

Leakage Current. For electrically powered units, measure chassis leakage current to the chassis of the device with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including On, Standby, and Off, and record the maximum leakage current. Leakage current should not exceed 300 µA.

2.10 Concentration Check. Data for up to three vaporizers can be recorded as Items 2.10, 2.11, and 2.12. Record the type and control number of the vaporizer being tested under each item. 2.11 See Item 2.10 2.12 See Item 2.10 Because there are various types of halogenated anesthetic analyzers, follow the manufacturer’s procedure for setup and use of the analyzer. Vaporizers should usually be tested with an oxygen flow of 4 to 5 L/min (nitrous oxide may affect the readings of some vapor analyzers). Test the vaporizers at low, medium, and high concentration settings in the normal clinical use range (e.g., 0.5%, 1.0%, and 3.0% for halothane).


Anesthesia Unit Vaporizers At one concentration setting (e.g., 1.0% for halothane, 10% for desflurane), test the vaporizer at another flow (e.g., 1 L/min). We recommend that the concentration be ±0.3% vapor or ±10% of the measured value, whichever is greater. If errors in concentration are observed, allow the vaporizer to operate for a minute or two and recheck the unit. Some units may require a short stabilization period.

3. Preventive maintenance 3.1

Clean the exterior.

3.2

Replace the battery, if so equipped (battery should be replaced at least once annually).

4. Acceptance tests Conduct major inspection tests for incoming vaporizers and, if a vaporizer is position sensitive, any time it is demounted from an anesthesia unit.

Before returning to use Return all controls to the off position, level and secure the unit, and tighten all fittings and tubing.


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Procedure Checklist 461-0595

Anesthesia Unit Ventilators Used For: Anesthesia Unit Ventilators [10-145]

Commonly Used In: Delivery rooms and operating rooms Scope: Applies to ventilators used to deliver inhalation anesthetic agents during surgical procedures that require general anesthesia Risk Level: ECRI Recommended, High; Hospital Assessment, Type

ECRI-Recommended Interval


Major

6 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Inspection and preventive maintenance intervals should be scheduled according to the manufacturer’s recommendations. However, units should have a major inspection at least every six months. Pre-use checks should be performed before each case by the anesthetist who will be operating the equipment.

Overview Patients undergoing surgery under general anesthesia are routinely paralyzed with muscle relaxants to stabilize the surgical field. Consequently, they are unable to breathe on their own and must be mechanically ventilated either manually by the anesthetist, who squeezes a reservoir bag in the breathing circuit, or automatically by an anesthesia ventilator. A switch valve allows the choice of the method by which ventilation is to be supported. The anesthesia ventilator is typically turned on and off independently of the switching between manual and automatic ventilation. Anesthesia ventilators use positive pressure to inflate a patient’s lungs and deliver a prescribed mixture of gases and vapors to them. This mixture is produced by the anesthesia machine. The ventilator can be built into the anesthesia machine or can be a stand-alone unit connected to the machine by gas tubing and, perhaps, sensor cables. Some anesthesia ventilators have built-in displays and alarms; others rely on the sensors, displays, and alarms of the anesthesia machine to monitor their performance.


In general, an anesthesia ventilator is less sophisticated than a critical care ventilator, having only a control mode of operation, with time cycling. (However, there is at least one ICU-type ventilator that can be used to administer inhalation anesthetics.) A pressure limit prevents exposure of the lungs to excessive pressure. Several other breathing waveshape parameters (e.g., inspiratory:expiratory [I:E] ratio, tidal volume, minute volume, flow) are settable by the operator and controlled by the ventilator. Ventilators designed solely for anesthetic administration typically do not have compressors. During extended procedures and procedures involving open breathing circuit configurations, a humidifier may be included in the breathing circuit. Otherwise, a circle system with an absorber, along with one-way inspiratory and expiratory valves, is used, typically without a humidifier. The ventilator’s pressure-relief and limit valve(s) should be connected to a waste gas scavenging system.

Citations from Health Devices Anesthesia systems [Evaluation], 1988 Jan; 17:3.


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Inspection and Preventive Maintenance System Who should service anesthesia equipment [User Experience NetworkTM], 1988 Feb; 17:70.

use by outside vendors can be produced to ensure that those items agreed upon are performed by the vendor.

Barotrauma from anesthesia ventilators [Hazard], 1988 Nov; 17:354.

The following framework should be supplemented by the manufacturer’s recommended preventive maintenance procedures for mechanical ventilators.

Damage to elastic components from Loctite [Hazard], 1989 Jul-Aug; 18:288. Risk of barotrauma and/or lack of ventilation with ventilatorless anesthesia machines [Hazard], 1994 Jan-Feb; 23:54.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse.

1.2

Mount/Fasteners. Check that ventilators mounted in anesthesia machines are properly installed. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of this attachment. Check the mounting security of all components.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Verify that they turn and swivel, as appropriate, and look for accumulations of lint and thread around the casters. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4

AC Plug. Examine the AC power plug for damage, if so equipped. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord for signs of damage, if so equipped. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Also check line cords of battery chargers.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord, if so equipped. Be sure that they hold the cord securely.

1.7

Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not cracked, kinked, or dirty. Check that they are connected to the correct locations.

Test apparatus and supplies Lung simulator with adjustable compliance or ventilator tester Pressure gauge or meter with 2 cm H2O resolution from -20 to +120 cm H2O Various breathing circuit adapters Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Additional items as required for specific manufacturers’ procedures

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Manufacturers’ recommended procedures for inspection and preventive maintenance of mechanical anesthesia ventilators vary in both methods and required accuracy. In addition, ventilator controls can vary greatly among manufacturers and models. This procedure provides the basic framework for complete ventilator inspection and preventive maintenance. Manufacturers’ recommended procedures should be added where appropriate. References to specific pages of the manufacturer’s manual should be added to the checklist. (The checklist includes blank spaces for the insertion of these reference numbers.) IPM Task ManagerTM, the software component of the Inspection and Preventive Maintenance System, enables easy production of customized procedures and checklists for specific ventilator models and clinical needs. Items performed by outside vendors can be excluded from the checklist; a separate checklist for

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Anesthesia Unit Ventilators 1.9

Cables. Inspect any cables (e.g., for sensors) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are securely gripped in the connectors at each end, which will prevent rotation or other strain. Where appropriate, verify that there are no intermittent faults by flexing cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all gas fittings and connectors for general condition. Gas fittings should be tight and should not leak. Verify that keyed connectors (e.g., pin-indexed gas connectors) are used where appropriate, that all pins are in place and secure, and that keying is correct. Connectors to hospital central piped medical gas systems should have the appropriate DISS or quick-connect fitting to eliminate the need for adapters. 1.12 Filters. Check the condition of gas filters, if included in the unit. Check for corrosion residue indicative of liquid, gaseous, or solid particle contaminants in the gas supply; if found, notify appropriate personnel. Clean or replace if appropriate, and indicate this on Lines 3.1 and 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for damage (e.g., from fingernails, pens). During the inspection, be sure to check that each control and switch performs its proper function.

1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if so equipped and if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage; for lead-acid batteries, measure the specific gravity and check the fluid level. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function. Record the reading of an hour meter, if present. 1.20 Alarms/Interlocks. Induce alarm conditions to activate audible and visual alarms. Check that any associated interlocks function. If the unit has an alarm-silence feature, check the method of reset (i.e., manual, automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time since some may require special conditions that must be established according to the manufacturer’s recommendations; include these in Item 2.4. Verify that any remote alarm indicator (e.g., within the mainframe anesthesia unit) functions properly. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories. Check the condition of reusable Bain circuit and adapters, if available. 1.24 Bellows. Check the physical condition and proper operation of the bellows.


1.15 Fan. Check physical condition and proper operation, if so equipped. Clean and lubricate if required, according to the manufacturer’s instructions, and note this on Lines 3.1 and 3.2 of the form.

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis of the ventilator or of


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Inspection and Preventive Maintenance System the system in which the ventilator is mounted. We recommend a maximum of 0.5 Ω. If the ventilator is a component within an anesthesia unit, grounding and leakage current measurements can be referenced to that unit. 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current.

Volume (e.g., tidal volume, minute volume, apnea) Fraction of inspired oxygen (FIO2; see Oxygen Analyzers Procedure/Checklist 417) Alarm settings (e.g., high PIP, low MAP, low pressure, low FIO2) should be inspected for proper and accurate activation. 2.5

Pneumatic lines (including air filters). Verify that appropriate gas-specific connectors are used. Check gas filters, if so equipped and accessible.

Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

Gas cylinders (and gauges and regulators, if so equipped). Verify that these are present, securely mounted, and in good condition and that there is an adequate gas supply. Verify that one and only one washer is used to seal the tank to its yoke. Verify that all index pins are present and protruding to the proper length to engage the hole in the tank valve stem and in the correct positions for the gas to be supplied through the yoke.

Chassis leakage current to ground should not exceed 300 µA. 2.3

2.4

Modes and Settings. Anesthesia ventilators are usually equipped only with a control mode. However, specialized units may have additional modes such as assist/control and pressure support. Adjustable positive end-expiratory pressure (PEEP) may also be available. The function of these modes should be inspected and verified for proper operation. Check the operation and accuracy of ventilation controls, which may include tidal volume, breath rate, inspiratory time, expiratory time, I:E ratio, pressure limit, or flow. Typically, these tests are performed by attaching the ventilator to a lung simulator or ventilator tester and comparing measured values to settings on the ventilator. The manufacturer should recommend the appropriate ventilator settings (e.g., tidal volume, rate, inspiratory time) to verify proper operation and accuracy (generally within 10%). Monitors and Alarms. The following breathing circuit parameters may be monitored by the ventilator or by the system in which the ventilator is mounted. They should be inspected for accuracy (generally within 10%) according to the manufacturer’s specifications:

2.6

Patient Circuit. Breathing circuit (including filters). Verify that these components are compatible with the ventilator according to the manufacturer’s recommendations (see Health Devices 1988 Apr; 17:109). Check for leaks, the absence of obstructions, and proper flow direction in the breathing circuit, ensuring the proper assembly and function of fittings, adapters, the CO2 absorber, inspiratory and expiratory valves and PEEP valves, the APL valve, the scavenger, and other components. With the ventilator connected to the anesthesia system, check for leaks in the entire system, including the breathing circuit. This does not have to be duplicated if done as part of the Anesthesia Units procedure (see Procedure/Checklist 400). Humidifiers. See Heated Humidifiers Procedure/Checklist 431.

Inspiratory time

Pressure-Relief Mechanism. Check the proper operation of the pressure-relief mechanism by occluding the breathing circuit and measuring the resulting peak pressure on the pressure gauge. Verify that pressure is vented in the breathing circuit.

Airway pressure (e.g., PIP, PEEP, MAP, apnea)

Absorber. See Anesthesia dure/Checklist 400.

Breathing rate

4

Gas Supply.


Units

Proce-

Anesthesia Unit Ventilators 3. Preventive maintenance

Before returning to use

3.1

Clean the exterior and interior, if needed.

3.3

Calibrate according to manufacturer’s instructions.

3.4

Replace components according to the manufacturer’s instructions.

Ensure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438.

Attach a Caution tag in a prominent position so that the user will be aware that control settings may have been changed. Recharge battery-powered devices, or equip them with fresh batteries, if needed.


5


Anesthesia Units Used For: Anesthesia Units [10-134]

Also Called: Anesthesia machines, anesthesia workstations Commonly Used In: Operating rooms, emergency departments, trauma rooms, delivery rooms, any areas where anesthetic agents are used Scope: Applies to anesthesia units; includes leak testing of vaporizers and should be used in conjunction with Anesthesia Unit Vaporizers Procedure/Checklist 436 (in the very rare case where an anesthesia unit may still use flammable anesthetic agents, refer to Conductive Furniture and Floors Procedure/Form 441); does not apply to oxygen monitors with an alarm, spirometers, other monitors, or ventilators that might be part of the breathing system (see Anesthesia Unit Ventilators Procedure/Checklist 461) Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

6 months

months

.

hours

Minor

NA

months

.

hours

Overview Most surgical procedures are performed while the patient is under general anesthesia. Usually, the patient is anesthetized by a narcotic or barbiturate injection followed by administration of an inspired gas mixture of oxygen, nitrous oxide, and the vapor of a volatile liquid anesthetic, typically a halogenated hydrocarbon. The anesthesia unit administers this mixture of anesthetic gases and life-sustaining oxygen, varying the proportions to control the patient’s level of consciousness. If respiratory assist is necessary (e.g., in cases of muscular blockade), a ventilator may be connected to the patient breathing system to force the gas mixture into the patient’s lungs. Improperly modified or inadequately maintained anesthesia units have injured and killed patients and hospital personnel. Gas leaks can adversely affect the accuracy of gas delivery to the patient, as well as add anesthetic agents to the OR atmosphere. Trace levels of anesthetics have been implicated as



Time Required

a health hazard to chronically exposed OR personnel and unborn children. Inadvertent switching of gas supplies, failure of an alarm to respond to an excessively low oxygen pressure, and misconnected or improperly calibrated flowmeters have also caused anesthesia-related accidents. Because mishandling and mistakes can have severe consequences, life-support devices such as anesthesia units should be operated and inspected only by qualified personnel who have a thorough knowledge of the units and their functions. If you are unsure of any aspect of the procedure, consult the manufacturer before inspecting an anesthesia unit. The anesthesia unit consists of four systems: the gas supply system, the gas control system, the vaporizers, and the breathing system. Gas supply. This system delivers a variety of gases to the patient. Cylinders containing oxygen and other gases at high pressure (see Table 1) are connected to the high-pressure system of the anesthesia unit by


●


Inspection and Preventive Maintenance System TABLE 1. Gases Used in Anesthesia Machines Gas

Chemical Formula

Color Code: U.S.

Color Code: International

Service Pressure, psi 21°C, Full Cylinder

Oxygen Carbon Dioxide Nitrous Oxide Helium Air

O2 CO2 N2O He

Green Gray Blue Brown Yellow

White Gray Blue Brown White and Black

1,800-2,400* 838 745 1,600-2,000* 1,800

* Depends on cylinder size.

yoke fittings that comply with the Compressed Gas Association (CGA) pin-index safety system (see Figure 1). Unique placements of pins and mating holes on the pin-index fittings prevent connection of a gas cylinder to the wrong inlet. Inside the unit, each high-pressure gas flows through a filter, a check valve (for one-way flow), and a regulator that reduces the pressure to approximately 45 psi. Because oxygen and nitrous oxide are used in relatively large quantities, they are usually drawn from the hospital’s central gas supplies, which are more convenient and economical than compressed-gas cylinders. However, cylinders of these gases are also

normally attached to the anesthesia unit as a reserve source if the central supply fails or if central supply outlets are not available. Centrally supplied gases are delivered directly to the intermediate-pressure gas control system at approximately 50 psi through low-pressure hoses and connectors. These connectors may not comply with a universal standard safety system, but each is designed to prevent mismating the gas supply and the machine inlet. Some units may provide an oxygen power outlet to drive auxiliary devices (e.g., a ventilator). Gas control. This system regulates gas flow rates so that the gases can be mixed and delivered under accurate, constantly metered control. The operator must be able to adjust the ratios or make rapid gross changes in flow rates without inducing system interactions that cause temporary delivery of undesirable mixtures. The flow of each gas is controlled by a valve and indicated by a glass-tube flowmeter. After gases pass the control valve and enter the low-pressure system, they can be administered to the patient.

Gas

Index Pins

CGA Connector Number

Oxygen Nitrous Oxide O2 - CO2 (CO2<7%) O2 - CO2 (CO2>7%) O2 - HE (He > 80%) O2 - HE (He < 80%) Air

2-5 3-5 2-6 1-6 4-6 2-4 1-5

870 910 880 940 930 890 950

Figure 1. Pin-index safety system

2

A fail-safe provision in many anesthesia units protects the patient against a fall in pressure of life-sustaining oxygen. If the oxygen pressure drops below about 25 to 30 psi, some units shut off the flow of all other gases, while others reduce all gas flow rates in proportion to the drop in oxygen pressure. Newer anesthesia machines have additional safety systems that provide a minimum percent of oxygen (around 25%) and/or deliver a minimum flow of oxygen (usually 150 to 250 mL/min) (see Item 2.11). Vaporizers. These devices add the vapor of a volatile liquid anesthetic (e.g., halothane, isoflurane, enflurane, sevoflurane, desflurane) to the gas mixture, when desired, and aid in controlling the vapor concentration. According to the American Society for Testing and Materials (ASTM) standard ASTM F1161-88, anesthetic agent vaporizers are required to be concentration calibrated (i.e., a calibrated knob controls the


Anesthesia Units output concentration). Older vaporizers, such as the Copper Kettle and the Vernitrol, do not have a single control for selecting the concentration of anesthetic vapor. Where possible, these units should be removed from service. Contemporary concentration-calibrated vaporizers are of two types: variable bypass and heated blender. The variable-bypass (conventional) vaporizer is used for most volatile agents (e.g., halothane, isoflurane, enflurane, sevoflurane). The total background gas flow that enters the unit is split into two streams. The smaller stream, which acts as the carrier gas, passes through the vaporizing chamber containing the anesthetic agent and becomes saturated with agent vapor; the remainder of the gas bypasses this chamber. A wick may be used in the vaporizing chamber to provide increased surface area for efficient evaporation of the drug and saturation of the carrier gas. The saturated carrier gas leaves the chamber and mixes with the bypass gas. One adjustment is made to set the desired concentration. This adjustment simultaneously balances the carrier and bypass flows to produce the blend required for the set concentration. The mixture exits the vaporizer and is delivered from the anesthesia machine as the fresh gas to be inspired by the patient. A heated-blender vaporizer is used only for desflurane. It requires electrical power to heat the agent to a thermostatically controlled 39°C, producing a stable, saturated vapor pressure of 1,500 mm Hg. No wick is used, and no carrier gas enters the sump chamber. Instead, a stream of vapor under pressure flows out of the sump; this stream blends with the background gas stream, which originates from the anesthesia machine’s flowmeters, to achieve the desired concentration. (Desflurane, a volatile inhalation anesthetic marketed by Ohmeda Pharmaceutical Products Division under the trade name Suprane, and sevoflurane, marketed by Abbott under the trade name Ultane, have characteristics that differ markedly from those currently in use — enflurane, halothane, and isoflurane. For example, their low solubilities allow rapid induction of and emergence from anesthesia. Thus, by increasing the speed of recovery, desflurane and sevoflurane have the potential to shorten hospital stays, although this has not yet been consistently demonstrated.) Breathing system. Although it is designed primarily for sustained, efficient gas delivery to the patient, the breathing system may also remove carbon dioxide and provide mechanical or manual ventilation of a

patient who cannot breathe spontaneously, as well as positive end-expiratory pressure (PEEP), if required. The breathing system typically includes a scavenging system to remove waste gases. Two types of breathing systems are used to deliver the anesthetic mixture from the unit to the patient, although they may assume a variety of configurations. The T-piece or open system may be a nonrebreathing system consisting of a reservoir bag and a gas-delivery hose connected through a nonrebreathing (one-way) valve to the face mask or endotracheal tube. The patient breathes the anesthetic mixture directly from the machine, and exhaled gas is vented out of the system. T-piece systems that do not include the nonrebreathing valve may allow partial rebreathing, depending on the inflow of fresh gas. The circle or closed system is a continuous loop in which check valves allow gas to flow in only one direction. The patient inhales from and exhales into the system. Fresh gases from the anesthesia machine enter at one point, mix with previously exhaled gases, and pass to the patient, who inhales the mixture. Newly exhaled gases are channeled to a carbon dioxide absorber, which removes almost all the carbon dioxide produced by body metabolism and routes the scrubbed gases back toward the patient. En route, the scrubbed gases become mixed with fresh machine gases. A scavenging system should be included to remove waste gas from the vent port of a T-piece breathing system or from the adjustable pressure-limiting (APL) valve and relief valve of a ventilator of a circle system to reduce the quantity of gas that escapes into the operating room. Such a scavenging system is necessary because trace levels of anesthetics are believed to cause an increased incidence of spontaneous abortion, congenital anomalies in offspring, and neoplastic disease and may affect the mental and physical abilities of exposed personnel. The breathing system should be checked before each use for leaking gases. It is also recommended that the concentration of waste anesthetic gas in the operating room be surveyed quarterly. The scavenging system must include pressure-relief mechanisms so that abnormal pressures cannot develop in the scavenging system and interfere with operation of the breathing system. Anesthesia units either come with physiological monitors integrated into the unit or provide shelving to support such monitors. Most also provide mounting for a suction regulator and canister and other accessories, along with storage for drugs, supplies, and related paraphernalia.


3

Inspection and Preventive Maintenance System

Citations from Health Devices Anesthesia units with a flowmeter-controlled vaporizer [Hazard], 1986 Dec; 15:336-7. Vaporizer leak with Mapleson breathing systems [Hazard], 1986 Dec; 15:344-5.

have a minimum pressure of 745 psi for nitrous oxide and 1,000 psi for oxygen Nondisposable corrugated breathing hose (disposable tubing may not provide reliable connections) Test lung (reservoir bag with 3 or 5 L capacity) Sphygmomanometer bulb with tubing and adapter

Concentration calibrated vaporizers [Hazard], 1987 Mar-Apr; 16:112-3. Pre-use testing prevents “helpful” reconstruction of anesthesia components [Hazard], 1987 May; 16:178-9. Anesthesia systems [Evaluation], 1988 Jan; 17:3-34. Who should service anesthesia equipment [User Experience NetworkTM], 1988 Feb; 17:70-1. Pre-use anesthesia check fails to find faults [Hazard], 1988 Sep; 17:274-6. (Contains pre-use checklist for anesthesia units.) Anesthesia systems [Evaluation Update], 1988 Dec; 17:366-7. Anesthesia units and breathing systems [Standard], 1989 Oct; 18:363. Monitoring and anesthesia systems: integration and a new option, 1991 Mar-Apr; 20:131-2. Use of inadequate (old) anesthesia scavenger interfaces [Hazard], 1993 Dec; 22:592. Anesthesia systems [Evaluation]. To be published in 1996.

Test apparatus and supplies Pressure gauge or meter, -10 to +80 cm H2O (accuracy ±5 cm H2O at 30 cm H2O) Flowmeters with ranges of approximately 0.1 to 1.0 L/min and 1 to 10 L/min, ±2% accuracy, calibrated separately for each of the gases used with the anesthesia machine, and one flowmeter for 10 to 100 L/min (±10% of reading) Stopwatch or watch with a second hand Hoses and adapters for connecting pressure gauges or meters and flowmeters to equipment being inspected Cylinder of each type of gas used with the unit being inspected; each cylinder on a unit that is ready for use should be more than half full if the gas is normally stored in gaseous form (e.g., oxygen) and should contain some liquid if the gas is normally liquefied for storage; cylinders should

4

Leak-detecting solution Conductive lubricant for conductive casters (e.g., Dow No. 41, graphited oil) Trichloroethylene cleaning solvent or solvent recommended by the manufacturer (be sure to review the manufacturer’s Material Safety Data Sheet and see the special precautions below) Lubricant as specified by manufacturer

Special precautions ECRI is aware of a number of incidents in which improperly serviced ventilation or anesthesia equipment was implicated in patient injury or death. Do not perform any procedures, adjustments, repairs, or modifications unless you thoroughly understand the device and have verified the appropriateness of the intended actions. Resolve any questions or uncertainties with the manufacturer, the anesthetist, or ECRI before placing a unit into use. To avoid the adverse effects of exposure to anesthetic gases, all testing should be done with an operating scavenging system in place or an alternative means to vent excess gases from the vicinity of inspecting personnel. If a flammable anesthetic is used, be sure all traces of the gas are cleared away before performing any electrical tests. Check that all valves, including the gas cylinder stem valves, are turned off at the beginning of the inspection. Turn all valves off again when the inspection is complete. When testing cyclopropane flowmeters, observe noted procedures to avoid a buildup of explosive levels of cyclopropane. Trichloroethylene is a common solvent particularly recommended for cleaning oxygen fittings because it does not leave a residue that is flammable in high-concentration oxygen. However, this solvent reacts with the soda lime used in carbon dioxide absorbers to form several poisonous gases, including phosgene. Although concentrations may not be lethal, the presence of these gases to any degree is highly undesirable. To prevent the generation of these gases, make sure that equipment recently cleaned with trichloroethylene is completely dry before using. When clean-


Anesthesia Units ing parts of the anesthesia unit with this solvent, first disconnect the line to the carbon dioxide absorber. After cleaning, allow time for the solvent to evaporate. When the parts appear dry, take the added precaution of briefly flushing them with a high oxygen flow rate.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely.

1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.8


1.9

Cables. Inspect the cables (e.g., sensor, electrode) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse.

1.2

Mount. Check any shelves, brackets, or supporting structures. Check the security of the attachments.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped. Check that gas hoses do not lie on the floor or loop near the casters.

1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacle.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Also check line cords of battery chargers.

1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical cable connectors and sockets, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Check that pins used with the pin-index safety system comply (location and length of protrusion) and are intact. Check the yoke clamping screw and make sure empty yokes have plugs. Check that appropriate keyed or indexed fittings are being used with corresponding gases. 1.12 Filters. Check the condition of all compressedgas filters. Clean or replace as needed, and indicate this on Line 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a pressure alarm control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function.


5

Inspection and Preventive Maintenance System Check that the concentration dial on each vaporizer moves freely and that only one vaporizer can be on at a time. Observe the float motion as its flow control valve is turned on. The valve should turn smoothly with only slight drag. Each valve should have a definite shutoff position at which the float should be motionless at its zero level. Check for free play in the control valve by pushing, pulling, and gently rocking the stem from side to side without rotation. The stem should feel firm, and the flowmeter float should not move. The control valve knob should require turning through at least 90° to change the flow rate from 10% to 100% of full scale. (Note: All recent anesthesia units should now have different sized and shaped knobs for oxygen and nitrous oxide to aid in differentiating between the two controls.) 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check the battery-operated power-loss alarms on AC and pneumatic devices, if so equipped. Operate the unit on battery power for several minutes to check that the battery has an adequate charge. Check remaining battery capacity by activating battery test function or measuring the output voltage. If appropriate, check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function. 1.19 Directional Valves. Check that directional valves are free from cracks and chips and fit smoothly against the valve seats. Check for free movement by shaking or lightly squeezing the hose connecting the two valves. The valves should flutter up and down and should not stick to their seats. Check for the possibility of reverse flow through directional valves by removing the breathing hoses from the absorber and attaching a thin disposable reservoir bag to the exhalation port. Attach a piece of hose to the bag mount, set the control for manual mode, close the APL valve, and occlude the inspiratory port with the palm of your hand. Then, connect a test lung to the hose and generate about 5 cm H2O

6

of pressure on the pressure gauge. Watch for any inflation of the flattened bag as a sign of expiratory valve leakage. Reconnect the bag to the bag mount and the hose to the inhalation port. With your hand occluding the expiratory port, use a test lung to again generate about 5 cm H2O of pressure and check for inspiratory valve leakage by watching for any inflation of the bag. 1.20 Alarms/Interlocks. Operate the device in such a way as to activate each audible and visual alarm. Check that any associated interlocks function (particularly the vaporizer interlocks, which should allow activation of only one vaporizer at a time). If the device has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. 1.21 Audible Signals. Operate the device in such a way as to activate all audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. Check that the audible signals are appropriate for the test conditions used. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. Check for proper color coding for corresponding parts (e.g., green for oxygen, blue for nitrous oxide). 1.23 Accessories. Verify accuracy and function of any accessories (e.g., spirometer, sphygmomanometer gauge). (Inspect ventilators, vaporizers, and oxygen monitors separately using the appropriate procedures, and record on separate forms.) 1.24 Fail-Safe Oxygen Valves and Alarms. Close all control valves. Open all cylinder stem valves and external gas source valves. Connect gas scavenging or other evacuation system to common gas outlet. Turn on the main gas control, and open the flow control valves until the flowmeter for each gas reads midscale. Then disconnect or turn off all oxygen sources. The flow of other gases should fall or stop as the oxygen flow decreases to half its previous level. All gas flow should cease when the oxygen flow reaches zero. (Cyclopropane flow rate normally falls more slowly than the others.) In addition to the automatic shutoff or reduction of gas flow, audible or visual alarms signifying low oxygen pressure should have been activated, if the unit is so equipped. Silence the


Anesthesia Units Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

alarm by raising the oxygen pressure above the preset alarm limit. If the unit has an alarm that does not respond, check for exhausted batteries or other source of the malfunction. 1.25 Common Outlet Back-Pressure Check Valve. Most anesthesia units manufactured after 1968 with mounted bubble-through vaporizers have a check valve in the gas delivery system to prevent pressures at the outlet (e.g., produced by a ventilator) from being transmitted to other parts of the unit where they could affect the accuracy of gas delivery and the concentration of anesthetic gases. To test this check valve, attach the -10 to +80 cm H2O pressure gauge or meter to the common gas outlet. Turn off all vaporizers, either filled or empty. Adjust the oxygen flow control valve to maintain an outlet pressure of 30 cm H2O. Turn on the vaporizer flow, and readjust, if necessary, to maintain 30 cm H2O. Carefully open the vaporizer filler cap (to prevent a sudden flow of oxygen into the vaporizer) and observe the outlet gauge pressure. A sudden pressure drop suggests a leaky check valve. If the check valve is missing or defective, replace it or alert appropriate personnel to replace the valve to avoid a possible hazardous buildup of vapor. Note: This test may not be possible on newer machines that always maintain a minimum flow of oxygen. On such devices, follow the manufacturer’s instructions for testing the common outlet back-pressure check valve.

Leakage current should not exceed 300 µA. 2.3

Cycle the flush control slowly several times; it should move smoothly and not have a tendency to stick. Check that the oxygen flow returns to 2 L/min within 2 sec each time the flush valve is closed. 2.4

High-Pressure Leaks. Close all flow control valves on the machine. Open all cylinder stem valves one full turn, noting any motion of the flowmeter floats. Float movement indicates a leaky flowmeter valve. Record pressure gauge or meter readings, verifying that they are close to the service pressure values listed in Table 1. Close the cylinder stem valves. The pressure drop over 30 sec should be negligible. Excess pressure drop indicates an unacceptable leak that should be located and repaired.

2.5

Intermediate Pressure System. Close all flow control valves on the anesthesia unit. Connect the hoses to the external pipeline gas source and test the supply line hoses with leak-detecting solution. Note the pressure on the pipeline/central gas supply pressure gauge. (Most machines should have such a gauge. If not, contact the manufacturer for instructions for testing the intermediate pressure system.) Disconnect the gas supply line hose from the machine, and check that the pressure drop in 30 sec is negligible. Excessive pressure drop indicates an unacceptable leak that should be located and repaired.

2.6

Low-Pressure Leaks. Attach the -10 to +80 cm H2O pressure gauge or meter to the unit’s common


Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms to measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the device has an accessory outlet, check its grounding to the main power cord.

2.2

Leakage Current. Measure chassis and patient lead leakage current to the chassis of the device with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, with all monitors and accessories connected to the unit’s accessory power receptacle(s), and record the maximum leakage current.

Oxygen Flush Valve. Attach the 100 L/min flowmeter to the common outlet. Set the oxygen flow rate to a 2 L/min indication on the machine’s oxygen flowmeter and actuate the oxygen flush control. The rate should rise to between 35 and 75 L/min. The machine flowmeter indication should remain near 2 L/min unless the manufacturer’s specification shows otherwise. If it falls more than 1 L/min, check for an inadequate oxygen supply, a partially occluded oxygen line in the machine, or a dirty oxygen inlet filter.


7

Inspection and Preventive Maintenance System steady 30 cm H2O, indicated on both the test gauge or meter and the pressure gauge in the breathing system, and verify that both gauges have the same readings. The oxygen flow rate should be less than 150 mL/min above the leak measured in Item 2.6.

gas outlet and pressurize the outlet section, including vaporizers, to approximately 30 cm H2O by opening the oxygen flow control valve slightly (this is about three times the average working pressure). Now reduce the flow rate to 30 mL/min. (Connect a flowmeter to the common gas outlet if necessary.) If the gauge or meter pressure continues to rise, the leak rate is less than 30 mL/min at 30 cm H2O (10 mL/min at 10 cm H2O), which is acceptable. If the pressure falls, the leakage rate is excessive. Locate the leak by shutting off all vaporizers and repeating the test with each vaporizer added in turn. For anesthesia units for which low flow rates cannot be generated (units that deliver minimum flows of oxygen), the low-pressure system can be tested in combination with the breathing system. Connect the -10 to +80 cm H2O pressure gauge or meter to a piece of breathing system tubing that is connected to the inspiratory and expiratory valve outlets. Occlude the outlet to the manual reservoir bag and close the APL valve. Turn on the minimum flow of oxygen. The pressure gauge or meter should read at least 30 cm H2O. A reading of less than 30 indicates an unacceptable leak that should be corrected. Proceed to Item 2.7 to identify whether the breathing system is the major source of the leak. Alternatively, follow the manufacturer’s recommendations for testing for low-pressure leaks. 2.7

Open the moisture-relief valve. (Note: Due to dust and moisture, some of these valves on older units will not turn and might break when force is applied.) The pressure should drop immediately. If the pressure does not drop, clean the valve of dried soda lime, repeat the pressurization, and open the relief valve again. 2.8

Breathing System. Check the carbon dioxide absorber housing for cracks or broken edges in the glass or plastic canister and in the check valve domes. Remove the canister from its holder, without inverting it, and inspect the gaskets for any absorbent dust and wear. Remove any dust from the bottom of the absorber. If the amount of dust seems excessive or if the canister appears seriously pitted, check for dust in the inspiratory valve and piping, and report the condition to department personnel. Check the absorber-elevating mechanism and clamps for proper operation. For anesthesia systems without minimum oxygen flows, connect a breathing hose from the patient inspiration valve to the patient expiration valve of the absorber. Close the pressure-limiting valve. Remove the reservoir bag, and replace it with a -10 to +80 cm H2O pressure gauge or meter. Pressurize the system with oxygen to a

8

For anesthesia systems with minimum oxygen flow, turn the anesthesia machine off and connect the -10 to +80 cm H2O pressure gauge or meter to a piece of breathing system tubing that is connected to the inspiratory and expiratory valve outlets. Close the APL valve. Remove the manual reservoir bag. In its place, connect a stopper with a fitting for a sphygmomanometer squeeze bulb. Use the bulb to pressurize the breathing system to 50 cm H2O. It should take at least 30 sec for the pressure to drop from 50 to 30 cm H2O. Less time indicates a leak in the breathing system that should be corrected.

APL Valve. Leave the setup as in Item 2.7 but remove the pressure gauge or meter, replacing it with the breathing bag, and restore the normal pressure-limiting valve setting. If the APL valve is not the bleeding type, squeeze the bag and verify that the valve holds pressure until a specific level is exceeded, and that it then opens. Check that the opening pressure is adjustable from approximately 1 to at least 30 cm H2O. Other valves, such as the Georgia and Drager valves, may operate in a completely different manner and at a higher pressure and should be tested according to the manufacturer’s specified procedure.

2.9

Scavenging System. Insert the pressure gauge or meter between the APL valve or exhaust port and the scavenging system intake. Leave the setup as in Item 2.8, with the APL valve closed or in its minimum-flow condition. With the scavenging system operating at maximum suction, the pressure gauge or meter reading should be between -0.5 and 0 cm H2O. Partially open the APL valve, and set a 10 L/min oxygen flow rate. With the scavenging system at the minimum vacuum, the gauge reading should be near ambient.


Anesthesia Units stipulated by the manufacturer (usually 100 to 250mL/min).

Repeat the last measurement with the APL valve fully open while occluding the vacuum hose and activating the flush valve for 5 sec. The pressure should remain at less than 10 cm H2O. 2.10 Flowmeters. The following procedure applies to each flowmeter on the anesthesia unit. Record the data on Line 2.10 (i.e., oxygen, nitrous oxide, and air). If other flowmeters are provided (e.g., helium, carbon dioxide), make similar checks and enter data on the back of the form. Examine flowmeters for signs of damage or abuse (e.g., internal nicks, scratches, cracks, condensation, debris). For each flowmeter, observe the float motion as the associated valve is turned. The float should rise and fall freely as the flow is raised or lowered. At maximum flow, the float should still be visible at the top of the flow tube. Connect one of the calibrated flowmeters to the common gas outlet with its discharge directed into the scavenging or other gas evacuation system. Level the flowmeter. For each gas in turn, set the flow rates at a high and low setting for each flowmeter that lies within the range of the calibrated flowmeter. Record the readings of both the machine and the calibrated flowmeters. Repeat the tests with the second calibrated flowmeter and the second group of flow rates. The readings on the unit’s flowmeters should agree with those on the calibrated flowmeters to within 10% of set values or the manufacturer’s specifications. If the error is excessive, check for damaged, inverted, or interchanged flowmeter tubes, condensation, or damaged floats. 2.11 Minimum Oxygen Flow and Percent. The following procedure applies to those systems that provide a minimum flow of oxygen or a minimum percent of oxygen. Close the valve to the anesthesia unit’s oxygen flowmeter. Connect the 0.1 to 1.0 L/min oxygen flowmeter to the common gas outlet. The flowmeter should read the minimum flow

Set the flow of oxygen to around 200 mL/min. Turn off the flow of nitrous oxide. Using an oxygen monitor, verify that at least the minimum percent of oxygen (stipulated by the manufacturer) is delivered as the flow of nitrous oxide is increased. 2.12 PEEP Valve. Set up the breathing system with a test lung. Use the -10 to +80 cm H2O pressure gauge or meter to measure the airway pressure at the test lung. Manually ventilate the test lung with the PEEP valve set to deliver 0 cm H2O water pressure. The end-exhalation pressure in the breathing system should be less than 1 cm H2O, although this depends on the fresh gas flow and APL valve setting. If the PEEP valve is calibrated, set it to deliver 5 and 10 cm H2O water pressure. The pressure in the breathing system at the end of exhalation should be within 1.5 cm H2O of the set value.


Clean any excess leak-detection solution from the exterior and interior of the unit; clean all compressed-gas filters, if needed.

3.2

Lubricate per the manufacturer’s specifications.

3.4

Replace compressed-gas filters and alarm batteries, if needed.


Before returning to use Depressurize external gas supply; return all flowmeters to zero position; turn all vaporizers to off position; and reconnect all tubing (e.g., main common gas outlet tubing). Return all controls to pre-use settings. Attach a Caution tag in a prominent position so the user is aware that control settings may have been changed.


9


Apnea Monitors Used For: Apnea Monitors [12-575] Apnea Monitors, Recording [17-885] Impedance Pneumograph Monitors [12-621] Respiration Monitors [12-662]

Also Called: Cardiorespiratory monitors, apnea alarms and respiration monitors, ventilatory effort monitors, apnea detectors Commonly Used In: Pediatric departments, homes, critical care units, nurseries, delivery rooms, ambulances Scope: Applies to apnea monitors, which alarm if a patient stops breathing, and respiration rate monitors, which display the patient’s breathing rate and alarm when previously selected high or low limits are exceeded; applies to adult and infant monitoring units or modules, as well as impedance-, motion-, thermistor-, and airway-pressure-type monitors; does not apply to other types of monitors with respiration monitoring functions (e.g., capnometers, pulse oximeters); some apnea monitors also include other monitoring capabilities (e.g., ECG and blood pressure), which should be checked using the appropriate procedure/checklist unless the function is very limited (e.g., heart rate alarm without other ECG features) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

3 months *

months

.

hours

Time Required

* Minor interval applies only to units used for home care.

Overview Our evaluations of infant apnea monitors have stressed that apnea monitoring is still an imperfect science. An ECRI poster (Poster HD 602-980) warned of the susceptibility of these monitors to artifact and provided succinct reminders and hints for clinical personnel. An additional poster (Poster HD 625-290) and warning notice (Health Devices 1990 Apr; 19:142-5) provide guidance for apnea monitors used in the home. When inspecting these monitors, in addition to making a qualitative and quantitative inspection of the monitor itself, be alert to indications of incorrect equipment usage and misapplication. Confirm that users are aware of proper monitoring techniques and the monitor’s limitations. See the device’s operating


manual and the Health Devices evaluations cited below for specific information.

Some apnea monitors have documentation capabilities that typically can record two or more channels of patient event data ranging from several hours to several months, depending on the amount and format of data and the parameters stored. Recorded data are available in two categories: patient (respiratory rate, heart rate) and equipment (power on/off, low battery). Patient data can be recorded and printed as either tabular data or waveforms. These data can be used to ensure that the monitor is being used properly, to distinguish true from false alarms, and to troubleshoot equipment problems.


●


Inspection and Preventive Maintenance System Activation of memory waveform recording can be automatic or continuous. Automatic activation is triggered when an event occurs that exceeds preset monitor limits. In the continuous mode, all data from the selected channels are recorded for a specific duration. The data stored in the memory can be managed one of three ways. Some units overwrite the old data with more recent events; others keep the data that satisfy specific criteria based on the duration of the events; and some documentation monitors stop storing data when the memory is filled.

to 5,000 Ω, variable respiration resistance change amplitude from 0.1 to 1 Ω, and an apnea function; simulators with fewer capabilities may be used for inspection, but additional equipment may be required to supplement missing functions ECG simulator with variable rate may be required (may be part of the respiration simulator or may be a separate unit) Memory interface and documentation hardware and software (where applicable)

Citations from Health Devices

Procedure

Infant apnea monitors [Evaluation], 1980 Aug-Sep; 9:247-83.

Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. If the monitor has memory and documentation capabilities, make sure the memory contents have been successfully downloaded and documented. Also, determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

Connection of electrode lead wires to line power [Hazard], 1987 Feb; 16:44-6. Infant apnea monitors [Evaluation], 1987 Mar-Apr; 16:79-88. Infant home apnea monitors [Evaluation update], 1987 Dec; 16:385-7. Infant home apnea monitors: Essential safety features and practices, 1990 Apr; 19:142-5. Infant home apnea documentation monitors [Evaluation], 1992 Oct; 21(10):342-79. Air-Shields System V Model HRRM71-2 heart rate and respiration monitor [User Experience NetworkTM], 1992 Oct; 21(10):383. Risk of electric shock from patient monitoring cables and electrode lead wires [Hazard], 1993 May-Jun; 22(5-6):301-3. Infant home apnea documentation monitors [Evaluation update], 1993 Dec; 22(12):564-5. Infant home apnea monitors: Essential safety features and practices [Hazard update], 1993 Dec; 22(12):598-601.

Do not test the monitor while it is in use. If a substitute monitor is not available, ask the nursing staff whether the patient can be temporarily removed from the unit. It may be necessary for someone to watch the patient in the interim. Alternatively, arrange to be notified when the monitor is available.

1. Qualitative tests When performing IPM on apnea monitors with memory and documentation capabilities, a log identifying the order, type, and duration of patient and equipment alarms and events should be recorded (e.g., using the IPM checklist). At the end of the procedure, the memory contents should be compared to the log contents. 1.1

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. If there are signs of fluid spills, inspect the interior of the monitor for intrusion of fluids into electronic circuitry. The monitor top should not be used as a storage area for other material (e.g., formula).

1.2

Mount. If the unit is mounted on a stand or cart, check the mount’s condition. Be sure that all fasteners are tight and that the mount is sturdy. Apnea monitors should not be placed on top of incubators where they can be easily dislodged

Loose-lead alarms resulting from dried-out disposable electrodes [User Experience NetworkTM], 1994 Jul; 23(7):309-10.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Stopwatch or watch with a second hand Respiration simulator (needed for impedance-type monitors only) that includes controls to vary the respiration rate, variable base impedance from 100

2


Apnea Monitors or obscure the view of an infant. A wall-supported shelf or bracket dedicated to the monitor is recommended. 1.4

1.5

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacle. Line Cord. Inspect the cord for signs of damage. If damaged, either replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire the new power cord or plug with the same polarity as the old one. Also, check battery charger line cords.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), affix the cord to the unit so that it cannot be removed by the operator. (See Health Devices 1993 May-Jun; 22[5-6]:301-3.)

1.7


1.9

Cables. Inspect the cables (e.g., patient sensor, remote alarm) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain. Electrode leads and cables are often fragile and may lack adequate strain relief; intermittent contact can provide false indications. The lead-electrode connector should be of the type that cannot be inadvertently plugged into a 115 VAC outlet or power cord. Attach a pair of electrodes to the patient cable and hold the RA and LA electrodes face to face. Connect the patient cable to the monitor, turn the unit on at maximum sensitivity, and jiggle the leads. If either breaths or lead faults are indicated, suspect damaged cables or weak contact with the electrodes.

For monitors using belts, bands, a thermistor, a mattress pad, or other sensor, connect the sensor to the monitor, turn on the monitor, and jiggle the sensor cable, being careful not to disturb the sensor in such a way as to simulate a breath. Observe the monitor for artifacts that would indicate a defective cable or connector. 1.10 Fittings/Connectors. Examine all fittings and connectors, including electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Electrodes/Transducers. Confirm that any necessary electrodes and/or transducers are on hand and check their physical condition. If disposable electrodes are used, be sure an adequate supply is on hand. Verify that the insulation on thermistor sensors is intact. Check that air mattresses are free of leaks and that the tubing that connects the segments of the mattress to the manifold fits well, without the use of tape. Keep spare tubing on hand to make necessary repairs. Carefully examine sensor belts, bands, or pads (magnetic, capacitive, or pressure transducer) for intact insulation. If there are cracks or defects in the insulation, remove the sensor from service. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Investigate questionable control settings on a home care monitor. Consult with the patient’s physician to determine correct settings. The parents should receive additional training if required. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so


3

Inspection and Preventive Maintenance System dized) metal on the chassis with an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms. We recommend a maximum of 0.5 Ω.

equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function.

If the device has an accessory outlet, check its grounding to the main power cord. 2.2

Leakage Current. Measure chassis leakage current with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off.

1.19 User Calibration. Confirm that the calibration or test function operates.

Chassis leakage current to ground should not exceed 300 µA.

1.20 Alarms/Interlocks. Operate the device in such a way as to activate each audible and visual alarm. Check that any associated interlocks function. If the device has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. Some apnea alarms that reset automatically when breathing resumes have a separate indication that an apneic episode has occurred; this reminds clinical personnel that the patient needs closer attention. To verify that this indicator functions properly, halt simulated respiration until the apnea alarm sounds, then resume the simulated respiration. Check that the reset control functions. If the unit is used with a remote alarm indicator, verify its function.

If a bedside or central station monitor is grounded through system interconnections in addition to power line grounding and is only used in this configuration, then do not disconnect the monitor from the system to measure leakage current during routine inspections. Verifying low grounding resistance is adequate.

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of the volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Verify that electrode gel, if used, is available. 1.24 CRT Display. If the unit includes a display of respiration waveform, check it for focus, slope, bow, baseline, position, burn spots, and 60 Hz interference or other noise. Verify that the display amplitude increases as the impedance change setting of the simulator is increased.


4

Grounding Resistance. Measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not ano-

2.3

Open Electrode Indicator. This check is for impedance-type monitors only. Connect the monitor to the respiration simulator. Vary the base impedance and determine the resistance value at which the unit first indicates an electrode fault. This is usually in the range of 1,000 to 2,000 Ω.

2.4

Sensitivity. Impedance-type monitors. If the monitor has a manual sensitivity control, set it at maximum sensitivity. Connect the respiration simulator and, if adjustable, set it for a base impedance of 500 Ω, resistance change of 1 Ω, and breathing rate of 30 bpm (15 bpm for an adult monitor). Verify that the monitor detects each resistance change. Decrease the resistance change on the simulator and record the minimum value for which breaths are reliably detected. Most monitors will detect resistance changes of 0.1 to 0.3 Ω at maximum sensitivity. Increase the rate to 100 bpm and verify that the sensitivity does not change abnormally. Discrepancies between similar monitors or from previous readings greater than 25% suggest significant deterioration of the monitor and should be investigated. With the monitor set at maximum sensitivity, verify that breaths are not detected when


Apnea Monitors

2.5

the simulator is set to 0 bpm or turned off. Some simulators, when turned off, may present a high base resistance to the monitor that can cause extraneous noise pickup.

activated when the indication falls below 22 bpm. Some monitors have fixed alarm delays; check the instruction manual to determine whether this feature is present.

Other types. Only qualitative tests of sensitivity can be made with other types of sensors. Simulate breaths in the appropriate manner for each monitor, and observe that the sensitivity varies with the control setting. In some cases, sensitivity will vary with the simulated respiration rate. Confirm the absence of artifacts at maximum sensitivity.

Next, simulate a rate of about 60 bpm, reset any alarms, then increase the simulated rate to 80 bpm or higher, and verify the operation of the high-rate alarm.

ECG Features. If the unit includes ECG and heart rate monitoring, perform trace quality and additional testing as part of a separate ECG Monitors procedure. If the unit has limited ECG features — such as a heart rate alarm — but no additional ECG functions, test these as part of this procedure. If more extensive ECG tests are required, see ECG Monitors Procedure/Checklist 409.

2.10 Apnea Alarm Delay Time. Check the apnea alarm delay by stopping simulated respirations. Time the delay between cessation of respiration and apnea alarm. Measured times should agree with indicated times within 20%. Check all times, if discrete times are available. If the control is continuously variable, check both shortest and longest times. Check the alarm-silence function, if so equipped. 2.11 Ratemeter Accuracy. Using the respiration simulator, check the rate display on respiration rate monitors at low rate (about 15 bpm for adult units and 30 bpm for infant units) and high rate (100 bpm). Read the ratemeter when it reaches equilibrium. Indicated rates should be accurate to within 10%. If the ratemeter is digital, vary the simulated rate to check for malfunctioning digits. A display of “8” in the tens and units position will check all elements of a segmented or dot display; a “1” and “0” in the hundreds place is all that is needed there. 2.12 Rate Alarm Accuracy. Set the low and high respiration rate alarms at 22 and 78 bpm, respectively. Simulate a respiration rate of about 30 bpm, set the apnea delay to at least 10 sec, and reset any alarms that may have been triggered during setup. Slow down the simulated respiration rate to about 20 bpm. Observe the ratemeter, and verify that the low-rate alarm is


Clean the exterior of the unit with a damp cloth, if needed.

4. Acceptance tests In addition to other considerations, every apnea monitor must include a heartbeat detector (or other backup mechanism to the primary apnea detection function). If battery-powered, the unit must indicate whether it is operating on battery power or is being powered (and charged) from line power. For home use, monitors must also include a power-loss alarm (nonbattery-operated unit) and a remote alarm. (See Health Devices 1990 Apr; 19:142-5 for further information.) Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests. 4.1

Sensitivity. Testing is similar to that described in Item 2.4; however, record the actual sensitivity at high and low breathing rates (at low, medium, and high sensitivity on manual units). Also, record the maximum sensitivity at a base impedance of 100 Ω.

4.2

Coincidence Circuit. Some monitors include coincidence circuitry designed to compare breathing and heart rate signals or data and to reject detected breaths that may, in fact, be erroneously detected QRS complexes. If possible, verify operation of coincidence circuitry during incoming inspection.

Before returning to use Remind clinical personnel of the limitations of the monitor and be sure that they understand the operating principles of that particular unit, since a hospital may own more than one type of apnea monitor. Also, make sure that the audible alarm volume, including remote alarm if needed, is set so that it can be clearly heard. If the monitor is being used at home, make sure that the controls are set correctly for the patient application.


5


Argon Surgical Lasers Used For: Lasers, Surgical, Argon [16-941]

Also Called: Argon lasers, blue/green lasers, surgical lasers, bronchopulmonary lasers, gastroenterology lasers, high-power ophthalmic lasers, photocoagulator lasers Commonly Used In: Operating rooms, short procedure areas, endoscopy laboratories, ophthalmic operating rooms Scope: Applies to general-purpose argon surgical lasers that include contact and/or noncontact flexible fiberoptic delivery systems (either reusable or disposable), emit blue-green visible light energy at 514 and 488 nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and high-power argon surgical lasers that are typically used for general surgery, gastroenterology, bronchopulmonary, neurosurgery, gynecology, and ENT surgery procedures; does not apply to ophthalmic argon lasers, which are typically low power (e.g., below 2 W); however, many of the tests listed herein can be used or modified for these other lasers Risk Level: ECRI-recommended, High; Hospital assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Argon lasers are normally checked before each use by the laser’s power-on self-test and by user examination of the aiming beam and the delivery system to be used. This minimizes the need for frequent additional periodic testing. Manufacturers or outside service vendors often maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be coordinated with these outside services. Failure of an argon surgical laser can cause patient or staff injury, abrupt interruption of a surgical procedure, or damage to the laser system. These lasers must be meticulously maintained in order to ensure proper and safe operation.



Time Required

Argon surgical lasers affect tissue by delivering blue-green visible light energy at a sufficient power density to cause vaporization and/or coagulation. The 488/514 nm argon energy is preferentially absorbed by pigmented tissue and hemoglobin and is typically absorbed within 3 mm of the tissue surface. Argon surgical laser fibers are most often used in contact with or close to tissue to cause coagulation and vaporization. Moving the fiber tip away from the tissue to lower the power density causes less tissue to be vaporized and coagulated. General-purpose argon surgical lasers have a laser tube containing an argon gas mixture that is caused to emit light energy by an electric field. This energy leaves the laser tube through a partially reflecting mirror and is typically directed into a flexible optical fiber that transmits the laser energy to the tissue. The fiber may be used with additional devices (e.g., through


●


Inspection and Preventive Maintenance System an endoscope), with a headpiece and lens, and/or with a laser handpiece or a laser micromanipulator (used to interface the laser with the surgical microscope). These attachments may focus the energy into a small spot size at a known working distance and/or a specific beam direction to accomplish special tasks (e.g., energy can be emitted from the surgeon’s headpiece through a handheld lens and focused on the patient’s retina). In addition, argon lasers can emit a single pulse or a train of pulses. Like most lasers, argon lasers are inefficient in converting electrical energy into laser energy. As a result, excess heat is generated in the laser cavity, requiring a cooling system. Most argon lasers use water/air cooling systems that are self-contained, connected to a freestanding chiller system, or connected to a water supply and drain.

Citations from Health Devices Laser use and safety [Guidance article], 1992 Sep; 21(9):306-10. Surgical lasers [Evaluation], 1991 Jul-Aug; 20(78):239-316.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter New, unused fiber delivery system Black Delrin block 1⁄2″ or more thick, 1″ or more wide, about 3″ to 4″ long; tongue depressors; or firebrick Laser radiometer (power meter) Laser safety signs Laser safety eyewear specifically designed for use with argon surgical lasers and of sufficient optical density to protect the wearer’s eye from laser injury Vise with padded jaws or ring stand with padded clamp Pressure gauges and coolant system tee fitting Outlet test fixture (optional) Insulating gloves, high voltage (optional) Grounding strap (optional) Calibrated flowmeter

Special precautions Inspecting and maintaining lasers is a dangerous as well as necessary process, and far greater care is required than with most devices. Personnel who inspect or service lasers should receive special training

2

from the manufacturer or from a qualified alternative training source. Laser energy can cause serious injury, particularly when the internal interlock is overridden or in any other situation in which the energy does not diverge significantly over long distances. Under some circumstances, the beam may not diverge significantly, even a full room length or more away from the laser (and can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser beam is accessible. Area security and use of personnel protective devices and practices should be consistent with hospitalwide laser safety procedures and/or should be approved by the laser safety committee. In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas. Wear appropriate laser safety eyewear at all times whenever the laser is in the Operating mode. WARNING: Do not stare directly into the aiming system beam or the therapeutic laser beam, even when wearing laser safety eyewear. Avoid placing the laser beam path at eye level (i.e., kneeling, sitting, or standing). Do not perform these procedures when a patient is present or clinical staff is working, and do not aim the laser across a path that a person might normally use as a thoroughfare. Furthermore, at minimum, post doors to the room with appropriate laser safety signs stating that the laser is in use and that it is unsafe to enter the room without authorization by the service person performing the procedure. A second person should be present, especially during procedures of recognized risk, to summon help in case of an accident. The laser should remain in the off position when not in use. When in use, it should be in the standby/disabled mode. Do not switch it to the operating mode until the procedure is about to begin and the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser operation key and store it in a controlled location. Do not use the laser in the presence of flammable anesthetics or other volatile substances or materials (e.g., alcohol), or in oxygen-rich atmospheres, because of the serious risk of explosion and fire. Remove from the working area or cover with flame-resistant opaque material all reflective surfaces likely to be contacted by the laser beam. Whenever possible, use a firebrick or other nonflammable material behind the target material (e.g., black Delrin) when the laser is to be activated. Target materials will ignite when exposed to high laser


Argon Surgical Lasers and ensure that they have been turned off after the last use. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that all housings are intact and properly aligned, that assembly hardware is present and tight, that any retractable parts slide easily and lock in place if so constructed, that there are no signs of spilled liquids or other evidence of abuse, and that there are no obvious signs of water or oil leakage.

energies; use short durations when practical. A CO2 fire extinguisher should be readily available. Some surgical lasers use high voltages (e.g., 20 kV), which can be lethal. Capacitors may store charges long after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and avoid contact with any portion of the high-voltage circuit until you are certain that the charge has been drained. In such instances, a good ground must be present; preferably, use a redundant ground strap if you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to measure, drain, or insulate high voltages carries the appropriate insulation rating (e.g., above 20 kV).

Shutters. If manual shutters for the aiming system or the therapeutic lasers are accessible, ensure that they operate smoothly and correctly. Be sure to leave the shutter in the proper position for normal operation. 1.2

Where possible, perform tests with the unit turned off. Because of the presence of high voltage, perform the Grounding Resistance test (Item 2.1) before any other test that requires operation of the laser.

Mounts/Holders. Check that the mounts securely contain any gas cylinders that may be in use. Be sure that mounts or holders intended to secure the fiber to the fiber support (to protect the fiber when in use) are present, in good working order, and being used. Similarly, check mounts or holders for other devices (e.g., external power meters, footswitches).

WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch, talc) on its inside surface because the agent could contaminate the gas recirculation system of the laser and ultimately contaminate a patient wound during a subsequent procedure.

1.3

Report any laser accident immediately to the laser safety officer or equivalent, as well as to the hospital risk manager.

Casters/Brakes. Verify that the casters roll and swivel freely. Check the operation of brakes and swivel locks.

1.4

AC Plug/Receptacle. Examine the AC power plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug, and listen for rattles that could indicate loose screws. If damage is suspected, open the plug and inspect it.

1.5

Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord, or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they grip the cord securely.

1.7

Circuit Breakers/Fuses. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse(s), check its value and type against what is marked on the chassis or noted in the instruction

If the device is mounted on a stand or a cart, examine the condition of the mount. Verify that the mounting apparatus is secure and that all hardware is firmly in place.

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s operator instructions and service manual; be sure that you understand how to operate the equipment, the significance of each control and indicator, and precautions needed to ensure safety and avoid equipment damage. Also, determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.


Chassis/Housing. General. Verify that the key has not been left in the laser. (Remove it if it has been, and inform users of the importance of storing the key in a controlled location.) Examine any external gas tanks that may be in use with the laser,


3

Inspection and Preventive Maintenance System service manual. Ensure that a spare is provided or readily available. 1.8

Tubes/Hoses. Check the condition of all cooling-system hoses and any other hoses or tubing the laser may have (e.g., drain, gas). Check that they are of the correct type; that they have not become cracked and do not show other signs of significant abuse; that they are connected correctly and positioned so that they will not leak, kink, trail on the floor, or be caught in moving parts; and that they are secured adequately to any connectors.

1.9

Cables. Inspect all cables and their channels or strain reliefs for general physical condition. Examine cables carefully to detect breaks in insulation and to ensure that they are gripped securely in the connectors at each end to prevent strain on the cable.

1.10 Fittings/Connectors. Examine all optical (e.g., fiber), gas, liquid, and electrical fittings and connectors for general physical condition. Gas and liquid fittings should be tight and should not leak. Electrical contacts should be straight, clean, and bright. There should be no visible dirt or residue in the optical path of the laser aperture. Ensure that any mechanism to close off the laser aperture (fiber port) is clean, operates smoothly, and is in use. If external gas tanks or wall-supply outlets can be used, gas-specific connectors should be present. Be sure that no pins are missing from yokes and that the keying and indexing of connectors for each gas to be used is correct. A laser that connects to a central piped medical gas system or to a freestanding medical gas system should have the matching DISS or quick-connect fitting for the gas that it is to be used with. Verify that suitable unique connectors are supplied so that adapters are not required. 1.12 Filters. Check the condition of all liquid and air filters. Some argon surgical lasers require deionized water, and most require special filtration. Measuring the pressure drop across a liquid filter can be helpful in determining whether the filter should be replaced. Clean or replace filters according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi), and indicate this in the preventive maintenance section of the inspection form. Clean or replace air filters that are obviously dirty.

4

1.13 Controls/Switches. General. Before moving any controls, check and record their positions. If any position appears inordinate, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical condition, secure mounting, and correct motion. If a control has fixed-limit stops, check for proper alignment as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from fingernails, pens, or surgical instruments). If you find such evidence, notify users to avoid using tape and sharp instruments. During the inspection, be sure that each control and switch works properly. Remote. Examine the exterior of the control for cleanliness and general physical condition. Be sure that housings are intact, that assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. If the remote control is attached by cable to the laser, ensure that the cable and any connectors are in good condition. Examine all controls and switches for general physical condition, secure mounting, correct motion, and intended range of settings. Where a control should operate against fixed-limit stops, check for proper alignment as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs properly. Footswitch. Examine the footswitch for general physical condition, including evidence of spilled liquids. Footswitches for lasers include an internal switch that activates according to the depth of pedal depression. It is usually possible to feel the vibration caused by closure of the switch, even through a shoe. Check that the internal switch is operating and that the footswitch does not stick in the on position. Some footswitches include two internal switches; in this case, verify the operation of both. Some footswitches also include a switch to operate the liquid- or gas-cooling system. Check to be sure that this switch operates reliably. During the procedure, check to be sure that the laser activates consistently when the footswitch is depressed and that the fiber-coolant system operates properly when the fiber-coolant switch is activated and deactivated. Flex the cable at the entry to the switch, and, using


Argon Surgical Lasers information expected. Ensure that user prompts occur in the proper sequence. Store some sample information, and verify that it is correct. If a feature to manually reset this information is available, ensure that it works.

an ohmmeter, check for internal wire breaks that cause intermittent operation. Confirm that strain reliefs are secure. Examine the male and female connectors for attaching the footswitch to the laser cabinet to be sure that no pins are bent and that no other damage is present. Ensure that the connector secures acceptably to the laser cabinet. 1.15 Motors/Pumps/Fans/Compressors. Check the physical condition and proper operation of these components, if present. If lubrication is required, note this in the preventive maintenance section of the form. 1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the manufacturer’s recommendations, and note this in the preventive maintenance section of the inspection form. If an external water supply is in use, ensure that the water pressure is properly regulated and at the appropriate pressure and that the supply and drain system is properly configured (e.g., filters are oriented for proper flow, drain hoses are positioned in a sink or drain). 1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible. If a remote control or display is battery powered, check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, verify proper operation of all lights, indicators, meters, gauges, and visual displays on the unit and remote control. Ensure that all segments of a digital display function. Note any error messages displayed during the power-on self-test.

1.19 Laser Delivery System Calibration. Some argon surgical lasers include a user-accessible calibration port or power meter that allows output calibration and/or testing of the laser fiber. This feature is provided because transmission of laser energy through a fiber may change as a result of fiber use. Based on the measurement from the calibration power meter, the laser may automatically recalibrate itself and/or adjust displays so that the power indicated to be delivered to the patient will be correct; or it may require the user to do this manually. Verify that this feature is functioning by using the manufacturer’s recommended calibration procedure to test one delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. A good-quality (e.g., >85% transmissibility, undamaged sheath) fiber or handpiece should be used for this test. 1.20 Alarms/Interlocks. Operate the device in a manner that will activate the self-check feature, if present, and verify that all visual and audible alarms activate according to the manufacturer’s documentation. If no self-check feature is present, operate the laser in a manner that will activate each audible and visual alarm; be sure to test only those alarms that will not cause damage to the laser or present an unnecessary risk of laser beam exposure to the user or bystanders. If a door or window interlock is used, ensure that it deactivates the laser properly. (Do not disassemble major parts of the laser to test internal interlocks.) After deactivating the laser and reclosing the door or window, check to be sure that the laser will restart. Be sure to check the interlocks in all locations where the laser is used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)

If primary and remote-control indicators and displays can be used at the same time or if control can be switched from one to the other during the course of a procedure, verify that the same information (e.g., settings, displays) is indicated on both control panels during laser operation. If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated energy counter), ensure that each display provides the

If the laser is equipped with an emergency “kill” switch, test this feature to be sure that it deactivates the laser and that the laser will subsequently restart. 1.21

Audible Signals. Operate the device to activate any audible signals (e.g., laser emission, setting change). Check for proper operation, and verify


5

Inspection and Preventive Maintenance System that the signal can be heard in the environment in which the laser will be used.

recommendations for the procedures and cleaning agents to use to clean lenses.

1.22 Labeling. Check that all placards, labels, and instruction cards noted during acceptance testing are present and legible. Check to see that an instruction manual is kept with the laser or is readily available.

Ensure that major subcomponents of the handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the handpiece(s) to the fiber are in good working order and that they reliably secure each handpiece to the fiber.

1.23 Accessories. General. Verify that all necessary accessories are available and in good physical condition. Set up reusable accessories with the laser to ensure compatibility and proper functioning. Checking all fibers or accessories during a single inspection and preventive maintenance procedure is unnecessary as long as accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person responsible for scheduling the use of the laser before beginning the procedure. Fibers. For the test fiber or before each use, examine the connector, cable, and tip of each fiber that may be used, as well as the fiber support, for cleanliness and general physical condition. Be sure that all hardware (e.g., laser gas tubing channels) is present, in good condition, and firmly attached. Ensure that the connector properly seats into the laser aperture of the laser cabinet. Examine the distal end of fibers to ensure that any connecting mechanisms (e.g., threads) are in proper working order. If a fiber appears to be dirty or damaged, remove it from service. If a fiber is reusable, notify the person(s) responsible for fiber repair. The fiber should be repaired and/or cleaned according to the manufacturer’s recommendations. Verify fiber performance. Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness and general physical condition. Examine individually only those components that are intended for removal during normal use and storage. (Do not remove other parts that are press-fit or attached by screws, bolts, or snap-rings.) If lenses are detachable, be sure not to touch the lens surface; handle lenses by the edges only. Consult the manufacturer’s

6

Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness and general physical condition. Be sure to handle it by the main body; do not hold it by the joystick, and do not touch the reflecting lenses in the body. Inspect micromanipulators provided by both the laser manufacturer and the laser accessory manufacturer. Ensure that the reflecting lenses are intact and clean. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean reflecting lenses. Examine the joystick to ensure that it is firmly attached and that it freely moves the reflecting lens. If a finger rest is present, ensure that it is firmly attached and properly oriented. If a zoom focus feature is present, be sure that it turns easily and does not slip. Examine each objective lens to ensure that it is intact and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean the objective lenses. Carefully insert each lens into the micromanipulator, and ensure that it fits snugly. Inspect the mechanism used to attach the micromanipulator to the microscope to ensure that all parts are present and that it is in good working order. Connect the micromanipulator to the microscope to check for a secure connection. Safety filters. Verify operation of safety filters in the microscope and endoscope delivery systems. 1.24 Aiming Beam. Argon lasers typically use an attenuated therapeutic beam as the aiming beam. Activate the aiming beam (without the therapeutic beam), and verify that it produces a round, uniformly bright spot, with no halo. For handpieces that provide adjustable spot sizes, verify that the spot size changes as expected and still remains uniform.


Argon Surgical Lasers on the chassis should not exceed 300 µA; in no case should it exceed 500 µA. Where it is greater than 300 µA, ensure that appropriate grounding is present.

1.25 Laser Aperture. WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser aperture. It should be clean and undamaged; replace if needed. There should be no visible dirt or residue in the optical path of the laser aperture.

2.3

1.26 Gas Regulators. Examine any gas regulators for cleanliness and general physical condition. Ensure that the gauges on the regulators are not broken. During the procedure, ensure that the regulator and the gauge operate as expected. Verify that the correct gas is attached to each regulator. Be sure that a key or wrench to facilitate changing the gas supply is with the unit or readily available.

Place and secure the laser fiber, handpiece, or micromanipulator with the aiming system focused on the black Delrin or a tongue depressor. With the laser set to about 10 W and the exposure set at a minimum duration, activate the laser and create a burn. Carefully move the Delrin to expose a clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this process until you have tested all exposure settings, except continuous, and have developed a series of burns. Compare the burns to verify that progressively larger burns occurred as the exposure duration increased.

If the laser includes a gas recirculation system, ensure proper operation by allowing it to control the gas supply into and out of a sealed plastic bag. WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch, talc) on its inside surface because the agent could contaminate the gas recirculation system of the laser and ultimately contaminate a patient wound during a subsequent procedure.

2.4

If proper operation is questionable, consider using a calibrated flowmeter to measure actual gas flow.


2.2

Grounding Resistance. Use an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms to measure and record the resistance between the grounding pin on the power cord and exposed (unpainted and not anodized) metal on the chassis, accessory outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω. (If the footswitch is of low voltage, grounding is not required.)

Repeat Pulse. If the unit includes a repeat pulse feature, which repeats the pulse at a fixed or adjustable rate, test this feature with the laser set at the minimum, median, and maximum repeat pulse settings, if adjustable. Some laser power meters can react quickly enough to be used to test this feature of the laser. If you are using such a power meter, test the laser to be sure that the correct power is repeatedly delivered over the correct time period. If your laser power meter cannot be used for this test, use the following alternative test method. Set the laser to about 10 W and a 0.1 sec exposure duration with the fiber, handpiece, or micromanipulator attached, and verify that the repeat pulse feature operates as expected by moving the Delrin or the colored tongue depressor slightly between each pulse. Be extremely careful to keep hands out of the laser beam path. If the number or duration between repeat pulses is adjustable, test that setting changes made throughout the range result in the expected performance.

Leakage Current. WARNING: Do not reverse power conductors for this or any other test. Improper attachment of conductors may damage the laser. With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the unit grounded and ungrounded. The leakage current

Exposure Duration. Some laser power meters can measure pulse duration. If the power meter can react to pulse duration (this is the preferred circumstance), test the laser at each setting. However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.

2.5

Footswitch Exposure Control. Set the output time for about 5 sec, activate the unit, and re-


7

Inspection and Preventive Maintenance System lease the footswitch after about 1 sec. Verify that the beam turns off when the footswitch is released. 2.10 Power Output. Select one delivery system (e.g., fiber, handpiece, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at the appropriate distance from the detector of the laser power meter to meet spot-size requirements specified in the instructions for the meter. (Do not focus the beam to a small spot on the power meter. Some power meters require that the unfocused or a defocused laser beam be projected into the power meter to cover the majority of the absorber surface. If the laser beam is focused on the detector of such meters, the meter may be damaged.) WARNING: Accessing the unfocused laser beam may require defeating internal interlocks. Because of the heightened risk associated with an unfocused, nondiverging laser beam, exercise great care if the interlocks are to be defeated. With the laser set at low (e.g., 10% of full scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient period to acquire acceptable readings. (Power meters use different time constants to acquire an acceptable reading, and you must know and meticulously follow them.) Compare the reading with the power display of the laser; the measured and displayed values should all be within 10% of one another. In addition, compare the reading obtained with the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the laser includes a low-power (e.g., mW) feature, test it in a similar fashion with a power meter of appropriate resolution in the low-power range.

3.3

Calibrate/adjust any components (e.g., printer) according to the manufacturer recommendations. Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses and tubes are tight.

3.4

Replace filters if needed. Check all fluid levels and supplement or replace fluids if needed.

4. Acceptance Testing Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. WARNING: Lasers may be damaged by switching between normal and reverse polarity while the device is on. If reverse-polarity leakage current measurements are made, turn off the unit being tested before switching polarity. Also, lasers powered by three-phase electrical systems may be damaged if proper electrical phase connections are not made initially and maintained thereafter. Thus, do not switch conductor connections or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical leakage current tests with reversed-polarity wiring. Also test the ability of the laser to deliver laser energy as expected in all configurations and with all provided laser accessories. In addition, perform the following tests. 4.1

Areas of Use. Visit the area(s) in which the laser is to be used and ensure that laser signs, eyewear, and window coverings are available and being used and that safety interlocks for doors or windows, if present, are functioning properly.

4.2

Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over when pushed or when a caster is jammed on an obstacle (e.g., a line cord, threshold), as may occur during transport. If the device is designed to rest on a shelf, ensure that it has nonslip legs or supports.

4.3

Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling information is typically found in the laser’s operator manual.

4.4

Electrical Wiring Configuration. Ensure that the branch circuits and the outlets for the laser are properly wired and rated for use with the laser. Examine the receptacles at each location where the laser is to be used to ensure that the proper electrical configuration (e.g., proper

3. Preventive maintenance Verify that all daily preventive maintenance procedures recommended by the manufacturer are carried out. 3.1

3.2

8

Clean the exterior. Clean accessible optical components (e.g., blast shield, microscope lenses), if necessary, using techniques and cleaning solutions recommended by the manufacturer. Lubricate any motor, pump, fan, compressor or printer components as recommended by the manufacturer.


Argon Surgical Lasers neutral and ground connections, proper phase rotation) has been installed. Verify proper wiring and connect the laser to each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction. 4.5

AC Plug. Verify that the plug is acceptable for use with the maximum current and voltage specifications for operating the laser. (Consult National Electrical Manufacturers Association [NEMA] configurations for general-purpose nonlocking and locking connectors if in doubt.)

4.6

Pulse Duration. Verify that progressive increases in pulse duration throughout its range of adjustment result in progressively larger burns.

4.7

Repeat Pulse. If the unit includes a Repeat Pulse feature, test this feature as described in Item 2.4, but over the full range of available settings.

4.8

Power Range. Using the technique described in the Power Output test (Item 2.10), test the power

output accuracy at several low, medium, and high settings. 4.9

Laser Delivery System Calibration. Use the manufacturer’s recommended calibration procedure to test each new reusable delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. Note the fiber transmission for each delivery system tested if this information is provided by the laser. Or, you can calculate it using the following formula: % Transmission =

Delivered power × 100% Power entering the fiber

Delivery systems with less than the manufacturer-recommended transmission (typically >80%) should be returned to the manufacturer.

Before returning to use Be sure to return controls to their starting position, and place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using the unit.


9


Aspirators Used For: Aspirators [10-208] Aspirators, Emergency [15-016] Aspirators, Low-Volume [10-215] Aspirators, Surgical [10-217] Aspirators, Thoracic [10-218] Aspirators, Tracheal [10-219] Aspirators, Uterine [10-222] Pumps, Breast [10-485]

Also Called: Portable suction units, gastric aspirators (low-volume aspirators), pleural aspirators (thoracic aspirators), Gomco (a registered trademark of Allied Healthcare Products, Inc. to be used only when referring to that device) Commonly Used In: Ambulances, critical care units, emergency departments, operating rooms; tracheal aspirators also found on “code carts” and low-volume (or intermittent) aspirators frequently used in medical-surgical units Scope: Applies to virtually all electric-powered portable and mobile suction sources; does not apply to suction regulators (see Procedure/Checklist 459) Risk Level: ECRI Recommended, High for Emergency and Tracheal Aspirators, Medium for Surgical, Thoracic, and Uterine Aspirators, Low for Low-volume Aspirators and Breast Pumps; Hospital Assessment, for Breast Pumps, for Emergency Aspirators, for for Surgical Aspirators, for Thoracic AspiraLow-volume Aspirators, tors, for Tracheal Aspirators, for Uterine Aspirators Type



Major

12 months

months

.

hours

Minor

6 months*

months

.

hours

Time Required

* Emergency and tracheal aspirators only.

Emergency, surgical, and tracheal (high-vacuum) aspirators, 0 to 200 mm Hg

Overview Aspirators are among the most common types of clinical equipment in use within the hospital; some (e.g., emergency and tracheal) are critical for life support. Aspirators are categorized by their vacuum levels as follows: Thoracic aspirators, 0 to 45 mm Hg Low-volume aspirators, 0 to 150 mm Hg


Multipurpose high-vacuum aspirators, 0 mm Hg to >400 mm Hg Low-volume aspirators typically operate intermittently, cycling between atmosphere and 120 mm Hg. In hospitals with central vacuum systems, suction regulators are commonly used as an alternative to aspirators.


●


Inspection and Preventive Maintenance System Suction, or aspiration, is used to remove obstructing secretions, blood, or vomitus from a patient’s airway to keep air passages to the lungs open and to allow spontaneous or mechanical ventilation. Suctioning can be either oropharyngeal (to prepare for emergency intubation or to remove secretions from the upper airway above the glottis) or tracheal (to remove obstructions from the trachea of an intubated patient). In emergency medical services (EMS) use (in ambulances and in the field), portable aspirators are usually used for oropharyngeal suctioning. However, more and more emergency medical technicians (EMTs) and paramedics are being trained in intubation and advanced airway maintenance in which, after suctioning, a rescuer intubates the clear airway with an endotracheal tube. Since the cuff of that tube interferes with the natural evacuation of mucus, tracheal aspiration is also used to remove obstructions after intubation. Tracheal aspiration may also be required during interhospital (nonemergency) transport of intubated patients. Portable emergency aspirators are used by EMS personnel outside the hospital and on bedside stands in the hospital. They draw power for charging their batteries from an AC line, an ambulance DC-to-AC inverter, or the ambulance’s 12 VDC electrical system. Data gathered during ECRI surveys of hospitals indicate that even serious performance degradation in suction apparatus is often not apparent to clinical personnel. This emphasizes the need for periodic inspection. Critical performance parameters for suction apparatus are vacuum, vacuum rise, and, in some types, free airflow. A supply of clean catheters, suction tips, and tubing should be stored near the aspirator or kept readily available.

Citations from Health Devices Suction canisters [Evaluation], 1983 Apr; 12:127-49. Portable emergency aspirators [Evaluation], 1991 Feb; 20:55-72. Should vacuum pump effluent be treated? [User Experience NetworkTM], 1994 Jul; 23:310.

Flowmeter, 10 to 50 L/min, ±5% Tubing and adapters for connecting vacuum gauge or pressure meter and flowmeter (a T fitting is needed) Disposable suction canister (if applicable)

Special precautions Aspirators may be contaminated with contagious microorganisms from contaminated aspirant. Keep your face away from the exhaust port of the unit. Never place your mouth on any part of the regulator to blow or suck as a qualitative test of operation or to blow dirt out of a part. Wash hands thoroughly after inspection, especially if any accessories were disassembled. When it is necessary to disassemble an aspirator for repair, wear latex gloves, wrap cellophane or another nonpermeable barrier around the handles of all tools, and work on a surface that can be easily disinfected. Dispose of gloves and tool handle wrappings as infectious waste.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. It is vital to identify the type and/or application of the aspirator to be inspected in order to define the performance criteria for the inspection. This is often difficult because most devices bear only a model or catalog number. Obtain this information from the manufacturer’s literature, previous inspection forms, or clinical personnel. Once the type of aspirator has been identified or when new units are purchased, enter this information on the equipment control or inventory record so that it can be determined quickly from the control number on the device in future inspections.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that housings are intact, that all assembly hardware is present and tight, and that there are no signs of spilled liquids or other abuse.

1.2

Mount. If the device is mounted on a stand or cart, examine the condition of the mount.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of

Test apparatus and supplies Ground resistance ohmmeter with resolution of 0.1 Ω Leakage current meter or electrical safety analyzer Stopwatch or watch with a second hand Vacuum gauge, 0 to 760 mm Hg, ±3%, or pressure meter with equivalent capabilities

2


Aspirators lint and thread around the casters, and be sure that they both turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped. 1.4

AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one. Also check line cords of battery chargers.

1.6


1.7


1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not cracked, kinked, or dirty. Replace if needed and indicate this on Line 3.4 of the inspection form.

1.10 Fittings/Connectors. Examine all fittings and connectors for general condition. Replace if needed and indicate this on Line 3.4 of the form. 1.12 Filters. Check the condition of all liquid and pneumatic (air) filters. Replace if needed and indicate this on Line 3.4 of the form. 1.13 Controls/Switches. Before moving any controls, check their positions. If any of them appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as for positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

If the device has an adjustable suction level, verify that the control is usable over the full range of vacuum settings. Although generally adjustable over a much wider range, tracheal aspirators should normally be operated at about 150 mm Hg during tracheal aspiration. Therefore, confirm that the unit is easily adjusted to this vacuum level (with the patient port occluded). 1.15 Motor/Pump. Confirm physical condition and proper operation. Lubricate if required, and note this on Line 3.2 of the form (but do not check 3.2 until you have completed all necessary lubrication). 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check remaining battery capacity by activating the battery test function or measuring the output voltage. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger if so equipped. Inspect the vacuum gauge for cracks and scale visibility. Make sure the indicator resets on zero without vacuum applied. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Verify that clean canisters, suction catheters, suction tips, and tubing are available. 1.24 Overflow Protection. To verify operation of the overflow protection on units so equipped, liquid must be aspirated into the collection bottle until the protective device is activated. (Observe while doing so that liquid will not be aspirated into the pump if the mechanism fails.) Place a bucket of water on the floor adjacent to the device being tested, connect a short length of hose to the patient fitting on the machine, and suction the water into the collection bottle. In units with relatively low flow rates (e.g., low-volume aspirators used for gastric suction), this test is expedited by pouring water directly into the collection bottle until it is nearly full, then reassembling the system and suctioning the remainder from the bucket. In


3

Inspection and Preventive Maintenance System devices where overflow protection is provided by a hollow plastic ball (e.g., a table tennis ball), the ball will not function reliably if it is dented or cracked or has solids adhering to it. Conduct this test only on units with reusable suction canisters or overflow mechanisms. Do not test completely disposable systems.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.

2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Record the maximum leakage current with the unit off and on. Leakage current should not exceed 300 µA.

2.3

Maximum Flow. Measure the maximum free airflow with the flowmeter and compare it with recommended values in the table. (This measurement need not be made on low-volume suction machines, since their flows are generally very low.) Set the unit for maximum suction. Test the aspirator with the collection bottle(s) or canister(s) in place, but without patient catheters. Use a short piece of large-diameter tubing from the flowmeter to the device, with the correct size adapters inserted at the aspirator end. Any restrictions (e.g., internal adapters) will tend to reduce the free airflow.

2.4

2.5

4

Rate of Vacuum Rise. This test is necessary only on tracheal, emergency, and intrauterine aspirators, where rapid vacuum rise is essential. Connect the vacuum gauge or pressure meter to one side of a T fitting and attach the T to the canister or collection bottle patient connector. Turn the unit on and set the unit for maximum suction. Occlude the open port of the T with a finger while using a stopwatch or watch with a second hand to measure the time required to reach maximum vacuum. Refer to the Aspirator Performance Values table to determine acceptable rise time values. Maximum Vacuum. Connect the vacuum gauge or pressure meter to the canister or collection bottle patient connector. Turn on the aspirator, adjust it to provide maximum vacuum, and record

Aspirator Performance Values These performance values represent best current opinion on clinical need and typical aspirator capability, not optimal design criteria. Discuss units unable to meet these criteria with clinical staff and schedule them for replacement or repair.

Type Emergency Low Volume Surgical Thoracic Tracheal Uterine Breast Pump

Maximum Vacuum (mm Hg)

Rise Time (sec/mm Hg)

Maximum Free Flow (L/min)

>400 >40 >400 >40 >400 >400 >200

<4/300 <30/30 <4/300 <4/30 <4/300 <3/300 <2/150

25 NA 25 20 25 30 NA

this value. If a unit does not provide the expected maximum vacuum (see the Aspirator Performance Values table above), look for air leaks, especially in the collection bottle caps and hoses. Some low-volume aspirators have “low” and “high” settings; record the vacuum attained for each, measuring the low level first. Thermal intermittent aspirators (e.g., Gomco Models 764/5, 200/2000) do not reach maximum vacuum during the first few cycles, and it is necessary to wait 5 to 10 min until maximum vacuum is reached. 2.6

Vacuum Gauge Accuracy. Check the accuracy of the vacuum gauges on units so equipped at a vacuum level typical for primary usage. To make this measurement, connect the vacuum gauge or pressure meter to the fitting on the collection bottle intended for the patient catheter or tubing. Turn the unit on and adjust it to the desired vacuum reading on the machine’s gauge. Record this reading and that of the test gauge or meter. Readings should be within 10%.



3.2

Lubricate the motor and pump, if needed.

3.4

Replace filter(s), hoses/tubing, fittings/connectors, if needed.


Before Returning to Use Recharge battery-powered devices, or equip them with fresh batteries, if needed.



Autotransfusion Units Used For: Autotransfusion Units, Blood Processing [17-537]

Also Called: Cell Saver (a registered trademark of Haemonetics Corp. to be used only when referring to that device) Commonly Used In: Operating rooms Scope: Applies to machines used for intraoperative separation and cleaning of red blood cells recovered from surgical sites Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

6 months

months

.

hours

Minor

NA

months

.

hours

Overview Autotransfusion, or autologous transfusion, is the process of reinfusing a patient’s own blood rather than relying on banked stores of homologous blood. Several types of intraoperative autotransfusion devices are available today. The simpler systems consist of collection canisters or cardiotomy reservoirs that are filled through suction tubing originating at the operative site. These systems generally include a means of infusing proportioned quantities of anticoagulant as blood is aspirated, and a filtration system to remove clotted blood and other debris that may be aspirated with the blood. Processing systems use a centrifuge to separate, wash, and pack the red blood cells (RBCs) extracted from salvaged whole blood. This procedure applies to blood processing systems that employ a centrifuge to separate RBCs from whole blood aspirated from the surgical site. Currently marketed units perform essentially the same procedures in separating cells from whole blood; differences among the units are related primarily to the degree of machine automation. Prices of the units reflect that degree of automation.



Time Required

During autotransfusion with these machines, blood that pools in the operative site is aspirated and simultaneously mixed with an anticoagulant, then deposited in a cardiotomy reservoir. After coarse filtration, the blood is either pumped or drained into the spinning centrifuge bowl. The lighter plasma separates from the RBCs and is discarded in a waste bag. Automated systems monitor the level of RBCs in the bowl with optical sensors and stop the centrifuge once the cells have filled the bowl. In manual operation, the operator must determine when the centrifuge bowl is full and initiate the next phase of processing, generally the RBC wash. During the RBC wash, cellular debris from ruptured cells, clots, and other contaminants are removed. RBC washing is accomplished by introducing normal saline into the full, spinning centrifuge bowl. Because saline is less dense than the RBCs, it disperses the cells and rises up through them, carrying debris out and into the waste bag. Automated systems will deliver a predetermined volume of saline during the wash phase; manual systems require that the operator monitor the clarity of the waste leaving the centrifuge bowl. When the waste fluid is clear, the wash phase is terminated.

5200 Butler Pike, Plymouth Meeting, PA 19462-1298, USA Telephone +1 (610) 825-6000 ● Fax +1 (610) 834-1275 ● E-mail [email protected]

Inspection and Preventive Maintenance System The final stage of processing involves pumping the packed and washed cells into an infusion bag. The filled infusion bag is hung with an infusion line and a microaggregate filter to reinfuse the cells into the patient. The infusion bags are generally provided (without infusion lines or filters) with the disposable centrifuge bowls and tubing sets for each autotransfusion machine. While intraoperative autologous transfusion may be safer than donor transfusion, which carries the risk of cross infection and transfusion reactions, autologous transfusion is not without risk. Some rare complications currently associated with autotransfusion include air embolism, kidney dysfunction, and disseminated intravascular coagulation. Of these complications, the latter two are thought to be related to blood damage that occurs during the processing. Excessive centrifuge speed, overheating of the blood, and excessive vacuum applied during aspiration can cause RBC damage. Air embolism has generally been associated with the use of pressure infusors for reinfusion of recovered cells or infusion occurring concurrently with processing. Some autotransfusion machines are equipped with air-in-line detectors that are designed to detect air in the reinfusion line returning packed cells to the patient. (For more details about the risks associated with autotransfusion, refer to the Health Devices articles cited below.)

Citations from Health Devices Air embolism from autotransfusion units [Hazard], 1986 Jul; 15:210-2. Automated intraoperative processing autotransfusion machines [Evaluation], 1988 Aug; 17:219-42. Autotransfusion machines [Evaluation update], 1988 Dec; 17:371. Hemolysis and renal dysfunction associated with autotransfusion, 1990 Jan; 19:25-7.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Leak-detect solution

Citrate solution to anticoagulate 2 L of blood, such as 80 g sodium citrate in 200 mL normal saline or CPD (citrate phosphate dextrose) anticoagulant solution (consult with pharmacy to determine correct concentration) 2 L of whole, fresh pig or cow blood anticoagulated with citrate (because of the risk of bloodborne pathogens, human blood should not be used for the procedures; animal blood may be obtained from a local slaughterhouse)

Special precautions Although the disposable components of the autotransfusion machines are intended to contain blood during processing, blood may be spilled on the machine housing or components during processing. When working on external components (including the centrifuge well) and the machine housing where blood may have been spilled, it is prudent to wear examination gloves. If a unit is contaminated with blood, especially if the blood is still liquid, it should be decontaminated (preferably by a machine operator or central supply personnel). Verify that the centrifuge well is clean before working on the unit. In addition to gloves, wear a gown and eye protection while the machine is cleaned. (See Infection Control in the “IPM Safety” article behind the Guidance Tab in this binder for additional precautions and suggestions.)

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also, determine if any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. For software-driven units, note the software revision number on Line 1.19 (System SelfTest) of the inspection form.

1.1

Stopwatch or watch with a second hand Bucket with capacity of at least 1 L Set of disposables for autotransfusion unit

2

The following may be necessary during acceptance testing:

1. Qualitative tests

1,000 mL graduated cylinder

Stroboscopic tachometer

Vacuum gauge, 0 to 600 mm Hg, or pressure meter with equivalent capabilities

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. (See Special Precautions.)


Autotransfusion Units 1.3

1.4

Casters/Brakes. If the device moves on casters, check their condition. Verify that they turn and swivel, as appropriate, and look for accumulations of lint and thread around the casters. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture of an area. (See Procedure/Inspection Form 441.) AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, verify presence of line power, insert an AC plug into each, and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacles.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with correct polarity.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), affix the cord to the unit so that it cannot be removed by the operator. (See Health Devices 1993 May-Jun; 22[5-6]:301-3.)

1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis and ensure that a spare is provided.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses in the unit. Be sure that they are not cracked, kinked, or dirty.

1.9

Cables. Inspect any cables and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that connections are secure. Gas fittings should be tight and should not leak. (If in doubt, check fittings using a leak-detect solution.) 1.12 Filters. Check the condition of all air filters. Clean or replace as appropriate and indicate this on Lines 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Some units may store modifications of standard processing procedures in memory even when the power is shut off; consult the operator’s manual if there is any question about the effect of changing controls if they are not set back to their original positions. (If in doubt, have the machine operator review settings before using the unit.) Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.15 Motor/Pump/Fan/Compressor. Check the physical condition and proper operation of these components. Clean and lubricate as required, and note this on Lines 3.1 and 3.2 of the inspection form. (However, do not check these items until all necessary cleaning and lubrication is completed.) Inspect brushes (if present) of pump, centrifuge, and compressor motors for wear. If worn, replace. If drive belts are present, check them for wear and replace if needed. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function (see Item 1.19).


3

Inspection and Preventive Maintenance System Using the disposable autotransfusion set (or tubing of the same size and hardness), verify that the clamp valves work by installing the tubing in the valves so that at least 3 ft of tubing is available on one side of the valve. With the 3 ft section of tubing held in a vertical position and the clamp valve closed, fill the tubing with water to verify that water will not leak through the valve.

1.19 System Self-Test. Many automated autotransfusion units have a software-based self-check feature that performs several diagnostic tests when the machine is powered up. Record the software version on the inspection form when the program is started. Verification of proper display and indicator function may also be checked during the self-check. 1.20 Alarms. Autotransfusion machines may have alarms, depending on the degree of automation of the unit. Some alarm conditions that should be checked (where appropriate) include full waste bag, empty wash reservoir, and open centrifuge cover. Induce alarm conditions to activate audible and visual alarms. Full waste bag alarms (present on some units) may be triggered by the weight of the bag or by the system’s volume-accounting system, which keeps track of how much fluid has been pumped into the waste bag. Empty reservoir alarms are typically triggered when the air-in-line detector senses that no fluid is in the line during the washing phase of processing. (Testing this alarm will also verify that the air-in-line detector is functioning.) Some autotransfusion machines may have centrifuge-cover interlocks that prevent the opening of the cover while the centrifuge is spinning; they may not alarm to warn that the cover is open. Consult the operator’s manual or the manufacturer to determine if the unit being tested has an alarm to detect an open centrifuge cover. (None of the tests in this section will require blood; water or saline may be used if fluid is required.)

Next, trigger the valve to open by operating the unit (consult manufacturer if it is not clear how to trigger valves to open). If clamps do not open or open sluggishly, consult the service manual or have the manufacturer repair or clean the valve. 1.25 Centrifuge Chuck. Inspect centrifuge chuck for wear or damage. Inspect entire centrifuge well for presence of debris. Install a centrifuge bowl in the chuck according to the operator’s manual, verify that the bowl is firmly seated and that, when the centrifuge is spinning, the bowl remains fairly quiet. If the chuck employs O-rings to secure the bowl, inspect the O-rings for wear or nicks; replace as necessary.


1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible.

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. If the device has an accessory receptacle, check its grounding to the main power cord.

1.23 Accessories. Confirm the presence and condition of accessories, such as tools, separate air-in-line sensors, and cardiotomy reservoir clamps.


1.24 Clamp Valves. Inspect clamp valves on each unit, if so equipped, to determine if they are clean and in good condition. If material has accumulated on the clamps, clean as needed.

Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the

4

2.2


Autotransfusion Units

2.3

primary device’s accessory receptacles, as well as equipment plugged into a multiple-strip outlet (“Waber strip”), so that all are grounded through a single line or extension cord.

3.2

Lubricate per manufacturer’s instructions.

3.4

Replace motor brushes, drive belts, and centrifuge bowl O-rings, as appropriate.


4. Acceptance tests

Roller Pumps. Check the rollers on pumps to make sure that they are running smoothly and that there are no unusual noises from bearings or other indications of excessive bearing wear. Using tubing of the correct size and hardness in the pump, immerse both ends of the tubing in a bucket of saline solution or water at atmospheric pressure and turn on the pump. (This may require triggering of some sensors for the more automated units; contact the manufacturer if it is not clear how to get the pump to run.) To check pump accuracy, set it to deliver 500 and 1,000 mL/min, and collect the volume for a convenient time interval in a calibrated 1,000 mL graduated cylinder. Flows should be accurate to within 5% of the setting or the manufacturer’s specifications.

2.4

2.5

Vacuum Pump. Check the accuracy of vacuum pump regulation on units equipped with vacuum pumps by connecting a length of tubing to the vacuum port and to a vacuum gauge. Vacuum levels should be within 50 mm Hg of the displayed value at full vacuum. Centrifuge Speed. Measure centrifuge speed with a stroboscope tachometer illuminating the centrifuge bowl chuck while the centrifuge is spinning. A piece of tape may be applied to the chuck to facilitate speed determination. Centrifuge speed should be within 10% of the specified speed or within the range specified by the manufacturer. If centrifuge speed is outside of acceptable specification, contact the manufacturer to inquire about adjustment.


Clean exterior and clamps, as needed.

Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, consider performing the following test. 4.1

Cycle Function. If a manufacturer-recommended procedure is available, verify that the blood-level detection system (in automated units) and the rest of the autotransfusion unit functions properly through one or more complete cycles. For the manufacturer-recommended test protocol, contact your representative. If the manufacturer does not provide a way to perform this test, use pig or cow blood to confirm complete functioning; other solutions will not activate sensors. Since there is no history of problems reported for new units, testing with animal blood is optional. If the autotransfusion machine is new to your clinical staff, and you will be testing with blood, consider including this testing as part of in-service instruction. To test with animal blood, install the disposable components, then suction fresh citrated blood into the collection reservoir. Blood should be collected in a solution of 8 g of sodium citrate dissolved in 200 mL of normal saline for every 2 L of blood required. Generally, 2 L of blood is more than adequate for testing. Operate the unit according to the operator’s manual, verifying that the system will detect the packed RBC level.

Before returning to use Make sure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Attach a Caution tag in a prominent position to alert users that control settings may have been changed.


5


Beds, Electric Used For: Beds, Air-Fluidized [16-889] Beds, Birthing [15-732] Beds, Circle Electric [10-345] Beds, Electric [10-347] Beds, Electric, Obese [15-760] Beds, Flotation Therapy [10-348] Beds, Low-Air-Loss [17-593] Beds, Rocking [10-363] Beds, Tilt [16-991] Tables, Examination/Treatment [13-958]

Commonly Used In: Most patient care areas Scope: Applies to electrically operated patient beds, treatment tables (not including OR tables), flotation therapy beds, turning frames, and a variety of specialty electric beds designed for prevention or treatment of pressure sores (decubitus ulcers) or burns, with additional tests for special features of these units Risk Level: ECRI Recommended, Low for most Electric Beds, Medium for Special Care Beds; Hospital Assessment, for most Electric Beds, for Special Care Beds Type



Major

12 months

months

.

hours

Minor

NA*

months

.

hours

Time Required

* Special care beds — including rocking beds (also called kinetic treatment tables), turning frames, circle beds, and air-fluidized and low-air-loss flotation therapy beds — should receive a minor inspection at least every six months, in addition to the annual major inspection (see Health Devices 1988 Jan; 17:3).

Overview Electrically operated beds are in widespread use in most hospitals. Properly used and maintained, they can provide long service, save much nursing staff time, and afford the patient comfort and convenience. Periodic inspection of electric beds is necessary, primarily because of their potential electrical risks. Electric motors tend to have leakage currents that increase with age and use, and the line cord, plugs, and control units on beds are often subject to abuse by patients and personnel. Periodic inspection of all beds, nonelectric as well as electric, can often detect impending failures at a stage where correction is relatively


simple (e.g., bed rails can be checked and repaired before they fail to restrain a patient; a missing IV pole can be replaced before it is urgently needed). Inspection of electric beds must be correlated with bed occupancy and coordinated with nursing personnel or the admissions office. If a bed is occupied at the time its inspection is due and the patient cannot leave the bed for the few minutes required for the inspection, request that the floor nurse advise the maintenance department when the inspection can be performed. In most hospitals, responsibility for inspection and preventive maintenance of electric beds rests with the plant or facilities engineering department, rather than


●


Inspection and Preventive Maintenance System with clinical engineering. However, because these beds are also medical devices, it is important that the documentation of their inspection be thorough and consistent with that of the clinical engineering department.

(e.g., walkaway down) that could result in potentially serious crushing injuries.


Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

Electrical safety of electrical beds, 1978 Apr-May; 7:152-3. Water mattresses on electric beds [Consultant’s Corner], 1978 Sep; 7:290. Electric beds in pediatric areas [Consultant’s Corner], 1982 Sep; 11:302.

Procedure

Electric beds — A status report, 1983 May; 12:177.


Electric beds and the pediatric patient [Hazard], 1983 Jun; 12:203-7.

1.1

Frame. Examine the bed frame for cleanliness and general physical condition. Be sure that all assembly hardware is present and tight. Verify smooth and secure operation of siderails. Check mechanical integrity and degradation (weld cracks, loose fasteners, caster security, stripped threads), especially on special care beds.

1.3

Casters/Brakes. If the bed moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the bed is so equipped.

1.4

AC Plug. Electric bed plugs are especially subject to physical abuse. Therefore, carefully examine the plug and use Hospital Grade plugs on all electric beds. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one.

1.6


1.7

Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

Hill-Rom electric beds [User Experience NetworkTM], 1986 Jun; 15:177. Electric beds [Evaluation], 1986 Nov; 15:299-316. (See also Erratum, 1987 Jan; 16:33.) Amedco electric hospital beds [Hazard], 1986 Nov; 15:317-8. Electric beds can kill children [Hazard update], 1987 Mar-Apr; 16:109-10. Electrical safety of electric beds [User Experience NetworkTM], 1987 Mar-Apr; 16:118. Special care beds require special attention [Hazard], 1988 Mar; 17:101-2. Electric beds can kill children [Hazard update], 1989 Sep; 18:323-5. Electric beds: Do not use in psychiatric wards [Hazard], 1991 Dec; 19:495-6.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Lubricants (20-weight low-detergent oil, graphited oil, grease)

Special precautions Keep fingers and clothing away from all moving parts during inspection. Perform parts inspection, cleaning, and lubrication with the power cord unplugged. Never get underneath a bed while the controls are being operated. Some controls will cause continued motion even after the switch is released

2


Beds, Electric 1.9

turer that they meet the requirements for protection against tampering set forth in UL 544, Section 23C4. For older beds, check with the manufacturer to determine the modification procedure to disable the feature. This recommendation is based on incidents in which children have been fatally crushed (see Health Devices, 1987 Mar-Apr; 16:109-10 and 1989 Sep; 18:323-5). Walkaway down capability can be included on four-poster beds.

Cables. Inspect the cables (e.g., pendants, interconnecting) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition, as well as all gas and liquid fittings and connectors, if present (e.g., in special care beds). Electrical contact pins or surfaces should be straight, clean, and bright. 1.13 Controls/Switches. Before moving any controls, check their positions. Examine all controls and switches, both patient and nurse actuated, for physical condition, secure mounting, and correct motion. Check membrane switches for membrane damage (e.g., from fingernails or pens). 1.15 Motors/Mechanisms. Inspect for general cleanliness, condition, and freedom from accumulated dirt and lint. Follow manufacturer’s recommendations for lubrication (but do not check Line 3.2 on the inspection form until all necessary lubrication has been completed). 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Note the general condition of the bed and mattress. If the bed should be equipped with an IV pole or a manual handcrank (e.g., stored behind the headboard), verify its presence and condition. The IV pole’s elevating latch or thumbscrew should function easily. Inspect IV sockets for cleanliness, alignment, and mechanical integrity. 1.24 Function and Limits of Nurse Controls/Lockouts. Operate each of the controls in both directions to the full extent of its limits. Note any unusual sounds or other deviations from normal performance of the controls themselves, the motors, or the limits. Verify operation of patient lockout switches. Pedestal-style electric beds should not have a walkaway down feature unless the bed has ULlisted controls. The bed should descend only as long as the down button is pressed; motion should stop as soon as the button is released. This applies to all areas of the hospital. If in doubt about new beds, verify with the manufac-

1.25 Function and Limits of Patient Controls. Operate each of the controls in both directions to the full extent of its limits. Note any unusual sounds or other deviations from normal performance of the controls themselves, the motors, or the limits.



2.2

Leakage Current. Measure chassis leakage current to the chassis of the unit with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Leakage current from the bed frame should not exceed 300 µA. This limit applies whether the bed is used in a general or special care area.

2.3

Supplemental Tests. Check any special features of the particular model for condition and operation.


Clean the exterior and interior (e.g., motors, mechanisms).

3.2

Lubricate motors, mechanisms.


Before returning to use Place the bed in its lowest position.


3


Blood Pressure Monitors, Electronic Indirect Used For: Sphygmomanometers, Electronic [16-157] Sphygmomanometers, Electronic, Automatic [16-173] Sphygmomanometers, Electronic, Manual [16-174]

Also Called: Noninvasive blood pressure (NIBP) units Commonly Used In: All patient care areas Scope: Applies to electronic noninvasive blood pressure monitors with either automatic or manual inflation; does not include manual sphygmomanometers (see Procedure/Checklist 424) or invasive blood pressure monitors or transducers (see Procedure/Checklist 434 or 435, respectively); can be used on physiologic monitoring systems and vital signs monitors that include NIBP measurement Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Electronic sphygmomanometers noninvasively measure and display a patient’s arterial blood pressure. The use of these devices may help to overcome some of the problems associated with manual sphygmomanometry, such as variations in user techniques and hearing acuity and the difficulty of obtaining measurements on hypotensive patients. In addition, many automatic blood pressure units can be programmed for readings at regular intervals and will sound an alarm if a patient’s blood pressure exceeds preset limits. Some units can display heart rates based on the blood pressure waveform. Arterial blood pressure measurement is an essential indicator of physiologic condition. As one of the most frequently used diagnostic tests, it is critical to the ongoing management of patients under anesthesia or undergoing drug and other therapies to determine the need for blood, a volume substitute (e.g., plasma expander), or a change in medication. Although invasive techniques for measuring blood pressure may



Time Required

provide greater accuracy and permit continuous measurement during cardiac and respiratory cycles, noninvasive techniques are most often used because of their low risk and simplicity, and they have proven sufficiently accurate for many clinical applications. Two primary methods of determining blood pressure are used with noninvasive electronic blood pressure monitors. The auscultatory method uses a transducer under the occluding cuff to detect arterial sounds (Korotkoff sounds) as cuff pressure is gradually lowered from above the systolic pressure. This enables the system to directly determine both systolic and diastolic values but not mean arterial pressure (MAP). Some of these units display a MAP that is calculated from the systolic and diastolic values using an empirically derived algorithm. Hypotensive patients and patients about to go into shock can be very difficult to monitor with this method because the Korotkoff sounds are difficult to detect at low pressures. The oscillometric method of determining arterial blood pressure does not require a transducer under the


●


Inspection and Preventive Maintenance System occluding cuff and is the most common method used. This method detects volume displacements that originate within the artery (as cuff pressure is reduced) and that are sensed as pressure oscillations in the occluding cuff. The point of maximal oscillation corresponds to the MAP. Systolic and diastolic pressures may be determined by special measurement techniques or clinically tested algorithms. This method may be more reliable than auscultation on hypotensive patients and patients who are likely to become hypotensive.

Physiologic monitoring and the standard of care, 1991 Mar-Apr; 20:79-80.

A third method, the differential sensor technique, is a composite of the two techniques described above. This method typically uses a dual-head sensor that is located under the occluding cuff. One side of the sensor is positioned above the artery and detects the signal generated by the Korotkoff sounds and the oscillometric pressure wave. The opposite side of the transducer detects only the oscillometric signal. By subtracting these two signals, this method filters out extraneous signals from the Korotkoff sounds, isolating the signal that identifies the systolic and diastolic pressures. The oscillometric method is used to measure MAP, even when Korotkoff sounds may be too weak to measure systolic and diastolic pressures.

Y connector compatible with cuff tubing connectors

There are several oscillometric NIBP simulators on the market, costing approximately $4,000 to $5,000. These devices attempt to simulate the dynamic signals that the occlusive cuff would sense if placed on a patient’s arm. The devices also have a test mode that can provide an easier means of performing the static accuracy test, leak test, and overpressure test. If the simulator does not use the NIBP monitor’s patient cuff (i.e., the simulator has an internal bladder), then the leak test will need to be repeated with the patient cuff in place. Simulators also provide a means of evaluating the dynamic performance of the NIBP monitor. However, while they are useful in looking at long-term trends of device performance, they are not necessarily useful in evaluating device accuracy. Since NIBP monitors calculate their readings based on an algorithm, and the simulators use a similar algorithm to generate their signals, if the two algorithms are not exactly matched, then what the simulator states the pressure should be may differ from the pressure that the monitor indicates. It is also necessary to take several readings at each setting and average them; this average, over time, should remain constant for each individual NIBP monitor.

Physiologic patient monitors [Evaluation], 1991 MarApr; 20:81-136.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Calibrated pressure gauge or meter (0 to 300 mm Hg) Cylindrical object to simulate an arm (e.g., can or pipe) with a 3 in to 4 in outer diameter Stopwatch or watch with a second hand NIBP simulator




1.2

Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of this attachment.

1.3

Casters/Brakes. If the device is mounted on a cart or stand, check the condition of its casters. Verify that they turn and swivel, as appropriate, and look for accumulations of lint and thread around the casters. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4

AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective

Citations from Health Devices Automatic sphygmomanometers [Evaluation], 1986 Jul; 15:187-208. (See also 1986 Aug; 15:247 and 1986 Nov; 15:317.)

2


Blood Pressure Monitors, Electronic Indirect portion. Be sure to wire a new power cord or plug with correct polarity. Also check line cords of battery chargers. 1.6


1.7

Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis and ensure that a spare is provided.

1.8

Tubes/Hoses/Bulbs. Check the condition of all tubing, all hoses, the cuff, and the bulb (if present). Be sure that they are not cracked, kinked, or dirty. Replace loose or cracked tubing.

1.10 Fittings/Connectors. Examine all fittings and connectors for general condition. Fittings should be tight (or within manufacturer’s specifications) and should not leak. If keyed connectors are used, make sure that the keying is correct. 1.11 Transducers (non-oscillometric units). Confirm that any necessary transducers are on hand and check their physical condition. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.15 Pump. Check the physical condition and proper operation of this component. 1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the

battery is charged and can hold a charge. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage. Confirm the operation of a charging indicator. Be sure that the battery is recharged or charging when the inspection is complete. If it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. 1.19 User Calibration. Verify that the calibration function operates. 1.20 Alarms. Induce alarm conditions to activate audible and visual alarms. Check that any associated interlocks (e.g., auto deflate) function. If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions that will be simulated later in this procedure. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Use of an improperly sized cuff can cause significant errors in measuring blood pressure. Clinical personnel should be instructed never to substitute an improper cuff. Verify that appropriate cuff sizes either are stored with the unit or are readily available (e.g., at a nearby nursing station). These should correspond to physical characteristics of the patients on whom the instrument is likely to be used (e.g., smaller cuffs in a pediatric area). All cuffs should be clean and in good condition with no torn stitching. Look for signs of degradation or cracking of the bladder. Check that Velcro closures hold firmly.


3

Inspection and Preventive Maintenance System If the unit has a printer/recorder, check to see that it operates when it is supposed to, that the paper folds smoothly, and that the printout is accurate and legible. 1.24 Deflation Switch. Confirm the operation of the control that enables manual deflation. 1.25 Operation on Volunteer. Apply the cuff to yourself or a volunteer, activate the unit, and verify that it cycles through the measurement correctly. Perform Item 2.4 at the same time (for major inspection).


2.2

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA.

2.3

Air Leakage. Wrap the cuff around a simulated limb. Inflate the cuff (use the calibration function) to about the maximum scale indication. Read the indicator after 1 min to determine the rate of pressure loss in mm Hg/min. This rate should not exceed 15 mm Hg/min. If it does, recheck all fittings and repeat the test. If a unit does not allow testing this way, an alternative leakage measurement can be used. Wrap the cuff around a simulated limb. Connect the blood pressure set to a calibrated gauge or meter as shown in Figure 1. The deflation rate should be 2 to 6 mm Hg/sec, unless the device has an algorithm that interpolates the reading between pulses. If the rate is faster, check all fittings and repeat the test.

4

Figure 1. Test setup. 2.4

Heart Rate. Connect the cuff to yourself or a volunteer. Displayed heart rate should correspond to manually palpated rate within 10%.

2.10 Pressure Accuracy. Connect the blood pressure set to a pressure gauge or meter as shown in Figure 1. Inflate the system to around 200 mm Hg with either the squeeze bulb or the unit’s calibration mode. The readings on the unit and the standard gauge should not differ by more than 3 mm Hg. Repeat the test for a pressure around 120 mm Hg and 80 mm Hg.


Clean as needed.

3.2


3.3

Calibrate per manufacturer’s instructions.

3.4

Replace tubing, hoses, connectors, cuffs, and batteries if needed.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following test. 4.1

Accuracy on Volunteer. Check the unit’s performance by comparing measurements made by a nurse to the blood pressure readings with the unit. The nurse’s reading and the unit’s reading should not differ by more than 10% mm Hg. Differences in readings may be due to technique, cuff location (i.e., right or left arm), and time (if not


Blood Pressure Monitors, Electronic Indirect taken simultaneously). If significant differences are obtained on repetitive tries, consider having another qualified person obtain the manual reading before contacting the manufacturer. 4.2

Auto Deflate Function. Using the simulated limb setup in Figure 1, inflate the cuff to the point of auto deflation activation. It should deflate at a point no higher than 330 mm Hg.

Before returning to use Make sure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Recharge battery-powered devices or equip with fresh batteries if needed.


5


Blood Pressure Monitors, Invasive Used For: Pressure Monitors, Blood, General/Invasive [16-764] Manometer Sets, Venous, Central/Peripheral [10-776]

Commonly Used In: Special care units, emergency department, operating rooms, cardiac catheterization laboratories; often included as a component of physiological monitoring systems Scope: Applies to invasive blood pressure monitors and is adaptable to other physiologic pressure monitors (e.g., uterine pressure monitors used in conjunction with fetal heart monitors) that use the same measurement principles; does not apply to noninvasive, indirect manual blood pressure measuring units (see Procedure/Checklist 424) or electronic indirect blood pressure monitors (see Procedure/Checklist 454); blood pressure transducers are covered in Procedure/Checklist 435 Risk Level: ECRI Recommended, High; Hospital Assessment, ECRI-Recommended Type Interval


Time Required

Major

12 months

months

.

hours

Minor

NA

months

.

hours

Electrical isolation of blood pressure channels [User Experience NetworkTM], 1986 Dec; 15:331.

Overview Monitoring blood pressure in addition to the ECG provides a more comprehensive view of cardiovascular status than the ECG alone can provide. However, invasive blood pressure monitoring requires more skill and involves greater risk. Blood pressure monitors are used to monitor systolic, diastolic, or mean arterial pressures, central venous pressures, and pulmonary artery wedge pressures.

Citations from Health Devices Blood pressure readings — Cuff versus monitor [Consultant’s Corner], 1977 Jul; 6:236. Air embolism during calibration of invasive blood pressure monitoring systems [Hazard], 1982 Nov; 12:22-5. Alternative in-use calibration techniques, 1982 Nov; 12:24. Patient monitoring systems [Evaluation], 1985 MarApr; 14:143.


Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Transducer simulator Transducer connector (without transducer attached) or small-diameter probe for leakage current meter to gain access to terminals on monitor (acceptance testing only)

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection and preventive maintenance procedures or frequencies are recommended by the manufacturer.


●


Inspection and Preventive Maintenance System This procedure is applicable to a stand-alone blood pressure monitor or a pressure module or a section of a multiple-parameter physiologic patient monitor. You need not perform Items 1.2 through 1.7 each time a different monitoring function of a multiple parameter monitor is inspected; these tests are usually performed during the ECG Monitors inspection (see Procedure/Checklist 409) and are recorded on that form. For efficiency, test all the monitors in one area with a transducer simulator (these devices were evaluated in Health Devices 1980 Jan; 9:59) or one transducer that is known to be accurate; then test all the transducers in that area (see Procedure/Checklist 435) using one monitor. When filling in the identifying information at the top of the form, include the control or serial number of the transducer used to test the monitor (unless a simulator is used). Testing the accuracy of blood pressure monitors and transducers presents a practical problem. Clinical requirements for blood pressure measurements call for an accuracy of ±5% for arterial pressure ranges and ±2 mm Hg for venous or pulmonary pressure measurements. Since the criteria apply to the measurement system, both the monitor and the transducer must be more accurate than this. Therefore, we recommend using a pressure simulator for testing pressure monitors. The simulator can be used to test monitor accuracy alone, without the need to maintain a well-calibrated pressure transducer. Moreover, the cost of a basic static pressure simulator is less than the cost of a pressure transducer. Also, a transducer alone cannot be used to establish the accuracy of the monitor. As long as the transducer-monitor combination is accurate to within 5% or ±2 mm Hg of a given static pressure, the monitor and transducer can be considered acceptably accurate. We have found that most pressure monitor and transducer problems result in either complete failure of the unit or relatively large errors.


1.2

2

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Mount. If the device is mounted on a stand or cart, examine the condition of the mount. If it is

attached to a wall or rests on a shelf, check the security of this attachment. 1.4

AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one.

1.6


1.7


1.9

Cables. Inspect the cables (e.g., reusable cables for disposable transducers) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Verify that the connector for the transducer cable is secure, clean, and lacks any signs of damage (e.g., cracks, bent connector pins, excessively worn pin receptacles). 1.11 Transducers. If they are normally stored with the unit, confirm that transducers are on hand, and check their physical condition. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be


Blood Pressure Monitors, Invasive Because some monitors do not compute the true mean, the indicated mean value may vary depending on the waveform and monitor used.

sure to check that each control and switch performs its proper function. 1.18 Indicators/Displays. During the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays. Be sure that all segments of the digital display function.


1.19 User Calibration. Verify that the zero-adjustment and any calibration controls function properly. Zero the monitor with a transducer or transducer simulator attached, making sure that the zero adjustment is not at an extreme setting. Confirm that the calibration function operates and that the calibration or gain adjustment, if user adjustable, provides an adequate range on both sides of the correct adjustment point. Some monitors have a calibration resistor inside the transducer cable connector. With such units, the monitor’s calibration function will not operate with a transducer simulator, which does not usually include this calibration resistor. Use the transducer intended for use with the monitor for this test. 1.20 Alarms. Operate the device in such a way as to activate each audible and visual alarm. If the monitor has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. Although it may not be possible to verify the operation of all alarms at this time (e.g., high blood pressure), it is important to understand all of the alarm capabilities and remember to check them at the appropriate time during the procedure. 1.24 Pressure Modes. Verify that the monitor correctly indicates systolic, diastolic, and mean arterial pressures by switching the transducer simulator between two pressure settings and noting that the indicated pressure in the systolic mode is highest, the mean pressure lower, and the diastolic pressure lowest. The pulse pressure, if available, should be the difference between the systolic and diastolic pressures. (A more quantitative and reproducible test can be performed if a transducer simulator with a dynamic pressure waveform output is available. However, the qualitative test is adequate, and we do not recommend purchasing a dynamic simulator solely for this purpose.)

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and nonanodized) metal on the chassis. We recommend a maximum resistance of 0.5 Ω. If the system is modular, verify grounding of the mainframe and each module. If the device has an accessory outlet, check its grounding to the main power cord.

2.2

Leakage Current. Measure the leakage current from the monitor chassis with the grounding conductor temporarily opened. Check the monitor while on and off and record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA.

2.10 Accuracy, High (Arterial) Pressure Range. This test checks the monitor’s accuracy and linearity. The most convenient method for testing the monitor’s accuracy is with a transducer simulator that contains a resistive network. Plug the transducer simulator into the monitor and zero it. Test pressures are 100 mm Hg and maximum (or 200 mm Hg) for the systolic, diastolic, and mean arterial modes. Normally, the monitor will read approximately the same in each mode. Record values from only one mode (the least accurate), and indicate on the form which mode was recorded. When using a pressure simulator, the pressure monitor should measure to within 2% of a given static pressure (or 1 mm Hg at pressures below 50 mm Hg). Although considerably less convenient, an accurate pressure transducer, a 0 to 300 mm Hg pressure gauge or meter, a sphygmomanometer squeeze bulb, a Y connector, and tubing may be substituted for the transducer simulator. Connect the stem of the Y connector to the transducer and the Y connector arms to the sphygmomanometer squeeze bulb and pressure gauge (see Figure 1). The monitor should be zeroed as it normally is during clinical use (with the transducer open to atmospheric pressure). Be sure that the dome is properly attached to the


3

Inspection and Preventive Maintenance System respectively), and test for the actual alarm values by varying the applied or simulated pressure. Record the actual values on the form. Alternatively, set appropriate applied or simulated pressures and raise and lower the high and low alarm settings, respectively, until the alarm activates. The unit should alarm within 5% of the set value. Many monitors have an alarm delay (up to about 11 sec), which must be taken into account when conducting this test. If the alarm delay is excessive, compare it to the manufacturer’s specification and arrange for adjustment or repair, if appropriate. Figure 1. Pressure accuracy test

3. Preventive maintenance

transducer, especially if a disposable dome is used. Test the monitor as described previously.

3.1

The overall accuracy of the transducer monitor system should be within 5% of a given static pressure (or 2 mm Hg at pressures below 50 mm Hg). If the error is excessive, determine whether it is introduced by the transducer, monitor, or both by using another transducer (or pressure simulator) to test the monitor or another monitor to test the transducer.

Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. Determine whether the unit is of an isolated input design to decide on appropriate leakage current limits from each transducer connector terminal to ground. If not labeled on the front panel, check with the manufacturer to see if the monitor is rated for this type of isolation test before proceeding.

2.11 Accuracy, Low Pressure Range. Repeat the pressure accuracy test, as described in Item 2.10, for the venous and pulmonary ranges. Be sure the monitor is accurately zeroed in each range before taking measurements. Suggested test pressures are 10 mm Hg and maximum (or 20 mm Hg). Accuracy should be within 1 mm Hg if a blood pressure transducer is used or 2 mm Hg if a transducer is used.

Perform the isolation test only if your monitor is designed with patient input isolation from ground. Some blood pressure monitors rely upon isolation at the transducer, rather than having isolated electronic circuitry; performing this test on such a monitor may damage the unit. If it is of isolated design, measure the currents to each transducer connector terminal.

2.12 Alarm Accuracy. Set the alarm at appropriate low and high settings (e.g., 100 and 180 mm Hg,

Return alarms and other controls to their preinspection settings.

4

Clean the exterior.

4. Acceptance tests




Blood/Solution Warmers Used For: Warmers, Blood/Solution [10-447]

Also Called: Blood warmers, fluid warmers, solution warmers Commonly Used In: Operating rooms, anesthesia departments, emergency departments, critical care areas, blood banks Scope: Applies to all types of warmers that heat blood or solutions in-line as they pass from the fluid bag or infusion device to the patient; does not apply to unregulated water bath warmers (i.e., those with little or no control over bath temperature) typically used for warming and/or thawing blood products in the clinical laboratory or to pretransfusion microwave (radio-frequency) warmers Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Blood/solution warmers are typically categorized by the method of in-line heat transfer they use to warm incoming solutions. Types of heat exchangers include countercurrent fluid flow, dry heat, forced air, microwave, and regulated water bath technologies. Countercurrent devices pump heated water around the blood or solution in a direction opposite to its flow. Dry heat warmers use a disposable cassette, pouch, or tubing set positioned against one or two heated metal surfaces. Forced air units utilize convective warming by pumping heated air around a disposable tubing set. Microwave devices control blood or solution temperature through the use of noninvasive radiometric sensing, allowing immediate power adjustment. Regulated water bath units typically consist of a disposable bag or coiled tubing immersed in a controlled temperature bath. Blood/solution warmers are generally used in the operating room by the anesthesia staff. Clinicians disagree on when a blood/solution warmer should be used for patient thermoregulation. Only under certain



Time Required

circumstances, such as during massive (generally accepted to be five units or more) and/or rapid transfusion, is it widely agreed that blood/solution warmers should be used. In these applications, effective blood/solution warmer operation is crucial. Should a temperature controller malfunction and allow the blood to overheat, damaged or lysed red blood cells can be delivered to the patient. Although overtemperature alarms are considered a necessary feature, some units lack them. Hospitals should replace such units with units equipped with alarms. Failure of the heater to adequately warm blood could significantly lower body temperature and further compromise the patient. Thus, periodic inspection of these units is particularly important to detect a malfunction likely to escape the user’s attention. Manufacturers should provide fluid output temperature data as a function of flow rate through a disposable set. Clinicians use such information in considering the actual contribution of a blood/solution warmer to patient thermoregulation. Although not required as a routine inspection procedure, assess-


●


Inspection and Preventive Maintenance System ment of this performance characteristic is covered in an acceptance test (Item 4.2). Data from this testing should be used in evaluating a unit for purchase.

Citations from Health Devices Blood warmers [Evaluation], 1984 Jul; 13:191-219.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer A mercury-in-glass calibration thermometer or electronic thermometer accurate to at least ±0.2°C over the range of 30° to 45°C Blood/solution warmer disposable set Wire or jumper leads Silicone heat sink compound or other thermally conductive medium (use on thermometer or temperature probe for better contact with heat exchanger in dry heat warmers) Hot (50° to 60°C) and room temperature water General-purpose infusion pump and infusion set Fluid container (0.5 to 1.0 L) filled with refrigerated (4° to 6°C) saline

Special precautions Caution: Treat blood warmers as contaminated devices. Follow manufacturer-recommended decontamination procedures; also see “IPM Safety,” behind the Guidance Tab of this binder, for infection control guidelines. Many warmers have special temperature measurement ports or accessories to assist biomedical personnel in determining heat exchanger temperature and alarm settings. However, even when properly used, these options may not correctly reflect the actual heat exchanger temperature, and the measurements obtained by these methods will not necessarily agree with the unit’s displayed temperatures. When using these options during quantitative inspections to determine display accuracy and alarm settings, check the service manual for correct thermometer or temperature probe placement and for allowable differences between measured and expected readings. Use a silicone heat sink compound to improve the contact between the thermometer or temperature probe and the measured surface. Be sure to remove the compound as soon as measurements are completed. If you find a slightly larger difference than expected between your measurements and the temperature values provided by the manufacturer, do not immediately remove the

2

unit from use; this may be due to test error or subtle differences in test methods. Contact the manufacturer to determine whether such a difference (e.g., >0.5°C beyond service manual limits) is acceptable. Testing alarms and thermostatic settings may require disassembly of the unit and temporary modification of the wiring. We hesitate to recommend such action as part of a routine inspection procedure because unskilled personnel may inadvertently damage the unit; however, there may be no other way to determine whether the backup thermostat or overtemperature alarms are functional. Unfortunately, for some units, temporarily bypassing the primary thermostat or similar control is the only way to determine whether backup or safety thermostats are functioning properly. Personnel responsible for inspecting blood/solution warmers must recognize their own limitations and, where appropriate, seek qualified help when performing this test. Return the unit to its normal operating condition immediately after completing the test. Perform the operating temperature test (Item 2.10 or 2.11) after the temperature protection test (Item 2.3) to help ensure that the device has been correctly returned to its proper operating condition.



Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact and are not cracked, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Check that all doors, hinges, and closure mechanisms work properly. Examine the interior surfaces where the disposable set will contact the heat exchange medium. Remove any corrosion, debris, or fungal buildup that may interfere with the temperature-sensing mechanism or heating of fluid in the disposable set.

1.2

IV Pole Mount. Examine mounting clamps, bolts, and other mechanisms for cracks and a secure fit. Verify that a water bath warmer is


Blood/Solution Warmers each control and switch performs its proper function. If the switch has a protective boot to guard against fluid infiltration, make sure that the boot is intact and protects the switch.

reasonably stable when filled with water and mounted on the IV pole. 1.3

1.4

1.5

Base Supports. If the warmer has a freestanding capability, check that all rubber feet or other supports are securely in place. Remount or reglue any loose supports to ensure stability and adequate clearance for any components (e.g., overtemperature alarms, reset features) that may be located on the base of the warmer. AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades and determine whether they are secure. Check for fluid infiltration in the plug. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it fully. Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. After any modifications, make sure that the line cord is long enough to preclude the need for an extension cord.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord; be sure that they hold the cord securely and that they have not become dislodged from the chassis of the unit.

1.7

Circuit Breaker/Fuse. If the warmer has a switch-type circuit breaker, check that it moves freely. If the warmer is protected by a fuse, check its value and type (as well as those of any spares provided) against that marked on the chassis or in the instruction manual.

1.11 Temperature Sensor (water bath units). The temperature sensor of a water bath unit may be located at the base of the water well. Inspect its sheath or surface for corrosion and mechanical integrity. Many units provide some form of protection or grid to isolate the disposable set from the temperature sensor and/or heaters. Confirm that the grid is in place and fits properly. Replace the grid if it is excessively corroded. 1.13 Controls/Switches. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that

1.14 Heater(s). If the heater component is readily available for visual inspection without disassembly, examine its physical condition (e.g., corrosion of its sheath, deteriorated insulation). Operate the warmer to ensure that it does heat up and that the display follows a reasonable pattern of increasing temperature. If the unit has an indicator light to show that the heater is operating, check that it functions normally. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. 1.20 Alarms. Many warmers have an alarm-test feature that activates their audible and visual alarms. If so equipped, operate the warmer, actuate this feature, and ensure operation of the high-temperature alarm. Otherwise, circulate hot water (50° to 60°C) through an installed disposable set, and verify that the alarm activates and that the heater cycles off. Most water bath units do not have an alarm-test feature, but the overtemperature alarm can be easily triggered by filling the well with hot water (50° to 60°C). 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm the adequacy of alarm volume. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.24 Alignment Features for Disposable Sets. Check for loose or missing pins, blocked channels, or missing guides that may hinder placement of the disposable set. Using the manufacturer’s instructions, position the disposable set and check that it is secure.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed bare (not painted or anodized) metal on the chassis. We recommend a maximum of 0.5 Ω.


3


2.3

Leakage Current. Measure chassis leakage current to ground with correct and reversed polarity wiring and with the grounding conductor temporarily opened. Operate the device in all normal modes, including on (while the heater cycles on and off) and off, and record the maximum leakage current. Leakage current should not exceed 300 µA. High-Temperature Protection. Determine the warmer’s various means of protection against overheating blood. If the manufacturer has provided a detailed method by which backup controllers and alarms can be tested, follow this procedure. Otherwise, obtain schematics and/or instructions to bypass the primary temperature control (see Special Precautions). If there are no procedures available, first bypass the primary temperature control in the warmer (by shorting or opening it, as appropriate) and turn on the warmer so that the heater is controlled by the backup mechanism. Follow the manufacturer’s recommended procedure for setting up the blood/solution warmer. With the thermometer or temperature probe in place within the heat exchanger, confirm that alarms go off at intended set points and that power to the heater is cut off at the intended settings. At no time should heat exchanger temperatures exceed 42°C. The difference between the values for alarm set points and backup control as given by the manufacturer and those observed on the blood warmer temperature display should not exceed 0.5°C. The difference may be greater for some units with alarms and backup control based on a thermostat with a lag. In these cases, check that the unit is not alarming at a point different from the point observed in acceptance testing, measure the actual heat exchanger temperature in several locations, and ensure that it does not exceed 42°C upon activation of the alarm. Caution: Remove any bypasses installed for this test. If any recalibration is carried out involving sealed potentiometer or thermostat screws, reseal them. When reassembling the unit, reseal the back or bottom plates or panels into place with silicone compound to prevent fluid infiltration.

2.10 Display Accuracy and Temperature Control. Most temperature displays on blood warmers indicate heat exchanger temperature, not the exiting temperature of blood or fluid. Therefore, in most units, it is necessary to measure only the heat exchanger temperature and compare it

4

with the displayed temperature to ascertain proper functioning of the display temperature sensors. (Applying power to some warmers when they lack a fluid flow through the unit’s disposable set may result in temperature overshoot and alarms that make assessing temperature sensor accuracy difficult. If, after reading the service manual, you find it necessary to establish a cold fluid flow through the disposable set before proceeding, perform Item 2.11 to determine display accuracy and temperature control.) To determine display accuracy and temperature control, position the thermometer or temperature probe against or within the unit’s heat exchange medium (some units require special accessories or have built-in ports for this purpose). If possible, position probes at three separate points within the heat exchanger and, if necessary, use a silicone heat sink compound to establish better thermal contact. (Remember to remove this compound and thermometer or temperature probe from the unit when finished.) The heat exchanger should be at room temperature before proceeding. Turn the unit on and compare the unit’s displayed temperature with the probe temperature(s) as the unit heats up and reaches a steady state. These temperatures should be within 1.0°C during warm-up and within 0.5°C during steady state. Observe the unit for 5 min at steady state for proper maintenance of heat exchanger temperature. Allow a total of 15 to 20 min to observe temperatures, because some warmers require 10 to 12 min to warm up and reach a stable heat exchanger temperature. 2.11 Temperature Controller Performance. (This procedure need not be followed if Item 2.10 can be successfully used to determine accuracy and temperature control.) Position the temperature probe against or within the heat exchanger, using any special adapters or ports designated for this purpose but insulated from the disposable set. Use refrigerated (4° to 6°C) saline and maintain a flow of 500 mL/hr through the unit with an infusion pump. During heat exchanger warm-up, compare the temperature displayed on the warmer with the thermometer at three separate points. If the probe has been successfully insulated from sensing the temperature of the cold fluid, the display and the heat exchanger temperature measurements should be within 1.0°C. Allow the warmer to stabilize for 5 min, and compare probe tempera-


Blood/Solution Warmers ture with the displayed temperature; the discrepancy should be within 0.5°C. Check that the operating range of the warmer, as determined from the display, conforms to values specified by the manufacturer.


Clean the unit’s exterior and heating plates or bath. Clean debris from door hinges. The interior of water bath units should be rinsed and dried after each use.

3.3

Calibrate if needed.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests. 4.1

Patient Lead Leakage Current. Prime the disposable set with saline, and allow a drip flow through the warmer. Measure the patient lead leakage current from a steel-hub hypodermic needle on the distal connector of the administration set to ground with correct polarity but with an open grounding pin. Operate the device in all modes, including on (while the heater cycles on and off) and off. Patient lead leakage current should not exceed 100 µA.

4.2

Fluid Temperature. (This procedure is optional, but may be particularly useful in evaluating a unit for purchase. It can be used to provide fluid output temperature data as a function of fluid flow.) To assess the warmer’s heating capability, select its maximum temperature setting and allow the unit to stabilize. Monitor and record ambient temperature (i.e., 18° to 22°C) for future comparison of results. Use a thermometer or temperature probe to measure the outflow temperature of refrigerated (4° to 6°C) saline at various flow rates corresponding to intended clinical applications or the manufacturer’s recommendations for use. Fluid temperature measurement should be at the end of the manufacturer’s disposable set or at the outlet of any extension tubing required to accurately simulate a clinical setting. Ideally, the unit should deliver fluids at 37° to 42°C at the highest flow setting that clinicians expect to use with this unit. If the unit’s heat exchanger exceeds 42°C, also measure the output fluid temperature as close to the heat exchanger as possible to verify that it does not exceed 42°C, as well. Record all output fluid temperatures and the corresponding flows for future reference.

Before returning to use Verify that any control circuits that were bypassed or deactivated for testing purposes have been returned to their normal operating conditions.


5


Capnometers and Multiple Medical Gas Monitors Used For: Carbon Dioxide Monitors, Exhaled Gas [16-938] Multiple Medical Gas Monitors [17-443] Multiple Medical Gas Monitors, Respired [17-444] Multiple Medical Gas Monitors, Respired/Anesthetic [17-445]

Also Called: Capnographs, end-tidal CO2 monitors Commonly Used In: Operating rooms, critical care units, emergency departments; portable units may be used by EMS Scope: Applies to monitors that analyze concentrations of respired and/or anesthetic gases, and that may also be equipped with additional capabilities, such as pulse oximetry or airway pressure and minute and tidal volume monitoring (inspection of the pulse oximetry capability is covered in Pulse Oximeters Procedure/Checklist 451) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Some manufacturers may recommend calibration at a semiannual or monthly interval.

Overview Carbon dioxide (CO2) monitors (e.g., capnometers) use infrared spectrometry to measure CO2 concentrations. Currently, CO2 monitors are used primarily in the operating room to monitor patients during anesthesia; the devices alert physicians to inadequate ventilation (i.e., minute volume that is too low), patient circuit disconnections, and airway leaks. CO2 monitoring can also detect ventilator failure and the inadvertent placement of the endotracheal tube in the esophagus. Interest in applying CO2 monitoring to intensive care mechanical ventilation is increasing, primarily to evaluate the effects of changing ventilation modes, of bronchodilator treatment effectiveness, and of the patient’s ability to breathe spontaneously after ventilator support is discontinued.


Capnometers, which are battery powered and lightweight, are suitable for emergency medicine (e.g., prehospital use, emergency departments, crash carts) and patient transport. These units are used clinically to detect esophageal intubation, monitor for and detect complete loss of ventilation or apnea, and assess respiration. Multiple medical gas monitors (MMGMs) incorporate monitoring of several gases, including CO2, along with other parameters such as pulse oximetry, respiration rate, and airway pressure. Information provided by MMGMs is easier to review, and an MMGM’s cost is lower than the combined cost of the monitors it replaces. Two types of MMGMs are available. Respired-gas MMGMs are used in critical care areas to monitor ventilation of mechanically ventilated patients and to


●


Inspection and Preventive Maintenance System assess the adequacy of their parenteral nutrient intake by tracking their metabolic rate. MMGMs that monitor respired and anesthetic gases are intended for use in the OR and can indicate malfunctions or disconnections in the gas delivery system and abnormalities in the uptake, removal, and delivery of gases.

mount. If it is attached to a wall or rests on a shelf, check the security of this attachment. 1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), affix the cord to the unit so that it cannot be removed by the operator. (See Health Devices 1993 May-Jun; 22:301-3.)

1.7


1.9

Cables. Inspect any cables and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

Citations from Health Devices Carbon dioxide monitors [Evaluation], 1986 Sep-Oct; 15:255-85. (See also 1986 Nov; 15:316.) Marquette Series 7000 capnometer [Update], 1987 Feb; 16:56. Hewlett-Packard Model 47210A capnometers [User Experience NetworkTM], 1987 Jun; 16:219. (See also 1987 Jul; 16:251.) Multiple medical gas monitors, respired/anesthetic [Evaluation], 1990 Feb; 20:43-54.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Calibration gas Stopwatch or watch with a second hand Flowmeter (0 to 1 L/min air)

Special precautions Exposure to waste anesthetic gas can be hazardous. Gases containing inhalated anesthetics (e.g., N2O, halogenated agents) should be scavenged.



1.2

2

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the

1.10 Fittings/Connectors. Examine gas sample inlet and exhaust port connectors, as well as electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that sensors and sampling lines are firmly gripped in their appropriate connectors. Fittings should be tight and should not leak. 1.11 Sensors/Sampling Lines. Examine these for general condition. If disposable sampling lines are used, verify that an adequate supply is available. 1.12 Filters. Check the condition of all gas (air) filters. Clean or replace if appropriate, and indicate this on Line 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., a gain control at


Capnometers and Multiple Medical Gas Monitors maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

displays a respiration rate and that the CO2 waveform indicates the breaths. 1.19 User Calibration. Verify that the calibration function operates. 1.20 Alarms. Induce each alarm condition with each procedure below, and verify that the unit activates an audible and visual alarm for each alarm limit that has been exceeded. If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. Verify that reset silenced alarms reactivate within the manufacturer’s specified time. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions that will be simulated later in this procedure.

1.15 Pump. Check the physical condition and proper operation of the pump. Clean and lubricate if required, and note this on Lines 3.1 and 3.2 of the inspection form. (However, do not check these items until all necessary cleaning and lubrication are completed.) 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage. Check the condition of the battery charger, and to the extent possible, confirm that it does in fact charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function and that the unit displays waveforms and trending information. Observe a signal on a CRT display, if present, and check its quality (e.g., distortion, focus, 60 Hz noise). Connect a clean airway adapter and sampling line to the unit, and blow several breaths into the adapter before stopping. Verify that the monitor

Gas concentration alarms. Set the gas alarm limits so that the concentration in the calibration gas will exceed the limits (i.e., set the high-concentration alarm limits below the calibration gas concentrations and the lowconcentration alarm limits above the calibration gas concentrations). Deliver the calibration gas to the monitor. Verify that visual and audible high-concentration and low-concentration alarms activate. Occlusion alarm. Block the sampling line, and observe the alarm. Other alarms. If the unit indicates any other alarm condition, induce the alarm, and verify that the alarm condition is indicated by the unit. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of breathing circuit adapters and sampling lines and, when applicable, water traps and filters.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin


3

Inspection and Preventive Maintenance System of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord. Chassis leakage current to ground should not exceed 300 µA.

2.3

Oxygen (O2) Concentration Display Accuracy. Deliver calibration gas containing O2 to the unit, and record the delivered and displayed O2 concentrations on the inspection form. The display should be within 2 vol% or within 5%, whichever is greater, of the delivered concentration. If the gas concentration display is inaccurate, calibrate the unit. Note: Vol% refers to the absolute value versus % of value. For example, a 5% (of value) error at 40 vol% of O2 is the same as a 2 vol% error.

2.4

2.5

4

Carbon Dioxide (CO2) Concentration Display Accuracy. Deliver calibration gas containing CO2 to the unit, and record the delivered and displayed CO2 concentrations on the inspection form. The display should be within 0.4 vol% (±3 mm Hg) or within 10%, whichever is greater, of the delivered concentration. If the gas concentration display is inaccurate, calibrate the unit. Halogenated Agent Concentration Display Accuracy. Select an agent on the monitor, and deliver

calibration gas containing that agent to the unit. Record the delivered and displayed agent concentrations on the inspection form. The display should be within 0.25 vol% of the delivered concentration. If the gas concentration display is inaccurate, calibrate the unit. 2.6

Nitrous Oxide (N2O) Concentration Display Accuracy. Deliver calibration gas containing N2O to the unit, and record the delivered and displayed N2O concentrations on the inspection form. The display should be within 5 vol% or within 10%, whichever is greater, of the delivered concentration. If the gas concentration display is inaccurate, calibrate the unit.

2.7

Sampling Flow Accuracy. Attach a flowmeter to the sampling inlet, and verify the sampling flow at the highest flow setting. The flow rate should be within the manufacturer’s specified range. If the manufacturer’s information is unavailable, the flow should be within 20% of the flow setting. Calibrate the unit per the manufacturer’s instructions, if the flow is inaccurate.


Clean if needed, including the internal sampling line if specified by the manufacturer.

3.2

Lubricate pump if required.

3.3

Calibrate if required per the manufacturer’s instructions.

3.4

Replace O2 cell, air filters, water traps, and the CO2 absorber, if needed. Record the replacement date on the O2 cell label before installing it in the monitor.


Before returning to use Make sure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Recharge battery-powered devices or equip them with fresh batteries if needed.



Carbon Dioxide Surgical Lasers Used For: Lasers, Surgical, Carbon Dioxide [16-942]

Also Called: CO2 lasers, surgical lasers, gynecology lasers, ENT lasers, neurosurgical lasers Commonly Used In: Operating rooms, short procedure areas, physicians’ offices Scope: Applies to general-purpose CO2 surgical lasers that include an articulating arm, emit mid-infrared energy at 10,600 nm, and provide sufficient power output to vaporize tissue; also applies to low- and high-power CO2 surgical lasers that are typically used for general surgery, gynecology, ENT, neurosurgery, podiatry, and dermatology procedures; does not apply to handheld CO2 lasers, other infrared lasers, Nd:YAG and argon lasers, and ophthalmic lasers; however, many of the tests listed herein can be used or modified for these other lasers Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview CO2 lasers are normally checked before each use by the laser’s power-on self-test and by user examination of the aiming beam and calibration of the system with the delivery system to be used. This minimizes the need for frequent additional periodic testing. Failure of a CO2 surgical laser can cause patient or staff injury, an abrupt interruption of a surgical procedure, or damage to the laser system. CO2 surgical lasers must be meticulously maintained to ensure proper and safe operation. CO2 surgical lasers affect tissue by focusing invisible, far-infrared energy at a sufficient power density to cause vaporization. This energy heats the water in the cells to the boiling point, which in turn vaporizes the tissue. The wavelength is readily absorbed by water and has little scatter in tissue. It cannot be transmitted through liquids (e.g., water, blood). CO2 surgical lasers are considered good cutting instruments.



Time Required

General-purpose CO2 surgical lasers have a flowinggas laser tube or a sealed or semisealed gas tube. Energy leaving the laser tube through a partially reflecting mirror is typically directed into an articulating arm. This arm contains a series of hollow tubes connected by knuckles at the ends to allow 360° rotation, with mirrors in the knuckles to redirect the energy down the next tube. A laser handpiece or a laser micromanipulator (used to interface the laser with the surgical microscope) is usually attached to the last tube of the articulating arm; these attachments focus the energy into a small spot size at a known working distance. Because the mid-infrared energy emitted by the CO2 laser is invisible, a second, nontherapeutic aiming helium-neon (He-Ne) laser emitting visible red light simultaneously traverses the articulating arm and is focused coincident (i.e., at the same point) with the CO2 laser beam. Some newer lasers have orange or yellow aiming beams. Like most lasers, CO2 lasers are somewhat inefficient in converting electrical energy from their standard 115 VAC source into laser energy of 0 to 100 W.


●


Inspection and Preventive Maintenance System As a result, excess heat is generated in the laser tube, requiring a cooling system. Some CO2 lasers use air cooling, although most use a combination water/air cooling system. Flowing-gas tube lasers require regulation of the pressure and flow of special gas mixtures. Hence, either an internal or external gas regulation system must be included. Flowing and semisealed lasers typically use a vacuum pump to maintain tube pressure.

Citations from Health Devices Lasers in medicine: An introduction, 1984 Jun; 13:15178. Lasers as investigational devices: Appendix A, 1984 Jun; 13:167-9. Lasers: Model policy and procedures statement: Appendix B, 1984 Jun; 13:169-71. Sharplan 733 carbon dioxide surgical lasers [User Experience NetworkTM], 1984 Sep; 13:291. Surgilase CO2 lasers [Hazard], 1987 May; 16:176. Lack of pin-indexing on laser gas supplies [Hazard], 1987 Jun; 16:216. Lack of pin-indexing on laser gas supplies [Hazard update], 1987 Aug; 16:286. Power requirements for Coherent Excelase 55 CO2 laser [User Experience NetworkTM], 1989 Oct; 18:365. Surgical lasers [Evaluation], 1991 Jul-Aug; 20:239-316. Loose caster screws on Sharplan lasers, 1992 Feb; 21:79.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Black Delrin block ≥1⁄2″ thick, ≥1″ wide, about 3″ to 4″ long; or firebrick Laser beam imaging media (e.g., thermal imaging paper, thermal imaging plates; wood tongue depressors may be an acceptable alternative) Laser radiometer (power meter) Laser safety signs Laser safety eyewear specifically designed for use with CO2 surgical lasers and of sufficient optical density to protect the wearer’s eyes from laser injury Vise with padded jaws or ring stand with padded clamp Outlet test fixture (optional)

2

Insulating gloves, high voltage (optional) Grounding strap (optional)

Special precautions Inspecting and maintaining lasers is a dangerous as well as necessary process, and far greater care is required than with most devices. Personnel who inspect or service lasers should receive special training from the manufacturer or from a qualified alternative training source. Laser energy can cause serious injury, particularly when the internal interlock is overridden or in any other situation in which the energy does not diverge significantly over long distances. Under some circumstances, the beam may not diverge significantly, even a full room length or more away from the laser (and can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser beam is accessible. Area security and use of personnel protective devices and practices should be consistent with hospitalwide laser safety procedures and/or should be approved by the laser safety committee. Wear appropriate laser safety eyewear at all times whenever the laser is in the Operating mode. WARNING: Laser safety eyewear may not protect the wearer from the aiming system light. Do not stare directly into the aiming system beam or the therapeutic laser beam, even when wearing laser safety eyewear. Avoid placing the laser beam path at eye level (i.e., when kneeling, sitting, or standing). (Window covers are not necessary with carbon dioxide lasers.) Do not perform these procedures when a patient is present or when clinical staff is working, and do not aim the laser across a path that a person might normally use as a thoroughfare. Furthermore, at minimum, post doors to the room with appropriate laser safety signs stating that the laser is in use and that it is unsafe to enter the room without authorization by the service person performing the procedure. A second person should be present, especially during procedures of recognized risk, to summon help in case of an accident. The laser should remain in the Off position when not in use. When in use, it should be in the Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser operation key and store it in a controlled location. Do not use the laser in the presence of flammable anesthetics or other volatile substances or materials


Carbon Dioxide Surgical Lasers and ensure that they have been turned off after the last use. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that all housings are intact and properly aligned, that assembly hardware is present and tight, that any retractable parts slide easily and lock in place if so constructed, that there are no signs of spilled liquids or other evidence of abuse, and that there are no obvious signs of water or oil leakage.

(e.g., alcohol) or in an oxygen-enriched atmosphere because of the serious risk of explosion and fire. Remove from the working area or cover with flame-resistant opaque material all reflective surfaces likely to be contacted by the laser beam. Whenever possible, use a firebrick or other nonflammable material behind the target material (e.g., black Delrin) when the laser is to be activated. A CO2 fire extinguisher should be readily available. Some surgical lasers use high voltages (e.g., 20 kV), which can be lethal. Capacitors may store charges long after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and avoid contact with any portion of the high-voltage circuit until you are certain that the charge has been drained. In such instances, a good ground must be present; preferably, use a redundant ground strap if you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to measure, drain, or insulate high voltages carries the appropriate insulation rating (e.g., above 20 kV).

Articulating arm. Examine the exterior of the articulating arm for cleanliness and general physical condition. Be sure that all hardware (e.g., laser gas tubing channels) is present, in good condition, and firmly attached. Ensure that the arm is properly counterbalanced and maintains its position without any motion after it has been moved and released. Ensure that each knuckle of the arm moves easily in each direction. Examine the distal end of the articulating arm to ensure that the mechanism (e.g., threads or quick-connect fitting) is in proper working order. Shutters. If manual shutters for the aiming or therapeutic laser are accessible, ensure that they operate smoothly and correctly. Be sure to leave the shutter in the proper position for normal operation.

Where possible, perform tests with the unit turned off. Because of the presence of high voltage, perform the Grounding Resistance Test (Item 2.1) before any other item that requires operation of the laser.

Telescoping columns. Examine the exterior of the telescoping column for cleanliness and general physical condition. Ensure that the column can be adjusted through its full range. If lubrication is required, note this on Line 3.2 of the inspection form.

Report any laser accident immediately to the laser safety officer or equivalent, as well as to the hospital risk manager.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and precautions needed to ensure safety and to avoid equipment damage. Also, determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

1.2



Chassis/Housing. General. Verify that the key has not been left in the laser. (Remove it if it has, and inform users of the importance of storing the key in a controlled location.) Examine any external gas tanks that may be in use with the laser,

Mounts/Holders. Check that the mounts securely contain the gas cylinders. Be sure that mounts or holders intended to secure the articulating arm to the chassis (to protect the arm when the unit is not in use) are present, in good working order, and being used. Similarly, check mounts or holders for other devices (e.g., external power meters, footswitch).

1.3



3


AC Plug/Receptacle. Examine the AC power plug for damage. Wiggle the blades to determine if they are secure. Shake the plug, and listen for rattles that could indicate loose screws. If you suspect damage, open the plug and inspect it.

1.5

Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord or, if the damage is very near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.6


1.7

Circuit Breakers/Fuses. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse(s), check its value and type against what is marked on the chassis or noted in the instruction or service manual. Ensure that a spare is provided or readily available.

1.8

Tubes/Hoses. Check the condition of all coolingsystem hoses and any other hoses or tubing the laser may have (e.g., drain, gas). Check that they are of the correct type; that they have not become cracked and do not show other signs of significant abuse; that they are connected correctly and positioned so they will not leak, kink, trail on the floor, or be caught in moving parts; and that they are secured adequately to any connectors.

used with. Verify that suitable connectors are supplied so that adapters are not required. 1.12 Filters. Check the condition of all liquid and air filters. Clean or replace filters according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi), and indicate this in the preventive maintenance section of the inspection form. Clean or replace air filters and radiators that are obviously dirty. 1.13 Controls/Switches.

1.9


1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical connectors, for general physical condition. Gas and liquid fittings should be tight and not leak. Electrical contacts should be straight, clean, and bright. Pin indexed gas connectors should be present. Ensure that no pins are missing and that the keying and indexing for each gas to be used is correct. If other hospital equipment will be attached to the connector, be sure that the connectors match. Lasers that connect to the central piped medical gas system or to a freestanding medical gas system should have the matching DISS or quick-connect fitting for the gas that it is to be

4

General. Before moving any controls, check and record their positions. If any position appears unusual, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical condition, secure mounting, and correct motion. If a control has fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from fingernails, pens, or surgical instruments). If you find such evidence, notify users to avoid using tape and sharp instruments. During the inspection, be sure that each control and switch works properly. Remote. Examine the exterior of the control for cleanliness and general physical condition. Be sure that plastic housings are intact, that assembly hardware is present and tight, and that there are no signs of spilled fluids or other serious abuse. If the remote control is attached by cable to the laser, ensure that the cable and any connectors are in good condition. Examine all controls and switches for general physical condition, secure mounting, correct motion, and intended range of settings. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs properly. Footswitch. Examine the footswitch for general physical condition, including evidence of spilled fluids. Footswitches for lasers include internal switches that activate according to the depth of pedal depression. It is usually possible to feel the vibration caused by closure of the switch, even through a shoe. Check that the internal switch is operating and that the footswitch does not stick in the On position. Some footswitches include two


Carbon Dioxide Surgical Lasers internal switches; in this case, verify the operation of both. During the procedure, check to be sure that the laser activates consistently when the footswitch is depressed. Flex the cable at the entry to the switch, and using an ohmmeter, check for internal wire breaks that might cause intermittent operation. During the procedure, check to be sure that the laser activates consistently when the footswitch is depressed. Confirm that strain reliefs are secure. Examine the male and female connectors for attaching the footswitch to the laser cabinet to be sure that no pins are bent and that no other damage is present. Ensure that the connector secures acceptably to the laser cabinet. 1.15 Motors/Pumps/Fans/Compressors. Check the physical condition and proper operation of these components. If lubrication is required, note this in the preventive maintenance section of the form. Clean any obvious dust from these components. 1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the manufacturer’s recommendations, and note this in the preventive maintenance section of the form. 1.17 Battery. If the remote control is battery powered, check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, verify proper operation of all lights, indicators, meters, gauges, and visual displays on the unit and the remote control. Ensure that all segments of a digital display function. Note any messages displayed during the power-on self-test. If primary and remote-control indicators and displays can be used at the same time or if control can be switched from one to the other during a procedure, operate the laser in a way that will verify that the same information (e.g., settings, displays) is indicated on both controls. If display screens or digital displays are provided for user prompts or for viewing accumulated

information (e.g., pulse or accumulated energy counter), ensure that each display provides the information expected. Ensure that user prompts occur in the proper sequence. Store some sample information, and verify that it is correct. If a feature to manually reset this information is available, ensure that it works. 1.20 Alarms/Interlocks. Operate the device in a manner that will activate the self-check feature, if present, and verify that all visual and audible alarms activate according to the manufacturer’s documentation. If no self-check feature is present, operate the laser in a manner that will activate each audible and visual alarm; be sure to test only those alarms that will not cause damage to the laser or present an unnecessary risk of laser beam exposure to yourself or bystanders. If a door or window interlock is used, ensure that it properly deactivates the laser. (Do not disassemble major parts of the laser to test internal interlocks.) After deactivating the laser and reclosing the door or window, check to be sure that the laser will restart. Be sure to check the interlocks in all locations where the laser is used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.) If the laser is equipped with an emergency “kill” switch, test this feature to be sure that it deactivates the laser and that the laser will subsequently restart. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., laser emission, setting change). Check for proper operation, and verify that the signal can be heard in the environment in which the laser will be used. 1.22 Labeling. Check that all placards, labels, and instruction cards noted during acceptance testing (see Item 4.3) are present and legible. Check to see that an instruction manual is kept with the laser or is readily available. 1.23 Accessories. General. Verify that all necessary accessories are available and in good physical condition. Set up each accessory with the laser to ensure compatibility and proper functioning. Checking all accessories during a single inspection and preventive maintenance procedure is unnecessary as long as accessories are routinely checked by the person(s) respon-


5

Inspection and Preventive Maintenance System are soluble in water. Carefully insert each lens into the micromanipulator, and ensure that it fits snugly.

sible for laser setup and operation. In addition, many of the accessories are sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person responsible for scheduling the use of the laser before beginning the procedure. Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness and general physical condition. Examine individually only those components that are intended for removal during normal use and storage. (Do not remove other parts that are press-fit or attached by screws, bolts, or snaprings.) If lenses are detachable, be sure not to touch the lens surface; handle lenses by the edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean lenses. Avoid exposing the lenses to water, since most CO2 lens materials are soluble in water. Ensure that major subcomponents of the handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the handpiece(s) to the articulating arm are in good working order and that they reliably secure each handpiece to the arm. Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness and general physical condition. Be sure to handle it by the main body; do not hold it by the joystick, and do not touch the reflecting lenses in the body. Inspect micromanipulators provided by both the laser manufacturer and the laser accessory manufacturers. Ensure that the reflecting lenses are intact and clean. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean reflecting surfaces and lenses.

Inspect the mechanism used to attach the micromanipulator to the microscope to ensure that all parts are present and that it is in good working order. Connect the micromanipulator to the microscope to check for a secure connection. Inspect the mechanism used to attach the micromanipulator to the articulating arm to ensure that it is in good working order. Connect the micromanipulator to the articulating arm to check for a secure connection. 1.24 Aiming Beam. Activate the aiming beam (without the therapeutic beam), and verify that it produces a round, uniformly bright spot with no halo. For handpieces that provide adjustable spot sizes, verify that the spot size changes as expected and still remains uniform. Check that the intensity control, if present, does change the brightness of the aiming beam. Similarly, check pulsing controls to verify that the aiming beam can be pulsed. If several color choices are available for the aiming beam, verify that each color is present and working properly. 1.25 Gas Regulators. Examine the gas regulators (if external to the cabinet) for cleanliness and general physical condition. Ensure that the gauges on the regulators are not broken. While performing the preventive maintenance items, ensure that the regulator and the gauge operate as expected. Verify that the correct gas is attached to each regulator. Be sure that a key or wrench to facilitate changing the gas supply is with the unit or readily accessible.



2.2

Leakage Current.

Examine the joystick to ensure that it is firmly attached and that it freely moves the reflecting lens. If a finger rest is present, ensure that it is firmly attached and properly oriented. If a zoom focus feature is present, be sure that it turns easily and does not slip. Examine each objective lens to ensure that it is intact and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean the objective lenses. Avoid exposing the lenses to water, since most CO2 lens materials

6

WARNING: Do not reverse power conductors for this or any other test. Improper attachment of conductors may damage the laser.


Carbon Dioxide Surgical Lasers Repeat Pulse settings, if adjustable. Some laser power meters can react quickly enough to be used to test this feature of the laser. If you are using such a power meter, test the laser to be sure that the correct power is repeatedly delivered over the correct time period.

With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the unit grounded and ungrounded. The leakage current on the chassis should not exceed 300 µA; in no case should it exceed 500 µA. Where it is greater than 300 µA, ensure that appropriate grounding is present. 2.3

Exposure Duration. Some laser power meters can measure pulse duration. If the power meters can react to pulse duration (this is the preferred circumstance), test the laser at each setting. However, if the laser power meter does not measure pulse duration, use the following less preferable alternative. Place and secure the laser handpiece with the aiming beam focused on the target material (e.g., black Delrin, a tongue depressor). With the laser set to about 5 W and the exposure setting at its minimum duration, activate the laser and create a burn. Carefully move the target material to expose a clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this process until you have tested all exposure settings, except continuous, and developed a series of burns. Compare the burns to verify that progressively larger burns occurred as the exposure duration increased (see Fig. 1).

2.4

If your laser power meter cannot be used for this test, use the following alternative test method. Set the laser to about 5 W and a 0.1 sec exposure duration with the fiber, handpiece, or micromanipulator attached, and verify that the Repeat Pulse feature operates as expected by moving the target material slightly between each pulse. Be extremely careful to keep hands out of the laser beam path. You should obtain a series of burn spots of similar density and size as long as you maintain the same handpiece-totongue-depressor distance and angle relationships for each exposure and as long as the laser is operating properly. If the number or duration between repeat pulses is adjustable, test that setting changes made throughout the range result in the expected performance.

Repeat Pulse. If the unit includes a Repeat Pulse feature, which repeats the pulse at a fixed or adjustable rate, test this feature with the laser set at the minimum, median, and maximum

Figure 1. Tongue depressor with laser burns produced during progressive exposure durations

2.5

Footswitch Exposure Control. Set the output time for about 5 sec, activate the unit, and release the footswitch after about 1 sec. Verify that the beam turns off when the footswitch is released.

2.6

Therapeutic and Aiming Beam Coincidence. CO2 surgical lasers include a He-Ne aiming laser and a CO2 therapeutic laser. These two lasers should create a spot at the same location. (It may be convenient to perform this test in conjunction with Item 2.7, since all reusable accessories will need to be checked for both coincidence and pattern.) First check beam coincidence and pattern with the microscope manipulator, since this will be more sensitive to misalignment and distortion problems. To check concentricity of the two lasers, position the micromanipulator so the lasing beam is perpendicular to the face of the wooden tongue depressor and focused to its smallest spot on the depressor. Circle the spot created by the aiming laser. With the laser set at about 5 W and an exposure duration of about 0.5 sec, activate the therapeutic laser, and compare the burn created by the therapeutic laser on the tongue depressor with the circled area. The burn and the circled area should overlap (although not necessarily be of the same size), and the center of the burn and the center of the circle should be in virtually the same location (see Fig. 2). The


7

Inspection and Preventive Maintenance System dirty mirror can disturb the beam pattern significantly and can affect the clinical performance of the laser. It is possible for the aiming and therapeutic lasers to appear to be concentric and to develop an even burn, despite a poor beam pattern; errors in mirror adjustment or dirt on the mirrors can qualitatively seem to cancel each other. (In this case, the maximum power [see Item 2.10] that can be developed usually drops. Comparing the results of this item’s testing with those of Item 2.10 can help to pinpoint the source of the problem.) Figure 2. Circled He-Ne aiming beam spot (shaded) and therapeutic laser spot (dark), demonstrating concentric alignment (left) and poor alignment (right) more the centers of the burn and circle diverge, the poorer the alignment, and the greater the risk that a surgeon will inadvertently irradiate unintended tissue. Lasers using mirrors in articulating arms are subject to beam wander, in which concentricity of the aiming and therapeutic laser may change as the physical orientation of the articulating arm (e.g., the angle or degree of rotation of one arm section in relation to another section or the chassis) changes. Hence, repeat this test with the articulating arm in several physical configurations. If the aiming and therapeutic lasers diverge significantly during any test, the system requires complete alignment. (Alignment is very difficult and should be performed only by qualified personnel.) Repeat this testing with each reusable accessory, including handpieces, laser laparoscopes, and laser bronchoscopes. Handpieces can be positioned and secured in the vise or ring stand. It is not necessary to test the effect of manipulating the articulating arm for each accessory. If a problem is found in beam alignment or pattern without a corresponding problem with the micromanipulator, the source of the problem is probably in the accessory. 2.7

8

Laser Beam Pattern. The spot created by a therapeutic laser beam perpendicular to the target should be circular, and the energy throughout the spot should be fairly uniform. Laser beam pattern is a measure of how well the mirrors of the laser tube, articulating arm, and handpiece are aligned and performing. A misaligned or

Beam pattern can be roughly assessed by evaluating the uniformity of a burn on a tongue depressor (as described in Item 2.6) or laser thermal imaging paper or by using thermal imaging plates. The surface of the thermal imaging plate is exposed to an ultraviolet light, and the surface fluoresces. When the therapeutic laser impacts the surface, the thermal energy creates a beam pattern that appears as a brown spot. Thermal imaging plates may provide an indication of beam pattern but do not provide a permanent record for later comparison, may be difficult to view with the aiming beam on, and may be easily damaged if accidentally overexposed. The plates are designed to respond to different power densities of CO2 laser energy. To minimize the risk of damaging a plate’s surface, always start with the least sensitive surface. Also, do not focus the beam on the surface. Position the target beyond the point of focus to expand the spot, thereby decreasing the power density in the spot. The beam must be perpendicular to the target surface. When using laser paper, the laser should be set at about 5 W and operated in the Pulsed mode at a 0.1 sec exposure setting or the nearest available setting. The burn (or spot on an imaging plate) should be fairly consistent in darkness throughout and circular in shape (see Fig. 3). Some laser delivery systems (e.g., micromanipulators) provide features that allow the user to change the spot size. Measuring absolute spot size from a laser is difficult, results are not always comparable, and the cost of equipment exceeds the expected benefits to an inspection program. However, measuring relative change in spot size caused, for example, by changing


Carbon Dioxide Surgical Lasers Because of the heightened risk associated with an unfocused, nondiverging laser beam, exercise great care if the interlocks are to be defeated. With the laser set at a low (e.g., 10% of full scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient period to acquire acceptable readings. (Power meters use different time constants to acquire an acceptable reading, and you must know and meticulously follow the power meter’s instructions for use.) Compare the reading obtained with the power display of the laser; the measured and displayed values should all be within 10% of one another. In addition, compare the reading with the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure; a significant change in output may indicate the need for service. If the laser includes a low-power (e.g., mW) feature, test it in a similar fashion with a power meter of appropriate low-power resolution.

Figure 3. Acceptable therapeutic beam pattern (left) and unacceptable (right) lenses or the aperture setting on micromanipulators is worthwhile and can be accomplished without undue cost. You can evaluate the change in relative spot size using either of the test methods detailed above (i.e., using a thermal imaging plate or laser paper). If you use different lenses to change the spot size, expose the thermal imaging plate or laser paper to the focused beam created when using each lens, and compare the relative spot size, spot shape, and beam uniformity of the images or imprints. If you use fixed points or continuously variable aperture control to change the spot size, expose the thermal imaging plate or laser paper to the focused beam created when the aperture control is set at its minimum, median, and maximum aperture settings. Compare relative spot size, spot shape, and beam uniformity. 2.10 Power Output. Place and secure the laser handpiece or aperture of the articulating arm at the appropriate distance from the laser power meter to meet spot-size requirements specified in the instructions with the meter. (Some power meters require that the aperture of the articulating arm be inserted into or placed in direct contact with the power meter. If the handpiece is used on these meters, the meter may be damaged by the high power density caused by the focused beam.) WARNING: Accessing the unfocused laser beam may require defeating internal interlocks.


Clean the exterior. Clean accessible optical components (e.g., microscope lenses) if necessary, using techniques and cleaning solutions recommended by the manufacturer.

3.2

Lubricate the telescoping column and any motor, pump, fan, compressor, or printer components with the lubricant recommended by the manufacturer.

3.3

Calibrate/adjust any components (e.g., printer) according to manufacturer recommendations. Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses and tubes are tight.

3.4

Replace filters, if needed. Check all fluid levels and supplement or replace fluids if needed.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. WARNING: Lasers may be damaged by switching between normal and reverse polarity while the device is on. If reverse-polarity leakage current measurements are made, turn off the unit being tested before switching


9

Inspection and Preventive Maintenance System polarity. Also, lasers powered by three-phase electrical systems may be damaged if proper electrical phase connections are not made initially and maintained thereafter. Thus, do not switch conductor connections or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical leakage current tests with reversed-polarity wiring.

proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction. 4.5

AC Plug. Verify that the plug is acceptable for use with the maximum current and voltage specifications for operating the laser. (Consult National Electrical Manufacturers Association [NEMA] configurations for general-purpose nonlocking connectors if in doubt.)

4.6

Pulse Duration. If the laser includes an enhanced pulse feature and the pulse duration is adjustable, verify that progressive increases in pulse duration throughout its range of adjustment result in progressively larger burns.

4.7

Repeat Pulse. If the laser includes a Repeat Pulse feature, test this feature as described in Item 2.4, but over the full range of available settings.

4.8

Power Range. Test the power output accuracy, using the technique described in Item 2.10, at several low, medium, and high settings. If the laser includes an enhanced pulse feature, verify that adjusting the power setting incrementally through its full range produces the expected effect on a tongue depressor. For all tests using high continuous-wave or Superpulse, it is particularly important to use a firebrick behind the tongue depressor for added safety.

The handpiece (which could conceivably come into contact with a patient’s heart) should meet the criteria for isolated input devices. Also test the ability of the laser to deliver laser energy as expected in all configurations and with all provided laser accessories. In addition, perform the following tests. 4.1

4.2

Areas of Use. Visit the area(s) in which the laser is to be used, and ensure that laser signs, laser safety eyewear, and window coverings are available and being used and that safety interlocks for doors or windows, if present, are functioning properly. Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over when pushed or when a caster is jammed on an obstacle (e.g., a line cord threshold), as may occur during transport. If the device is designed to rest on a shelf, ensure that it has nonslip legs or supports.

4.3


4.4

Electrical Wiring Configuration. Ensure that the branch circuits and the outlets for the laser are properly wired and rated for use with the laser. Examine the receptacles at each location where the laser is to be used to ensure that the

10

Before returning to use Be sure to return controls to their starting position, and place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using the unit.



Cardiac Resuscitators Used For: Resuscitators, Cardiac [13-361]

Also Called: External cardiac compressor, Thumper (registered trademark of Michigan Instruments, Inc., to be used only when referring to that device) Commonly Used In: Emergency departments, critical care areas, ambulances Scope: Applies to cardiac resuscitators; does not apply to cardiac presses that are not pneumatically powered Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

*An interval of 6 months should be considered if a resuscitator is frequently used and/or located in an ambulance.

Overview

Test apparatus and supplies

Pneumatically powered cardiac resuscitators are used during emergency cardiopulmonary resuscitation (CPR) as an alternative to manual cardiac compression. They can provide consistent cardiac compression, with adequate sternal depression and rhythmic compression rates, as well as oxygen-enriched ventilation. By eliminating the need to rotate personnel for the fatiguing task of cardiac compression, these devices reduce the number of people required to maintain support of the patient. Use of pneumatically powered cardiac resuscitators does not eliminate the need to train hospital and ambulance personnel in effective airway maintenance, manual external cardiac compression, and mouth-to-mouth breathing. In all cases, the patient must be maintained by manual techniques until the cardiac resuscitator is available, applied, and placed in operation.

Citations from Health Devices External cardiac compressors [Evaluation], 1973 Apr; 2:136-50.


Pressure gauge or meter with a range of at least 0 to 80 cm H2O Spirometer or gasometer Beam balance patient floor scale Stopwatch or watch with a second hand Ruler

Special precautions Never oil any part of an oxygen-powered cardiac compressor. Oil in the presence of oxygen is a dangerous fire and explosion hazard.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.


●


Inspection and Preventive Maintenance System make it more versatile for a wider range of patients.



1.2

Mount. If the device is mounted on a stand or cart, examine the condition of the mount.

1.8


1.10 Fittings/Connectors. Confirm that appropriate quick-connect fittings are being used with corresponding gases. Observe that pin-index safety system pins are present and intact. 1.13 Controls/Switches. Before moving any controls, check their positions. If any of them appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all indicators, gauges, and visual displays on the unit.

Use only transparent masks with resuscitators. If opaque masks are in use, order transparent replacements but do not remove opaque masks from use until replacements are available and the change has been discussed with users. Inspect the masks for signs of deterioration. Reinflate inflatable rims if they are collapsed, and check for leaks or damage by immersing the mask in water. Replace if necessary. 1.24 Ventilation Hose Fitting. Verify that the ventilation hose terminates at the patient end in a standard 15/22 mm coupling to allow connection to a standard ventilator mask and tracheal or tracheostomy tube. If it does not, an adapter should be provided.


Compression Rate with Ventilation. Using a stopwatch or watch with a second hand, count the number of compressions over a 1 min period. If the unit includes a ventilator, count the number of compressions per minute with it operating. The compression rate, unless otherwise specified by the manufacturer, should be in accordance with AHA/ARC two-person CPR standards (i.e., 60 to 80/min).

2.4

Piston Displacement. With the unit not operating, check that the compression piston moves freely in and out of its cylinder. The maximum displacement should not exceed 5 cm (2 in).

2.5

Compression Force. Position the compression piston on the weighing platform of a conventional patient floor scale by tilting the scale back and sliding the compressor base plate under the platform. If the scale is at a significant angle from its original position, use blocks or other objects to level it again.

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. List the accessories that are to be stored with each resuscitator. Check that the items on the accessories list are found with the resuscitator at each inspection. Examine all accessories for cleanliness and mechanical integrity. Cylinders. If an oxygen cylinder is stored with the resuscitator, check the amount of oxygen it contains. Maintain a full cylinder with the unit. A cylinder wrench should be chained to the regulator and yoke assembly. Masks. An assortment of masks (e.g., adult, infant) should be stored with the resuscitator to

2

Connect the compressor to its normal oxygen source. Set the scale to 45 kg (100 lb) and adjust the compression force control to its maximum point. Activate the compressor. It should raise the balance beam. 2.6

Ventilator Regulation. Determine if the ventilation gauge measures pressure (cm H2O) or volume (cc). If the gauge measures pressure, connect the ventilator output to a pressure gauge or meter or a water manometer and compare the


Cardiac Resuscitators measured ventilation pressure to that indicated on the gauge at 30 and 50 cm H2O. If the gauge measures volume, connect the ventilator output to a spirometer or gasometer. Compare the measured ventilation volume to that indicated on the unit’s gauge at the 1 L setting. The difference between measured and indicated values should not exceed 20%. (Such high errors are tolerable in short-term emergency equipment but would not be acceptable in other ventilators.) 2.7

2.8

Inspiratory Pressure. Connect the patient end of the ventilator tubing to a pressure gauge or meter. Adjust the ventilator control to its maximum setting and measure the maximum ventilatory pressure. It should not exceed 60 cm H2O. This test confirms operation of the inspiratory pressure-relief valve. Ventilator Volume Output. Connect the output of the ventilator to a spirometer or gasometer. Adjust the ventilator control to its maximum

setting and measure the maximum inspiratory volume. It should be at least 1.5 L. 2.9

Compression/Ventilation Ratio. With the compressor and ventilator operating, count the number of piston thrusts between each ventilation. There should be five compressions per ventilation.


Clean the exterior.

4. Acceptance tests Conduct major inspection tests for this procedure.

Before returning to use Make sure controls are set at normal positions and oxygen cylinders are turned off. Place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before use.


3


Centrifuges Used For: Centrifuges [10-778] Centrifuges, Blood Bank [15-115] Centrifuges, Cell Washing, Automatic [16-815] Centrifuges, Cytological [16-765] Centrifuges, Floor [15-116] Centrifuges, Floor, Nonrefrigerated [17-177] Centrifuges, Microhematocrit [10-779] Centrifuges, Refrigerated [15-117] Centrifuges, Tabletop [10-780] Microcentrifuges [17-452] Ultracentrifuges [15-193]

Commonly Used In: General clinical laboratories, as well as specific laboratory departments (e.g., blood bank, hematology, clinical chemistry) Scope: Applies to all types of centrifuges Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Centrifuges use centrifugal force to separate suspended particles from a liquid or to separate liquids of various densities. These liquids can include body fluids (blood, serum, urine), commercial reagents, or combinations of the two with other additives. Centrifugation is used for most sample preparations in a clinical laboratory. There are three general classifications of centrifuges: low speed (≤6,000 rpm), high speed (6,000 to 25,000 rpm), and ultraspeed (25,000 to 110,000 rpm). These three types of centrifuges are available as tabletop and/or floor models, and some are refrigerated units. Microhematocrit centrifuges are specialized centrifuges used in a hematology department to determine an accurate packed cell volume of red blood cells. The speed of a microhematocrit centrifuge ranges from 7,000 to 15,000 rpm.



Time Required

Certain hazards are associated with the operation of centrifuges. Sample tubes may break; breakage is most likely to occur if manufacturers’ instructions, such as using correct tube sizes and locations and using cushions, are not followed. Rotors may detach or fail, possibly because of a loose retaining nut or imbalanced tube placement; rotor or tube failures may result in operator exposure to physical or infectious hazards. Aerosols may be created from the samples. Or the operator may be harmed while attempting to slow down or stop the rotor by hand. Therefore, the lid should never be opened while the rotor is spinning, and safety inner protective lids should be used when available. Hazards also exist when the centrifuge is not in operation; for example, broken glass, possibly contaminated with blood, may be found inside the centrifuge during cleaning or IPM.


●


Inspection and Preventive Maintenance System In addition to careful adherence to use and maintenance instructions, equipment with appropriate safeguards should be used. As a minimum, units should have a lid and a latch that will prevent the lid from opening in the event of a failure while the rotor is spinning. A safety interlock, which permits the lid to be opened only after the rotor has stopped (or reached a very low speed), is preferred, and all new units should have this feature. Laboratory personnel are required by the College of American Pathologists (CAP) to do the following: Clean and properly maintain all centrifuges. (Note: Contact the manufacturer for guidance if the operator’s manual does not specify cleaning or disinfecting agents. Prolonged contact with some disinfection solutions [e.g., 10% sodium hypochlorite] may damage the rotor and other centrifuge components; ensure that such solutions are removed by rinsing well with water.) Check and record timer accuracy monthly. Check and record speed (rpm) accuracy monthly (critical use) or quarterly. Check and record built-in tachometer monthly. (Note: Operators should refer to CAP’s Laboratory Instrument Evaluation Verification & Maintenance Manual, 4th edition, 1989.)

Citations from Health Devices Tabletop centrifuges [User Experience NetworkTM], 1987 Feb; 16(2):55. IEC DPR-6000 refrigerated centrifuges [User Experience NetworkTM], 1987 Jul; 16(7):255. Missing roll pin from Beckman Spinchron centrifuge rotor [User Experience NetworkTM], 1992 May; 21(5):182. Risks from centrifuges [Hazard], 1992 Aug; 21(8):290. Improper sealing of Baxter Megafuge C1725-2 centrifuges [Hazard], 1992 Sep; 21(9):331. Centrifuges [Hazard summary], 1992 Dec; 21(12):459. Centrifuges [Hazard report summary], 1995 Apr; 24: 158-9.

Test Apparatus and Supplies Wrench to tighten the rotor nut Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Stopwatch or watch with a second hand

2

Electronic thermometer accurate to 0.5°C (for refrigerated units only) Tachometer or phototachometer

Special Precautions Check with laboratory personnel before performing any maintenance or shipping centrifuges to the manufacturer for repair. Laboratory personnel should have properly decontaminated the centrifuge. A centrifuge should be vacuumed out before any testing is started. (Broken glass, which may be contaminated with blood, is sometimes found inside. In addition, visible blood may be located on or in the centrifuge.) Be careful not to touch a spinning rotor if an interlock fails or if you are operating the unit with the lid open. NEVER attempt to stop a moving rotor with your hands or with a tool or object. Ensure that the centrifuge tubes are properly balanced and that the speed and tube length are in accordance with the tube and centrifuge manufacturers’ recommendations. Use proper-sized tubes for the rotor. If using a swinging-bucket rotor, ensure that the tubes are placed in accordance with the manufacturer’s instructions; long tubes (e.g., 100 mm) placed in the corner tube holders closest to the rotor shaft will probably break when the rotor buckets swing out. ALWAYS follow universal precautions when centrifuging blood or body fluids. These precautions include wearing gloves, face protection (e.g., shields), gowns or laboratory coats, and plastic aprons, and are described in detail in the National Committee for Clinical Laboratory Standards (NCCLS) Document M29-T2, Vol. 11, No. 14, Protection of Laboratory Workers from Infectious Disease Transmitted by Blood, Body Fluids, and Tissue (tentative guideline),* as well as in the Occupational Safety and Health Administration’s (OSHA) bloodborne pathogens standard.**

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. * This document can be obtained from the NCCLS, 771 E. Lancaster Ave., Villanova PA 19085; (610) 525-2435. ** Occupational exposure to bloodborne pathogens. Fed Regist 1991 Dec 6; 56(235):64004-182.


Centrifuges

1.1


1.2

Mount/Fasteners. If the device is mounted on a stand, examine its condition. If it rests on a shelf, check the security of the shelf. If units have suction-type feet, check the integrity of the feet.

1.4


1.15 Motor/Rotor/Pump. Check the physical condition and proper operation of these components. Check the brushes, commutator, and bearings of the motor. Check the condition of gaskets, seals, and mounts. Check the rotor for balance and the condition of trunnion bearings, and check the rotor attachment for tightness and excessive wear. (Note: If using an ultraspeed centrifuge, follow the manufacturer’s derating schedule for the rotor. It should be outlined in the operator’s manual.) Clean and lubricate components as required, and note this on Lines 3.1 and 3.2 of the inspection form (however, do not check these items until all necessary cleaning and lubrication are completed). If a unit has a vacuum or diffusion pump, check its condition, and perform appropriate maintenance according to the manufacturer’s specifications.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display illuminate and function properly.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), attach the cord to the unit so that it cannot be easily removed. (See Health Devices 1993 May-Jun; 22[5-6]:301-3.)

1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against those marked on the chassis and ensure that a spare is provided.

1.20 Alarms/Interlocks. Induce alarm conditions, and verify that alarms are activated. Refrigerated units should indicate whether the unit is at the appropriate temperature. Check the lid latching mechanism for wear, and verify that it holds the lid securely. A lid interlock should either shut off the motor when the lid is opened or keep the lid latched until the rotor has stopped. The centrifuge should not start with the lid open. If the lid can be opened with the rotor spinning at high speed, check for appropriate labeling on or near the centrifuge, warning the operator not to open the centrifuge lid during operation. If the lid can be opened while the centrifuge rotor spins at a low speed, the buckets or rotor should have an inner protective lid. Replace or modify any centrifuges that lack a latch. Do not use centrifuges that lack a lid; if a lid is retrofitted, it should have a safety latch.


1.13 Controls/Switches. Before changing any controls, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories (e.g., sample buckets, sample


3

Inspection and Preventive Maintenance System holders). Check for the proper type of accessory (e.g., proper-sized tubes for the buckets used). Check that every tube holder has a cushion. If protective lids for the buckets or the rotor (inner safety lid) are available for that model centrifuge, verify that they are kept with the centrifuges and are routinely used; also ensure that the protective lids form a tight seal and positively lock onto the bucket. 1.24 Brake. Check the action of the mechanical or electrical brake. When the brake is applied (e.g., by pushing the STOP button), the centrifuge should decelerate smoothly.


2.2

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. If the unit has heating and cooling modes, set the thermostats so that each operates while taking measurements. Chassis leakage current to ground should not exceed 500 µA.

2.10 Temperature Accuracy. Check the temperature control on refrigerated centrifuges using an electronic thermometer. Place the electronic thermometer probe in the centrifuge bowl near the automatic temperature control sensor. (Refer to the manufacturer’s specifications to determine where the temperature control sensor is located.) Close the centrifuge, sealing the gasket around the thermometer cable. Compare the temperature control with the electronic thermometer at each setting or at the settings being used. The readings should not differ by more than ±3°C. 2.11 Timer Accuracy. Check the timer against a stopwatch or watch with a second hand. A centrifuge

4

should not vary by more than ±10%. Depending on various state regulations, this value may need to be recorded on the inspection tag. 2.12 Accuracy of Speed Setting. Determine the range of speeds at which the centrifuge is used and a typical load (e.g., number of filled containers). Set the centrifuge to two or three speeds, and measure the different speeds using a tachometer. If a unit has an opaque cover, refer to the manufacturer’s service manual to check the speed accuracy. (Note: A vibrating reed-type tachometer may be used with most centrifuges with opaque covers.) The measured speed should not vary by more than ±10% of the displayed speed. (Note: If brushes have been changed, check speed settings after brushes are properly replaced.)


Clean exterior (interior if appropriate).

3.2


3.4

Replace brushes, brake, gaskets, seals, and vacuum pump, if needed. (For the proper procedure for replacing brushes, refer to the manufacturer’s manual and to the CAP Laboratory Instrument Evaluation Verification & Maintenance Manual.)

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. All new centrifuges should have a lid and a safety interlock that prevents the lid from being opened while the rotor is spinning at high speeds. Purchase only those centrifuges on which the rotor stops completely before the lid can be opened and/or, for units that operate at a low speed, those that have a protective lid for the buckets or an inner safety lid for the rotor. Give preference to those centrifuges that have protective lids for the buckets or rotor. If the units being purchased allow the lid to be opened while the rotor is spinning at low speeds, protective lids should be included.

Before Returning to Use Make sure controls are set in their normal pre-use positions. Attach a caution tag in a prominent position to alert the user that control settings may have been changed.



Circulating-Fluid Pumps Used For: Pumps, Circulating-Fluid, Localized Heat [17-647]

Also Called: Heating pads; K-Module, a registered trademark of Baxter to be used only when referring to that device; T-Pump, a registered trademark of Gaymar Industries Inc. to be used only when referring to that device Commonly Used In: Most patient care areas Scope: Applies to circulating-fluid heating pad pumps Risk Level: ECRI Recommended, Low; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

NA

months

.

hours

Time Required

Overview


Circulating-fluid pumps and pads are used for applying long-term mild heating to the skin.

Circulating-fluid pumps and heating pads [Evaluation], 1989 May; 18:154-73.

A fluid pump consists of a reservoir that holds a supply of distilled water; a heater, mounted in the reservoir, that warms the fluid; a pump that circulates the fluid to the heating pad; a controller that maintains the fluid temperature; and safety devices that deactivate the unit if the fluid temperature exceeds the maximum allowable temperature limit. The pump circulates the distilled water through a plastic pad; the pad is placed under or on the skin to allow conductive heat flow. Heating pads are available in three types: all-plastic single-patient-use, some of which can be reused; covered single-patient-use, which have a layer of fabric bonded to their surface; and all-plastic reusable, made from thick plastic sheets to resist wear and improve durability (these come with a repair kit). Pads are constructed from two plastic sheets that are heat-sealed together; each manufacturer uses a unique flow pattern.


Circulating-fluid pumps and heating pads [Evaluation Update], 1989 Dec; 18:418. Circulating-fluid pumps: Do not use for ECMO [Hazard], 1992 Jan; 21:39.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Shunt thermometer with appropriate connectors to install in series with the pump and heating pad to check the temperature of the circulating fluid (temperature calibration assemblies may be available from manufacturers of circulating-fluid pumps and may be used in place of the temperature-measuring procedure described in Item 2.4) Flowmeter (0 to 20 gallons per hour [gph] range) with water Heating pad


●


Inspection and Preventive Maintenance System portion. Be sure to wire a new power cord or plug with the correct polarity.

Special precautions Some testing requires disabling temperature control circuits; to avoid damage to the unit, this testing should be performed only by qualified personnel familiar with unit design. Although we hesitate recommending such wiring modifications as part of a routine inspection procedure because unskilled personnel may inadvertently damage the unit, there may be no other way to determine whether the backup thermostat or overtemperature alarms are functional. Personnel responsible for inspecting heating pads must recognize their own limitations and, where appropriate, seek qualified help when performing this test. Return the unit to its normal operating condition immediately after completing the test. Performing the operating temperature test (Item 2.4) after the high-temperature protection test (Item 2.3) will help ensure that the device has been correctly returned to its proper operating condition.



Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse.

1.2

Mount/Fasteners. If the device is mounted on a stand or bracket, examine the condition of the mount. Verify that the mounting apparatus is secure and that all hardware is firmly in place. Check for weld cracks. Ensure that the assembly is stable.

1.4


1.5

2

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or, if the damage is near one end, cut out the defective

1.6


1.7


1.8


1.10 Fittings/Connectors. Examine liquid fittings and connectors, as well as all electrical cable connectors, for general condition. 1.13 Controls/Switches. Before moving any controls, check their positions. If any of them appear inordinate (e.g., a temperature control at maximum), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.14 Heater. Operate it to be sure that its controls function properly (e.g., that a variable temperature control does, in fact, determine the amount of heating; that On/Off controls work). Verify that the pad warms up when the unit is operated to ensure that the heater and the pump are functioning. 1.15 Motor/Pump/Fan. Check physical condition and for proper operation. 1.16 Fluid Levels. Check all fluid levels. Replenish any fluids that are low. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, or visual displays on the unit.


Circulating-Fluid Pumps Determine from the manufacturer’s literature how backup thermostats can be tested. Connect the shunt thermometer in series with the input line to the heating pad. Record the maximum water temperature for each backup thermostat, and note any alarms or indicators. Maximum temperatures should be within the manufacturer’s specified range, but should not exceed 43°C. Remove any bypasses installed for this test.

1.20 Alarms. Many units have low-water-level and high-temperature alarms. Operate the unit in such a way as to activate the low-water-level alarm and any other audible and visual alarms (e.g., tilt). Verification of the high-temperature alarm requires abnormal operating conditions that will be simulated in Item 2.3. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Verify that the pad is clean, free of leaks, and stored without sharp folds or creases. Also verify the presence and operation of a key for adjusting fluid temperature.


2.2

2.3

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. Leakage Current. Measure chassis leakage current to the chassis of the device with the grounding conductor temporarily opened. Operate the device in all normal modes, including on (with the heater operating) and off, and record the maximum leakage current. Leakage current should not exceed 300 µA. High-Temperature Protection. Circulating-fluid pumps should have high-temperature protection (backup thermostats) to limit the water temperature if the main temperature control fails.

2.4

Operating Temperature. Operate the pump at 37°C and at maximum control settings with the thermometer shunt still installed as in Item 2.3. Actual water temperature should be within 1°C of the set temperatures.

2.5

Flow. Remove the temperature shunt, and place a flowmeter (0 to 20 gph range) in series with the input line to the heating pad. Record the flow rate. The flow should exceed the minimum flow specified by the manufacturer.


Clean the exterior.

3.4

Flush/fill the reservoir, if needed.


Before returning to use Verify that any control circuits that were bypassed or deactivated for testing purposes have been returned to their normal operating condition.


3

Procedure/Form 441-0595

Conductive Furniture and Floors Used For: Flooring, Conductive [15-832]

Used In: Operating rooms, other flammable anesthetizing locations Scope: Complies with the requirements for periodic testing of conductive casters on equipment and furniture used in flammable anesthetizing locations and conductive flooring installed in these areas

Type



Major

1 month*

months

.

hours

Minor

NA

months

.

hours

Time Required

*

This procedure is not required in areas where flammable anesthetics are no longer used and where the floors have been treated to make them nonconductive.

Overview Some inhalation anesthetics (e.g., cyclopropane, diethyl ether, ethyl chloride, ethylene) are flammable and pose a considerable fire and explosion risk when mixed with air, oxygen, and nitrous oxide. The most likely ignition source for these gas mixtures in the operating room or other flammable anesthetizing locations is a spark caused by an electrostatic (static electricity) discharge. Other possible sources of ignition include heating or sparking in electrically powered devices, electrosurgical or electrocautery equipment, and percussion sparks. Conductive floors and electrical interconnection of all furniture and devices with conductive surfaces minimize the risk of electrostatic charge accumulation and resultant spark. NFPA 99, Standard for Health Care Facilities, 1993 Edition, Section 12-4.1.3, contains requirements calling for all furniture and devices located in a flammable anesthetizing location to have conductive casters (or equivalent means) to ensure continuity with the conductive flooring.


Unlike the requirements for grounding medical devices to ensure safety from electrical shock, low resistance is not required for conductivity established for the purpose of electrostatic control. Rather, it is sometimes preferable to ensure that a certain minimum level of resistance be maintained to minimize electric shock hazards. For example, conductive flooring for this purpose is required to offer an average resistance of at least 25,000 Ω and less than 1 MΩ. Flammable anesthetics were once a necessary part of surgery; however, nonflammable inhalation anesthetics are now available and are used in most cases. Flammable anesthetics are used only for rare circumstances (e.g., where a flammable anesthetic is claimed to offer some pharmacologic advantage or a physician is familiar with a flammable anesthetic and unwilling to change technique). In areas designated and posted for the use of only nonflammable anesthetics, antistatic precautions are not required. Equipment or furniture with conductive casters can be used in nonflammable anesthetizing locations, but conductivity need not be maintained or


Inspection and Preventive Maintenance System measured. Conductive floors in nonflammable anesthetizing locations, unless they are treated to make them nonconductive, must be inspected to ensure that each of the five floor-resistance measurements in each room yields a reading of 10,000 Ω or more to minimize electric shock risk from an excessively conductive floor. No further testing is required once this criterion is met. ECRI recommends treating or replacing floors to make them nonconductive, especially if the power supply is changed from isolated to grounded.

Test apparatus and supplies High-voltage megohmmeter intended for this type of application, which has an open-circuit voltage of 500 VDC and meets the requirements of NFPA 99 Two 5 lb, 21⁄2″ diameter circular electrodes that meet the requirements of NFPA 99 Metal plate and insulating plate or sheet (for caster conductivity tests)

Special precautions The megohmmeter used for this testing is capable of shocking personnel. Never touch the leads or equipment under test when the ohmmeter is activated.

Procedure Equipment/Furniture. Inspect leg tips, casters, or other conductive devices on furniture and equipment to ensure that they are free of wax, lint, or other materials that interfere with conductivity. Lubricate casters if needed with dry graphite or graphited oil. Avoid excessive lubrication, since this can cause accumulations of oil and grime on caster wheels and sides. Test conductive casters, chains, or other mechanisms by placing one caster on a metal plate that is insulated from the floor. The resistance between the metal plate

2

and metal frame or chassis should not exceed 250,000 Ω. Only one caster need meet this requirement to ensure continuity and to conform with NFPA 99; however, we recommend testing all casters during initial acceptance testing of the device or furniture. For convenience, perform routine periodic tests of furniture and equipment conductivity by placing one of the 5 lb electrodes on the conductive floor and another on the furniture or equipment. Unplug the device (and remove any nonpermanent grounding straps). The resistance should not exceed 5 MΩ; if it does, perform the entire inspection procedure. Indicate on the form whether floor-to-frame or caster-to-frame tests were performed. It is not necessary to record the resistance value, but space is provided on the form if it is desired in the event of a failure. Conductive floors. Make sure that the floor is clean and dry. Place the electrodes 3 ft apart on the floor, and measure and record the resistance between the two electrodes and from one electrode to a ground point (e.g., grounding jack, grounded exposed metal in the room). Measure the resistance at five different locations in the room, and average each set of five readings. Each of the five individual floor resistance readings should be no greater than 5 MΩ and no less than 10,000 Ω, and the average should be no greater than 1 MΩ and at least 25,000 Ω. Each measurement from the floor to a ground point should be at least 10,000 Ω, and the average resistance should be at least 25,000 Ω. Conductive flooring is not required in nonflammable anesthetizing locations. However, if a conductive floor is present, test as above. No individual reading should be less than 10,000 Ω. If the floor does not meet this criterion, test the floor conductivity every month until the condition is corrected. No further testing is required once the criterion is met.


Conductive Furniture and Floors


3


Critical Care Ventilators Used For: Ventilators, Intensive Care [17-429] Ventilators, Intensive Care, Neonatal/Pediatric [14-361] Ventilators, Pressure-Cycled [14-360] Ventilators, Transport [18-098]

Also Called: Respirators Commonly Used In: Critical care units, general medical/surgical units, emergency departments Scope: Applies to all ventilators except jet ventilators, negative-pressure ventilators, portable ventilators (see Procedure/Checklist 471), and anesthesia unit ventilators (see Procedure/Checklist 461) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

6 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Inspection and preventive maintenance intervals should be scheduled according to the manufacturer’s recommendations, which may be related to hours of use. However, units should have a major inspection at least every six months. Pre-use checks should be performed by a respiratory therapist or respiratory equipment technician.

Overview Mechanical ventilators are used to compensate for deficiencies in normal breathing. A ventilator may aid or augment spontaneous breathing or may completely regulate a prescribed breathing pattern for patients who cannot breathe for themselves. Most modern ventilators use positive-pressure inflation of the lungs to accomplish these functions. Ventilators are classified according to the method in which ventilation is accomplished. Most adult ventilators are volume cycled, in that they are set to deliver a predefined volume of gas to the patient. Most infant ventilators are time cycled, in that they are set to deliver gas for a predefined inspiratory time. A pressure-cycled ventilator delivers gas until a predefined pressure is reached. Volume- and time-cycled ventilators also have a pressure-limit control to prevent the


attainment of dangerous pressures in the patient’s lungs. The ventilator provides direct control of the patient’s ventilatory variables, as well as other variables (e.g., the concentration of inspired oxygen), and the limits on certain variables for safe operation. All these controls allow the clinician to provide better patient management, even for patients with serious respiratory impairments. A mechanical ventilator is composed of four basic subsystems: the ventilator and its controls; monitors and alarms; gas supply; and patient circuit (which includes the breathing circuit and may include a humidifier and nebulizer). Each subsystem requires its own inspection and preventive maintenance procedures. Many microprocessor-controlled ventilators have self-diagnostic programs. When the ventilator’s


●


Inspection and Preventive Maintenance System hardware (e.g., solenoid valves, transducers) is checked by its own software, manual inspection items can be eliminated.

Citations from Health Devices Inadequate pressure relief in infant ventilators [Hazard], 1983 Apr; 12:150-1. Leaving ventilator-dependent patients unattended [Hazard], 1986 Apr; 15:102-3. Infant ventilators [Evaluation], 1986 Aug; 15:219-46. Remote alarms for ventilators and other life-support equipment, 1986 Dec; 15:323-4.

IPM Task ManagerTM, the software component of the Inspection and Preventive Maintenance System, enables easy production of customized procedures and checklists for specific ventilator models and clinical needs. Items performed by outside vendors can be excluded from the checklist; a separate checklist for use by outside vendors can be produced to ensure that those items agreed upon are performed by the vendor. The following framework should be supplemented by the manufacturer’s recommended preventive maintenance procedures for mechanical ventilators.



1.2

Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of this attachment. Check the mounting security of all components or attached monitors.

1.3


1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Also, check line cords of battery chargers.

1.6


1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves

Microprocessor-controlled third-generation critical care ventilators [Evaluation], 1989 Feb; 18:59-83.

Test apparatus and supplies Lung simulator with adjustable compliance or ventilator tester Pressure gauge or meter with 2 cm H2O resolution from -20 to +120 cm H2O Various breathing circuit adapters Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Additional items as required for specific manufacturers’ procedures

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Manufacturers’ recommended procedures for inspection and preventive maintenance of mechanical ventilators vary in both methods and required accuracy. In addition, ventilation modes, controls, and algorithms for calculated variables vary greatly according to manufacturer and model. This procedure provides the basic framework for complete ventilator inspection and preventive maintenance. Manufacturers’ recommended procedures should be added where appropriate. References to specific pages of the manufacturer’s manual should be added to the checklist. (The checklist includes blank spaces for the insertion of these page references.)

2


Critical Care Ventilators freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis and ensure that a spare is provided. 1.8


1.9

Cables. Inspect any cables and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are securely gripped in the connectors at each end, which will prevent rotation or other strain. Where appropriate, verify that there are no intermittent faults by flexing cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all gas fittings and connectors for general condition. Gas fittings should be tight and should not leak. Verify that keyed connectors (e.g., pin-indexed gas connectors) are used where appropriate, that all pins are in place and secure, and that keying is correct. Connectors to hospital central piped medical gas systems should have the appropriate DISS or quick-connect fitting to eliminate the need for adapters. 1.12 Filters. Check the condition of gas filters. Check for corrosion residue indicative of liquid, gaseous, or solid particle contaminants in the gas supply; advise appropriate personnel if found. Clean or replace if appropriate, and indicate this on Lines 3.1 and 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Investigate questionable control settings on a home care unit. Consult with the patient’s physician to determine correct settings. The patient or caregiver should receive additional training, if required. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for damage (e.g., from

fingernails, pens). During the inspection, be sure to check that each control and switch performs its proper function. 1.14 Heater (for heated portions of the breathing circuit). Check the physical condition and proper operation of the heater. 1.15 Fan/Compressor. Check the physical condition and proper operation of these components. Check for automatic activation of the compressor when the piped gas supply pressure falls below operating pressure. Clean or replace fan and/or compressor filters and lubricate as required, according to the manufacturer’s instructions, and note this on Lines 3.1 and 3.2 of the form. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage; for lead-acid batteries, measure the specific gravity and check the fluid level. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. Confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function. Record reading of an hour meter, if present. 1.20 Alarms/Interlocks. Induce alarm conditions to activate audible and visual alarms. Verify alarm messages on displays. Check that any associated interlocks function. If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require special conditions that must be established according to the manufacturer’s recommendations; include these in Item 2.4. Verify that the remote alarm indicator functions properly. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume,


3

Inspection and Preventive Maintenance System may include tidal volume, respiration rate, inspiratory time, expiratory time, inspiratory:expiratory (I:E) ratio, flow, and waveshape, among others. Typically, these tests are performed by attaching the ventilator to a lung simulator or ventilator tester and comparing measured values of pressure, flow, and/or volume and time to settings on the ventilator. The manufacturer should recommend the appropriate ventilator settings (e.g., tidal volume, rate, inspiratory time) at which to verify proper operation and accuracy (generally within 10%). Check the accuracy of flowmeters on infant ventilators.

as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories, including the humidifier and the nebulizer (see Procedure/Checklist 431 for heated humidifiers). 2.4


2.2

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component.

2.3

4

Breathing rate Inspiratory time Peak inspiratory pressure (PIP) Peak or mean inspiratory flow PEEP Mean airway pressure (MAP) Volume (both tidal and minute volume)

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

Monitors and Alarms. The following parameters are commonly monitored and should be inspected for accuracy (generally within 10%) according to the manufacturer’s specifications:

Fraction of inspired oxygen (FIO2); see Oxygen Analyzers Procedure/Checklist 417 Temperature of inspired air Other monitors Alarm settings (e.g., high PIP, low MAP, low pressure, low FIO2) should be inspected for proper and accurate activation. 2.5

Gas Supply. Oxygen-air proportioner. See Procedure/Checklist 444. Compressor. Test according to the manufacturer’s recommendations.


Pneumatic lines (including air filters). Verify that appropriate gas-specific connectors are used.

Modes and Settings. The following modes are commonly found on most ventilators: control, assist/control, intermittent mandatory ventilation/synchronized intermittent mandatory ventilation (IMV/SIMV), pressure support, and continuous positive airway pressure/positive end-exhalation pressure (CPAP/PEEP). The function of these modes should be inspected and verified for proper operation. Check the operation and accuracy of ventilation controls, which

Gas cylinders, gauges, and regulators (for transport ventilators). Verify that these components are present, securely mounted, and in good condition and that there is adequate gas supply. 2.6

Patient Circuit. Breathing circuit (including filters). Verify that these components are compatible with the ventilator according to the manufacturer’s recommendations (see Health Devices 1988


Critical Care Ventilators Apr; 17:109). Check for leaks in the breathing circuit, ensuring that fittings, adapters, and other components (e.g., exhalation valves, H-valves, PEEP valves, water traps, nebulizers) are properly assembled and functioning correctly. Humidifiers. See Heated Humidifiers Procedure/Checklist 431. Pressure-relief Mechanism. Check the proper operation of the pressure-relief mechanism by occluding the breathing circuit and measuring the resulting peak pressure on the pressure gauge. Verify that pressure is vented in the breathing circuit.


3.4



Before returning to use Ensure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. If the unit is being used at home, ensure that controls are set correctly before it is returned to the patient.

3.1

Clean the exterior, interior, and components if needed.

Attach a Caution tag in a prominent position so that the user will be aware that control settings may have been changed.

3.3

Calibrate according to the manufacturer’s instructions.

Recharge battery-powered devices, or equip them with fresh batteries, if needed.


5


Cryosurgical Units Used For: Cryometers [11-066] Cryosurgical Units [11-067] Cryosurgical Units, Ophthalmic [11-068]

Also Called: CSUs Commonly Used In: Operating rooms; OB/GYN, urology, proctology, and dermatology professional offices; surgical clinics Scope: Applies to all cryosurgical units, except disposable ophthalmic cryoextractors; portions of this procedure are applicable to tissue-temperature and tissue-impedance cryometers that may be integral to a CSU Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Cryosurgical units (CSUs) apply a gaseous or liquid refrigerant (cryogen) to freeze target tissue either through direct application of liquid cryogen (open-system CSUs) or indirectly through contact with a cryogen-cooled probe (closed-system CSUs). Cryosurgically treated tissue is usually allowed to become necrotic and slough off. The advantages of cryosurgery for tissue destruction include ease of use, the need for little or no anesthesia, the avoidance of hemorrhage, and relatively few postoperative complications. Cryosurgery is used in dermatology, oral surgery, gynecology, urology, ophthalmology, otolaryngology, and proctology. Although some CSUs and their probe tips are designed for use within only one specialty (e.g., ophthalmology, gynecology), most units have a wide range of applications and associated interchangeable tips. The two types of CSUs — those that use liquid nitrogen and those that use N2O or CO2 — have significantly different freezing capabilities. Liquid nitrogen units can attain temperatures as low as -196°C and are



Time Required

suitable for both benign and malignant tumors. N2O and CO2 units are most suitable for benign and inflammatory diseases, although they have been used successfully to treat small malignancies; the lowest probe-tip temperatures they can attain are -89° and -79°C, respectively. Liquid nitrogen CSUs deliver the cryogen to the tip as a liquid, where its rapid vaporization cools the probe. In closed-system N2O units and CO2 units, cooling occurs through the Joule-Thompson effect, in which a compressed gas (often at or near room temperature) is allowed to expand suddenly through a small aperture inside the probe tip, causing a considerable drop in gas temperature and liquefaction of some of the cryogen. The vaporization of the liquefied cryogen from the interior of the tip, combined with the drop in gas temperature caused by expansion, lowers the tip temperature to near the boiling point of the cryogen. Cryogen flows through an insulated probe shaft, cooling the tip, and exhausts back through the probe (closed-system design) or is applied directly to the


●


Inspection and Preventive Maintenance System target tissue (open-system design). CSUs using N2O or CO2 are not usually suitable for use as open systems because cryogen “snow” builds up on target tissue and insulates the lesion from the cryogen spray. Liquid nitrogen CSUs can be either open or closed. Most closed-system CSUs have active defrosting of the probe tip to allow its safe and rapid removal from the target tissue. Active defrosting warms the probe from within and allows the tip to be removed safely and quickly, usually within seconds; it can be achieved using an electric heater within the probe tip, exhaust occlusion (resulting in gas pressure buildup in the tip that causes the cryogen to heat up), or gas flooding of the tip with low-pressure cryogen at room temperature. CSUs are available in three basic configurations: console, stand-alone, and handheld. Consoles are freestanding units that typically contain the cryogen gas cylinders, pressure regulators, indicators, and operating controls. Stand-alone units are freestanding cryogen tanks on carts without controls or displays. Handheld units are lightweight, portable CSUs that use liquid nitrogen as the cryogen. Gun-type and pencil-shaped probes attach to both console and stand-alone units. To ensure that the unit is freezing properly, the probe tips on many console CSUs contain a cryometer (usually incorporating a thermocouple) to measure probe-tip temperature. This reading, however, does not directly reflect the cryolesion temperature and is not used as the definitive indicator of the depth and temperature of the frozen tissue. Some console CSUs also have a tissue-temperature cryometer; hypodermic thermocouples are used to monitor the target-tissue temperature. Alternatively, the unit may be equipped with an impedance cryometer, which uses hypodermic needle electrodes to assess the extent of freeze. Questions have arisen over whether it is advisable, practical, or safe for a hospital to repair its own cryosurgical equipment. We do not recommend such a practice; the units operate at very high pressures, and undetected probe damage can result in explosion and serious patient injury. Furthermore, the equipment needed to safely service and inspect CSUs is expensive. However, clinical engineering staff should perform annual routine general equipment inspections to detect any impending problem or improper scavenging of exhausted N2O. Scavenging exhausted N2O from CSUs is essential. N2O is both teratogenic and mutagenic; the reported long-term hazards of exposure to this and other anesthetic gases include increased rate of spontaneous abortion, increased incidence of hepatic and renal disorders,

2

and cancer. Because exposure of clinical engineering personnel to the gas will be only occasional, a more acute concern for their safety during the inspection is to guard against temporary N2O intoxication. Most older N2O CSUs expose personnel to levels well in excess of the 25 parts per million time-weighted average concentration limit of N2O gas recommended by the National Institute of Occupational Safety and Health (NIOSH). In addition, the flow of gas from CSUs is much higher than that from anesthesia machines, so the total quantity of N2O used during a cryosurgical procedure or inspection is substantial and potentially very dangerous. We recommend switching to CO2 as the cryogen. Alternatively, the hospital must scavenge all N2O from CSUs and vent it to the outside, away from air-intake ducts; N2O should never be vented into a sink, drain trap, or the piped medical/surgical suction system. Users should contact the manufacturer of their unit and request information on scavenging the N2O exhaust; the manufacturer or a local supplier can probably order the proper size and type of exhaust hose for equipment with an N2O scavenging port. An N2O CSU should not be used or tested unless its exhaust is properly scavenged. If an N2O CSU is used in an OR with 100% outside air ventilation, one end of the exhaust hose should be placed 1 to 2 ft into the room air exhaust vent (permanent installation of a short length of exhaust hose through the vent grill is advisable if vents are inconveniently located [e.g., near the ceiling]), and the exposed hose end should be equipped with a connector appropriate for attachment to the exhaust hose. If the OR has a dedicated system for venting scavenged anesthetic gases with a flow capacity 100 L/min (3.5 ft3/min), the N2O exhaust can be vented through this system rather than the return air system if it is more convenient. For treatment rooms in clinics and offices (and for ORs where the N2O cannot be vented as discussed above), N2O can be vented to the outside through a window or small hole drilled in the window frame or the wall of the room where the equipment is used. CO2 should be used for CSUs if scavenged N2O cannot be safely or conveniently vented or if N2O cannot be scavenged because of the design of the CSU. Facilities that can operate with either N2O or CO2 should strongly consider using CO2 — even if scavenging is possible — because it is intrinsically safer. N2O units that cannot be scavenged or converted for use with CO2 should be removed from use and only CO2 units purchased. If an unscavenged N2O CSU must be used while awaiting proper scavenging modifications or before switching to a CO2 CSU, it should be used in an extremely well-ventilated area, such as a hospital


Cryosurgical Units operating room. Pregnant staff members should never be present during use or testing of an unscavenged N2O CSU.

Citations from Health Devices Nitrous oxide exhausted from cryosurgical units [Hazard], 1979 Oct; 8:293. Update: Nitrous oxide exhausted from cryosurgical units, 1980 May; 9:180. Siphon gas cylinders and cryosurgical units [Hazard], 1980 May; 9:187. Personnel exposure to waste anesthetic gases, 1983 May; 12:169-77. Frigitronics Model CCS-100 cryosurgical cart [User Experience NetworkTM], 1986 Jan; 15:24. Should hospitals repair cryosurgical units? [User Experience NetworkTM], 1986 Dec; 15:332-3. N2O cryosurgical units must be scavenged [Hazard update], 1987 Dec; 16:407-9. Surgical devices omitted from equipment control programs [Hazard], 1989 Feb; 18:86.

States, liquid N2O tanks are usually blue with a silver neck; gaseous N2O tanks are entirely blue. All cylinders should be tested before they are connected to the CSU. First, make sure that the valve is not pointed toward anyone. Then, open the valve one half to one full turn for 2 to 4 sec; no mist should be seen. If a continuous mist is observed, the cylinder contains a siphon and should be used only with CSUs specified for liquid N2O use.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Although many CSUs are gas powered, we have included tests for electrical safety and special functions for use on those units that are so equipped.



1.2

Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of this attachment. Gas cylinder mounts should securely fasten the cylinders to the CSU stand or console.

1.3


1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter 10× loupe Stopwatch or watch with a second hand Cup filled with tap water (temperature not critical)

Special precautions Liquid nitrogen must be handled with care to prevent operator injury. Read and follow the precautions and warnings for handling liquid nitrogen presented in the equipment manual for any CSU using this cryogen. All N2O CSUs must have their exhaust safely scavenged during inspections to prevent acute physical and psychological impairment and possible long-term adverse health effects to the inspector. Siphon-type gas cylinders used with liquid N2O CSUs can be mistakenly installed on a CSU designed for gaseous N2O use if the cylinders are mislabeled or if medical personnel are unaware that siphon cylinders should not be used with gas units. Very few N2O CSUs are designed to accept siphon cylinders of liquid N2O. If a siphon cylinder is fitted to a gas unit, liquid N2O can leak from the fittings or seals of the cryoprobe, resulting in patient or operator injury. In the United

If the device has electrical receptacles for accessories, verify presence of line power; insert an AC plug into each and check that it is held firmly. If


3

Inspection and Preventive Maintenance System accessories are plugged and unplugged often, consider a full inspection of the receptacles. 1.5

1.6

1.7

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Also check line cords of battery chargers. Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), we recommend that the cord be affixed to the unit so that it cannot be removed by the operator. (See Health Devices 1993 MayJun; 22[5-6]:301-3.) Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.8


1.9

Cables. Inspect any cables (e.g., sensor, electrode, remote control) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that leads and hoses are firmly gripped in their appropriate connectors. Gas and liquid fittings should be tight and should not leak; listen for audible leaks and look for dripping cryogen. Complaints of excessive gas usage indicate that the CSU may have a leak between the cryogen gas cylinder and the console/regulator. Pin-indexed gas cylinder yokes should be present. Make sure that no keying pins are missing and that the keying is correct for the gas that is used. If a yoke has no keying pins — which some manufacturers have omitted, in violation of ac-

4

cepted safety standards — immediately replace the yoke with one correctly keyed for that gas. Destroy and discard the unkeyed yoke. 1.11 Probes and Probe Tips. Confirm that appropriate probes and probe tips are on hand and check their physical condition. For ophthalmic probe tips, use a 10× loupe to inspect them. They should not have any cracks, abrasion, corrosion, kinks, dents, or evidence of bending. The presence of such damage suggests that these delicate probes have been bent or crushed and must be replaced. Operate the unit for about 30 sec with each tip immersed in water (water temperature is not critical) and check to make sure that ice forms on the tip. During each tip test, make sure that there is no leakage of cryogen (seen as bubbles in the water) from the probe/tip connector. Examine the probe shaft thermal insulation for cracks or signs of degradation. 1.12 Filters. Check the condition of all liquid and gas (air) filters. Clean or replace as appropriate and indicate this on Lines 3.1 and 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Also, make sure that users turn off the gas cylinder valves between uses. This will minimize the chance of high-pressure leaks. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily accessible, including battery-operated cryometers. Check the condition of the battery charger, if present, and, to the extent possible, confirm that it does in fact charge the battery. When it is necessary to replace a battery, label it with the date.


Cryosurgical Units 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Check that gas pressure gauges and flowmeters read zero when the gas is not turned on. Be sure that all segments of a digital display function. Record reading of an hour meter, if present.

If the CSU console has an accessory receptacle, check its grounding to the main power cord. 2.2

1.19 User Calibration. Verify that the self-test function operates and indicates normal operation, if so equipped. 1.20 Alarms. Induce alarm conditions to activate audible and visual alarms. Check that any associated interlocks function. If the unit has an alarm-silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to check all alarms at this time, since some may require abnormal operating conditions that will be simulated later in this procedure.

Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. Chassis leakage current to ground should not exceed 300 µA. 2.3

Probe-Tip Cryometer. Repeat the defrost control test described in Item 1.24. The ice ball should release from the probe tip when the tip temperature readout indicates 0°C, ±1°C.

2.4

Tissue-Temperature Cryometer. Touch a tissuetemperature probe to the probe tip and immerse them both in water. Activate the CSU at its maximum freezing power (if adjustable) for approximately 3 min. The tissue-temperature probe and probe tip will freeze within the ice ball. The tissue temperature and probe-tip temperature should be within 5°C of each other.

2.5

Elapsed-Time Meter/Timer. Where present, verify the accuracy of a timing mechanism with a stopwatch or watch with a second hand for 5 min. The error should not exceed 10 sec.

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.24 Defrost Control. Verify that the defrost feature operates. An ice ball on a tip should dislodge within approximately 30 sec after activation of the defrost mode. 1.25 Scavenger. For N2O CSUs, verify the presence of a scavenging attachment and hose. An N2O CSU should not be used or tested unless its exhaust is properly scavenged.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value.



Clean exterior (interior if appropriate).

3.3

Calibrate cryometer, if needed.

3.4

Replace probe-tip O-rings, if needed.


Before returning to use Make sure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Be sure that the inspection did not deplete the cryogen supply to a level that disables the unit. Turn off the cryogen gas cylinder valves after completing the inspection.


5


Defibrillator/Monitors Used For: Defibrillator/Monitors, Line-Powered [15-029] Defibrillator/Monitor/Pacemakers [17-882]

Commonly Used In: Coronary and special care areas, emergency departments, operating rooms, resuscitation carts, ambulances, patient care areas Scope: Applies to battery- and line-powered defibrillator/monitors; does not apply to defibrillators or ECG monitors (see Defibrillators Procedure/Checklist 407 and ECG Monitors Procedure/Checklist 409); see Pacemakers, External Noninvasive Procedure 460 for units with this accessory Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Defibrillator/monitors combine the functions of an ECG monitor and defibrillator into a single unit, which allows the operator to quickly assess and monitor the ECG and apply a defibrillating pulse, if appropriate. Most units are battery-powered so that they can be used during transport within a hospital or in an ambulance or carried into the field. Defibrillator/monitors are critical resuscitation instruments. Their failure to perform effectively may result in the death of a patient undergoing resuscitation or cause further cardiac damage or even death in a patient undergoing elective cardioversion or emergency cardioversion of a life-threatening arrhythmia. Failure to successfully defibrillate a patient may occur for a number of reasons, including inadequate predefibrillation cardiopulmonary resuscitation (CPR) technique, operator error (e.g., poor paddle application), or depleted or defective batteries (the most common cause of defibrillator failure with battery-powered units). There is no time to troubleshoot or correct even minor difficulties during emergencies,

A NONPROFIT AGENCY

Time Required

since every minute of delay significantly decreases the probability of a successful resuscitation attempt.

Overview

009020 408-0595


In addition to periodic inspections, clinical staff should perform visual inspections and ensure that batteries are charging at the beginning of each work shift and after each use of the device. They should also perform discharge testing at least once a week. A User Checklist for Defibrillators/Monitors/Pacemakers is included in Health Devices 1993 May-Jun; 22:291-2.

Citations from Health Devices User error and defibrillator discharge failures [Hazard], 1986 Dec; 15:340. Deteriorating insulation on internal defibrillator paddles [Hazard], 1987 Feb; 16:46. Defibrillator paddle resistance (continuity) testing [User Experience NetworkTM], 1987 Feb; 16:55. Battery-powered defibrillator/monitors [Evaluation], 1987 Jun; 16:183-216. (See also 1987 Jul; 16:251.) Mains (AC Line) power switches on battery-powered equipment [Hazard], 1987 Sep-Oct; 16:345.


Inspection and Preventive Maintenance System Battery-powered defibrillator/monitors [Evaluation Update], 1987 Dec; 16:389. Misuse of “Quick Look” defibrillator paddles [Hazard], 1988 Feb; 17:68. Lifepak 8 defibrillator/monitors [Hazard], 1988 Aug; 17:244. Lifepak 8 defibrillator/monitors [Hazard Update], 1988 Sep; 17:273. Physio-Control Lifepak 6 and 6s defibrillator/monitors [Hazard], 1988 Aug; 17:245.

Overheating of replacement batteries in Physio-Control Lifepak 6, 6s, and 7 defibrillator/monitors [Hazard Update], 1992 Jun-Jul; 21:250. Defibrillator/monitors and external noninvasive pacemakers [Evaluation], 1993 May-Jun; 22:212-94. Defibrillator/monitors and external noninvasive pacemakers [Evaluation Update], 1993 Dec; 22:579-82. Misalignment of mating cable and defib cassette connectors on Physio-Control Lifepak 8 defibrillator/monitor [Hazard], 1993 Dec; 22:595-7.

Physio-Control develops Mains Power switch cover [Hazard Update], 1988 Nov; 17:356.

Sparking during discharge testing on Physio-Control Lifepak 9 defibrillator/monitors [User Experience NetworkTM], 1994 Mar; 23:98-9.

Battery pins on Lifepak 5 defibrillator/monitors [Hazard], 1989 Feb; 18:84.

Fires from defibrillation during oxygen administration [Hazard], 1994 Jul; 23:307-9.

Porta Fib III defibrillator/monitor paddles [Hazard], 1989 May; 18:175.

Difficulty synchronizing with Zoll PD 1200 defibrillator/monitor/pacemaker [User Experience NetworkTM], 1994 Aug-Sep; 23:374-5.

Mismatch of CCP R2 181-239 cables and HP43100 defibrillators [Hazard], 1989 Jun; 18:233. Maintenance and user errors with the Physio-Control Lifepak 8 [User Experience NetworkTM], 1990 Feb; 19:59. Replacement batteries for the Physio-Control Lifepak 6 and 7 [User Experience NetworkTM], 1990 Feb; 19:61. Disposable difibrillator pads and electrodes [Evaluation], 1990 Feb; 19:33-56. Hewlett-Packard defibrillator/monitors and Darox R2 electrodes [User Experience NetworkTM], 1990 Jul; 19:246. Alarm lockup on ZMI PD 1200 defibrillator/monitors [Hazard], 1990 Aug; 19:293-4.

Spontaneous charging of Hewlett-Packard 43100A defibrillator/monitor used with anterior/posterior paddle set during monopolar electrosurgery [Hazard], 1994 Oct-Nov; 23:455-6.

Test apparatus and supplies Defibrillator analyzer ECG simulator (calibrated output amplitudes and rates are required for some tests) Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Stopwatch or watch with a second hand The following equipment is necessary during acceptance testing only: Function generator

Heart-rate alarms on ZMI ZOLL PD 1200 pacemaker/defibrillators [Hazard], 1990 Dec; 19:455-6.

Attenuator

Physio-Control Lifepak 10 defibrillator/monitor Sync mode [User Experience NetworkTM], 1991 Jan; 20:30-1.

Transparent metric scale

ECG artifact and defibrillator/monitors [User Experience NetworkTM], 1991 Mar-Apr; 20:141. Internal defibrillator paddles [User Experience NetworkTM], 1991 Dec; 20:497-8. Use of Physio-Control Lifepak 8 defibrillator/monitors with optional QUIK-PACE pacing cassette [User Experience NetworkTM], 1992 May; 21:183.

2

Oscilloscope Isolation test supply (included in some electrical safety analyzers)

Special precautions CAUTION: The high voltage present on defibrillator paddles during discharge is extremely dangerous and possibly lethal. Never perform tests alone. A second person must be present to summon help and/or apply CPR in the event of an emergency. Never hold or contact the conductive electrode portion of the paddles


Defibrillator/Monitors unless you have confirmed that the defibrillator is disarmed (not charged) and preferably off.

1.4

Testing input isolation requires the use of a line voltage source. Although this source should include a current-limiting resistor, use caution to avoid contact with any portion of the circuit while it is energized.

If the device is mounted on a cart that has electrical receptacles for additional equipment, insert an AC plug into each, and check that it holds firmly. Inspect resuscitation cart receptacles, including testing for wiring (e.g., using an outlet tester) and tension of all three connections. Also inspect the resuscitation cart plug for damage as described above.

A defibrillator/monitor must always be available in the event of an emergency during the inspection. Thus, perform the inspection in the vicinity of the unit’s usual storage location, or ensure that a unit that the clinical staff is familiar with is available as a substitute. Inspection testing may deplete the battery of battery-powered units. Ensure that a replacement unit or a fully charged battery is available before you begin testing. Do not test all the units in an area at one time, since this will leave the staff inadequately equipped to handle emergencies.

1.5

Line Cord. Inspect the cord (including resuscitation cart line cord, if appropriate) for signs of damage. If damaged, replace the entire cord, or if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one. Check line cords of battery chargers.

1.6


1.7


1.9

Cables. Inspect the cables of internal and external paddles, disposable defibrillation electrodes (if applicable), and ECG electrodes for their strain reliefs and general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that an ECG can be displayed with either paddles or ECG leads used as input. Wiggle, bend, and pull the cable to check that continuity is not affected.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Defibrillator energies may be specified in either joules (J) or watt-seconds; these are equivalent units (i.e., 1 J = 1 watt-second).



1.2

Mount. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of this attachment.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulation of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped.


1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact pins or surfaces should be straight and clean. Verify that leads and electrodes are firmly gripped in their appropriate connectors. During major inspections, disconnect the paddle connectors and look for misaligned pins, damaged receptacles, and carbon deposits from arcing.


3

Inspection and Preventive Maintenance System 1.11 Paddles/Electrodes. Confirm that special paddles (e.g., pediatric, internal) and electrodes (e.g., disposable difibrillation electrodes) are available, if appropriate. Examine all paddles for physical condition and cleanliness. Alert clinical personnel responsible for the instrument to the presence of dried electrode gel, physiologic fluids, or debris on the paddle surface or handles. Dirty electrodes prevent good electrical contact and can cause burns. Electrode gel or other debris on the insulating portion of the paddle can cause operator shocks. Clean the paddles, if needed, including the electrode surface and handle seams, and make sure that they are completely dry before proceeding with any further testing. Confirm that an adequate supply of ECG electrodes and disposable defibrillation electrodes (if used) are available and that they are stored properly and are within their expiration dates. 1.13 Controls/Switches. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, check that each control and switch performs its proper function. If the unit has redundant control functions (e.g., a charge button on the front panel and on a paddle), ensure that both controls function properly. Verify that activating just one paddle discharge button will not cause the unit to discharge. A front-panel discharge button should control only internal paddles (or disposable defibrillator electrodes, on some units) and should not cause discharge when external paddles are connected. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Verify that the charger of battery-operated units is plugged into a live AC outlet and that the charger is attached to the defibrillator (i.e., charger cable is attached, unit is firmly seated into charging stand or mount, instrument end of line cord is attached, and charging light is on). For units with removeable batteries that are charged in a separate charger, verify that the batteries are properly installed and that the charging, or ready, light is on.

4

If the monitor can be separated from the defibrillator, make sure that it is securely connected to the defibrillator. Inform clinical personnel of any deficiencies so that problems can be avoided in the future. Perform the inspection with the unit on battery power to check that monitor and defibrillator batteries are charged and can hold a charge. Check battery capacity by activating the battery test function or measuring the battery-powered operating time. When it is necessary to replace a battery, label it with the date. Some batteries require periodic deep discharges and recharging to maintain maximum battery capacity. If the manufacturer recommends this procedure, verify that it is being performed on schedule. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, and visual displays on the unit and charger. Be sure that all segments of a digital display function. Observe a simulated ECG signal on the display, and verify compliance with the following criteria: The baseline should stay in focus across the display. The baseline should be horizontal and should not be noticeably sloped or bowed. The pulses from an ECG simulator should be regularly spaced (uneven spacing indicates a sweep nonlinearity). All portions of a simulated ECG waveform should be clear and visible, including the P-wave and QRS. When the vertical position of the baseline is varied by adjusting the vertical position control, the baseline should move throughout most of the vertical height of the display. There should be no distortion in the baseline as it is moved up or down on the screen. In monitors that incorporate a self-centering baseline and therefore lack a position control, the baseline should be correctly positioned. Ambient light should not affect the visibility of the trace. (If monitors are located so that ambient light reflects from the face of the display, making the ECG difficult to see, control the ambient light or use a filter over the display.)


Defibrillator/Monitors alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., charge tone). Confirm appropriate volume, as well as the operation of a volume control. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. Figure 1. The calibration pulse or step response leading edge should have square corners (left). Slight rounding (middle) or small overshoot is acceptable. Excessive rounding or overshoot (right) indicates the need for adjustment. “Burn spots” should not be visible on the cathode-ray tube. (The phosphor may “burn” if the intensity is set too high. The cathode-ray tube face will be discolored if this condition exists.) Sixty-hertz or other noise (interference) should not be superimposed on the baseline with the ECG simulator attached. Baseline interference may be apparent as a thick baseline at high gain settings, but should be invisible throughout the lower two-thirds of the gain control range.

1.23 Accessories (gel, pads, or electrodes). Verify that defibrillator gel, disposable defibrillator pads, or disposable defibrillator electrodes are stored with the unit and are within their expiration dates. Confirm that defibrillator gel is being used, not skin lubricant or ultrasound or TENS gel. Notify appropriate clinical personnel if any accessories are missing. 1.24 Internal Discharge of Stored Energy. To protect personnel from accidental shock, it should be possible to discharge the stored energy safely in the event that the operator decides not to use the defibrillator after it has been charged. Verify that the unit rapidly releases the stored energy when the power is turned off. If the unit also has a front-panel button for this purpose, verify its operation.

1.19 1 mV Step Response. Depress and hold the 1 mV calibration button (or apply an external 1 mV pulse) for about 3 sec. The trace should exhibit a sharp, square-cornered leading edge that is neither rounded nor spiked (up to 10% spike or overshoot is acceptable but will usually not be observed in a unit that is functioning optimally; see Figure 1). After 1 to 2 sec, the pulse should have decayed to no more than half its original amplitude (see Figure 2). With the gain set to yield about 20 mm deflection for a 1 mV input (×2 or 0.5 mV/div), compare the amplitude of the internal calibration pulse and an external 1 mV signal (from a calibrated ECG simulator). At a 20 mm deflection, they should be within about 2 mm (10%) of each other. 1.20 Alarms. Operate the device in such a way as to activate each audible and visual alarm (e.g., heart rate alarm, if so equipped). Check for adequate alarm tone volume and any associated features (e.g., automatic direct writer activation, display freeze function). If the device has an

Figure 2. Sag time is measured to the half-amplitude point. The upper trace indicates a low-frequency response of about 0.05 Hz. The lower trace indicates a low-frequency response of between 0.07 and 0.09 Hz.


5

Inspection and Preventive Maintenance System continuity checks. The resistance from the paddle or electrode connector to the appropriate pin of the connector should not exceed 0.15 Ω.

1.25 Special Features. Synchronizer (major inspection only). If the unit has a synchronization mode, verify that the unit will not discharge while in this mode when no ECG signal is present and that it will discharge when a simulated ECG is applied. Recorder. If the unit has a recorder, confirm that it operates smoothly, that the paper feeds evenly and does not stray from side to side, and that the trace is of good quality (i.e., dark and thin) at all paper speeds. Perform the 1 mV step response test (Item 1.19) on the recorder.

2.4

Rate Calibration. Using a simulated ECG with rates of 60 and 120 pulses per minute, verify that the heart rate indicator displays a rate within 5% or 5 bpm, whichever is greater, of the set rate (55 to 65 bpm, 119 to 126 bpm). Verify that the QRS visual and audible indicators are functioning.

2.5

Rate Alarm. The setup remains the same as for the previous test. Verify that the alarm activates when the input rate is set just below or above typical low and high rate alarm settings (e.g., 40 and 120 bpm, respectively). The difference between the rate displayed on the rate indicator and that at which the alarm activates should not exceed 5% or 5 bpm, whichever is greater.

2.6

Internal Paddle Energy Limit. When used with internal paddles for application of the defibrillator output directly to the heart, the energy should not exceed 50 J. Test this feature on any unit that is located where it may be used with internal paddles or that may be moved to such a location. Connect the internal paddles, charge the defibrillator to maximum energy, and discharge it into the defibrillator analyzer. Verify that the output does not exceed 50 J.


2.2

2.3

6

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord (if so equipped) and exposed (unpainted and not anodized) metal on the defibrillator chassis. Repeat this test for the charger, if applicable. We recommend a maximum of 0.5 Ω. Chassis Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened and the unit off, on, charging, and charged. Record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA. Paddle Continuity. Paddle continuity is typically checked by verifying the presence of an ECG signal obtained through the paddles (Item 1.9). However, if additional paddles or disposable defibrillation electrodes are available for use with the defibrillator (e.g., internal or pediatric paddles), these must be checked. Either attach the paddles or electrode cable to the unit (e.g., in conjunction with Item 2.6) and verify continuity with an ECG signal, or use an ohmmeter to verify continuity from each paddle or electrode connector to the appropriate pin of the connector. Wiggle, bend, and pull the cable, especially near the paddle and connector, to check that continuity is not affected. (Current may jump across a small break in the paddle lead and may not be detected during defibrillator output tests. A continuity test will detect such a defect before it gets worse.) This check should also be done for the reusable cable used with disposable defibrillation electrodes. Internal paddles may require more frequent

2.10 Output Energy. During major inspections, measure output energy at minimum, intermediate, and maximum energy settings. If the defibrillator is commonly used for cardioversion, a 50 J level is satisfactory for the intermediate range. At each energy level, record the control setting, indicated energy (on the unit’s energy meter), and delivered energy (measured by a defibrillator analyzer) after discharging the defibrillator into the analyzer as soon as it is charged. At its maximum setting, the unit should be able to deliver at least 250 J. The output energy should be within 4 J at low settings (below 25 J) or 15% of the set energy (and indicated energy if so equipped) at higher energies. If the output of a defibrillator is unusually low at very low control settings, check for a break in the cables or a defective connector.


Defibrillator/Monitors same day unless provisions are made for backup units or spare charged batteries. Batteries may take considerable time to recharge, and a fully charged unit must be available for emergencies.

During minor inspections, verify output at only one energy level. Use the defibrillator’s internal test load, if so equipped. Typically, this provides either a numeric or a pass/fail indicator to verify that energy was delivered. 2.11 Energy After 60 Sec. Deterioration of the energy storage capacitors in some defibrillators results in charge leakage after the charging circuit has been de-energized. In these units, it is possible for the available energy to decrease if the unit is not discharged at the earliest possible moment. The following test will identify this deficiency.


Clean the exterior, paddles, rollers, and platen.

3.2

Lubricate the chart recorder paper drive per the manufacturer’s recommendations, if required.

3.4

Replace the battery if any of the test procedures indicate it is weak or defective, even after charging for 12 hr or more.

Charge the defibrillator to its maximum setting, but do not discharge for 1 min. The delivered energy should be at least 85% of that obtained when the unit is discharged immediately (as in Item 2.10) and should meet manufacturer specifications for charge leakage. (Note that some units are designed to intentionally bleed or discharge the capacitor charge if the defibrillator is not discharged within a set time period. These units should meet manufacturer specifications.) 2.12 Charge Time and Max Energy (10th Charge). In resuscitation attempts, it is not uncommon for the operator to call for multiple defibrillation shocks in rapid succession. Battery-powered defibrillators may not have sufficient energy left in their batteries to deliver 10 shocks. These deficiencies are best discovered during periodic inspections, rather than during clinical use. Charge battery-powered units to maximum energy and discharge 10 times through the analyzer (verify that the analyzer load will not be damaged by repeated discharge). On the 10th cycle, record the charging time (i.e., the time for the meter to equilibrate or for the ready light to come on) and the delivered energy. To avoid excessive battery depletion, stop the test and record the number of discharges and the values measured if the charging time exceeds 15 sec before the 10th discharge. Also stop the test if the battery-condition meter indicates a weak battery or, on some defibrillators, if the internal circuitry terminates the charge early. The time to charge to maximum energy should not exceed 15 sec. The output energy should remain within 4 J or 15% of the selected energy throughout the test. CAUTION: Do not perform this test on all battery-operated defibrillators in an area on the

Some users have also reported that periodic prophylactic battery replacement, either annually or every other year, increases reliability and decreases service calls. In this case, mark the date of the battery replacement on the battery or unit and check it during each inspection. Perform the inspection after battery replacement and a suitable charge period. Some units have more than one battery (e.g., one for the monitor and one for the defibrillator, batteries that can be switched by the user). Be sure that all batteries are checked, maintained, and replaced as required.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. CAUTION: Do not measure paddle leakage current with the unit charged or charging or during discharge. Most ECG monitors should meet the requirements for isolated input devices for ECG lead-to-ground, interlead, and input isolation tests. Interlead testing should include both ECG-to-ECG and ECG-paddle tests. AAMI DF-2-1989, Standard for Cardiac Defibrillator Devices, calls for applying isolated input risk current tests (source, sink, and interlead) to defibrillator paddles, but with limits of 100 µA for external paddles and 50 µA for internal paddles. In addition, perform the following tests. 4.1

Synchronizer Operation. Check the synchronizers of units so equipped. The thoroughness of this test will depend upon the availability of test equipment. Set the defibrillator to deliver low output energy (50 J or less). Use an ECG signal to trigger


7

Inspection and Preventive Maintenance System the synchronizer and fire the defibrillator into a 50 Ω load (e.g., a defibrillator analyzer). Confirm that, with the ECG simulator off, the defibrillator does not discharge. With a signal applied, confirm that the synchronizer marker or other indicator is functioning properly. Use a dual-channel oscilloscope to note the time delay between the peak of a QRS pulse (from an ECG simulator) and the defibrillator pulse (from a defibrillator analyzer). Use the ECG signal to trigger the oscilloscope’s sweep. Some defibrillator analyzers have synchronizer test functions. With an ECG amplitude sufficient to activate the marker or indicator and the discharge buttons depressed, the defibrillator should discharge in 60 msec or less following the R-wave peak. Most units will trigger on the first QRS pulse after the buttons are depressed, although some units are designed to delay until the second or third QRS to avoid unintentional discharges. 4.2

Internal Paddle Energy Limit. During acceptance testing, perform Item 2.6 on all units equipped with this feature, regardless of intended location for the device.

4.3

Integral Output Tester. Check the operation and accuracy of any integral defibrillator test load, if so equipped.

4.4

Common Mode Rejection Ratio (CMRR). The ECG monitor includes a differential amplifier so that it can display the voltage difference between two electrodes (the RA and LA in Lead 1) while using a third (RL) as a reference. If the same, or common, voltage is applied to RA and LA simultaneously, there should be no output from the differential amplifier because the voltage difference between the two inputs is zero. The extent to which a differential amplifier produces no output when the same signal is applied to both inputs is called its common mode rejection ratio. Common mode rejection is needed in monitors because of the presence of stray signals, common to all input leads primarily at power-line frequency (60 Hz). While these signals are too minute to be hazardous, they can interfere with the ECG display of a monitor with a low CMRR at 60 Hz. The CMRR is defined as:

CMMR =

Differential mode deflection factor, or DMD (mm ⁄ mV) Common mode deflection factor, or CMD (mm ⁄ mV)

Calculate the common mode deflection factor by dividing the resultant deflection (in mm) by the

8

Figure 3. Signal input test setup. input signal (in mV). The CMRR may then be calculated as the differential mode deflection factor divided by the common mode deflection factor. A deflection factor is the change in trace position corresponding to a given input voltage to the monitor. Use an unbalanced CMRR measurement that has a 5,000 Ω resistor in series with one of the input leads to the monitor. This simulates unequal impedances in the electrode/skin interface of the monitor electrodes, as commonly exists in practice. Since most common mode voltage in the hospital is at 60 Hz, it is most significant to measure the CMRR at or near that frequency. (A frequency of 55 Hz is often used to minimize interference from power-line frequency noise.) Using the test setup shown in Figure 3, apply a sinusoid test signal of 1 mV peak-to-peak at about 60 Hz to the monitor. Turn up the monitor gain so that the deflection is at least 20 mm. Measure the deflection in millimeters, and record it on the inspection form as the differential mode deflection factor. Since the input signal for this measurement was 1 mV, the differential mode deflection factor expressed in mm/mV is numerically equal to the resultant deflection in millimeters. Do not vary the gain of the monitor or the signal frequency for the remainder of this test. Record the frequency on the form. Use the test setup shown in Figure 4 for the second part of this measurement. Note that there is only one connection from the output of the attenuator to the patient leads. The other output terminal is grounded. It is essential that all instruments used in this test be connected to a common ground to minimize noise.


Defibrillator/Monitors correction should be made in calculating paper speed. The paper speed should be accurate to within 2% (although 5% is allowed by some organizations). At a chart speed of 25 mm/sec and a pulse interval of 1,000 msec (60 bpm on an ECG simulator), the distance between the first and last of 5 successive peaks should be 100 ±2 mm; at a chart speed of 50 mm/sec, the distance between the first and last of 5 successive peaks should be 200 ±4 mm. 4.8

Alarm Delay. In addition to checking rate alarm accuracy (Item 2.5), use the same test setup to determine alarm delay. First, set the high rate alarm to 100 bpm and the ECG simulator to 60 bpm. Quickly change the simulator rate to 120 bpm, and use a stopwatch or watch with a second hand to measure the time until the alarm sounds. Check the low rate alarm similarly (set alarm for 40 bpm, change rate from 60 to 30 bpm). Generally, alarm delays should not exceed about 10 sec.

4.9

Repeated Discharge and Operating Time.Verify that the battery meets hospital or manufacturer specifications for number of defibrillation shocks and monitor operating time. Units should meet requirements with all functions operating (including alarms sounding) unless otherwise specified.

Figure 4. Common mode rejection ratio test setup. Increase the amplitude of the sinusoid signal (up to 10 V peak-to-peak) until some measurable deflection is observed on the monitor. If the unit has an ungrounded or plastic case, measure the CMRR with the unit resting on a grounded metal plate. CMRR should meet the manufacturer’s specification and be at least 10,000:1. 4.5

4.6

4.7

Gain. Apply a 2 mV signal at a gain setting of 10 mV/mm (or ×1) and measure the displayed amplitude with a transparent scale. Verify that the displayed signal size changes appropriately (within 10%) as the gain setting is changed. For example, if a 2 mV signal produces a 20 mm deflection at a ×1 gain, the deflection should be 36 to 44 mm at ×2. Test both the monitor display and recorder.

Perform Item 2.12 on line-powered units to verify that each unit is able to provide at least 10 sequential defibrillation shocks.


QRS Sensitivity. If the monitor includes a QRS indicator or beeper or a heart rate meter, verify that the QRS detector circuit is functioning properly. Connect an ECG simulator with variable output to the monitor, and set it for a rate of 60 bpm. Vary the output amplitude over a range of 0.5 to 5 mV (use the monitor, display to estimate amplitude if the simulator does not have a calibrated output). The monitor should reliably detect all beats and should not doublecount. It should not detect QRS amplitudes of less than 0.15 mV. If the unit has a manual sensitivity control, check that it is functioning properly as evidenced by the need to change the setting during this test.

Return the energy select control to its normal setting. Before connecting the charger on battery-powered units, check the battery condition to verify that there is adequate battery charge. If there is not, or if doubt exists, ensure that a suitable replacement defibrillator is available, and allow the unit just inspected to charge in an out-of-the-way location (i.e., where it will not be taken for use by clinical personnel). Battery-powered units should be connected to the charger, with the charger plugged into a wall outlet and the charging light on. For units with removable batteries that are charged in a separate charger, replace the battery used during testing with a fully charged battery, and place the used battery in the charger for proper charging.

Paper Speed. On units with a chart recorder, use an ECG simulator set to 60 bpm or a signal or pulse generator set to 1 Hz that has been set or calibrated with a counter. If the interval between pulses is not within 10 msec of 1,000 msec, an appropriate

Conduct a performance verification check, including pressing all the front-panel function buttons, to verify that the unit is in a standard service mode. Performance-verification procedures are often included in the service manual.


9


Defibrillators Used For: Defibrillators, Battery-Powered [11-134] Defibrillators, Line-Powered [11-137]

Also Called: Cardioverters Commonly Used In: Coronary and special care areas, emergency departments, operating rooms, resuscitation carts, patient care areas, emergency medical vehicles Scope: Applies to battery- and line-powered defibrillators used with external and internal paddles and/or disposable defibrillation electrodes; does not apply to units that have both defibrillation and monitoring functions (see Defibrillator/Monitors Procedure/Checklist 408) Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Defibrillators are critical resuscitation instruments. Their failure to perform effectively may result in the death of a patient undergoing resuscitation or cause further cardiac damage or even death in a patient undergoing elective cardioversion or emergency cardioversion of a life-threatening arrhythmia. Failure to successfully defibrillate a patient may occur for a number of reasons, including inadequate predefibrillation cardiopulmonary resuscitation (CPR) technique, operator error (e.g., poor paddle application), or depleted or defective batteries (the most common cause of defibrillator failure with battery-powered units). There is no time to troubleshoot or correct even minor difficulties during emergencies, since every minute of delay significantly decreases the probability of a successful resuscitation attempt. In addition to periodic inspection, clinical staff should perform inspections and ensure that batterypowered units are charging at the beginning of each work shift and after each use of the device. They should



Time Required

also perform discharge testing at least once a week. A User Checklist for Defibrillator/Monitor/Pacemakers is included in Health Devices 1993 May-Jun; 22:291-2.

Citations from Health Devices Daily checks of defibrillators [Consultant’s Corner], 1983 Mar; 12:120-1. Line-powered defibrillators [Evaluation], 1983 Oct; 12:291-314. Defibrillating patients connected to electrocardiographs [Evaluation], 1984 Aug; 13:254. User error and defibrillator discharge failures [Hazard], 1986 Dec; 15:340. Deteriorating insulation on internal defibrillator paddles [Hazard], 1987 Feb; 16:46. Defibrillator paddle resistance (continuity) testing [User Experience NetworkTM], 1987 Feb; 16:55. Disposable defibrillator pads and electrodes [Evaluation], 1990 Feb; 19:33-56.


●


Inspection and Preventive Maintenance System Hewlett-Packard defibrillator/monitors and Darox R2 electrodes [User Experience NetworkTM], 1990 Jul; 19:246. ECG artifact and defibrillator/monitors [User Experience NetworkTM], 1991 Mar-Apr; 20:141. Internal defibrillator paddles [User Experience NetworkTM], 1991 Dec; 20:497-8. Use of Physio-Control Lifepak 8 defibrillator/monitors with optional QUIK-PACE pacing cassette [User Experience NetworkTM], 1992 May; 21:183. Overheating of replacement batteries in Physio-Control Lifepak 6, 6s, and 7 defibrillator/monitors [Hazard Update], 1992 Jun-Jul; 21:250. Defibrillator/monitors and external noninvasive pacemakers [Evaluation], 1993 May-Jun; 22:212-94. Defibrillator/monitors and external noninvasive pacemakers [Evaluation Update], 1993 Dec; 22:579-82. Misalignment of mating cable and defib cassette connectors on Physio-Control Lifepak 8 defibrillator/monitor [Hazard], 1993 Dec; 22:595-7. Fires from defibrillation during oxygen administration [Hazard], 1994 Jul; 23:307-9. Spontaneous charging of Hewlett-Packard 43100A defibrillator/monitor used with anterior/posterior paddle set during monopolar electrosurgery [Hazard], 1994 Oct-Nov; 23:455-6.


you have confirmed that the defibrillator is disarmed (not charged) and preferably off. Testing input isolation requires the use of a line voltage source. Although this source should include a current-limiting resistor, use caution to avoid contact with any portions of the circuit while it is energized. A defibrillator must be available in the event that an emergency occurs during the inspection. Thus, perform the inspection in the vicinity of the unit’s usual storage location, or ensure that a similar unit that the clinical staff is familiar with is available as a substitute. Battery depletion may occur as a result of the inspection testing of battery-powered units. Ensure that a replacement unit or a fully charged battery is available before you begin testing. Do not test all batterypowered units in an area at the same time, since this will leave the staff inadequately equipped to handle emergencies until the batteries recharge.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Defibrillator energies may be specified in either joules (J) or watt-seconds; these are equivalent units (i.e., 1 J = 1 watt-second).

Defibrillator analyzer Ground resistance ohmmeter


Leakage current meter or electrical safety analyzer

1.1


1.2


1.3

Casters/Brakes. Check the condition of cart casters. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the cart is so equipped.

Stopwatch or watch with a second hand ECG simulator and ECG monitor (only for units with synchronization capability) Oscilloscope (acceptance testing only) Isolation test supply (included in some electrical safety analyzers; acceptance testing only)

Special precautions CAUTION: The high voltage present on defibrillator paddles during discharge is extremely dangerous and possibly lethal. Never perform testing alone. A second person must be present to summon help and/or apply CPR in the event of an emergency. Never hold or contact the conductive electrode portion of the paddles unless

2


Defibrillators 1.4

AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device is mounted on a cart that has electrical receptacles for additional equipment, insert an AC plug into each and check that it is held firmly. Inspect resuscitation cart receptacles, including testing for wiring (e.g., using an outlet tester) and tension of all three connections. Also inspect the resuscitation cart plug for damage as described above.

1.5

Line Cord. Inspect the cord (including resuscitation cart line cord, if appropriate) for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Check line cords of battery chargers.

1.6


1.7


1.9

Cables. Inspect the cables of internal and external paddles, disposable defibrillation electrodes (if applicable), and synchronizer cables for their strain reliefs and general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact pins or surfaces should be straight and clean. Verify that leads and electrodes are firmly gripped in their appropriate connectors. During major inspections, disconnect the paddle connectors and look for misaligned pins, damaged receptacles, and carbon deposits from arcing. 1.11 Paddles/Electrodes. Confirm that special paddles (e.g., pediatric, internal) and electrodes (e.g., disposable defibrillation electrodes) are available if appropriate for the area of use. Examine all paddles for physical condition and

cleanliness. Alert clinical personnel responsible for the instrument to the presence of dried electrode gel, physiologic fluids, or debris on the paddle surface or handles. Dirty electrodes prevent good electrical contact and often cause burns. Electrode gel or other debris on the insulating portion of the paddle can cause operator shocks. Clean the paddles if needed, including electrode surfaces and handle seams, and ensure that they are completely dry before proceeding with any testing. Confirm that an adequate supply of ECG electrodes and disposable defibrillation electrodes (if used) are available and that they are stored properly and are within their expiration dates. 1.13 Controls/Switches. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, check that each control and switch performs its proper function. If the unit has redundant control functions (e.g., a charge button on the front panel and on a paddle), ensure that both controls function properly. Verify that activating just one paddle discharge button will not discharge the unit (both buttons must be pressed simultaneously to discharge). A front-panel discharge button should control only internal paddles (or disposable defibrillator electrodes on some units) and should not cause discharge when external paddles are connected. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Verify that the charger of battery-operated units is plugged into a live AC outlet and that the charger is attached to the defibrillator (i.e, charger cable is attached, unit is firmly seated into charging stand or mount, instrument end of line cord is attached, and charging light is on). For units with removable batteries that are charged in a separate charger, verify that the batteries are properly installed and that the charging, or ready, light is on. Inform clinical personnel of any deficiencies or improper use. Perform the inspection with the unit on battery power to check that the defibrillator batteries are


3

Inspection and Preventive Maintenance System charged and can hold a charge. Check battery capacity by activating the battery test function or measuring the battery-powered operating time. When it is necessary to replace a battery, label it with the date.

exposed (unpainted and not anodized) metal on the defibrillator chassis (and charger if applicable). We recommend a maximum of 0.5 Ω. 2.2

Chassis Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened and the unit off, on, charging, and charged. Record the maximum leakage current. Leakage current from chassis to ground should not exceed 300 µA.

2.3

Paddle Continuity. Use an ohmmeter to verify continuity from each paddle (internal and external) to the appropriate pin of the paddle connector. Wiggle, bend, and pull the cable, especially near the paddle and connector, to check that continuity is not affected. (Current may jump across a small break in the paddle lead and may not be detected during defibrillator output tests. An ohmmeter test will detect such a discontinuity before it gets worse.) This check should also be done for the reusable cable used with disposable defibrillation electrodes. Internal paddles may require more frequent continuity checks. The resistance from the paddle to the appropriate pin of the paddle connector should not exceed 0.15 Ω.

2.4

Energy After 60 Sec. Deterioration of the energy storage capacitors in some defibrillators results in charge leakage after the charging circuit had been deenergized. In these units, it is possible for the available energy to decrease if the unit is not discharged at the earliest possible moment. Use the following test to identify this deficiency.

Some batteries require periodic deep discharges and recharging to maintain maximum capacity. If the manufacturer recommends this procedure, verify that it is being performed on schedule. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., charge tone). Confirm appropriate volume, as well as the operation of a volume control. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories (gel, pads, or electrodes). Verify that defibrillator gel, disposable defibrillator pads, or disposable defibrillator electrodes are stored with the unit and that they are within their expiration dates. Confirm that defibrillator gel is being used, not skin lubricant or ultrasound or TENS gel. Notify appropriate clinical personnel if any accessories are missing. 1.24 Internal Discharge of Stored Energy. To protect personnel from accidental shock, it should be possible to discharge the stored energy safely in the event that the operator decides not to use the defibrillator after it has been charged. Verify that the unit releases the stored energy when the power is turned off. If the unit has a front-panel button for this purpose, verify proper operation.

Charge the defibrillator to its maximum setting, but do not discharge it for 1 min. The delivered energy should be at least 85% of that obtained when the unit is discharged immediately (as in Item 2.10) and should meet manufacturer specifications for charge leakage. (Some units are designed to intentionally bleed or discharge the capacitor charge if the defibrillator is not discharged within a set time period. These units should meet the manufacturer’s specifications.)

1.25 Synchronizer. If the unit has a synchronization mode, verify that the unit will not discharge while in this mode when no ECG signal is present and that it will discharge when a simulated ECG signal is applied. 2.5


4

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord (or charger power cord) and

Internal Paddle Energy Limit. Defibrillator output, when used with internal paddles, should not exceed 50 J. Test this feature on any unit that is located where it may be used with internal paddles or that is portable and may be moved to such a location. Connect the internal paddles, charge the unit to maximum energy, and discharge it


Defibrillators The time to charge to maximum energy should not exceed 15 sec. The output energy should remain within 4 J or 15% of the selected energy throughout the test.

into the defibrillator analyzer. Verify that the output does not exceed 50 J. 2.10 Output Energy. During major inspections, measure output energy at minimum, intermediate, and maximum energy settings. If the defibrillator is commonly used for cardioversion, a 50 J level would be satisfactory for the intermediate range. At each energy level, record the control setting, indicated energy (on the unit’s energy meter), and delivered energy (measured by an analyzer) after discharging the defibrillator into the analyzer as soon as it is charged.

CAUTION: Do not perform this test on all battery-operated defibrillators in an area on the same day unless provisions are made for backup units or spare charged batteries. Batteries may take considerable time to recharge, and a fully charged unit must be available for emergencies.


Clean the exterior and paddles.

3.4

Replace the battery if any of the test procedures indicate a weak or defective battery, even after charging for 12 hr or more.

At its maximum setting, the unit should be able to deliver at least 250 J. The output energy should be within 4 J at low settings (below 25 J) or 15% of the set energy (and the indicated energy, if so equipped) at higher energies.

Some users have also reported that periodic prophylactic battery replacement, either annually or every other year, increases reliability and decreases service calls. In such a case, mark the date of the battery replacement on the battery or unit and check it during each inspection. Perform the inspection after battery replacement and a suitable charge period.

If the output is unusally low at very low control settings, check for a break in the cables or a defective connector. During minor inspections, verify output at only one energy level. Use the defibrillator’s internal test load, if so equipped. Typically, this provides a numeric or a pass/fail indicator to verify that energy was delivered.

Since some units have more than one battery, be sure that all batteries are checked, maintained, and replaced as required.

4. Acceptance tests 2.11 Charge Time and Max Energy (10th Charge). In resuscitation attempts, it is not uncommon for the operator to call for multiple defibrillation shocks in rapid succession. Battery-powered defibrillators may not have sufficient energy left in their batteries to deliver 10 shocks. These deficiencies are best discovered during periodic inspections, rather than during clinical use. Charge battery-powered units to maximum energy and discharge 10 times through the analyzer (but first verify that the analyzer load will not be damaged by repeated discharge). On the 10th cycle, record the charging time (i.e., the time it takes the meter to equilibrate or the ready light to come on) and the delivered energy. To avoid excessive battery depletion, stop the test and record the number of discharges and the values measured if the charging time exceeds 15 sec before the 10th discharge. Also stop the test if the battery-condition meter indicates a weak battery or, on some defibrillators, if the internal circuitry terminates the charge early.

Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. CAUTION: Do not measure paddle leakage current with the unit charged or charging or during discharge. AAMI DF-2-1989, Standard for Cardiac Defibrillator Devices, calls for applying isolated input risk current tests (source, sink, and interlead) to defibrillator paddles, but with limits of 100 µA for external paddles and 50 µA for internal paddles. In addition, perform the following tests. 4.1

Synchronizer Operation. Check the synchronizers of units so equipped. An independent monitor must be used in conjunction with the defibrillator to allow synchronized operation (although this can be done, AAMI does not recommend it). The thoroughness of this test will depend upon the availability of test equipment. Connect the monitor that will be used clinically to the defibrillator. Supply an ECG signal from an ECG


5

Inspection and Preventive Maintenance System simulator to the monitor to trigger the discharge of the defibrillator into a 50 Ω load (e.g., a defibrillator analyzer). Set the defibrillator to deliver low output energy (50 J or less). Confirm that, with the ECG simulator off, the defibrillator does not discharge. With a signal applied, confirm that the synchronizer marker or other indicator is functioning properly. Use a dual-channel oscilloscope to note the time delay between the peak of a QRS pulse (from an ECG simulator) and the defibrillator pulse (from a defibrillator analyzer). Use the ECG signal to trigger the oscilloscope’s sweep. Some defibrillator analyzers have synchronizer test functions. With an ECG amplitude sufficient to activate the marker or indicator, the defibrillator should discharge within 60 msec or less following the peak of the R wave, after the discharge buttons are depressed. The monitor should provide its synchronizing signal within 35 msec of the R wave peak. The delay time between the application of the most recent synchronizing signal from the monitor and the discharge should not exceed 25 msec. Thus, the overall delay from the defibrillator and monitor should not exceed 60 msec. Most units will trigger on the first QRS after depressing buttons, although some units are designed to delay until the second or third QRS to avoid unintentional discharges.

6

4.2

Internal Paddle Energy Limit. During acceptance testing, perform Item 2.5 on all units equipped with this feature, regardless of the location intended for the device.

4.3

Repeated Discharge. Verify that the battery meets hospital or manufacturer specifications for the number of defibrillator shocks that can be delivered. Perform Item 2.11 on line-powered units to verify that the unit is able to provide at least 10 sequential defibrillation discharges.

4.4

Integral Output Tester. Check the operation and accuracy of any integral defibrillator test load, if so equipped.

Before returning to use Return the energy-select control to its normal setting. Before connecting the charger on battery-powered units, check the battery condition to verify that there is an adequate battery charge. If there is not, or if doubt exists, ensure that a suitable replacement defibrillator is available, and allow the unit just inspected to charge in an out-of-the-way location (i.e., where it will not be taken for use by clinical personnel). Otherwise, connect battery-powered units to the charger, plug the charger into a wall outlet, and verify that the charging light is on. For units with removable batteries that are charged in a separate charger, replace the battery used during testing with a fully charged battery and place the used battery in the charger for proper charging.



ECG Monitors Used For: ECG Monitors [12-599]

Also Called: Cardiac monitors Commonly Used In: Operating rooms, emergency rooms, critical care units as part of a physiologic monitoring system, other special care areas, cardiac catheterization laboratories Scope: Primarily applies to stand-alone ECG monitors (line or battery powered); appropriate for use in conjunction with other procedures when inspecting physiologic monitoring systems that include multiple physiologic parameters; adaptable for use with ECG telemetry systems and systems with central stations; also applies to rate meters and direct writers for monitors with these features; does not apply to ECG arrhythmia monitors or to monitors in defibrillator/monitor units (use Defibrillator/Monitors Procedure/Checklist 408) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

*

This procedure is generally not required for a permanently installed system if the hospital routinely performs a visual inspection of the area, paying reasonable attention to the monitors.

Overview ECG monitors are routinely used on patients with known or suspected cardiac arrhythmias. The monitors display the patient’s electrocardiogram so that those attending the patient may continuously observe the electrical activity of the heart. Since the monitor is used only to observe the patient’s basic cardiac rhythm, it need not meet the accuracy and fidelity criteria expected of an electrocardiograph.

Citations from Health Devices Artifacts from piezoelectric voltages [Consultant’s Corner], 1982 Nov; 12:27. Patient monitoring systems [Evaluation], 1985 MarApr; 14:143. GIGO: A compendium of ECG monitoring problems, 1985 Mar-Apr; 14:158.


Physiologic patient monitors [Evaluation], 1991 MarApr; 20:81. ECG artifact in the OR [User Experience NetworkTM], 1991 Mar-Apr; 20:140. Thermal injuries and patient monitoring during MRI studies [Hazard], 1991 Sep; 20:362. Physiologic patient monitors [Evaluation update], 1992 Mar-Apr; 21:123-8. Risk of electric shock from patient monitoring cables and electrode lead wires [Hazard], 1993 May-Jun; 22:301.

Test apparatus and supplies ECG simulator (calibrated output amplitudes and rates may be required for some tests) Leakage current meter or electrical safety analyzer


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Inspection and Preventive Maintenance System Ground resistance ohmmeter The following equipment is necessary during acceptance testing only: Signal generator Attenuator Oscilloscope Transparent metric scale Stopwatch or watch with a second hand

Special precautions Testing monitor isolation requires the use of a line voltage source. Although this source should include a current-limiting resistor, use caution to avoid contact with any portions of the energized circuit. Inspection testing may deplete the battery of battery-powered units. Ensure that a replacement unit or a fully charged battery is available before you begin testing. Do not test all the units in an area at one time, since this will leave the staff inadequately equipped.

Some monitors or monitoring systems provide multilead ECG signal processing and display (simultaneous display of two ECG leads). Conduct display quality and performance tests on each channel. On singlechannel units that have lead switching, except where otherwise indicated, all tests can be performed in one lead, using the appropriate electrode leads (e.g., lead I, using LA and RA as inputs). When a monitor is part of a system with a remote or central station display, use a separate inspection form to record results for each display. Verify interactive functions from each bedside (e.g., central station alarm sounds, chart recorder activates when heart rate exceeds set limits). Test displays for each bedside separately, but test common elements (e.g., quality of central chart recorder tracing) from only one bedside. This is most easily accomplished with two people.



1.2


1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture of an area (see Procedure/Form 441, Conductive Furniture and Floors).

1.4


1.5


Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Enter cross-referenced data related to the ECG monitor at the top of the inspection form. Since the monitor may be installed in a mainframe along with other removable modules (e.g., blood pressure unit, body temperature unit, recorder), assign a separate control number to the mainframe and to each discrete module. Enter the mainframe control number in the Control No. space of the inspection form to identify the entire device. This will help you locate the whole monitor or an individual module if follow-up action is needed. Enter all module control numbers in the System Components box on the form, and indicate which are covered on separate forms. If the device is configured (i.e., different functions are not in removable modules but are contained within a single integral housing), assign only one control number. In the System Components box, list any functions that will be inspected but recorded on separate inspection forms (e.g., blood pressure), and note the use of other forms.

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ECG Monitors 1.6


1.7


1.9

Cables. Inspect the patient cable and leads and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain. Connect the unit to an ECG simulator and verify that an adequate trace is received at each patient lead selection. Flex the patient cable near each end to verify that there are no intermittent faults.

1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact pins or surfaces should be straight and clean. Verify that leads and electrodes are firmly gripped in their appropriate connectors. 1.11 Electrodes. Confirm that an adequate supply of electrodes is on hand, and check the electrodes’ physical condition.

1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Perform the inspection with the unit on battery power or operate the unit on battery power for several minutes to check that the batteries are charged and can hold a charge. Check battery capacity by activating the battery test function or measuring the output voltage. When it is necessary to replace a battery, label it with the date. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. Some batteries require periodic deep discharges and recharging to maintain maximum battery capacity. If this is recommended by the manufacturer, verify that it is being performed on schedule. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, and visual displays on the unit and the charger (if appropriate). Be sure that all segments of a digital display function. Observe a simulated ECG signal on a CRT display, and verify compliance with the following criteria: The baseline should stay in focus across the display.

1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection.

The baseline should be horizontal and should not be noticeably sloped or bowed.

Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, check that each control and switch performs its proper function.

When the vertical position of the baseline is varied by adjusting the vertical position control, the baseline should move throughout most of the vertical height of the display. There should be no distortion in the baseline as it is moved up or down on the screen. In monitors that incorporate a self-centering baseline (and thus lack a position control), the baseline should be correctly positioned.

Check alignment of touchscreen sensors. Verify that functions are activated when the center of the desired function box is touched.

The pulses from an ECG simulator should be regularly spaced (uneven spacing indicates a sweep nonlinearity). All portions of a simulated ECG waveform should be clear and visible, including the Pwave and QRS.

Ambient light should not affect the visibility of the trace. (If monitors are located so that ambient light reflects from the face of the display, making the ECG difficult to see, con-


3

Inspection and Preventive Maintenance System step response test (Item 1.19) on the direct writer.

trol the light or use a filter over the display faceplate.) “Burn spots” should not be visible on the cathode ray tube. (If the intensity is set too high, the phosphor may “burn”; the cathode-ray tube face will be discolored if this condition exists.)


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the defibrillator chassis (and charger chassis if appropriate). We recommend a maximum of 0.5 Ω. If the system is modular, verify grounding of the mainframe and each module.

2.2

Chassis Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA.

60 Hz or other noise (interference) should not be superimposed on the baseline with the ECG simulator attached. Baseline interference may be apparent as a thick baseline at high gain settings but should not be visible throughout the lower two-thirds of the gain control range. 1.19 1 mV Step Response. Depress and hold the 1 mV calibration button for about 3 sec (or apply an external 1 mV pulse if the unit does not have a calibration pulse). The trace should exhibit a sharp square-cornered leading edge that is neither rounded nor spiked (any spike should be less than 10%). After 1 sec, the pulse should have decayed no more than half its original amplitude (see Figure 1). With the gain set to yield about 20 mm deflection for a 1 mV input (×2 or 1/2 mV/div), compare the amplitude of the internal calibration pulse and an external 1 mV signal (from a calibrated ECG simulator). At a 20 mm deflection, they should be within 2 mm (±10%) of each other. 1.20 Alarms. Operate the device in such a way as to activate each audible and visual alarm. Check for adequate alarm tone volume and any associated features, such as automatic direct writer activation or display freeze function. If the device has an alarm-silence feature, check that the unit resets automatically or that the manual reset functions. Check bed-to-bed and bed-to-central station alarm networking (where appropriate).

If a bedside or central station monitor is grounded through system interconnections in addition to power-line grounding (and is used only in this configuration), do not disconnect the monitor from the system to measure chassis leakage current during routine inspections. Verifying low grounding resistance is adequate. 2.10 Rate Calibration. Using simulated ECG rates of 60 and 120 pulses per minute, verify that the heart rate indicator displays a rate within 5% or 5 bpm, whichever is greater, of the set rate (55 to 65 bpm, 119 to 126 bpm). Verify that the QRS visual and audible indicators are functioning.

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.24 Direct Writer. If the unit has a direct writer, confirm that it operates smoothly, that the paper feeds evenly and does not stray from side to side, and that the trace is of good quality (i.e., dark and thin) at all paper speeds. Perform the 1 mV

4

Figure 1. The calibration pulse or step response leading edge should have square corners (left). Slight rounding (middle) or small overshoot is acceptable. Excessive rounding or overshoot (right) indicates the need for adjustment.


ECG Monitors 2.11 Rate Alarm. Use the same setup as for the previous test. For typical low- and high-rate alarm settings of 40 and 120 bpm, respectively, verify that the alarm activates when the input rate is set just below or above the respective rate alarm settings. The difference between the rate displayed on the rate indicator and that at which the alarm is activated should not exceed 5% or 5 bpm, whichever is greater.

Common mode rejection is needed in monitors because of the presence of stray signals common to all input leads primarily at power-line frequency (60 Hz). While these signals are too minute to be hazardous, they can interfere with the ECG display of a monitor with a low CMRR at 60 Hz. The CMRR is defined as: CMRR =


Clean the exterior, rollers, and platen, if needed.

3.2

Lubricate the chart recorder paper drive per the manufacturer’s recommendations, if required.

3.4

Replace filters and batteries, if required. Some units have air filters that accompany the cooling fan. These filters should be checked and replaced if needed. If any of the test procedures indicate a weak or defective battery, even after charging for 12 hr or more, replace the battery. Some users have also reported that periodic, prophylactic battery replacement, either annually or every other year, increases reliability and decreases service calls. If the battery is replaced, mark the date of the replacement on the battery or unit. Perform the inspection after battery replacement and a suitable charge period.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. Most ECG monitors should meet the requirements for isolated input devices for ECG lead-to-ground, interlead, and input isolation tests.

Differential mode deflection factor or DMD (MM / mV) Common mode deflection factor or CMD (MM / mV)

A deflection factor is the change in trace position corresponding to a given input voltage to the monitor. Use an unbalanced CMRR measurement that includes a 5,000 Ω resistor in series with one of the input leads to the monitor, to simulate unequal impedances in the electrode/skin interface of the monitor electrodes, as commonly occurs in practice. Since most common mode voltage in the hospital is at 60 Hz, it is most significant to measure the CMRR at or near that frequency. Using the test setup shown in Figure 2, apply a sinusoid test signal of 1 mV peak-to-peak at about 60 Hz to the monitor. A frequency of 55 Hz is often used to minimize interference from line frequency noise. Turn the monitor gain so that the deflection is at least 20 mm. Measure the deflection (mm), and record it on the inspection form as the differential mode deflection factor. Since the input signal for this measurement is 1 mV, the differential mode deflection factor expressed in mm/mV is numerically equal to the resultant deflection in mm. Do not vary the gain of the monitor or the signal frequency for the remainder of this test. Record the frequency on the inspection form.

In addition, perform the following tests. 4.1

Common Mode Rejection Ratio (CMRR). The ECG monitor includes a differential amplifier so that it can display the voltage difference between two electrodes (the RA and LA in lead 1) while using a third electrode (RL) as a reference. If the same, or common, voltage is applied to RA and LA simultaneously, there should be no output from the differential amplifier because the voltage difference between the two inputs is zero. The extent to which a differential amplifier produces no output when the same signal is applied to both inputs is called its common mode rejection ratio.

Figure 2. Signal input test setup.


5

Inspection and Preventive Maintenance System Connect an ECG simulator with variable output to the monitor and set it for a rate of 60 bpm. Vary the output amplitude over a range of 0.5 to 5 mV (use the monitor display to estimate amplitude if the simulator does not have a calibrated output). The monitor should reliably detect all beats and should not double-count. It should not detect QRS amplitudes of less than 0.15 mV. If the unit has a manual sensitivity control, check that it is functioning properly as evidenced by the need to change the setting during this test.

Use the test setup shown in Figure 3 for the second part of this measurement. Note that there is only one connection from the output of the attenuator to the patient leads. The other output terminal is grounded. It is essential that all instruments used in this test be connected to

4.4

Paper Speed. Use an ECG simulator set to 60 bpm or a signal or pulse generator that has been set to 1 Hz with a calibrated counter. If the interval between pulses is not within 10 msec of 1,000 msec, an appropriate correction should be made in calculating paper speed. Paper speed should be accurate to within 2%. At a chart speed of 25 mm/sec and a pulse interval of 1,000 msec (60 bpm on an ECG simulator), the distance between the first and last of five successive peaks should be 100 ±2 mm; at a chart speed of 50 mm/sec, the distance between the first and the last of five successive peaks should be 200 ±4 mm.

4.5

Alarm Delay. In addition to checking rate alarm accuracy (Item 2.11), use the same test setup to determine alarm delay. First, set the high-rate alarm to 100 bpm and the ECG simulator to 60 bpm. Quickly change the simulator rate to 120 bpm and use a stopwatch or a watch with a second hand to measure the time until the alarm sounds. Check the low-rate alarm similarly (set alarm for 40 bpm, change rate from 60 to 30 bpm). Generally, alarm delays should not exceed 10 sec.

4.6

Battery Operating Time. If the unit can operate on battery power, verify that it meets hospital or manufacturer specifications for operating time. Units should meet requirements with all functions operating (including alarms sounding) unless otherwise specified by the manufacturer.

Figure 3. Common mode rejection ratio test setup. a common ground to minimize noise. Increase the amplitude of the sinusoid signal (10 V peak-to-peak) until some measurable deflection is observed on the monitor. Calculate the common mode deflection factor by dividing the resultant deflection (in mm) by the input signal (in mV). The CMRR can then be calculated as the differential mode deflection factor divided by the common mode deflection factor. If the unit has an ungrounded or plastic case, measure the CMRR with the unit resting on a grounded metal plate. CMRR should meet the manufacturer’s specification and be at least 10,000:1. 4.2

4.3

6

Gain. Apply a 2 mV signal at a gain setting of 10 mV/mm (or ×1) and measure the displayed amplitude with a transparent scale. Verify that the displayed signal size changes appropriately (within 10%) as the gain setting is changed. For example, if a 2 mV signal produces a 20 mm deflection (at a ×1 gain), the deflection should be 36 to 44 mm at ×2. Test both the monitor display and recorder. QRS Sensitivity. If the monitor has a QRS indicator or beeper or a heart rate meter, verify that the QRS detector circuit is functioning properly.

Before returning to use Return controls and alarm limits to their original positions, and make sure that the unit is not left in a service mode. Check the battery condition meter indicator on battery-powered units to verify that there is adequate charge.



Electrical Receptacles Used For: Receptacles, Hospital Grade [15-859]

Also Called: Electrical outlets Scope: Applies to three-wire parallel-blade grounding-type electrical receptacles used in grounded electrical distribution systems throughout the hospital; does not apply to explosion-proof or other special types of receptacles (for information on testing of isolated power systems, see Procedure/Form 439) Risk Level: ECRI Recommended, Low; Hospital Assessment, ECRI-Recommended Interval: See Overview below for NFPA requirements and ECRI recommendations

Overview A defective or deteriorating electrical system exposes patients and staff to the risk of electrical shock and potential interruption of power required to operate medical equipment. A periodic inspection program designed to detect and correct deficiencies at each receptacle is required to reduce these risks. NFPA 99, 1993 Edition, specifies that receptacles in general care areas be tested every 12 months and that those in critical care areas and designated wet locations be tested every 6 months. (See the Patient Care Areas box for explanations of the italicized terms used in the NFPA standard.) NFPA permits extending the intervals if documented performance data justify longer intervals. Initially, inspections should be conducted at the specified 12- and 6-month intervals. The data obtained during these initial inspections should then be examined and used to determine appropriate intervals. Although there is no formal guideline on an acceptable number of defects, ECRI believes that the testing interval can be extended if fewer than 2% of the receptacles in an area require replacement or other corrective action. A recent study by ECRI of more than 800,000 receptacles inspected between 1987 and 1994 indicates that more than 13% failed to meet one or more of the criteria in this procedure. However, little is known about the history of these receptacles. Annual testing should be adequate in areas where receptacles receive frequent use; other areas may require even less frequent testing. (Note that NFPA


99 requires semiannual testing in wet areas in existing facilities that are not supplied with special protective systems, such as ground fault circuit interrupters [GFCIs] or isolated power.) NFPA 99, Section 3.5.2.1, specifies that voltage and impedance tests be performed to measure the effectiveness or quality of the grounding system. This section specifies that these tests be performed before acceptance on all new construction and when the electrical system has been altered or replaced. Sections 3.5.2.2 and 3.6.2.3.1 require that the physical integrity, polarity, retention force of the grounding blade, and continuity of the grounding circuit of each receptacle be verified every 12 months in general care and wet locations and every 6 months in critical care areas. The ECRI procedures given in the sections on Ground Potentials and Grounding Resistance below cover both of these requirements. A power plug and receptacle combination should: Provide a safe, reliable means of connecting and disconnecting an electrically powered device Permit only devices intended for use with that supply to be connected Allow only one orientation of plug contacts in the receptacle Have low electrical contact resistance between the plug and the receptacle Withstand normal use and reasonable mechanical abuse


●



Patient Care Areas In specifying testing requirements for electrical receptacles, NFPA refers to general care areas, critical care areas, and wet locations; these terms are explained below. General care areas are patient bedrooms, examining rooms, treatment rooms, clinics, and similar areas in which it is intended that the patient shall come into contact with ordinary appliances, such as a nurse call system, electric beds, examining lamps, a telephone, and entertainment devices. In such areas, it may also be intended that patients be connected to electromedical devices (e.g., heating pads, electrocardiographs, drainage pumps, monitors, otoscopes, ophthalmoscopes, peripheral intravenous lines). Critical care areas are those special care units, intensive care units, coronary care units, angiography laboratories, cardiac catheterization laboratories, delivery rooms, operating rooms, and similar areas in which patients are intended to be subjected to invasive procedures and connected to line-operated electromedical devices. Wet locations are patient care areas that are normally subject to wet conditions while patients are present; this includes standing fluids on the floor or drenching of the work area, either of which condition is intimate to the patient or staff. Routine housekeeping procedures and incidental spillage of liquids do not define a wet location. (Note: Areas that may typically be designated as wet locations include hydrotherapy areas, dialysis units, and certain wet laboratories. Operating rooms, even though there may be significant amounts of spilled fluids, are generally not considered wet areas.) Ensure that the grounding pin on the plug cap is the first to engage and the last to disengage in the receptacle at all angles of entry and withdrawal Provide strain relief for the power cord where it enters the plug cap Several plug and receptacle configurations are available for specific applications. The two-pole, three-wire, parallel-blade grounding-type receptacle is most familiar because of its widespread use. This configuration can be made to satisfy the requirements for a reliable plug-receptacle combination. Other receptacle configurations, which generally

2

have higher current or voltage ratings, are used in hospitals for housekeeping equipment, food carts, and mobile x-ray units. Explosion-proof plugs and receptacles are required in operating rooms where flammable anesthetics are used and in other areas where arcing when inserting or removing a plug could ignite flammable gases. Only two conductors are required to operate a 120 V device, and two-wire parallel-blade plugs and receptacles have been in common use for many years. One of these conductors is connected to earth ground near the point where the power enters the building. This conductor, colored white, is commonly called the neutral wire but is frequently referred to in codes as the grounded conductor. The other conductor, carrying power to the receptacles, is called the hot conductor and is usually colored black. Its voltage is approximately 120 V with respect to the neutral conductor or ground reference. The third conductor in a three-wire power cord for conventional equipment does not carry normal load current. At the equipment end of the cord, it connects to the chassis and exposed metal. When the plug is inserted into a properly installed three-slot grounding receptacle, the third wire is connected to ground. This grounding wire (not to be confused with grounded connector), usually green, is intended to carry normally small leakage currents, as well as large fault currents resulting from shorts, from the hot conductor to the chassis. By connecting the equipment chassis to ground, this third wire protects people touching the chassis against electric shocks. Because load current does not normally flow through it, the green wire will be closer to ground potential than the neutral wire. The grounding slot of the receptacle is attached to the yoke with which the receptacle mounts in its box, and the box is grounded through the metal conduit through which the wires run. The receptacle ground terminal can also be grounded by a separate grounding conductor connected to the grounding point in the electrical distribution system panel board. The separate wire, or pulled ground, is a more reliable means of grounding, because the conduit is made of a material that can corrode and has mechanical joints that can loosen. Current electrical codes for new construction require that the ground terminals of all receptacles in patient care areas be connected to ground by a separate insulated copper conductor. An exception to the code allows existing construction that does not use a separate grounding conductor to continue in use provided it meets the specified grounding performance requirements. The common three-slot, parallel-blade, groundingtype receptacle is intended for branch circuits rated at


Electrical Receptacles 15 A, which is adequate for most 120 V devices. Receptacles and plugs of a slightly different configuration are available for branch circuits and equipment that require between 15 and 20 A. The 20 A receptacle is designed to accept both the 20 A and 15 A plugs, but the 20 A plug cannot be used in a 15 A receptacle. The conventional three-prong plug and three-slot receptacle are polarized so that they will mate in only one direction. Assuming that the receptacle and equipment are wired correctly, the polarization ensures that the hot, neutral, and ground wires in the power cord connect to their counterparts in the receptacle. The conventional two-slot receptacle provides for polarization by the difference in the size of the receptacle slots (the hot wire slot is smaller than the neutral slot). Thus, equipment requiring polarization is equipped with plugs that have blades of different sizes.

Citations from Health Devices Ground fault circuit interrupters [Evaluation], 1973 Mar; 2:112-5. Hospital Grade duplex receptacles [Evaluation], 1978 Nov; 8:3-18. OR renovations and the use of isolated power and explosion-proof plugs [User Experience NetworkTM], 1992 Sep; 21:334. Electrical outlets in anesthesizing locations, 1993 AugSep; 22:420.

Test apparatus and supplies Three-lamp receptacle wiring polarity tester AC voltmeter, range 100 to 140 V Low-resistance ohmmeter, resolution to 0.01 Ω in the 0 to 0.2 Ω range Leakage current meter or voltmeter capable of measuring 20 to 500 MV Receptacle tension tester Leads and adapters to connect receptacle and other ground points GFCI tester (electrical safety analyzer or isolated power tester) Defective receptacle tags Test equipment that combines the function of the above test devices or that automates the testing described in this procedure is available and may be substituted.

Special precautions Testing in occupied areas must not pose a hazard to patients. Devices used to determine ground quality or grounding impedance apply power to the grounding circuit. To minimize risks to the patient and equipment in the testing area and potentially in other areas served by the same circuit, the output of the testing devices should be limited to 500 mV RMS (1.4 V peak to peak) or 1.4 VDC even under open-circuit conditions. Receptacles should be tested with all equipment unplugged. Consult clinical personnel before disconnecting patients from devices or unplugging equipment and before turning off a branch circuit breaker to correct defective receptacles. Do not attempt to unplug life support and critical monitoring devices that are in use; return when the bed is unoccupied or occupied by a patient better able to withstand the transfer of devices to alternate power sources.

Procedure Before beginning the receptacle inspections, determine the extent to which inspecting personnel should correct deficiencies on the spot. Certainly, such minor defects as a loose screw on the cover plate should be corrected. Inspecting personnel might also carry a supply of new receptacles and cover plates and replace and retest defective receptacles as identified. Alternatively, inspectors can identify defective receptacles with “Defective — Do Not Use” tags; qualified personnel can follow up by correcting defective receptacles and retesting. Because the Universal Inspection Form does not apply, use the special Electrical Receptacles Form 437 included with this procedure. Identify the area to be tested; this may be a room, special care area, corridor, or an area with many receptacles (e.g., coronary care unit, isolated power system). If failures occur, note these on the form and identify the location of the receptacle. Using a standard method for numbering the receptacles in an area will prove helpful. One way is to enter the area and start to the left of the door, proceeding clockwise around the area. If a defective receptacle is not repaired or replaced at the time of inspection, put a “Defective — Do Not Use” tag on it. Exception reporting can save time when using the form. If no defects are encountered in an area or room, indicate the area, room, and outlet on the form, write OK in the “Status” box and check off the “Exception Reporting Used” box. You need only record measurements that fall outside the criteria for any test in the appropriate box on the form. If you are planning to adjust the inspection intervals, record the total number of outlets inspected


3

Inspection and Preventive Maintenance System (use the margin) so that the percentage of defective receptacles can be determined. Inspect every receptacle in the area with all equipment unplugged from the receptacle under test. Caution: Consult clinical personnel before unplugging any equipment. If deficiencies are found, identify the defective outlet on the form and indicate the need for corrective action in the “Comments” column. If the space provided on the form is inadequate, write “See note” in the block and use the back of the form. Be sure to include the receptacle number on all such notes. If more than one form is needed for an area, number each sheet, and attach them together. To save time, you may want to perform all of the tests, except Ground Potentials and Grounding Resistance, on each individual receptacle in a room or area, then proceed with the remaining tests on all receptacles.

Mechanical condition Visually inspect the receptacle and cover plate for physical damage and security of physical mounting of the receptacle and outlet box. Replace the receptacle if its face is badly chipped or broken. Replace the cover plate if it is cracked. Correct any defects in physical mounting. If any sensation of heat is noted when touching the surface of the receptacle or when unplugging connected equipment, investigate further. Heating within the receptacle can be caused by several deficiencies, including high resistance at the receptacle contact due to wear, damage, or loose wiring, especially if improper techniques have been used with aluminum wiring. Rarely will a receptacle develop internal leakage. Before condemning the receptacle, rule out any defect in the equipment that causes it to draw excessive current or poor connections in the plug cap.

Wiring polarity Check each receptacle for wiring errors with a threelamp polarity tester. This tester will indicate loss from hot, neutral, or ground wires and whether hot and neutral or hot and ground wires have been interchanged. It does not detect neutral/ground reversal and does not verify that grounding is adequate to carry fault currents. Correct any wiring errors. Look for flickering of the tester’s lights as it is inserted, jiggled moderately in place, and withdrawn. Such flickering may indicate poor contacts and should be investigated.

4

Line voltage The following line voltage tests are not required by NFPA 99. We have included them as optional tests. These tests should be performed following new construction, renovations, or major repairs to the electrical distribution system to ensure that voltage taps are set correctly on distribution transformers. Repeating the tests after typical loads are applied or in existing facilities may indicate poor wiring or inadequate system capacity. The tests may also be helpful in diagnosing suspected problems and indicating whether a more extensive investigation of the electrical distribution system is necessary. Use an AC voltmeter to measure the hot-to-neutral voltages at representative receptacles in an area or in the branch circuit panel board. The hot-to-neutral voltage should normally be within the 115 to 125 V range. It should not fall below 100 V with heavy loads on the circuit or rise above 130 V during no-load conditions. A significant difference in line voltages to receptacles taken under typical load conditions indicates overloaded circuits or faulty wiring and requires further investigation. An optional means of testing for adequate wiring is to measure the line voltage with and without a load connected to the other half of the duplex receptacle being tested. Measure the AC voltage between the neutral and ground connections. A reading of above 4 V indicates possible miswiring of the neutral and/or ground systems or excessive resistance in the wiring.

Ground potentials The purpose of this test is to determine whether voltage differences exist between points that should be at ground potential. These voltage differences could be caused by high ground-to-ground resistances and/or heavy currents flowing through the ground system. For new construction, NFPA 99 requires that the voltage limit between a reference point and grounding contact of each receptacle in the patient vicinity not exceed 20 mV. In existing construction, the voltage should not exceed 500 mV in general care areas and 40 mV in critical care areas. However, voltages in modern construction are usually less than 10 mV; voltages exceeding 20 mV may indicate a deteriorating condition and should be investigated. It should be understood that these limits are not precise, and differences of less than 20% should be considered insignificant. Measure ground potentials with a voltmeter or leakage current meter. Leakage current readings can be converted to millivolts if the leakage current meter’s


Electrical Receptacles impedance is known. (Most leakage current meters have a 1,000 Ω impedance at line frequency; the reading in µA is then numerically equivalent to the voltage in mV.) Connect one lead of the meter to a reference ground point that is known to be securely grounded. It is usually most convenient to use the ground contact of one receptacle, but a ground plug or structural member can also be used. Do not use the cover plate screw because this may not be adequately grounded. Connect the other lead to the ground contact of each receptacle in turn. To save time, measure ground potentials on an entire room or area at one time, rather than while performing other tests on each receptacle. Ground potentials will not be constant with time but will depend on what equipment is connected and operating at the time of measurement. A high ground potential measurement at a receptacle grounding contact may indicate that the ground and the neutral conductor in the receptacle wiring are reversed. The three-lamp testers will not detect such reversal (which, in fact, will often be undetected during ground potential measurements, since the outlet ground contact will usually be grounded through the conduit).

Neutral-to-ground resistance The safety provided by a good ground system can be compromised if the neutral wires of the receptacles are not properly connected to the grounding system at an appropriate location. For example, if a device plugged into a receptacle with high neutral-to-ground resistance develops a hot-wire-to-chassis short circuit, then 120 V would exist as a shock hazard to anyone touching that chassis. If the neutral-to-ground resistance were low, then the heavy currents flowing from the grounded chassis back to the neutral wire would trip the receptacle’s circuit breaker. ECRI suggests a minimum of 1.0 Ω between the neutral and ground contact of each receptacle.

Grounding resistance The three-lamp testers used to check receptacle wiring as part of the basic inspection will indicate the complete lack of ground. However, a ground whose resistance is as high as several thousand ohms may be considered acceptable by these testers. The purpose of the grounding resistance test is to determine whether the grounding circuit resistance is low enough to serve its intended function. Originally, the ground contact in a receptacle was designed to prevent the chassis of connected equipment from becoming energized in the event of a lineto-chassis fault. In this application, the ground must

carry sufficient current to quickly blow the branch fuse or circuit breaker. More recently, the grounding system has been called upon to drain leakage current and fault currents not large enough to blow a fuse or breaker and to protect hospital patients against microshock under these conditions. In this application, the grounding system resistance must be low enough to prevent dangerous voltages when anticipated leakage or fault currents flow through it. To avoid risk to patients in the area in which testing is being conducted and in areas distant from the testing site, any device used to determine ground quality or grounding resistance on occupied patient care areas must limit the output to 500 mV RMS (1.4 V peak to peak) or 1.4 VDC. Several test devices are available using different measurement methodologies. Any of these special-purpose devices or an ohmmeter with resolution to 0.01 Ω may be used. For periodic measurement in existing construction, the measurement current can be either AC or DC. Select a ground reference point (such as that used for the ground potential test), and measure the resistance between each receptacle ground contact and the reference. The resistance should not exceed 0.2 Ω and, in new construction, should not exceed 0.1 Ω. Action required as a result of ground potential and grounding resistance failures may not be restricted to replacement of a receptacle but may involve the entire area’s wiring and grounding. The need for corrective action should be discussed with the plant engineer or other responsible person. When performing ground potential and resistance tests on new construction and renovations, note the appropriate criteria for new construction included in those test methods. NFPA 99 requires the use of an AC measuring source for postconstruction impedance measurement (but allows the use of AC or DC devices on existing construction).

Contact tension Contact tension — the force with which the spring contacts of the receptacle grip the blades of the plug — affects the performance of the plug/receptacle combination both electrically and mechanically. If contact tension is insufficient, reliable, low-resistance electrical connections cannot be assured. High resistance in the hot and neutral connections can cause internal heating of the receptacle. Plugs with bent blades may not make electrical contact at all. This will be easily recognized with the hot and neutral blades, since the equipment will not function. However, loss of contact


5

Inspection and Preventive Maintenance System on the ground will not be obvious and will compromise the safety of the equipment. In addition, the contact tension must be sufficient to prevent the plug from inadvertently coming out of the receptacle. On the other hand, contact tension should not be so great that the plug cannot be easily inserted or withdrawn. Also, in the event that someone trips over a line cord, the plug should withdraw from the outlet, rather than the equipment being pulled down or the line cord severing. It has been shown that good electrical contact requires a lower gripping force than is needed to grasp the plug firmly. Thus, a mechanical test of tension is sufficient. Measure contact tension on each receptacle while withdrawing the tester straight and smoothly from the outlet. Retention force on the ground prong must be 4 oz or more. We recommend measuring the retention force on the hot and neutral prongs, although this is not required. A retention force of 4 oz is also adequate for the hot and neutral prongs, and forces of 2 to 4 oz are satisfactory if the plug brand in use tends to stabilize at this value and does not continue to deteriorate. (See the Contact Tension Testers box.)

Contact tension testers are available in many configurations and brands. Inaccurate probe sizes and surface finishes, measurement inaccuracies, and poor repeatability can cause erroneous results. Also, many testers are not rugged enough to survive transport in a tool box. We offer the following suggestions for purchase and use of these devices: Check for an appropriate test range of up to at least 8 oz. Make sure that the tester has a specified accuracy or is accurate to within 10%. Ask the manufacturer about probe sizes and finishes. They should be made of tool steel or a metal of equivalent hardness. Though directed at manufacturers, UL and ANSI values may serve as guidelines for hospitals: — Ground probe — cylindrical, 0.4674 to 0.4826 cm (0.184 to 0.190 in) diameter, 8 µ in finish (UL). — Power probe — 0.1397 to 0.1651 cm (0.055 to 0.065 in) thick (ANSI).

GFCIs A GFCI is a device designed to interrupt the electrical circuit to the load when a fault current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device (fuse or circuit breaker) of the supply circuit. The device is usually installed as part of the electrical wiring supplying power to a receptacle. In many cases, it is an integral component of the power receptacle. The GFCI continuously senses the difference in current flow between the hot and neutral wire of the receptacle circuit. Normally, this difference is quite small. However, under fault conditions, current returns to the source by a path other than the neutral wire, thus causing the difference to increase. When the GFCI senses that this difference is greater than some critical value (usually 6 mA), it interrupts the circuit to the receptacle. GFCIs are used for added protection against macroshock hazards in areas where the risk of these hazards is increased due to environmental conditions, such as the presence of water. The use of GFCIs is an acceptable method of reducing macroshock hazards in areas designated as wet locations. NFPA 99 specifies that GFCIs used in wet locations be tested at least every 12 months. The GFCI test procedure is included

6

Contact Tension Testers

Before each receptacle inspection, calibrate the tester to ensure accuracy. Suspend a known weight from the tester, check its scale reading, and adjust if necessary. When using the tester, be sure the probes are clean and dry. Inadvertent lubrication can significantly affect readings. Carry alcohol wipes and clean the probes periodically. as an additional test that applies only to receptacles protected by a GFCI. NFPA specifies that a device or component that causes 6 mA of current to flow to ground shall be momentarily connected between the energized conductor of the power distribution circuit being protected and ground to verify that the GFCI does indeed interrupt the power. Many GFCIs have a built-in test circuit and reset button. We believe this is an adequate test for routine testing. If such a circuit is not built into the receptacle or for a more accurate validation, many electrical safety analyzers and isolated power test devices have a built-in test for GFCIs, and simple GFCI test devices are available commercially.



Electrocardiographs Used For: Electrocardiographs, Interpretive [16-231] Electrocardiographs, Multichannel [11-411] Electrocardiographs, Single-Channel [11-413]

Also Called: EKG units, ECG units, EKG machines Commonly Used In: Electrocardiography departments, emergency departments, and most patient care areas Scope: Applies to single-channel and multichannel electrocardiographs typically used for recording an electrocardiogram on paper; may also be adapted for some systems that digitally store data and later provide hard-copy tracings; not suitable for verifying performance of automated diagnostic functions; does not apply to strip-chart recorders or direct writers, which should be inspected with the ECG monitor or the defibrillator/monitor they are used in conjunction with (use ECG Monitors Procedure/Checklist 409 and Defibrillator/Monitors Procedure/Checklist 408, respectively) Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview An electrocardiograph detects the electrical activity of the heart and produces a graphic record, an electrocardiogram (ECG), of voltage versus time. Each portion of the ECG is directly related to an electrical cardiac event, and variations or abnormalities seen in the ECG can often be traced to a particular site in the heart. Each ECG trace, which is derived from the electrical activity detected by two or more electrodes placed at certain points on the patient’s skin surface, is called a lead. A full-lead ECG records 12 leads derived from 10 electrode locations. By using a high-fidelity recording of multiple leads, it is possible to accurately examine and quantify rhythm and waveform morphology. Voltage levels and timing between events are measured with calipers or automatically by the electrocardiograph. Comparing



Time Required

the various lead signals provides a more specific and accurate diagnosis than would be possible with a single-lead recording. Several standards and guidelines include performance criteria to ensure that recording errors do not interfere with accurate interpretation of the ECG. While verification that an electrocardiograph meets these criteria is an important part of a prepurchase evaluation program and should be included as part of acceptance testing, experience indicates that most of these characteristics do not change on modern electrocardiographs unless there is a major (and usually obvious) equipment failure. Therefore, the inspection procedure has been designed to reduce the amount of testing required. Portable and mobile electrocardiographs deserve special attention; rough handling may change circuit


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Inspection and Preventive Maintenance System characteristics and adversely affect recording or safety. Mishandling frequently damages the delicate writing stylus, galvanometer, chart drive or paper feed, and power cords and plugs.

Citations from Health Devices Single-channel electrocardiographs [Evaluation], 1973-74 Dec-Jan; 3:31-56. Three-channel electrocardiographs [Evaluation], 1984 Aug; 13:235. Defibrillating patients connected to electrocardiographs, 1984 Aug; 13:254. Signal-averaging ECGs: An update, 1990 Sep; 19:328-30. 12-lead multichannel interpretive electrocardiographs [Evaluation], 1991 Oct; 20:367-408.


Some older electrocardiographs may fail to meet current criteria for performance and safety. While units that show deteriorating performance or safety should be repaired or replaced, those that meet their original design specifications may still be suitable for use. When evaluating these units, take into account clinical needs, realistic levels of safety, and funding priorities. Because this Procedure/Checklist covers electrocardiographs used in their conventional application and not as components of larger systems, auxiliary inputs or outputs of the writer are not tested here. If these are used, test them for performance characteristics that pertain to the specific application. Encourage ECG technicians to check their instruments at the start of each shift and to ensure that the units are clean when returned.



1.2


1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one. Also check line cords of battery chargers, if applicable.

1.6


ECG simulator with calibrated output amplitudes and rates Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Contact cleaner and lubricant Counter (optional) The following equipment is necessary during acceptance testing only: Function generator Attenuator Oscilloscope Transparent metric scale Isolation test supply (included in some electrical safety analyzers)

Special precautions Testing input isolation requires the use of a linevoltage source. Although this source should include a current-limiting resistor, use caution to avoid contact with any portions of the energized circuit.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

2


Electrocardiographs 1.7

1.9

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided. Cables. Inspect the cables and leads for their strain reliefs and general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain. Connect the unit to an ECG simulator, and verify that an adequate trace is received at each patient lead selection. (Checking all leads in some units will require either a 12-lead simulator or connection and disconnection of every lead.) Flex the patient cable near each end to verify that there are no intermittent faults.

battery-operated power-loss alarms, if so equipped. Perform the inspection with the unit on battery power or operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check battery capacity by activating the battery test function or measuring the battery-powered operating time. When it is necessary to replace a battery, label it with the date. Check the condition of the battery charger, and to the extent possible, confirm that it does, in fact, charge the battery. Some batteries require periodic deep discharges and recharging to maintain maximum battery capacity. If this is recommended by the manufacturer, verify that it is being performed on schedule.

1.10 Fittings/Connectors. Examine all cable connectors for general condition. Electrical contact pins or surfaces should be straight and clean. Leads and electrodes should be firmly gripped in their appropriate connectors.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function.

1.11 Electrodes. Confirm that an adequate supply of ECG electrodes is available, and check their physical condition and that they are within their expiration dates.

1.19 1 mV Step Response. Depress and hold the 1 mV calibration button (or apply an external 1 mV pulse) for about 3 sec. The trace should exhibit a sharp, square-cornered leading edge that is neither rounded nor spiked. (Up to 10% spike or overshoot is acceptable but will usually not be observed in a unit that is functioning optimally; see Figure 1.) After 2 sec (50 mm of paper at a speed of 25 mm/sec), the pulse should have de-

1.13 Controls/Switches. Before moving any controls, check their positions. If any appear inordinate (e.g., a filter switch in the monitor mode rather than the diagnostic mode), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of

Figure 1. The calibration pulse or step response leading edge should have square corners (left). Slight rounding (middle) or small overshoot is acceptable. Excessive rounding or overshoot (right) indicates the need for adjustment.


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Inspection and Preventive Maintenance System need to be set near either extreme to obtain a satisfactory setting. All portions of a simulated ECG waveform should be clearly visible, including the P wave and QRS. There should be no 60 Hz noise when the lead selector switch is set to the lead 0 or standard position and the chart motor is activated.

Figure 2. Sag time is measured to the half-amplitude point. The upper trace indicates a low-frequency response of about 0.05 Hz. The lower trace indicates a low-frequency response of between 0.07 and 0.09 Hz. cayed to no more than half its original amplitude (see Figure 2 on page 4).

1.25 Paper Transport. Verify that the paper moves smoothly and without hesitation at all paper speeds. Problems might be caused by the transport mechanism or by a roll of paper that is wound too tightly. The paper should not drift sideways in the transport mechanism. If a formatted output is used (i.e., unit prints a single formatted sheet for each electrocardiogram), verify that all alphanumerics and tracings appear in the correct location and that the paper starts and stops at the correct points.



2.2

Chassis Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA.

2.3

Calibration. This test determines the accuracy of both the sensitivity control and the internal 1 mV calibration signal and requires the use of an external source of known amplitude (e.g., calibrated ECG simulator). If this calibration source is battery powered, check its output with a precision voltmeter or similar instrument to confirm that the output is not affected by changing battery voltage. An ECG simulator can be used, even if its output is not precisely 1 or 2 mV, provided its amplitude is accurately known and appropriate corrections are made in interpreting the results.

1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Verify that an adequate supply of electrodes and paper and a fuse are stored with the device or in the nursing unit for those electrocardiographs that remain in a fixed location. A spare patient cable and stylus (or pen) may be kept with units on crash carts. 1.24 Trace Quality. Observe the tracing with the unit in the standard lead select position (no input) and in lead I with a simulated ECG signal applied. Verify compliance with the following criteria: The baseline should have constant thickness; it should be horizontal and not drift vertically. It should be possible to move the baseline from the lower to the upper border of the chart paper with the vertical position control, except on those units where mechanical stops prevent such travel. The baseline should remain within 1 mm of its initial position upon pushing the reset control. If so equipped, the operator-adjustable stylus heat control should function and should not

4

With sensitivity at 20 mm/mV, record a 1 mV pulse from the external reference generator and one from the internal 1 mV calibration signal of


Electrocardiographs the writer. For an externally generated pulse of exactly 1 mV, the tracing should be between 19 and 21 mm. Deviation greater than this can often be corrected with the variable gain control (a screwdriver adjustment in many units). If the internally generated pulse and a 1 mV external pulse produce tracings of heights that differ by more than 0.5 mm, the internal calibrator is not within the recommended 5% accuracy. Next, record 1 mV pulses, either from the internal calibrator or the reference generator, at sensitivity settings of 2.5, 5, 10, and 20 mm/mV. At each setting, the trace should double in height (within 5%). Because of the difficulty in resolving small errors, investigate any deviation of more than 0.5 mm. 2.6

Linearity. Apply a calibrated 2 mV input to the writer. Record the deflection at 10 mm/mV. It should be twice the deflection (within 5%) observed for a 1 mV signal.

2.7

Paper Speed. Use an ECG simulator set to 60 bpm or a signal or pulse generator set to 1 Hz that has been set or calibrated with a counter. If the interval between pulses is not within 10 msec at a pulse interval of 1,000 msec, an appropriate correction should be made in calculating paper speed. The speed should be accurate to within 2%. At a chart speed of 25 mm/sec and a pulse interval of 1,000 msec (60 bpm on an ECG simulator), the distance between the first and last of five successive peaks should be 100 ±2 mm; at a chart speed of 50 mm/sec, the distance between the first and last of five successive peaks should be 200 ±4 mm.


Clean the exterior (including front panel controls), all rollers, paper guides, and knife edges, if needed.

3.2

Lubricate the recorder mechanism and paper drive per the manufacturer’s specifications.

3.3

Calibrate damping and stylus, if required.

3.4

Replace filters and batteries, if required. Some units have air filters that accompany the cooling fan. Check and replace these filters, if needed. If any of the test procedures indicate a weak or defective battery, even after charging for 12 or more hours, replace the battery.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. Electrocardiographs should meet the requirements for isolated input devices for ECG lead-to-ground, interlead, and input isolation tests. In addition, perform the following tests. 4.1

Frequency Response. Use the test setup shown in Figure 3. Set the function generator and attenuator for a sinusoidal output of 2 Hz with a peak-to-peak amplitude of 1 mV. Set the electrocardiograph gain to 10 mm/mV to obtain a peakto-peak deflection of 1 cm. (The deflection amplitude is not critical. If your signal generator output is not easily adjusted, set the output for any convenient peak-to-peak display and note the height.) Measure between the extreme top and bottom of the trace. Increase the output frequency from the sinusoidal generator until the display drops to 0.7 cm peak-to-peak, or 0.7 times the 2 Hz deflection. (The waveform may be slightly distorted.) Record this frequency as the upper 3 dB point. When changing the output frequency of the function generator, measure the output amplitude peak-to-peak with the oscilloscope (DC response) to ensure that a constantamplitude sinusoid, 1 mV peak-to-peak, is delivered to the electrocardiograph throughout the bandwidth. The low-frequency response point can be determined in a similar way by decreasing the frequency from 2 Hz until the display again drops to 0.7 cm peak-to-peak, or 0.7 times the 2 Hz deflection. However, it is much simpler to determine the low-frequency response point using the step response test (see Item 1.19), Figure 2, and the

Figure 3. Signal input test setup.


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Inspection and Preventive Maintenance System Relationship Between Sag and Low-Frequency Response Distance to Half Amplitude 10 mm 20 30 40 50 55 60 80

Lower 3 dB Frequency 0.27 Hz 0.13 0.092 0.069 0.055 0.050 0.046 0.034

Relationship Between Sag and Low-Frequency Response table on page 6. While the technique may not accurately predict the low-frequency response of all units, it does provide an equally (if not more) clinically relevant response test. Some units have selectable frequency response modes. In the Filter In mode, low- and high-frequency components of the electrocardiogram are attenuated. This mode can be used to reduce baseline wander and high-frequency noise, but because small distortions of the ECG can occur, it should not be used when recording diagnostic ECGs. The diagnostic response mode provides an expanded bandwidth, as recommended by the American Heart Association. This should produce a display that reproduces more of the low- and high-frequency qualities of the electrocardiogram than the Filter In (or monitor) mode. The electrocardiograph should normally be operated in the diagnostic mode. The manufacturer’s specification for each frequency response mode should be used as a reference. The diagnostic mode bandwidth should be at least 0.67 to 100 Hz. Some units include a notch filter to minimize 60 Hz noise. On such units, confirm the notch filter’s operation by sweeping past 60 Hz on the signal generator and looking for a sharp dip in the response. If the response increases as the frequency is increased past the notch filter frequency, then the upper 3 dB point may be above the notch filter frequency rather than occurring where the filter begins to attenuate. 4.2

6

Common Mode Rejection Ratio (CMRR). The electrocardiograph includes a differential amplifier so that it can display the voltage difference between two electrodes (the RA and LA in Lead 1) while using a third (RL) as a reference. If the same, or common, voltage is applied to RA and

LA simultaneously, there should be no output from the differential amplifier because the voltage difference between the two inputs is zero. The extent to which a differential amplifier produces no output when the same signal is applied to both inputs is called its common mode rejection ratio. Common mode rejection is needed because of the presence of stray signals common to all input leads primarily at power-line frequency (60 Hz). While these signals are too minute to be hazardous, they can interfere with the ECG recording on a unit with a low CMRR at 60 Hz. The common mode rejection ratio is defined as: CMMR =

Differential mode deflection factor, or DMD (mm ⁄ mV) Common mode deflection factor, or CMD (mm ⁄ mV)

A deflection factor is the change in trace position corresponding to a given input voltage. Use an unbalanced CMRR measurement that includes a 5,000 Ω resistor in series with one of the input leads. This simulates the unequal impedances that usually exist in the electrode/skin interfaces. Since most common-mode voltage in the hospital is at 60 Hz, it is most significant to measure the CMRR at or near that frequency. (A frequency of 55 Hz is often used to minimize interference from line-power frequency noise.) Using the test setup shown in Figure 3, apply a sinusoid test signal of 1 mV peak-to-peak at about 60 Hz to the electrocardiograph. Set the gain to 20 mm/mV, measure the deflection in mm, and record it on the inspection form as the differential mode deflection factor. Since the input signal for this measurement was 1 mV, the differential mode deflection factor expressed in mm/mV is

Figure 4. Common mode rejection ratio test setup.


Electrocardiographs Using the internal calibration button, generate a pulse with the baseline set at the bottom margin of the chart, another with the baseline at the middle of the chart, and a third with the baseline as close to the top margin of the paper as possible while still allowing the pulse to remain on the ruled chart. The height of the calibration pulse should not vary more than 0.5 mm with baseline position.

numerically equal to the resultant deflection in mm. Do not change the gain setting or the signal frequency for the remainder of this test. Record the frequency. Use the test setup shown in Figure 4 for the second part of this measurement. Note that there is only one connection from the output of the attenuator to the patient leads. The other output terminal is grounded. It is essential that all instruments used in this test be connected to a common ground to minimize noise. Increase the amplitude of the sinusoid signal (up to 10 V peak-to-peak) until some measurable deflection is observed on the recorder. Calculate the common mode deflection factor by dividing the resultant deflection (in mm) by the input signal (in mV). The CMRR may then be calculated as the differential mode deflection factor divided by the common mode deflection factor. If the unit has an ungrounded or plastic case, measure the CMRR with the unit resting on a grounded metal plate. CMRR should meet the manufacturer’s specification and be at least 10,000:1. 4.3

Display range. The monitor should be able to faithfully display signals of up to 5 mV. Using the test setup shown in Figure 3 (signal generator set to about 2 Hz) or an ECG simulator with an appropriate output range, apply a 5 mV peak-to-peak signal, and observe the trace using gain and position settings that keep the trace on the recording paper rulings. Note any distortion or clipping of the signal. 4.4

Crosstalk. Verify that activation of time and event markers does not cause a deflection on the ECG trace. Check for channel crosstalk on multichannel electrocardiographs by attaching an ECG simulator to one lead pair while the others are shorted together. There should be no visible trace deflection in any of the channel tracings except the one with the simulated ECG.

Linearity. In addition to the linearity test described in Item 2.6, test the effect of baseline position on linearity and linear input range.


Baseline position. Vary the centering or position control to change baseline position, if possible.

Set all controls to their original settings, and recharge the battery, if needed.


7


Electrosurgical Units Used For: Electrosurgical Units [11-490] Electrosurgical Units, General-Purpose [16-137] Electrosurgical Units, Specialty [16-138]

Also Called: ESUs, electrocautery units (although this term more appropriately refers to a different type of surgical device), Bovie (a registered trademark of MDT Diagnostic Co. to be used only when referring to that device) Commonly Used In: Operating rooms, outpatient surgical units Scope: Applies to units that perform surgical functions (e.g., cutting, coagulation) by using high-frequency electrical currents that pass through the body (units may include other functions such as insufflation); does not apply to electrocautery units that use an electrical current to heat a tip for surgical effects Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Surgical use of high-frequency current dates back to the early 1900s. Tesla and Oudin coil resonators in conjunction with spark gaps produced high voltages at very low currents, which were used to destroy superficial tissue with a spray of sparks from the active electrode (fulguration). No return connection was provided between the patient and the electrosurgical unit. Vacuum tubes were later introduced and provided continuous sinusoidal wave generation. Circuits could then be designed to produce lower voltages but higher currents. However, the higher currents required a reliable conductive path to complete the circuit, and the dispersive electrode (also called the butt, safety, patient, or ground plate, or return or indifferent electrode) was introduced. Most currently marketed units are solid-state devices that permit size reduction and the generation of a variety of waveforms without the use of a spark gap.



Time Required

They also incorporate microprocessor-controlled circuitry to monitor unit performance, adjust power settings, and, in some units, interrogate the quality of contact of the return electrode. Undamped, continuous sinusoidal currents (about 0.2 to 3.0 MHz) cut tissue with a cutting electrode or loop with minimal coagulation. The intense heat explodes and volatilizes tissue cells. This type of current can also be used to coagulate with large surface electrodes or hemostats. Damped waves and current bursts coagulate, fulgurate, and desiccate with minimal cutting by generating heat in a wider region of tissue immediately surrounding the active electrode. The dry, fibrous residue left by the rapid dehydration of cells blocks vessels and prevents bleeding. A combination of damped and undamped waveforms cuts and coagulates simultaneously. In electrosurgery, the heat that destroys tissue is not produced by a heated wire as in electrocautery, but


●


Inspection and Preventive Maintenance System by conversion of the high-frequency electrical energy in the tissue. Current density and duration determine the amount of heat generated and tissue destroyed at and near the electric arc. Active electrodes have small tips to increase the current density at the surgical site. Electrodes used specifically for cutting have small points or edges to concentrate the electrosurgical current; coagulation electrodes have larger surface areas. Both characteristics can be combined into a single electrode (a blade type) so that electrodes need not be changed during shifts between cutting and coagulation. Since no tissue heating is desired elsewhere, the dispersive electrode must contact a much larger area of the patient’s skin to reduce the return current density to harmless levels. Periodic inspection is not a substitute for routine pre-use verification of electrosurgical unit safety features and current use practices. Reusable active electrodes and accessories, such as bipolar and laparoscopic forceps and leads, should be inspected periodically, but they are not usually readily available with the electrosurgical unit. Where practical, users or processing personnel should routinely inspect these items.

Citations from Health Devices Electrosurgical units [Evaluation], 1977 Jan-Feb; 6:59-86. (See also: 1977 Jun; 6:194.)

Ellman International Manufacturing Surgitron and Surgitron FFPF [Hazard], 1986 Aug; 15:248. ESU burns from poor return electrode site preparation [Hazard], 1987 Jan; 16:35. Electrosurgical units [Evaluation], 1987 Sep-Oct; 16:291-333. Return electrode monitors: Assessing your needs [Risk analysis], 1987 Sep-Oct; 16:335-7. Controlling the risks of electrosurgery [Risk analysis], 1987 Sep-Oct; 16:337-9. Bovie CSV: Still accepted? 1987 Sep-Oct; 16:340-1. Do ESU output characteristics affect instrument performance? 1987 Sep-Oct; 16:341-2. Pacemakers and electrosurgery: What precautions are needed? 1987 Sep-Oct; 16:342. Electrosurgical units [Evaluation update], 1988 Dec; 17:363-5. Update: Controlling the risks of electrosurgery [Risk analysis], 1989 Dec; 18:430-2. Electrosurgery checklist, 1989 Dec; 18:432.

Electrosurgical unit safety, 1977 Mar; 6:119-21.

Update: ESU return electrode contact quality monitors [Risk analysis], 1989 Dec; 18:433-6.

Fires during surgery of the head and neck area [Hazard], 1979 Dec; 9:50.

Argon beam coagulation systems [Evaluation], 1990 Sep; 19:299-320.

Fires during surgery of the head and neck area [Hazard update], 1980 Jan; 9:82.

Argon beam coagulation systems [Evaluation update], 1990 Dec; 19:444-5.

Adapters and cables for electrosurgical dispersive electrodes [Hazard], 1981 Jan; 10:74-5.

Stryker Surgical microsurgical drills: Activation by ESUs [Hazard], 1991 Oct; 20:409-10.

Adapters and cables for disposable electrosurgical dispersive electrodes [Hazard update], 1981 Feb; 10:99.

Stryker Surgical microsurgical drills: Activation by ESUs [Hazard update], 1991 Nov; 20:446.

Using two ESUs on one patient [Consultant’s Corner], 1982 Sep; 11:301-2.

Stryker Surgical microsurgical drills: Activation by ESUs [Hazard update], 1991 Dec; 20:496-7.

ESU return electrode contact quality monitors [Evaluation], 1985 Feb; 14:115.

Birtcher 4400 electrosurgical units and 6400 argon beam coagulation systems [Hazard], 1992 Jun-Jul; 21:249-50.

Electrosurgical unit activation tone control [Hazard], 1985 Nov; 14:407.

Burns and fires from electrosurgical active electrodes [Hazard update], 1993 Aug-Sep; 22:421-2.

Isolated incidents: Electrosurgical units [User Experience NetworkTM], 1986 May; 15:143.

ESU burns from poor dispersive electrode site preparation [Hazard], 1993 Aug-Sep; 22:422-3.

Hand-switched electrosurgical active electrode pencils [Evaluation], 1986 Jun; 15:151.

Burns and fires from electrosurgical active electrodes [Hazard update correction], 1993 Oct; 22:502.

2


Electrosurgical Units Use of an incompatible footswitch with Aspen Excalibur, Birtcher 5000, and Valleylab Force electrosurgical units [Hazard], 1993 Dec; 22:593-4.

Never activate the unit with the active and dispersive electrodes connected together (short-circuited), since this may damage the unit.

Electrosurgical units with accessory outputs [User Experience NetworkTM], 1993 Dec; 22:601-2.

Procedure

Fatal gas embolism caused by overpressurization during laparoscopic use of argon enhanced coagulation [Hazard], 1994 Jun; 23:257-9. Risk of electrosurgical burns at needle electrode sites [Hazard], 1994 Aug-Sep; 23:373-4. Monopolar electrosurgical safety during laparoscopy [Guidance article], 1995 Jan; 24:6-27. Misconnection of bipolar electrosurgical electrodes [Hazard], 1995 Jan; 24:34-5.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter High-resistance (20 MΩ) ohmmeter Connectors, adapters, active electrode and/or return electrode, as required; open-circuited dispersive electrode connector may be required Electrosurgical unit analyzer

Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Use an electrosurgical unit analyzer with appropriate load resistances for measuring electrosurgical unit output. A number of methods for testing electrosurgical output have been suggested, including the use of light-bulb loads, sparking the active electrode to the return electrode, and cutting a slice of beef placed on the return electrode. However, none of these provide quantitative performance data, and some methods may damage the electrosurgical unit. When measuring output (e.g., Items 2.3 and 2.10), do not use excessive lead lengths or coil the leads because either may affect measurement accuracy.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse.

1.2


1.3


1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug into each, and check that it is held firmly. If

Oscilloscope and high-voltage probe (acceptance testing only)

Special precautions Electrosurgical units deliver high voltage and high power that can cause serious electrical burns. Be sure that all connections are secure and well insulated before performing any power output test. Do not contact either the active or dispersive electrode while the unit is activated (under some circumstances, burns can occur even from contact with the dispersive electrode). When making connections and whenever testing is not being performed, make sure the unit is off or in the standby mode. Never operate any electrosurgical unit for prolonged periods during testing, especially at maximum control settings. Electrosurgical units can be damaged by such operation. Hazardous high voltages are present inside electrosurgical units. Do not open the electrosurgical units for inspection or adjustment unless you are qualified to do so.


3

Inspection and Preventive Maintenance System accessories are plugged and unplugged often, consider a full inspection of the receptacle. 1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one.

1.6


1.7

1.9

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided. Cables. Inspect the cables (e.g., footswitch) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Examine electrical connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Dispersive Electrodes. Inspect reusable dispersive electrode cables carefully for any breaks in the insulation and other obvious damage. Examine the electrosurgical unit and return electrode connectors for signs of damage. Confirm that their strain reliefs are secure. Check that several dispersive electrodes and dispersive electrode cables (separate or preattached) are stored with the electrosurgical unit. (If reusable dispersive electrodes are in use, replace them with single-use dispersive electrodes with preattached adhesive. Using disposable dispersive electrodes with preattached adhesive is much less likely to result in patient burns.) 1.12 Filters. Check the condition of all filters. Clean or replace if needed, and indicate this on Line 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before moving any controls, check their positions. If any of them appear inordinate (e.g., a control set at maximum output), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the

4

inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. 1.20 Dispersive Cable Continuity Monitor. Confirm that this sentry triggers an audible (and on some units, a visual) alarm if continuity of the return cable is interrupted. The electrosurgical unit should be locked out of activation in this alarm mode. To test the cable continuity monitor, turn all output controls to minimum, disconnect any active electrodes, connect a complete cable and dispersive electrode assembly to the electrosurgical unit, and turn the unit on but do not operate it. Suspend the dispersive electrode in the air so that it does not touch any metal surface or object that might provide a ground pathway back to the electrosurgical unit. Do not touch the electrode. The alarm should not sound. A loose panel connection to the dispersive cable often causes the return cable continuity monitor’s alarm to sound, which may annoy the OR staff. Wiggle the dispersive cable connection at the unit. If this cable motion sets off the alarm, suspect a weak connector, and arrange for repairs. Unplug or unscrew the cable connector from the dispersive electrode. The unit should alarm immediately and should resist activation. If this does not occur, the return cable may be shorted or the alarm itself may be defective. To determine the cause, unplug the dispersive electrode cord from the electrosurgical unit. If the alarm does not activate, it is defective and needs repair. If the alarm activates, the dispersive cable is defective and should be replaced. If the dispersive electrode is permanently attached to the dispersive cable and the electrosurgical unit is designed to automatically disable the buzzer alarm when the dispersive cable is


Electrosurgical Units Dispersive electrode grounding resistance. Measure the resistance between the dispersive electrode and the ground pin of the power cord. This measurement should indicate an open circuit (exceeding 20 MΩ or largest reading of the ohmmeter) for isolated-output units or grounded units equipped with a capacitor between the dispersive electrode and ground; the latter are called ground-referenced units. A value less than 20 MΩ for ground-referenced units suggests a defective capacitor between the dispersive electrode and ground inside the electrosurgical unit. An initial low resistance that drifts up to a value over 20 MΩ is acceptable; this phenomenon is due to a charging capacitor. There should be a short circuit (approximately 0.15 Ω) for grounded-output units without a capacitor. ECRI recommends that units with the dispersive electrode connected directly to ground be replaced with isolatedoutput or ground-referenced units.

unplugged, use an open-circuited connector to test the alarm. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., activation indicator, dispersive cable continuity monitor). Confirm appropriate volume, as well as the operation of a volume control. Serious injury has been associated with warning signals (e.g., activation indicator) whose volume controls had been set so that the signals were not audible. If volume controls have been set too low, discuss this problem with users so that clinical practices can be corrected. Units that lack audible activation indicators should be removed from service. Units with audible activation indicators that can be set to inaudible levels should also be removed from service or modified by the manufacturer so that the alarm cannot be set to an inaudible level. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Footswitch. Examine the footswitch for general condition, including evidence of spilled fluids. Check for any tendency of the footswitch to stick in the On position. Activate the switch in both the Cut and Coagulation modes and flex the cable at the entry to the switch to check for internal wire breaks that may cause intermittent device operation. 1.24 Special Protective Features. Test alternative protective features according to instructions from the manufacturer’s literature. These include features intended to monitor the integrity of the patient circuit (e.g., dispersive electrode contact quality monitors), ensure absence of inadvertent ground contacts (e.g., return fault monitors), or minimize injury from active electrode insulation failures or capacitive coupling (e.g., monopolar electrode shielding devices). These features can be either integral to the electrosurgical unit or add-on devices.


Grounding Resistance. Measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis, accessory outlet, ground pins, and footswitch. We recommend a maximum of 0.5 Ω.

2.2

Chassis Leakage Current. While electrosurgical units are generally operated from isolated power systems in the operating room, power line frequency and leakage current measurements must be made with the unit connected to a grounded (conventional) power supply to obtain valid readings. This is most readily accomplished by removing the electrosurgical unit from the operating suite to an area with grounded power distribution. An adapter cord will be needed if the unit is equipped with a specialized operating room plug. Before measuring the leakage currents, turn all the unit’s power controls to zero. Connect a return electrode if the unit cannot be activated without one. Connect one lead of the leakage current meter to ground, and position the meter away from the electrosurgical unit. With the other lead of the leakage current meter in the vicinity of the electrosurgical unit but not in contact, activate the unit in its various operating modes, keeping the output at the minimum settings. Any significant reading on the leakage current meter indicates that the meter is susceptible to high-frequency interference and cannot be used when the electrosurgical unit is activated. A 0.1-microfarad capacitor connected across the leakage current meter terminals may reduce this interference and will not unduly affect the line frequency leakage current readings. CAUTION: Never measure 60 Hz leakage currents from the active electrode while the unit is


5

Inspection and Preventive Maintenance System activated. Also, when testing an isolated output electrosurgical unit, do not measure currents from the return electrode when the unit is activated. These measurements can expose you to high voltage and can damage the leakage current meter. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Measure with the unit off, on (standby), and activated in each mode (e.g., Cut 1, Cut 2) with power controls set at minimum. Record the value for the mode that yields the highest leakage current. Leakage currents from the chassis should not exceed 300 µA. 2.3

ate the unit for long periods or at maximum control settings, since this will stress the unit. 2.10 Output Current/Power. Connect the output current or power meter to the active and dispersive connections on the electrosurgical unit. On units with a return electrode continuity monitor, use a dispersive electrode or an appropriately wired adapter. Output power should be tested according to the manufacturer’s recommendations. If the electrosurgical analyzer in use does not have the load resistance suggested by the manufacturer, it can still be used, but output powers may be different from those given in the service manual (some manuals may indicate how output varies with load resistance). Record the load resistance of the output meter on the inspection form.

Output Isolation. This test is intended for isolated output units to determine whether the isolation has been degraded. Do not perform this test on units with directly grounded dispersive electrodes or with dispersive electrodes connected to ground through a capacitor. Consult the unit’s manual if you are uncertain whether it is an isolated output device. The isolation test is normally conducted after the output power measurement (Item 2.10).

Test the unit at the manufacturer’s recommended output settings or at a typical clinical setting (or at a dial setting about one-third of maximum and at maximum). Using all the operating modes available on the electrosurgical unit, record the output current or power from the meter. Confirm that power is delivered to secondary monopolar terminals. Also measure output at bipolar terminals. The output should increase smoothly from zero or nearly zero to maximum. Do not operate the unit at high control settings for prolonged periods, since this places an unrealistic and unnecessary strain on both the electrosurgical unit and the tester. It will not be possible to read low-current values precisely. Compare output power to the manufacturer’s specifications. Erratic output power in spark-gap units suggests that spark gaps may need maintenance or adjustment. This should be done only by qualified, experienced personnel. Use Lines 2.11 and 2.12 of the inspection form as needed for additional output power measurements.

If the tester has an Isolation Test mode, follow the tester’s instructions. Otherwise, connect the output current/power meter between the active cable and a ground (e.g., the chassis of the unit). The dispersive cable and dispersive electrode of the electrosurgical unit must not be in contact with ground. If the unit has no dispersive circuit monitor, unplug the dispersive cable from the unit. If the unit has a dispersive sentry, suspend the dispersive electrode in the air by hanging the dispersive cable over a hook. CAUTION: To avoid the possibility of burns, do not touch the electrode. With the unit in the Pure Cut or Cut 1 mode, increase the controls gradually to one of the moderate levels used in the output power test and record the power to ground. The extent of output reduction, compared with the output recorded in Item 2.10, is an indication of the degree of isolation. Isolation % = 1 –

P ower (W ) of isolation test (Item 2.3) x 100% Output power (W ) at the sam e setting (Item 2.10)

3.1


3.4

Replace the filter.

4. Acceptance tests

x 100%

Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438.

Isolation should meet the manufacturer’s specifications or be ≥80%. As before, do not oper-

CAUTION: Never measure 60 Hz leakage currents from the active electrode while the unit is activated. Also, when testing an isolated output electrosurgical

or = 1 –

6


Current2 (amps) of isolation test (Item 2.3) Output current2 (amps) of same setting (Item 2.10)


Electrosurgical Units unit, do not measure currents from the return electrode when the unit is activated. These measurements can expose you to high voltage and can damage the leakage current meter. Leakage current from the active and return electrode should not exceed 50 µA. In addition, perform the following tests. 4.1

Waveform Analysis. If a manufacturer has provided output waveform characteristics (e.g., frequency, waveform repetition or burst rate, waveform on-off time), these may be studied and documented by using an oscilloscope connected to the appropriate jack on the output power/current meter. This test is optional. A high-voltage probe should be used for these measurements to prevent damage to the oscilloscope and to view the full waveforms.

4.2

Output Isolation (for isolated output units only). In addition to the test described in Item 2.3, make a similar power measurement from dispersive electrode to ground, preferably with a handswitched active handle connected to the unit. This will ensure that excessive power is not available from the dispersive electrode. Set the unit to Pure Cut, maximum output. Power exceeding 5 W suggests a fault or design deficiency.

Before returning to use Ensure that the volume of audible activation indicators can be clearly heard, turn off the main power switch, rotate the power control knobs to zero, neatly coil and store all cables, and store all accessories.


7


Frequency-Doubled Nd:YAG Surgical Lasers Used For: Lasers, Surgical, Nd:YAG, Frequency-Doubled [17-729]

Also Called: KTP lasers, 532 lasers, green lasers, surgical lasers, endoscopic lasers Commonly Used In: Operating rooms, short procedure areas, endoscopy laboratories Scope: Applies to general-purpose frequency-doubled Nd:YAG surgical lasers that include contact and/or noncontact flexible fiberoptic delivery systems (either reusable or disposable), emit visible green light energy at 532 nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and high-power frequency-doubled Nd:YAG surgical lasers that are typically used for general surgery, gastroenterology, bronchopulmonary, neurosurgery, gynecology, and ENT surgery procedures; does not apply to frequency-doubled Nd:YAG lasers used solely for ophthalmic surgery; also does not apply to other ophthalmic lasers or to CO2 lasers, Nd:YAG lasers, argon lasers, or other surgical lasers; however, many of the tests listed herein can be used or modified for these other lasers Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Frequency-doubled Nd:YAG surgical lasers are normally checked before each use by the laser’s power-on self-test and by user examination of the aiming beam and the delivery system to be used. This minimizes the need for frequent additional periodic testing. Manufacturers or outside service vendors often maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be coordinated with these outside services. Failure of a frequency-doubled Nd:YAG surgical laser can cause patient or staff injury, abrupt interruption of a surgical procedure, or damage to the laser system. These lasers must be meticulously maintained to ensure proper and safe operation. Frequency-doubled Nd:YAG surgical lasers affect tissue by delivering green visible light energy at a



Time Required

sufficient power density to cause vaporization and/or coagulation. The 532 nm light energy is preferentially absorbed by hemoglobin and is typically absorbed within 3 mm of the tissue surface. Frequency-doubled Nd:YAG surgical laser fibers are most often used in contact with or close to tissue to cause coagulation or vaporization. Moving the fiber tip away from the tissue lowers the power density, causing less tissue to be vaporized or coagulated. General-purpose frequency-doubled Nd:YAG surgical lasers direct the beam of an Nd:YAG laser through a crystal that halves the 1,064 nm wavelength (i.e., doubles the frequency) to 532 nm. (The Nd:YAG laser uses an yttrium-aluminum-garnet [YAG] crystalline rod that is doped with neodymium [Nd].) Energy exiting the crystal is typically directed into a flexible optical fiber that transmits the laser energy to the tissue. The fiber may be used with additional devices (e.g., through an endoscope) and/or with a laser handpiece or a laser


●


Inspection and Preventive Maintenance System micromanipulator (used to interface the laser with the surgical microscope). These attachments can focus the energy into a small spot size at a known working distance and/or a specific beam direction to accomplish special tasks. In addition, frequency-doubled Nd:YAG lasers can emit a train of pulses or a single pulse.

of sufficient optical density to protect the wearer’s eyes from laser energy

Like most lasers, frequency-doubled Nd:YAG lasers are inefficient in converting electrical energy into laser energy. As a result, excess heat is generated in the laser cavity and doubling crystal, requiring a cooling system. Most frequency-doubled Nd:YAG lasers use water/air cooling systems that are self-contained, connected to a freestanding chiller system, or connected to a water supply and drain.

Outlet test fixture (optional)

With frequency-doubled Nd:YAG surgical lasers, unlike those lasers that use mirror delivery systems (e.g., articulating arms on CO2 lasers), it is not necessary to periodically verify coincidence of the aiming and therapeutic beam or to assess the therapeutic beam pattern (e.g., TEM00) within the beam or spot. Since the therapeutic and aiming laser beams are transmitted through a single optical fiber, these two beams are coincident as they exit the fiber. Any beam pattern distortion at the fiber entrance would be eliminated as the laser beams travel through the fiber because of internal reflections within the fiber. Misalignment of the beam at the fiber entrance would result in decreased power output or loss or distortion of the aiming beam. In a well-aligned system, any significant problem with the therapeutic beam pattern introduced by an accessory would be apparent by examining the visible aiming beam.

Citations from Health Devices Laser use and safety [Guidance article], 1992 Sep; 21(9):306-10. Surgical lasers [Evaluation], 1991 Jul-Aug; 20(78):239-316.

Test apparatus and supplies Leakage current meter or electrical safety analyzer

Vise with padded jaws or ring stand with padded clamp Pressure gauges and coolant system tee fitting

Insulating gloves, high voltage (optional) Grounding strap (optional) Calibrated flowmeter

Special precautions Inspecting and maintaining lasers is a dangerous as well as necessary process, and far greater care is required than with most devices. Personnel who inspect or service lasers should receive special training from the manufacturer or from a qualified alternative training source. Laser energy can cause serious injury, particularly when the internal interlock is overridden or in any other situation in which the energy does not diverge significantly over long distances. Under some circumstances, the beam may not diverge significantly, even a full room length or more away from the laser (and can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser beam is accessible. Area security and use of personnel protective devices and practices should be consistent with hospitalwide laser safety procedures and/or should be approved by the laser safety committee. In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas. Wear appropriate laser safety eyewear at all times whenever the laser is in the Operating mode. WARNING: Do not stare directly into the aiming system beam or the therapeutic laser, even when wearing laser safety eyewear. Avoid placing the laser beam path at eye level (i.e., when kneeling, sitting, or standing).

Ground resistance ohmmeter New, unused fiber delivery system Black Delrin block 1⁄2″ or more thick, 1″ or more wide, about 3″ to 4″ long; tongue depressors; or firebrick Laser radiometer (power meter) Laser safety signs Laser safety eyewear specifically designed for use with frequency-doubled Nd:YAG surgical lasers and

2

Do not perform these procedures when a patient is present or clinical staff is working, and do not aim the laser across a path that a person might normally use as a thoroughfare. Furthermore, at minimum, post doors to the room with appropriate laser safety signs stating that the laser is in use and that it is unsafe to enter the room without authorization by the service person performing the procedure. A second person should be present, especially during procedures of recognized risk, to summon help in case of an accident.


Frequency-Doubled Nd:YAG Surgical Lasers The laser should remain in the Off position when not in use. When in use, it should be in the Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser operation key and store it in a controlled location. Do not use the laser in the presence of flammable anesthetics or other volatile substances or materials (e.g., alcohol), or in oxygen-enriched atmospheres, because of the serious risk of explosion and fire. Remove from the working area or cover with flame-resistant opaque material all reflective surfaces likely to be contacted by the laser beam. Whenever possible, use a firebrick or other nonflammable material behind the target material (e.g., black Delrin) when the laser is to be activated. Target materials will ignite when exposed to high laser energies; use short durations when practical. A CO2 fire extinguisher should be readily available. Some surgical lasers use high voltages (e.g., 20 kV), which can be lethal. Capacitors may store charges long after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and avoid contact with any portion of the high-voltage circuit until you are certain that the charge has been drained. In such instances, a good ground must be present; preferably, use a redundant ground strap if you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to measure, drain, or insulate high voltages carries the appropriate insulation rating (e.g., above 20 kV).



General. Verify that the key has not been left in the laser. (Remove it if it has been, and inform users of the importance of storing the key in a controlled location.) Examine the exterior of the unit for cleanliness and general physical condition. Be sure that all housings are intact and properly aligned, that assembly hardware is present and tight, that any retractable parts slide easily and lock in place if so constructed, that there are no signs of spilled liquids or other evidence of abuse, and that there are no obvious signs of water or oil leakage. Shutters. If manual shutters for the aiming system or the therapeutic laser are accessible, ensure that they operate smoothly and correctly. Be sure to leave the shutter in the proper position for normal operation. 1.2

Where possible, perform tests with the unit turned off. Because of the presence of high voltage, perform the Grounding Resistance test (Item 2.1) before any other test that requires operation of the laser. WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch, talc) on its inside surface because the agent could contaminate the gas recirculation system of the laser and ultimately contaminate a patient wound during a subsequent procedure. Report any laser accident immediately to the laser safety officer or equivalent, as well as to the hospital risk manager.

Chassis/Housing.

Mounts/Holders. Check that the mounts securely contain any gas cylinders that may be in use. Be sure that mounts or holders intended to secure the fiber to the fiber support (to protect the fiber when in use) are present, in good working order, and being used. Similarly, check mounts or holders for other devices (e.g., external power meters, footswitches). If the device is mounted on a stand or a cart, examine the condition of the mount. Verify that the mounting apparatus is secure and that all hardware is firmly in place.

1.3


1.4

AC Plug/Receptacle. Examine the AC power plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug, and listen for rattles that could indicate loose screws.


3

Inspection and Preventive Maintenance System If damage is suspected, open the plug and inspect it. 1.5

Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord, or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with same polarity as the old one.

1.6


1.7


1.8

Tubes/Hoses. Check the condition of all coolingsystem hoses and any other hoses or tubing the laser may have (e.g., drain, gas). Check that they are of the correct type; that they have not become cracked and do not show other signs of significant abuse; that they are connected correctly and positioned so that they will not leak, kink, trail on the floor, or be caught in moving parts; and that they are secured adequately to any connectors.

1.9


1.10 Fittings/Connectors. Examine all optical (e.g., fiber), liquid, and electrical fittings and connectors for general physical condition. Liquid fittings should be tight and should not leak. Electrical contacts should be straight, clean, and bright. There should be no visible dirt or residue in the optical path of the laser aperture. Ensure that any mechanism to close off the laser aperture (fiber port) is clean, operates smoothly, and is in use. 1.12 Filters. Check the condition of all liquid and air filters. Some frequency-doubled Nd:YAG surgical lasers require deionized water, and most require special filtration. Measuring the pressure drop across a liquid filter can be helpful in determining whether the filter should be re-

4

placed. Clean or replace filters according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi), and indicate this in the preventive maintenance section of the inspection form. Clean or replace air filters and radiators that are obviously dirty. 1.13 Controls/Switches. General. Before moving any controls, check and record their positions. If any position appears unusual, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical condition, secure mounting, and correct motion. If a control has fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from fingernails, pens, surgical instruments). If you find such evidence, notify users to avoid using tape and sharp instruments. During the inspection, be sure that each control and switch works properly. Remote. Examine the exterior of the control for cleanliness and general physical condition. Be sure that housings are intact, that assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. If the remote control is attached by cable to the laser, ensure that the cable and any connectors are in good condition. Examine all controls and switches for general physical condition, secure mounting, correct motion, and intended range of settings. Where a control should operate against fixed-limit stops, check for proper alignment as well as positive stopping. During the inspection, be sure to check that each control and switch performs properly. Footswitch. Examine the footswitch for general physical condition, including evidence of spilled liquids. Footswitches for lasers include an internal switch that activates according to the depth of pedal depression. It is usually possible to feel the vibration caused by closure of the switch, even through a shoe. Check that the internal switch is operating and that the footswitch does not stick in the on position. Some footswitches include two internal switches; in this case, verify the operation of both. Some footswitches also include a switch to operate the liquid- or gas-cooling system.


Frequency-Doubled Nd:YAG Surgical Lasers Check to be sure that this switch operates reliably.

(e.g., settings, displays) is indicated on both control panels.

During the procedure, check to be sure that the laser activates consistently when the footswitch is depressed and that the fiber-coolant system operates properly when the fibercoolant switch is activated and deactivated. Flex the cable at the entry to the switch, and, using an ohmmeter, check for internal wire breaks that cause intermittent operation. Confirm that strain reliefs are secure.

If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated energy counter), ensure that each display provides the information expected. Ensure that user prompts occur in the proper sequence. Store some sample information, and verify that it is correct. If a feature to manually reset this information is available, ensure that it works.

Examine the male and female connectors for attaching the footswitch to the laser cabinet to be sure that no pins are bent and that no other damage is present. Ensure that the connector secures acceptably to the laser cabinet.

1.19 Laser Delivery System Calibration. Some frequency-doubled Nd:YAG surgical lasers include a user-accessible calibration port or power meter that allows output calibration and/or testing of the laser fiber. This feature is provided because transmission of laser energy through a fiber may change as a result of fiber use. Based on the measurement from the calibration power meter, the laser may automatically recalibrate itself and/or adjust displays so that the power indicated to be delivered to the patient will be correct, or it may require the user to do this manually. Verify that this feature is functioning by using the manufacturer’s recommended calibration procedure to test one delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. A good-quality (e.g., >85% transmissibility, undamaged sheath) fiber or handpiece should be used for this test.

1.15 Motors/Pumps/Fans/Compressors. Check the physical condition and proper operation of these components, if present. If lubrication is required, note this in the preventive maintenance section of the form. Clean any obvious dust from these components. 1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the manufacturer’s recommendations, and note this on the preventive maintenance section of the inspection form. If an external water supply is in use, ensure that the water pressure is properly regulated and at the appropriate pressure and that the supply and drain system is properly configured (e.g., filters are oriented for proper flow, drain hoses are positioned in a sink or drain). 1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible. If a remote control or display is battery powered, check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the inspection, verify proper operation of all lights, indicators, meters, gauges, and visual displays on the unit and remote control. Ensure that all segments of a digital display function. Note any error messages displayed during the power-on self-test. If primary and remote-control indicators and displays can be used at the same time or if control can be switched from one to the other during a procedure, verify that the same information

1.20 Alarms/Interlocks. Operate the device in a manner that will activate the self-check feature, if present, and verify that all visual and audible alarms activate according to the manufacturer’s documentation. If no self-check feature is present, operate the laser in a manner that will activate each audible and visual alarm; be sure to test only those alarms that will not cause damage to the laser or present an unnecessary risk of laser beam exposure to yourself or bystanders. If a door or window interlock is used, ensure that it deactivates the laser properly. (Do not disassemble major parts of the laser to test internal interlocks.) After deactivating the laser and reclosing the door or window, check to be sure that the laser will restart. Be sure to check the interlocks in all locations where the laser is used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.)


5

Inspection and Preventive Maintenance System If the laser is equipped with an emergency “kill” switch, test this feature to be sure that it deactivates the laser and that the laser will subsequently restart. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., laser emission, setting change). Check for proper operation, and verify that the signal can be heard in the environment in which the laser will be used. 1.22 Labeling. Check that all placards, labels, and instruction cards noted during acceptance testing are present and legible. Check to see that an instruction manual is kept with the laser or is readily available. 1.23 Accessories. General. Verify that all necessary accessories are available and in good physical condition. Set up reusable accessories with the laser to ensure compatibility and proper functioning. Checking all fibers or accessories during a single inspection and preventive maintenance procedure is unnecessary as long as accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person responsible for scheduling the use of the laser before beginning the procedure. Fibers. For the test fiber and before each use, examine the connector, cable, and tip of each fiber to be used, as well as the fiber support, for cleanliness and general physical condition. Ensure that the connector properly seats into the laser aperture in the laser cabinet. Examine the distal end of fibers to ensure that any connecting mechanisms (e.g., threads) are in proper working order. If a fiber appears to be dirty or damaged, remove it from service. If a fiber is reusable, notify the person(s) responsible for fiber repair. The fiber should be repaired and/or cleaned according to the manufacturer’s recommendations. Verify fiber performance. Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness and general physical condition. Examine individually only those components that are intended for removal during normal

6

use and storage. (Do not remove other parts thatarepress-fitorattachedbyscrews,bolts, or snap-rings.) If lenses are detachable, be sure not to touch the lens surface; handle lenses by the edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean lenses. Ensure that major subcomponents of the handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the handpiece(s) to the fiber are in good working order and that they reliably secure each handpiece to the fiber. Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness and general physical condition. Be sure to handle it by the main body; do not hold it by the joystick, and do not touch the reflecting lenses in the body. Inspect micromanipulators provided by both the laser manufacturer and the laser accessory manufacturer. Ensure that the reflecting surfaces and lenses are intact and clean. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean reflecting surfaces and lenses. Examine the joystick to ensure that it is firmly attached and that it freely moves the reflecting lens. If a finger rest is present, ensure that it is firmly attached and properly oriented. If a zoom focus feature is present, be sure that it turns easily and does not slip. Examine each objective lens to ensure that it is intact and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean the objective lenses. Carefully insert each lens into the micromanipulator, and ensure that it fits snugly. Inspect the mechanism used to attach the micromanipulator to the microscope to ensure that all parts are present and that it is in good working order. Connect the micromanipulator to the microscope to check for a secure connection. Safety filters. Verify operation of safety filters in the microscope and endoscope delivery systems.


Frequency-Doubled Nd:YAG Surgical Lasers clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this process until you have tested all exposure settings, except continuous, and have developed a series of burns. Compare the burns to verify that progressively larger burns occurred as the exposure duration increased.

1.24 Aiming Beam. Frequency-doubled Nd:YAG surgical lasers typically use an attenuated therapeutic beam as the aiming beam. Activate the aiming beam (without the therapeutic beam), and verify that it produces a round, uniformly bright spot, with no halo. 1.25 Laser Aperture. WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser aperture. It should be clean and undamaged; replace if needed. There should be no visible dirt or residue in the optical path of the laser aperture.

2.4


2.2


If your laser power meter cannot be used for this test, use the following alternative test method. Set the laser to about 10 W and a 0.1 sec exposure duration with the fiber, handpiece, or micromanipulator attached, and verify that the Repeat Pulse feature operates as expected by moving the target material slightly between each pulse. Be extremely careful to keep hands out of the laser beam path. If the number or duration between repeat pulses is adjustable, test that setting changes made throughout the range result in the expected performance.

Leakage Current. WARNING: Do not reverse power conductors for this or any other test. Improper attachment of conductors may damage the laser. With the laser attached to a grounded powerdistribution system, measure the leakage current between the chassis and ground with the unit grounded and ungrounded. The leakage current on the chassis should not exceed 300 µA; in no case should it exceed 500 µA. Where it is greater than 300 µA, ensure that appropriate grounding is present.

2.3

Exposure Duration. Some laser power meters can measure pulse duration. If the power meter can react to pulse duration (this is the preferred circumstance), test the laser at each setting. However, if the laser power meter does not measure pulse duration, use the following less preferable alternative. Place and secure the laser fiber, handpiece, or micromanipulator with the aiming system focused on the target material (e.g., black Delrin or a tongue depressor). With the laser set to about 10 W and the exposure set at minimum duration, activate the laser and create a burn. Carefully move the target material to expose a

Repeat Pulse. If the unit includes a Repeat Pulse feature, which repeats the pulse at a fixed or adjustable rate, test this feature with the laser set at the minimum, median, and maximum Repeat Pulse settings, if adjustable. Some laser power meters can react quickly enough to be used to test this feature of the laser. If you are using such a power meter, test the laser to be sure that the correct power is repeatedly delivered over the correct time period.

2.5


2.10 Power Output. Select one delivery system (e.g., fiber, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at the appropriate distance from the detector of the laser power meter to meet spot-size requirements specified in the instructions for the meter. (Do not focus the beam to a small spot on the power meter. Some power meters require that the unfocused or a defocused laser beam be projected into the power meter to cover the majority of the absorber surface. If the laser beam is focused on the receiver of such meters, the meter may be damaged.)


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Inspection and Preventive Maintenance System WARNING: Accessing the unfocused laser beam may require defeating internal interlocks. Because of the heightened risk associated with an unfocused, nondiverging laser beam, exercise great care if the interlocks are to be defeated. With the laser set at low (e.g., 10% of full scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient period to acquire acceptable readings. (Power meters use different time constants to acquire an acceptable reading, and you must know and meticulously follow them.) Compare the reading with the power display of the laser; the measured and displayed values should all be within 10% of one another. In addition, compare the reading obtained with the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the laser includes a low-power (e.g., mW) feature, test it in a similar fashion with a power meter of appropriate resolution in the low-power range.

polarity. Also, lasers powered by three-phase electrical systems may be damaged if proper electrical phase connections are not made initially and maintained thereafter. Thus, do not switch conductor connections or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical leakage current tests with reversed-polarity wiring. Also test the ability of the laser to deliver laser energy as expected in all configurations and with all provided laser accessories. In addition, perform the following tests. 4.1


4.2

Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over when pushed or when a caster is jammed on an obstacle (e.g., a line cord, threshold), as may occur during transport. If the device is designed to rest on a shelf, ensure that it has nonslip legs or supports.

4.3

Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling information is typically found in the laser’s Operator Manual.

4.4

Electrical Wiring Configuration. Ensure that the branch circuits and the outlets for the laser are properly wired and rated for use with the laser. Examine the receptacles at each location where the laser is to be used to ensure that the proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.

4.5


4.6



Clean the exterior. Clean accessible optical components (e.g., blast shield, microscope lenses), if necessary, using techniques and cleaning solutions recommended by the manufacturer.

3.2

Lubricate any motor, pump, fan, compressor, or printer components as recommended by the manufacturer.

3.3

Calibrate/adjust any components (e.g., printer) according to the manufacturer’s recommendations. Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses and tubes are tight.

3.4

Replace filters as needed. Check all fluid levels and supplement or replace fluids as needed.

4. Acceptance Testing Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. WARNING: Lasers may be damaged by switching between normal and reverse polarity while the device is on. If reverse-polarity leakage current measurements are made, turn off the unit being tested before switching

8


Frequency-Doubled Nd:YAG Surgical Lasers 4.7

4.8

4.9

Repeat Pulse. If the unit includes a Repeat Pulse feature, test this feature as described in Item 2.4, but over the full range of available settings. Power Range. Using the technique described in Item 2.10, test the power output accuracy at several low, medium, and high settings. Laser Delivery System Calibration. Use the manufacturer’s recommended calibration procedure to test each new reusable delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. Note the fiber transmission for each delivery system tested if this information is

provided by the laser. Or, you can calculate it using the following formula: % Transmission =



Before returning to use Be sure to return controls to their starting position and place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using the unit.


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General Devices Commonly Used In: Patient and nonpatient areas Risk Level and Inspection intervals depend on device and circumstances Type

Interval

Time Required

Major

months

.

hours

Minor

months

.

hours

Overview This procedure provides guidance for inspection of any device for which no specific procedure is applicable; it also provides more detailed instructions for some tasks commonly encountered in other procedures, along with general acceptance tests for all devices. It can be used as is for many simpler devices. Other devices will require additional performance checks derived from manufacturer-supplied information and the clinical engineer’s or technician’s understanding of the device and its clinical application.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter with a resolution of about 0.1 Ω to around 0.5 Ω Hydrometer

it, even if it entails doing part of one test early and the rest of it later. However, do not check the Pass or Fail column until the item has been completed. To the extent possible, perform preventive maintenance tasks first; the inspection will reveal any deficiencies that may have been introduced by improper or inadequate maintenance. If the inspection indicates the need for maintenance, reconfirm the functioning and accuracy of the affected portions of the device following the repair. Before beginning any inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures are recommended by the manufacturer. Skip items that are not relevant to the device being inspected. Modify or add items if needed.

Special precautions If there is evidence of blood or body fluid contamination, submit the device for cleaning and decontamination before inspecting it.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Ensure that plastic housings are intact, that all assembly hardware (e.g., screws, fasteners) is present and tight, and that there are no signs of spilled liquids (e.g., stains, dried patches), physical damage, or other serious abuse.

1.2

Mount/Fasteners. If the device is mounted on the wall or on a stand, IV pole, or cart, examine the condition of the mount. Verify that the

See the article on IPM Safety, behind the Guidance Tab of this binder, for additional precautions and guidelines.

Procedure Do not feel constrained to follow the order of items in this or the device-specific procedures and checklists. If a different order is more convenient, feel free to adopt



●


Inspection and Preventive Maintenance System and that the clinical engineering (or other appropriate) department should be notified when a fuse blows so that it can investigate the cause and provide another spare fuse.

mounting apparatus is secure and that all hardware is firmly in place. Check for weld cracks. Ensure that the assembly is stable. 1.3

1.4

Casters/Brakes. If the device moves on casters, check their condition. Check that the casters roll and swivel freely. Check the operation of brakes and swivel locks. Conductivity checks, if necessary, are generally conducted as part of a check of all furniture or devices within an area (see Conductive Furniture and Floors Procedure/Form 441). AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine if they are secure. Shake nonmolded plugs and listen for rattles that could indicate loose screws. If damage is suspected, open the plug and inspect it. If the device has electrical accessory outlets, inspect them for damage and insert an AC plug into each to check that it is held firmly. If the outlets are used for critical devices (e.g., outlets on a resuscitation cart) or devices are plugged and unplugged frequently, consider more extensive testing. Use a tension tester to measure the tension of each contact. With the device plugged in, use an outlet test fixture to verify that the accessory outlet is energized and correctly wired. See Electrical Receptacles Procedure/Form 437 for more information.

1.5

Line Cord. Inspect all line cords, including the battery charger line cord, for signs of damage or inappropriate repairs (e.g., taped sections). If replacement is necessary, be sure to wire the new power cord or plug with the correct polarity. (Reversed hot and neutral wiring may pose a hazard to service personnel since the on/off switch may not open the hot line in the off position.)

1.6


1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its current rating and type against that marked on the chassis. If there is a spare fuse holder, verify that a fuse of the same rating and type is provided. If the spare fuse is missing, advise clinical personnel that a spare fuse is provided primarily to expedite a rapid return of the device to operation

2

1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Check that they are correctly connected and positioned so they will not kink, be caught by moving parts, interfere with the operator, or be damaged during operation.

1.9

Cables. Inspect any cables (e.g., sensor, electrode, remote control) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are securely gripped in the connectors at each end, which will prevent rotation or other strain. Where appropriate, verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical cable connectors, for general condition. Electrical contacts should be straight, clean, and bright. Gas and liquid fittings should be tight and should not leak. Cracked or brittle O-rings should be replaced. If keyed connectors are used (e.g., pin-indexed gas connectors), ensure that no pins are missing and that the keying is correct. Keying pins should be securely seated in “blind” holes so that they cannot be forced in farther. 1.11 Electrodes/Transducers. Verify that all electrodes, transducers, and probes are available, including spares and optional units and — especially for emergency and resuscitation devices — an adequate supply of disposables. Check that appropriate transducers and probes are being used; the use of incorrect probes (e.g., those from another manufacturer) has caused patient injury and erroneous results. Examine the physical condition of reusable units. 1.12 Filters. Check the condition of all liquid and gas (air) filters. Clean or replace as appropriate, and indicate this on Line 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be


General Devices returned to their original positions following the inspection.

Check the condition of the battery charger, and verify that battery charge indicators function.

Check parameters that may be set on “hidden” user or service menus, including special modes and alarm on/off, volume, and default values.

1.18 Indicators/Displays. During the course of the inspection, verify the operation of any lights, indicators, meters, gauges, and visual displays on the unit and charger. Ensure that all segments of a digital display function. Observe a signal on a waveform display, and note any problems (e.g., distortion, poor focus, 60 Hz interference).

Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. If a control has fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, ensure that each control and switch performs its proper function. 1.14 Heater. Examine the heater for damage (e.g., corrosion of its sheath, deteriorated insulation). To the extent possible, operate the heater to verify that its controls function properly (e.g., that a variable temperature control does, in fact, control heater power). 1.15 Motor/Pump/Fan/Compressor. Check the physical condition and proper operation of these components. Check mechanical alignment and proper adjustment of any pulleys, gears, belts, chains, etc. Look for any signs of improper or excessive wear, such as metal filings. Lubricate if required, and note this on Line 3.2 of the form. (However, do not check the line until all lubrication is completed.) 1.16 Fluid Levels. Check all fluid levels, including those in lead-acid batteries. 1.17 Battery/Charger. Inspect the physical condition of all batteries and battery connectors if readily accessible. Disposable carbon zinc batteries may leak and must be inspected. We are not aware of significant leakage problems with most other battery types. Check operation of battery-maintained memory and battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to verify that the battery is charged and can hold a charge. Activate the battery test function (if so equipped), or measure the output voltage with the unit on to assess battery capacity. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Measure the specific gravity of lead-acid batteries. When it is necessary to replace a battery, label it with the date.

1.19 Calibration/Self-Test. Verify that the calibration function operates. (Where a quantitative check is required, add it to the quantitative section.) Activate self-test or service-mode functions that allow simple performance verification. 1.20 Alarms/Interlocks. Induce alarm conditions to activate audible and visual alarms. Check that all associated interlocks or features function (e.g., an infusion pump initiates KVO rate upon alarm). If the device has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. Verify that alarms are loud, distinctive, and/or bright enough to be noticed in the environment in which the device will normally be used. If a remote alarm-indicator is required, verify that it is available and functioning. Audible alarm-volume controls should not allow the alarm to be turned off or lowered to an indiscernible volume. Check alarm parameters that may be set on hidden menus (see Item 1.13). If inspections repeatedly reveal that alarms have been turned off or silenced or that the volume has been adjusted too low, inappropriate use is indicated, and user in-service training is required. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., QRS beeper). Check for proper operation of the volume control, and verify that the signal can be easily heard in the area in which the device will be used. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present, legible, and easy to understand. 1.23 Accessories. Verify that all necessary accessories are available and in good condition. A copy of the instruction manual should be readily available to the user.


3

Inspection and Preventive Maintenance System connecting cord. The instrument is not usually grounded. Assuming that the device has met incoming inspection requirements, grounding is not required.

2. Quantitative tests Most quantitative tests are device specific. Appropriate tests are listed in the individual procedures or should be derived from device specifications and an understanding of the device’s clinical application and design. However, the following electrical safety tests are common to all line-powered devices. (Refer to the article on Electrical Safety, behind the Guidance Tab of this binder, for the rationale, recommended intervals, and additional discussion of electrical safety testing requirements.) 2.1

Ground Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed metal on the chassis. Conductive portions of the chassis or housing that may become energized must be grounded. Metal trim, nameplates, and handles that are unlikely to be exposed to current-carrying components of the device need not be grounded. Since poor test lead contact can increase ground resistance measurements, ensure that both test leads are in firm contact with a portion of the ground prong or chassis that is clean and shiny (e.g., unpainted and not anodized). Also check that the ohmmeter reads zero when the leads are shorted together. Verify that all modules or cable-connected parts of a system are grounded. If the device has an accessory outlet, check its grounding to the main power cord. Although a stable grounding resistance as high as 0.5 Ω is acceptable, an increase in grounding resistance from one inspection to another may indicate a loosening connection. Open the unit or plug, look for the cause of the increase (e.g., a loose or corroded connection), and repair it. Double-insulated devices may or may not be grounded. ECRI believes that either design is satisfactory. Do not measure grounding resistance of double-insulated devices unless designed to be grounded; just indicate “DI” on the inspection form. Some double-insulated devices may have a three-prong plug, but the grounding prong may be unconnected; this poses no safety risk. Some devices are powered (or recharged) by an AC adapter that plugs into a wall outlet and carries a low voltage to the instrument by a

4

2.2

Chassis Leakage Current. With the polarity of the power line normal and the equipment ground wire disconnected, measure chassis leakage current with the device operating in all normal modes, including on, standby, and off. If the unit has heating and cooling modes, set the thermostats so that each operates while readings are taken. Record the maximum leakage current; it should not exceed 300 µA for equipment used in patient care areas or 500 µA for devices in nonpatient care locations (e.g., nurses’ station, clinical laboratory). The measurements should be made with all accessories that are normally powered from the same line cord connected and turned on. This applies to devices that are plugged into accessory outlets on the device and to devices that are plugged into a multiple-outlet strip (“Waber strip”) so that the devices are grounded through a single line or extension cord. Leakage current must be measured with the device powered by a conventional (grounded) power system, even if it is normally used in an area with isolated power. If the device has a special plug (e.g., explosion proof), a corresponding adapter is required. During routine inspections, it is necessary to test leakage current only in the correct-polarity, ungrounded mode. If testing in the reversed-polarity mode, remember that some devices, especially those incorporating a microprocessor, motor, or compressor, may be damaged by switching polarity while the device is on. To avoid damage, turn off the unit until the motor stops or for at least 10 sec before switching polarity. Routine lead leakage current measurements are also not required. Interference from stray radio-frequency (RF) fields or currents produced by some high-frequency devices (e.g., electrosurgical units, diathermy units) may cause erroneous leakage current readings. Two signs of such interference are readings obtained with the leakage current probe held near (but not contacting) the device and needle deflection that does not change accordingly as the meter scales are changed. In the event of interference, try a different leakage


General Devices current meter, place a small capacitor (0.1 µf) across the leakage current meter input terminals, or measure leakage currents with the RF generator off.

Inspect/clean interior. Opening the housing for internal cleaning is unnecessary and not recommended for many devices. Where appropriate (e.g., units with ventilation fans without air filters, units with evidence of spilled fluids that may have entered the unit, some units with high DC voltages), inspect the interior of the unit and look for accumulations of dirt, dust, spilled fluids, foreign objects, excessive lubrication, and signs of mechanical wear. Clean as necessary. Refer to the Preventive Maintenance and Cleaning article, behind the Guidance Tab of this binder, for guidelines on the selection of cleaning solvents and appropriate techniques.

Though confirmation of grounding integrity provides reasonable assurance of safety for devices with permanent redundant grounding (e.g., a bedside monitor grounded through the line cord and its central station connection), NFPA 99 calls for measurement of chassis leakage current with the redundant ground intact. 2.2.

(Alternative) Ground Voltage (For Installed Equipment). Chassis leakage current of permanently wired equipment cannot be readily measured after installation is completed. Though confirmation of grounding integrity provides reasonable assurance of safety, NFPA 99 calls for voltage measurements for installed devices in the patient vicinity. Using a voltmeter, electrical safety analyzer, or multimeter with appropriate resolution, measure and record the voltage between a reference grounding point (e.g., the grounding pin of an electrical receptacle or some other known ground) and exposed (i.e., unpainted and not anodized) metal on the chassis. A voltage reading of 500 mV is acceptable for general care areas, and 40 mV is acceptable in critical care areas.

3.2

Lubricate. Lubricate mechanical components such as motors, bearings, chains, wheels, hinges, latches, etc. that have friction points. Excessive or inappropriate lubrication can cause damage; refer to the manufacturer’s literature for lubrication requirements. Refer to the Preventive Maintenance and Cleaning article, behind the Guidance Tab of this binder, for additional information on lubrication.

3.3

Calibrate/Adjust. Electrical components. Perform calibration and adjustments as recommended by the manufacturer or indicated by inspection results.


Mechanical components. Verify the integrity and proper operation of all mechanical components and hardware. Inspect for loose and worn components, and tighten as necessary. Align and tighten external control knobs, switches, and indicators. Ensure the proper operation of mechanical brakes and interlocks.

Most preventive maintenance tasks are device specific. Appropriate tasks are called out in the individual procedures or should be derived from device specifications and an understanding of the device’s clinical application and design. However, the following items should be considered and incorporated as appropriate. 3.1

Clean. Exterior and accessories. Cleaning the exterior of the equipment is normally the responsibility of the user; however, some users grow complacent or accustomed to the appearance of the equipment. Thus, a periodic extra effort may be required to maintain the appearance and prevent operational problems. Refer to the article on Preventive Maintenance and Cleaning, behind the Guidance Tab of this binder, for guidelines on the appropriate cleaning solvents and techniques. Clean filters as appropriate (most filters are disposable and should be replaced as needed). Flush fluid lines and reservoirs as necessary.

3.4

Replace. Replace liquid, gas, and ventilation (air) filters; deteriorating, cracked, or dry-rotted tubing; motor brushes; missing spare fuses; Orings; and other components as needed or at intervals recommended by the manufacturer.

4. Acceptance tests Upon initial receipt of a device or following repair, make a thorough visual inspection. Add the following supplemental items to the qualitative and quantitative tests that would be conducted during a major inspection. In addition, conduct appropriate specific tests as indicated in the individual inspection procedures and as required to verify purchase order and manufacturer specifications.


5

Inspection and Preventive Maintenance System A.1 Qualitative acceptance tests A.1.1 Chassis/Housing. Check for shipping damage; report any damage to the manufacturer, shipper, or service organization, and arrange for repair or replacement. Check that the unit is suitably constructed to withstand normal hospital use and abuse. For instance, a unit with venting on the top of the housing or poorly protected or sealed controls and indicators may be prone to fluid entry. (Such design deficiencies should usually be recognized during prepurchase evaluation. However, if any are evident, discuss corrective action with the manufacturer. If not correctable, warn users or take other preventive measures.) A.1.2 Mount. Ensure that the assembly and weight distribution is stable and that the unit will not tip over when pushed or when a caster is jammed on an obstacle (e.g., line cord threshold), as may occur during transport. If the device is designed to rest on a shelf, ensure that it has nonslip legs or supports. Inspect wall-mounted devices at the time of installation to verify that the mounting technique is appropriate for the weight of the device. Attaching the unit to wallboard (e.g., with Molly bolts) is unacceptable except for very light devices. Generally, objects should not be mounted over a patient. The device should be mounted in a position and height where it can be easily viewed, adjusted, and used by clinical personnel and where it will not be bumped or hinder access to the patient for routine or emergency care. If the unit has a heating element, keep hoses, wires, and cables away from the unit and place the unit so that patients, staff, and visitors are protected against contact with hot surfaces. A.1.3 Casters/Brakes. Verify that the correct casters have been supplied with the unit (e.g., size, correct swivel). (ECRI recommends 5 in [12.7 cm] diameter casters for mobile devices to reduce shock to the unit and to minimize the effort required to roll the unit across elevator thresholds and other uneven surfaces.) Verify brake operation. A.1.4 AC Plug/Receptacles. Verify that the plug is Hospital Grade (identifiable by a green dot and/or labeling). (A plug of good quality, even if not Hospital Grade, may be left on a device that is plugged and unplugged infrequently. Rightangle plugs are unacceptable for devices that are

6

moved frequently. A good quality two-prong plug is acceptable for double-insulated devices.) If a special plug is required (e.g., explosion proof), it should be of suitable type and quality. Replace the plug or have the supplier replace it if it is not Hospital Grade or otherwise suitable. Hospital Grade molded plugs are acceptable. If the device has electrical accessory outlets, use an outlet test fixture, and with the device plugged in, verify that the accessory outlet is energized and correctly wired. A.1.5 Line Cord. Ensure that the line cord is long enough for the unit’s intended application; an extension cord should not be required. (A length of 10 ft [3 m] is suitable for most applications, although 18 ft [5.5 m] has been suggested for operating room equipment.) The cord should be of suitable quality and current-carrying capacity. Hard Service (SO, ST, or STO), Junior Hard Service (SJO, SJT, or SJTO), or an equivalent-quality cord should be used. If the line cord is operator detachable, affix the cord to the unit so that it cannot be removed by the operator, or at least label the cord prominently (e.g., 120 V), especially for devices that are used in the vicinity of monitors that use patient leads. (Electrode lead wires have been inserted into line-cord connectors; see Health Devices 1993 May-Jun; 22:301-3.) A.1.7 Circuit Breaker/Fuse. If the device is protected by an external fuse, verify that the fuse type is labeled and that all fuses and spares are the proper current rating and type. If the value and type are not labeled, check the manual for the proper current rating and type and permanently mark this information on the unit housing near the fuse holder. If no spare fuse is provided, consider attaching a fuse clip and spare fuse, particularly for high-risk devices. Especially for critical or life-support devices, verify that accessory outlets have independent overcurrent protection (fuse or circuit breaker) so that a short in a device plugged into the accessory outlet or an accessory overload will not disable the primary device. If this is not available, then consider labeling the primary device to clearly indicate where the unit’s fuse or circuit breaker is located, and/or install a fused Hospital Grade (or similar quality) plug on any commonly used accessories that are not


General Devices already provided with suitable overcurrent protection. A.1.10 Fittings/Connectors. Verify that other hospital equipment or systems to which the device is to be connected have the matching connectors. Devices that connect to the central piped medical gas system should have the matching DISS or quickconnect fitting for the appropriate gas. Verify that suitable connectors are supplied with the device so that adapters are not required. A.1.13 Controls/Switches. Verify that software setup parameters accessible through hidden or service menus are correctly set for the appropriate application and are consistent for all units. Instruction and service manuals may contain instructions regarding such modes. If they do not, contact the manufacturer. Discuss appropriate settings with the department head and users. If alarm capabilities are included, see Item A.1.20. A.1.17 Battery/Charger. To determine operating time, charge the battery overnight (or install fresh batteries), then operate the device on battery power with all commonly used functions activated. For critical care monitors and therapeutic devices, it may be desirable to disconnect the battery and determine if the device still operates on line power. A.1.20 Alarms. Verify that critical alarms cannot be turned off, silenced, or defeated without adequate warning to the operator or automatic alarm reactivation after a short delay (see Health Devices 1987 Feb; 16:39-44 and 1989 Dec; 18:426-7.) Such deficiencies should usually be recognized during prepurchase evaluation. However, if any are found, review the justification for purchasing this device and discuss corrective action with the manufacturer. (Alarm features may be optional or programmable.) If no remedy is available, a user training program should be instituted to reduce the risk of incorrect use. A warning label on the device or a poster in the area of use may be appropriate. A.1.23 Accessories. Verify that all necessary features and accessories (e.g., transducers) have been supplied with the unit. At least one copy each (two are generally preferred) of the instruction and service manuals, including schematics, should be shipped with the unit and filed in the central equipment file. A copy of the instruction manual should be kept with the unit and read by all operators before the device is put in use.

A.2 Quantitative acceptance tests A.2.2 Chassis Leakage Current. Note: Some devices (especially devices incorporating a microprocessor, motor, or compressor) may be damaged by switching polarity while the device is on. If you perform reverse polarity testing, turn off the unit until the motor stops or for at least 10 sec before switching polarity. Measure chassis leakage current as described in Item 2.2. Reversed polarity testing is not required, although some hospitals perform this measurement; it may be advisable on a device of questionable quality or on devices used in the home. Be alert for leakage current of the device in the off mode that is greater than about 30 µA and is greater than or equal to the leakage current in the on mode. Although this may be normal and proper for the device, it may indicate that the on/off switch is incorrectly wired in the neutral (instead of the hot) line. Incorrect switch wiring poses a risk to service personnel who believe that the power is disconnected when the switch is off. Check the wiring, or contact the manufacturer. Inspect AC adapters used to power (or recharge) certain devices for UL (or other testing laboratory) listing and to verify that it is labeled to identify the device with which it is to be used. ECRI recommends testing of adapters, particularly those that are not listed, by measuring the leakage current from each secondary (low voltage) connection to ground. The leakage current should not exceed the limits for the device chassis leakage current to ground (300 µA in patient care areas, 500 µA in nonpatient care areas). See the article on Electrical Safety, behind the Guidance Tab of this binder, for further details and a discussion of the use of these devices in hospitals. Measure chassis leakage current of permanently installed (hardwired) equipment during installation only. Before connecting the equipment to ground, measure the leakage current from chassis to ground. The ungrounded leakage current should be less than 5 mA. ■ ■ ■ Experience has not demonstrated the need for lead leakage and input isolation testing (Items 4.1 through 4.3) on a routine basis. NFPA 99 specifically excludes


7

Inspection and Preventive Maintenance System the need for periodic lead leakage current testing. We recommend that these tests be performed only during acceptance testing or following input circuitry repairs. 4.1

Lead-to-Ground Leakage Current. Measure leakage current from patient leads (or other applied parts, such as probes) to ground on any electrical device that has leads that are intentionally attached to or held against the patient or on any device that has a conductive invasive connection. Perform the test with the device on and with the ground wire intact and open, in all normal operating modes. If the device is of nonisolated design and is not intended to be connected to the heart by a conductive lead or fluid-filled catheter, leakage current should be 100 µA or less, measured from all the leads connected together to ground. If the device has isolated patient connections (see the article on Electrical Safety, behind the Guidance Tab of this binder, for a discussion of isolation), it should be labeled “Isolated” on the front panel by the manufacturer or have the IEC symbol signifying isolation (a heart within a square). These units are designed to be safe for use when connected to a conductive lead or fluidfilled catheter that is within, or in contact with, the heart. Normally, only one lead of the device will be in contact with the heart (or create a conductive path to the heart); individually test each lead that may be connected to confirm that leakage current to ground is 10 µA or less with the unit ground intact and 50 µA or less with the ground open (the open ground limit is a change introduced in the 1990 version of NFPA 99). If the device housing is not grounded, measure leakage current from each lead to the housing.

4.2

Interlead Leakage Current. Measure the leakage current between leads on devices with multiple patient leads or contacts. Measure between each lead (except ground). Perform the test with the device on and with the ground wire both intact and open, in all normal operating modes. For nonisolated connections, the leakage current should not exceed 50 µA (grounded or ungrounded). For isolated input connections, the leakage current should not exceed 10 µA with the device ground intact or 50 µA with the ground open.

4.3

Lead Input Isolation. This test should be performed only during acceptance testing or following input circuit repairs.

8

WARNING: Testing input isolation requires the use of a line voltage source. Perform this test only with an electrical safety analyzer or other setup that allows safe application of the voltage to the patient leads. Be sure that a current-limiting resistor is included in the setup, but continue to be careful not to contact any exposed leads, since it is still possible to receive a shock. Apply 120 VAC (line voltage applied through a current-limiting resistor) to each isolated patient connection individually, and measure the resulting current (sink current) with the unit turned on and operating and the power cord grounding connector intact. The current should not exceed 50 µA at the patient end of the cable.

Before returning to use Ensure that all controls are set properly. Set alarms loud enough to attract attention in the area in which the device will be used. Other controls should be in their normal pre-use positions. Attach a Caution tag in a prominent position on life-support equipment or any other device where the user must be aware that control settings may have been changed. With battery-powered devices, either recharge the battery or equip the device with fresh batteries. When a new battery is installed, label it with the date.

General Devices Checklist Template The checklist associated with this procedure is a template that can be used to develop checklists and accompanying procedures for any device. The General Devices procedure is the foundation for the template and will provide many of the IPM ingredients common to line- or battery-powered devices. The first step in using the template is to place a check mark in the Major column for each item that applies to the device. The second step is to determine the specific IPM elements that will ensure the safe and effective operation of the device. This task focuses on identifying unique accessories and any parameters requiring measurement (e.g., temperature, pressure, flow). At this point, the author of a new IPM procedure must specify performance criteria, methods for assessing the criteria, and the frequency for conducting the major and, if needed, minor IPM procedures. IPM Task ManagerTM, the software component of the IPM System, can then be used to prepare a final procedure and device-specific checklist.



Heart-Lung Bypass Units Used For: Heart-Lung Bypass Units [11-969] Pumps, Extracorporeal Perfusion [13-203]

Also Called: Cardiopulmonary perfusion equipment, heart-lung machines, heart-lung pumps, bypass machines Commonly Used In: Operating rooms for cardiac surgery Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Heart-lung machines and accessories should be inspected after every 100 hours of use or quarterly, whichever comes first, barring specific hospital circumstances or manufacturer recommendations to the contrary. The perfusionist should check pump occlusion before each procedure.

Overview Cardiopulmonary perfusion equipment, commonly referred to as heart-lung machines, provides cardiopulmonary support for a patient during open-heart surgery, permitting cardiovascular surgeons to isolate the heart from the circulatory system to perform cardiac repairs or valve replacements. The great vessels returning to (venae cavae) and leaving (aorta) the heart are cannulated, allowing an external circuit to provide circulation and oxygenation while the heart and lungs are bypassed. (For more detailed information on the procedure, see: Reed CC, Stafford T. Cardiopulmonary bypass. 2nd ed. Houston: Texas Medical Press, 1985.) Cardiopulmonary perfusion systems usually consist of blood pumps; control and monitoring devices; and a disposable oxygenator, cardiotomy reservoir, tubing set, and filters. Blood pumps. Blood pumps propel blood through the extracorporeal circuit and return extravascular blood to the circulating volume using suction (e.g., autotransfusion, intracardiac suction). The arterial pump propels blood through the oxygenator to the patient and may


operate at up to 6 L/min, depending on patient requirements. A backup arterial pump is usually provided. Venous blood normally requires no pumping because it flows by means of gravity to a reservoir. Membrane oxygenators (the most common variety; bubble oxygenators are rarely used today) require that the arterial pump be positioned between the venous reservoir and the oxygenator and that it actively pump blood from the reservoir to the oxygenator. Because continuous operation is imperative, the arterial pump must be connected to a battery pack, as well as to the emergency power system. As an additional precaution, a hand crank should be kept with each pump in the event of a power failure. Control and monitoring devices. A number of accessories are needed for controlling and monitoring perfusion. Blood temperature in the extracorporeal circuit is regulated to produce hypothermia or normothermia. Oxygenators typically incorporate a heat exchanger, and water must be delivered to the exchanger at a specified temperature. A mixer valve regulates hot and cold water delivered to the heat exchanger; it usually has a thermometer and water pressure relief valves to prevent overpressurizing the


●


Inspection and Preventive Maintenance System exchanger part of the oxygenator. A separate electrically powered heater/cooler may be used instead of a mixer to provide temperature-regulated water to the heat exchanger. Oxygen is delivered to venous blood from tanks or a central oxygen supply. A flowmeter and bacteriologic filter are usually incorporated in the oxygen circuit. Blood oxygen and carbon dioxide concentrations are usually monitored by blood gas determinations from drawn samples, but they may be monitored using an in-line differential oxygen monitor. An oxygen saturation meter may be used to assess oxygenation. Other devices may be used to provide blood chemistry information throughout the perfusion. Temperature monitors may be used, with probes placed at various points on the patient or in the extracorporeal blood circuit. Level detectors may be used to monitor the level of blood in the reservoirs. These detectors are often equipped with audible and visual alarms and may also stop the arterial blood pump to avoid pumping air into the patient in the event of a low blood level in a reservoir or to avoid too much blood volume in the extracorporeal circuit in the event of a high blood level. A special valve may be incorporated in the arterial tubing to prevent infusion of large amounts of air. Air bubble detectors give audible and visual alarms and may also stop the arterial blood pump if air is detected in the arterial line. Pressure monitors record left atrial, pulmonary artery, and arterial pressures. These monitors, which may be included in the console, the drive pressure transducers, or the monitors, may be slaved to other pressure monitoring equipment. Blood contact with foreign surfaces requires that the coagulation (clotting) mechanism of the blood be controlled to a point where coagulation is inhibited, but in a reversible manner. Heparin is the anticoagulant used in perfusion, and its level must be monitored throughout the perfusion to prevent clot formation or overheparinization. Oxygenator, cardiotomy reservoir, filters, and tubing set. These disposable components form the extracorporeal blood circuit. The perfusionist usually lays out the circuit, which is made up as a sterile custom pack by a manufacturer. Blood taken from the venae cavae normally flows by gravity (a venous clamp may be used to regulate flow) to a venous reservoir and is then pumped through the oxygenator. After leaving the oxygenator, blood flows

2

to the patient, usually after passing through a bloodline filter in the arterial line. A shunt around the blood-line filter permits continued flow if a clogged filter must be changed. Some perfusionists incorporate a filter in this shunt line as well, since releasing clamps to change filters may cause unloading of the filtrates. Suction pumps recover blood at the surgical site and return it to the circulating volume. Intracardiac suction returns extravascular blood to the cardiotomy reservoir, where it is filtered and then drained or pumped to the venous side of the oxygenator. Suction for ventricular vents may also be controlled by suction pumps. Blood from the cardiotomy reservoir may be passed through an additional blood-line filter before returning to the oxygenator.

Citations from Health Devices Heart-lung bypass machines, 1973 Apr; 2:152. Sarns air bubble detector system [Evaluation], 1981 Jan; 10:55. Delta automatic shutoff valve [Evaluation], 1981 Jan; 10:62. Improper bulb replacement causes Sarns model 7000 MDX heart-lung bypass pump failure [Hazard], 1987 Jun; 16:218-9.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Equipment for inspecting blood pressure monitors and pressure transducers, as specified in Blood Pressure Monitors, Invasive Procedure/Checklist 434 and Pressure Transducers Procedure/Checklist 435, respectively Thermometer accurate to at least 0.5°C over a range of 15° to 43°C (a temperature-monitoring device made of a thermometer sealed into one leg of a Y or T connector, such as is used for the inspection of hypo/hyperthermia units, may also be used) Stopwatch or watch with a second hand Hydrometer Oxygen flowmeter with 1 to 10 L/min range and 2% accuracy Graduated cylinder with at least 1 L capacity (a fluid flowmeter with 0 to 10 L/min range and 5% accuracy may be used) Large bucket (5 L) for collecting fluid when checking high flow settings


Heart-Lung Bypass Units that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacle.

Disposable supplies, such as tubing and assorted fittings for connecting tubing and test equipment Conductive lubricant, such as Dow #41 graphited oil or the equivalent, for conductive casters

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or if the damage is near one end, cut out the defective portion. Ensure that the line cord is of sufficient length to preclude the use of extension cords. Be sure to wire a new power cord or plug with the same polarity as the old one. Also check line cords of battery chargers.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord and all accessory cords. Be sure that they hold the cord securely.

1.7


1.8

Tubes/Hoses. Check the condition of all tubing and hoses in the water mixer. Be sure that they are not cracked, kinked, or dirty. Check for evidence of leaking.

1.9

Cables. Inspect the cables of the level sensor and bubble detector and oxygen, temperature, and pressure monitors, if so equipped, and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain.

Torque measurement device for checking pump (if required)

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Because some inspection items require multiple data points and several pumps need to be checked, enter additional data on the reverse side of the inspection form.



1.2

Mount/Fasteners. Examine each pump module and any other accessories mounted to the cart or console for security of attachment. Check the integrity of all special mounting hardware for oxygenators and cardiotomy reservoirs.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where appropriate, are usually done more effectively as part of a check of all equipment and furniture of an area.

1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug into each, and check

1.10 Fittings/Connectors. Check the general condition of all gas and liquid fittings and connectors, such as those on the oxygen flowmeter and water mixer, as well as all electrical cable connectors. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Electrodes/Transducers. Confirm that necessary electrodes and/or transducers are on hand, and check their physical condition. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection.


3

Inspection and Preventive Maintenance System indicators, meters, gauges, and visual displays on the unit and the charger, if so equipped. Be sure that all segments of a digital display function.

Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.14 Heater/Mixer. If the unit uses a heater for temperature control, examine the heater for physical condition (e.g., verify that a variable temperature control does, in fact, determine the amount of heating; verify that on/off controls work). If the unit uses a mixer valve for temperature control, examine the valve for proper operation. If a high-temperature cutoff is incorporated in the valve, check its function. Be sure that hot and cold connectors are adequately placarded to prevent cross connection. 1.15 Motors/Pumps. Confirm the physical condition and proper operation of all pump heads and their associated motors and transmissions. Eccentricity of rollers, belt tension, and occlusion mechanisms should be within the manufacturer’s specifications. Lubricate bearings if required, and note this on Line 3.2 of the inspection form. Ensure that an emergency hand crank is attached to the unit and that the hand crank will turn the pump when power is disconnected. 1.16 Fluid Levels. Check all fluid levels, including those in lead-acid batteries. Replenish if low. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check remaining battery capacity by activating battery test function or by measuring the output voltage; for lead-acid batteries, measure the specific gravity. For sealed lead-acid batteries, it may be necessary to perform a capacity test by running the equipment until the batteries are depleted. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights,

4

Examine the oxygen flowmeter for signs of damage or abuse, such as internal nicks, scratches, cracks, condensation, or debris. The valves on some machines do not have a fixed-end stop; take care not to overtighten. Check for free play in the control valve by pushing, pulling, and rocking the stem from side to side with rotation. The stem should feel firm, and the flowmeter float should not move. 1.20 Alarms/Interlocks. Operate the device in such a way as to activate each audible and visual alarm. Check that any associated interlocks function. Check that, once the alarm condition has been corrected, the pumps will start and function properly. If the device has an alarm-silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of such accessories as a level sensor and an oxygenator light. If a venous line clamp is used, check that it operates smoothly. 1.24 Water Supply. If the water supply used for temperature control has gauges, check for appropriate water pressure and temperature. Verify that incoming water temperature and pressure controllers or limitation devices are in place, and if possible, verify that they are functioning. (A pressure-relief valve should be used to prevent overpressurizing the oxygenator.)


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the device has an accessory outlet, check its grounding to the main power cord.


Heart-Lung Bypass Units 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. (Be sure that connections at the inlet or outlet ports or conductive casters on a conductive floor do not establish alternate ground paths.) Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. If the unit has heating and cooling modes, be sure that thermostats permit each mode to operate while taking readings. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord. Chassis leakage current should not exceed 300 µA.

2.3

Pressure Monitors/Transducers. Perform the blood pressure monitor (Procedure/Checklist 434) and pressure transducer (Procedure/Checklist 435) inspection and preventive maintenance procedures on the respective components. Use separate inspection forms, but record the system’s pass/fail determination on the heart-lung bypass units inspection form.

2.4

Thermometer Accuracy. To check the accuracy of thermometers in heater/coolers or water mixers, connect the outflow of the heater or mixer to the temperature-monitoring device. For heater/ coolers, connect the in-line temperature-monitoring device, allow the unit to stabilize for 15 min, and compare temperatures. When checking water mixers, connect the outflow of the temperature-monitoring device to a drain, and compare temperatures. Thermometers should agree within 1°C. Check at low, medium, and high points in the temperature range (29°, 34°, and 38°C).

2.5

Temperature Alarms. For units incorporating high-temperature alarms, keep the temperature-monitoring device where it was for the previous test. For heater/coolers, place hot water in the reservoir, and record the alarm value. For mixers, alter the water mixture, and record the alarm value. Alarms should occur at 42° ±1°C or within manufacturer’s specifications. Examine

any associated interlocks (e.g., stop flow, turn off heater) or alarms at this time. 2.9

Blood Pump Occlusion. In order to operate correctly, the pump rollers must occlude the tubing throughout its travel across the backplate. Check tube occlusion with a section of tubing installed in the pump and filled with water to a height of about 76 cm (30 in) above the pump. Leave the other end of the pump open and empty. Any drop in level should be less than 1 cm/min or within the manufacturer’s specifications. Check occlusion at various roller positions on the back plate.

2.10 Blood Pumps. Check the rollers on each pump to ensure that they are running smoothly and that there are no unusual noises from the bearings or other indications of excessive bearing wear. If the manufacturer provides torque specifications for the pump, check this with torque measuring tools. With correct-size tubing in the pump, immerse both ends of the tubing in a tank of saline solution or water at atmospheric pressure, and turn on the pump. For greater accuracy, attach a cannula to the outflow side of the pump to simulate back pressure. To check the pump accuracy at a mid-range flow setting, set it to deliver 3 L/min, and collect the volume for a convenient time interval in a graduated cylinder (a fluid flowmeter may also be used). Also check operation at low and high flow settings. At higher settings, it may be necessary to collect fluid in a large bucket and measure out volume in the graduated cylinder. Flows should be accurate to within 5% of the setting or the manufacturer’s specifications. For centrifugal pumps, used on some units, operate with saline and measure flow rate by pumping saline from a “reservoir” into the graduated cylinder. Compare this flow rate with the electronically determined rate, and make sure it is within 5%. When checking blood pump flow on pumps without direct flow setting indication, it may be useful to draw a graph of flow setting versus dial setting and placard it on the pump. Be sure to indicate tubing size and brand on the graph. 2.11 Oxygen Flowmeter. Check the accuracy of the flowmeter by connecting it in series with the calibrated flowmeter. Set it to deliver a known flow, and compare this flow to that of the calibrated


5

Inspection and Preventive Maintenance System meter. Check low, medium, and high ranges. The valve should turn smoothly, with only slight drag, and the float should rise and fall freely as the flow is raised or lowered. Accuracy of the machine flowmeters should agree within 5% of full scale or the manufacturer’s specifications. Also check other flowmeters (e.g., CO2), if so equipped. 2.12 Temperature Monitors. Check the accuracy of all probes with the temperature monitor. Test the accuracy of thermometers in a water bath of known temperature or with a patient probe simulator. Accuracy should be checked at 20°C, 37°C, and 39°C. Check thermometers intended for wide temperature range application (e.g., hypothermia monitoring) at temperatures near the high and low extremes of the range. Thermometers should be accurate within 0.5°C or within the manufacturer’s specifications. It may be necessary to allow for errors in the measuring system.


6

Clean the exterior.

3.2

Lubricate casters and motors.

3.3

Calibrate if required.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. It may be useful to indicate with luminous tape or paint the direction that the hand crank should be turned for normal pump rotation in the event of power failure.

Before returning to use Ensure that controls are set at normal positions and that alarm volumes (if adjustable) are set loud enough to be heard in the clinical setting. Place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using the unit.



Heated Humidifiers Used For: Humidifiers, Heated [12-050]

Commonly Used In: Respiratory care area, critical care areas, recovery rooms, nurseries, operating rooms Scope: Applies to servo-controlled units, units used in combination with separate temperature controllers (servo control), and non-servo-controlled units Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview During normal inspiration, the mouth, nose, and pharynx warm and humidify air. However, during long-term ventilatory support or anesthesia when the patient is intubated with an oral or nasal tracheal tube or tracheostomy tube, this natural humidification process is bypassed; dry, cool gases are delivered directly to the trachea and lungs, thus increasing heat and moisture demand on the lower respiratory tract. As water is vaporized to increase inspired water vapor concentration and the inspired gas is warmed by convection, tracheal mucosa loses heat and moisture. As the mucosa dries and its temperature drops, secretions thicken and ciliary activity is reduced, and the ability to clear mucus and debris is diminished. The formation of thick mucus plugs can result in atelectasis (i.e., collapse of the alveoli) or obstruction of the airway. Using an artificial means to heat and humidify inspired gases minimizes the complications associated with artificial airways. Usually, an electrically heated, water-filled humidifier is applied to the inspiratory gas line. The humidifier simultaneously supplies heat and humidity when the gas passes over a



Time Required

heated wet surface; efficient design ensures saturation of the gas mixture leaving the humidifier. The gas cools as it flows to the patient, producing rainout (condensation), and is inspired saturated and at a reduced temperature. The simplest units heat water by means of a thermostatically controlled heat transfer surface in contact with a body of water, which in turn heats the gas stream. Controlling the temperature of the heater prevents excessive water and gas temperatures. Most units have a control for varying the gas temperature; servo-controlled units use a temperature sensor in the patient circuit for more reliable temperature control of the gas delivery to the patient. There is a risk of hyperthermia and respiratory tract burns if the inspired gas exceeds 40°C for an extended period of time. Increases in temperature and exposure time correspondingly increase this risk. Thus, we recommend monitoring inspiratory air temperature during every heated humidifier application, and we prefer units that regulate the temperature by means of a patient circuit probe, rather than reading water or heater surface temperature.


●



Citations from Health Devices Heated humidifiers [Evaluation], 1987 Jul; 16:223-50. Heated humidifiers can burn infants during CPAP [Hazard], 1987 Dec; 16:404. Heated wires can melt disposable breathing circuits [Hazard], 1989 May; 18:174.

and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Test the humidifier, temperature monitor, and alarm together.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Check that plastic housings are intact with no cracks or poor seals that spilled fluid can penetrate, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Check for discoloration, peeling, melted plastic, or swelling that may indicate overheating.

1.2

Mount/Fasteners. Examine the mounting security of the humidifier and associated accessories.

1.4

AC Plug. Examine the AC power plug for signs of damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the line cord for signs of damage. If damaged, either replace the entire cord or, if damage is near one end, cut out the defective portion. Be sure to wire the new power cord or plug with the same polarity as the old one. Ensure that the line cord is sufficiently long to preclude the need for extension cords.

1.6


1.7

Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely. If the unit is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare fuse is provided. If there is no provision for a spare fuse, consider installing a simple spring clip or old fuse holder. If the unit has a separate fuse for the heated circuit, be sure to check it (its type and rating are critical).

1.8

Tubes/Hoses. Check the condition of all tubing and hoses in the unit. Be sure that they are not cracked, kinked, brittle, or dirty. Check for any evidence of leaking.

1.9

Cables. Inspect the controller and temperature sensor cables, if any, as well as their strain reliefs, for general condition. Check reusable heated

Test apparatus and supplies Thermometer (bimetallic or electronic) accurate to at least 0.5°C over a range of 30° to 45°C T-adapter for positioning a thermometer in series with the patient inspiratory temperature sensor of the humidifier Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Source of medical compressed air or oxygen capable of providing a flow rate of approximately 10 L/min Distilled water for filling the humidifier Patient circuit or tubing for use with the humidifier Pressure gauges or meters with ranges of 0 to 30 cm H2O and 0 to 100 cm H2O (such as those provided by a pneumatic tester) with adapters for various humidifiers to be inspected (acceptance testing only) Large syringe or sphygmomanometer bulb and adapter that can be connected to the humidifier input for pressurizing it to 30 cm H2O (acceptance testing only)

Special precautions When inspecting heated humidifiers (and other thermostatically controlled equipment), verify that the unit is not operating on its backup or secondary thermostat. If the normal (primary) thermostat fails in the on condition, the secondary thermostat will limit the temperature to protect the heater from burning out, but the heater may still generate a temperature excessive for the patient. Thus, if output temperature is high and the control thermostat does not appear to adjust it properly, the unit may be operating on its backup thermostat. Most units do not have an alarm to alert the user to this condition. CAUTION: Heater surfaces may be hot.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control

2


Heated Humidifiers wires for cracks, kinks, and brittleness. Verify that the wires are compatible with this unit. 1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors (e.g., patient circuit, water supply, electrical cable connectors) for general condition. 1.11 Transducers/Temperature Sensor. Check that the patient inspiratory temperature sensor is present and properly fitted into the center of its adapter for use in the patient circuit. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., temperature control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

1.22 Labeling. Check that all necessary placards, labels, flow rate and temperature calibration charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of such accessories as separate controllers, temperature sensors, and water supplies. Make sure all necessary parts are present (e.g., valve flaps, removable stoppers). 1.24 Flow/Output. With distilled water in the humidifier, connect it to a source of medical compressed air and its output to the patient circuit tubing. Set the unit for a mid-range temperature and the gas source for 10 L/min, and turn on the humidifier and gas source. Confirm that the gas flow in a bubble-type unit actually bubbles up through the water. Also check that gas is being humidified after the unit has warmed up, as evidenced by condensation in the output hose. (During major procedures, perform Items 2.1 and 2.2 before this test, so that it will be possible to proceed directly to 2.10 after this test.)

2. Quantitative tests Perform the following tests (except Item 2.1) with distilled water added to the unit before applying power to the heater. 2.1

Grounding Resistance. Measure and record the resistance between the grounding pin of the power cord and all exposed metal on the unit (including heater sheath or surface) except small external trim pieces. Tug and flex both ends of the line cord and any connected accessory cords while making the measurement. We recommend that the resistance not exceed 0.5 Ω. Grounding resistance and leakage current measurements are not required if the unit is constructed primarily of plastic and has no exposed metal surfaces.

2.2

Leakage Current. Measure chassis leakage current with the grounding connection temporarily opened. Obtain measurements with the unit off and on and with the unit on and the heater cycle on and off, and record the maximum leakage current. Leakage current should not exceed 300 µA. (Since only water vapor and condensate reach the patient through the inspiratory hose, special measurements of leakage current from the water reservoir are not required. However, if the water supply is readily accessible for leakage current measurement, this will provide further

1.14 Heater. Examine the heater or heat transfer surface for physical condition (e.g., corrosion or pitting of its sheath, deteriorated insulation). 1.16 Fluid Levels. Check that the maximum fluid level is marked and clearly visible. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, and visual displays. If the unit has a digital temperature display, be sure that all its segments function. 1.20 Alarms. Operate the unit in such a way as to activate audible and visual alarms. High-temperature alarms may need to be checked during Item 2.11. If the unit has a probe-disconnect alarm, verify that it is activated and that the heater is turned off when the probe is disconnected. 1.21 Audible Signals. Operate the unit to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped.


3

Inspection and Preventive Maintenance System assurance of heater insulation integrity, especially if the sheath or heater surface is not of a grounded design.) 2.3

Low-Temperature Alarms. Verify the functions and the accuracy of low-temperature alarms and indicators. Some units alarm if they detect room-temperature gas (although this may not occur until after several minutes of operation on some units); other units have a user-selectable low-temperature alarm.



Pressure Drop. With a T-adapter in the humidifier input, connect the 0 to 10 cm H2O pressure gauge or meter to measure the input pressure to the unit. Measure the pressure drop with 10 L/min gas flow exhausting to the atmosphere. The pressure drop should be less than 5 cm H2O for bubble-type humidifiers and much less for other units. (This measurement can be performed while the humidifier is warming up for the output temperature tests.) This test need not be performed on units that use disposable humidity chambers or units that allow complete visual inspection of the flow path, since the absence of any constriction can be verified.

4.2

Leaks. Attach the syringe or sphygmomanometer bulb and 0 to 100 cm H2O pressure gauge or meter to the input and the output to seal the humidifier. Pressurize it to 30 cm H2O and observe the pressure drop over 1 min. The pressure drop multiplied by the unit’s internal compliance (specified by the manufacturer) should not exceed 6 mL. For example, if the unit’s internal compliance is 0.4 mL/cm H2O and the pressure drop over 1 min is 10 cm H2O, the leakage is 4 mL and within the 6 mL limit.

2.10 Output Temperature. Connect the humidifier input to a medical compressed-air source and the output to the patient circuit or tubing. Attach the test thermometer adapters and the humidifier’s temperature sensor at the patient Y as close to each other as the adapters will permit. Set the temperature controller to low or mid range (35° to 40°C), set the gas source for 10 L/min, and turn on the humidifier and the gas source. When the thermometer equilibrates, record the output temperature and the temperature indicated by the unit’s temperature monitor or controller. Also, record the controller or thermostat setting. Repeat the test at the maximum temperature setting. Verify that the output temperature changes when the setting is changed to maximum. If it does not, the primary temperature control may not be functioning, and the unit may be operating on its backup thermostat. Temperature monitor and temperature settings (if so equipped) should be accurate within 1°C for servo-controlled units (other units are not calibrated). The maximum temperature of any unit should not be higher than that specified by the manufacturer. (We believe that the maximum obtainable temperature should not exceed 40°C. However, many units are capable of delivering gases at considerably higher temperatures.) 2.11 High-Temperature Alarms. Using the same setup as in 2.10, verify that the high-temperature alarm activates whenever the output gas temperature exceeds the alarm set point by more than 1°C. If the unit has an adjustable high-temperature alarm, verify alarm function at a low and high alarm setting.

4

Clean the exterior and heat transfer surface with a damp cloth. (Be sure that the heat transfer surface is cool.)

To determine nonspecified internal compliance, occlude one end of the humidifier, inject 50 mL of air through the open humidifier port with a syringe, and measure the increase in pressure in cm H2O. The internal compliance equals 50 mL divided by the pressure increase. Record this value for future use.

Before returning to use Adjust the temperature setting to minimum or normal. Empty or remove the water reservoir. If the unit is equipped with an adjustable alarm volume, ensure that the volume is appropriate for a clinical setting. Return the unit for processing (e.g., cleaning, sterilizing) to prepare it for patient use.



Hemodialysis Units Used For: Dialysate Delivery Systems, Multipatient [11-211] Dialysate Delivery Systems, Single-Patient [11-213] Hemodialysis Units [11-218]

Also Called: Dialysis machines, dialysis units, artificial kidney machines, hemodialyzers (which more appropriately applies to the dialyzer component of the machine) Commonly Used In: Hemodialysis departments, critical care units, freestanding hemodialysis treatment centers, patient homes Scope: Primarily applies to single-patient hemodialysis units, although portions may be applied to central hemodialysis systems; also see Peritoneal Dialysis Units Procedure/Checklist 455 Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

3 months

months

.

hours

Time Required

* Temperature, conductivity, and pH (if applicable) monitors should be checked by the operator before each dialysis.

Overview Hemodialysis is used to remove accumulated waste products, organic salts, and water from the blood of a patient with impaired kidney function or to remove toxins in cases of blood poisoning. Hemodialysis units consist of an extracorporeal blood delivery unit (blood circuit), a dialysate delivery unit (dialysate circuit), a dialyzer, and monitoring units. Blood circuit. In the blood circuit, blood is taken from an artery, circulated through the dialyzer by a blood pump, cleansed, and returned to a vein. Usually, one or two needles inserted in an arteriovenous (A-V) fistula (the linking of an artery and vein) in the patient’s arm provide access to the circulatory system. The single-needle technique halves the number of punctures but requires either a Y connection and a controller to alternate withdrawal and infusion of


blood, or a special single-needle access catheter. Heparin is infused into the arterial (inflow) side of the blood circuit to prevent clotting. Blood pressure sensors on the venous side of the dialyzer (and sometimes also on the arterial side) may alarm and stop the blood pump when pressure is outside preset limits. Most units have an air-bubble and/or foam detector or blood-level detector, which clamps the venous blood line and stops the blood pump if air is detected in the venous line to prevent infusing air emboli into the patient. Newer units may combine air-bubble, foam, and blood-level detectors in one monitor unit. Dialyzer. In the dialyzer, a semipermeable membrane separates the blood from the dialysate solution. Substances from the blood pass through the membrane into the dialysate solution by diffusion, ultrafiltration,


●


Inspection and Preventive Maintenance System and osmosis. The dialysate solution initially contains none of the waste substances to be removed from the blood. The resulting concentration gradients across the membrane promote selective diffusion from the blood to the dialysate solution. Substances that should remain in the blood are present in equivalent concentrations in the dialysate solution. The dialysate solution has a lower hydrostatic pressure than the blood to promote removal of excess water from the blood by ultrafiltration. Dialysate circuit. Dialysate solution, a mixture of treated (purified) water and concentrated dialysate, is pumped through the dialyzer at a prescribed temperature, concentration, and flow rate. Dialysate solution is prepared continuously in some machines by a proportioning system that meters and mixes precise proportions of concentrated dialysate and treated water (a common ratio is 1 part dialysate to 34 parts water). This proportioning system may be a fixed ratio (i.e., proportioning a known volume of concentrate and water) or may be servocontrolled, using a control sensor to regulate the flow of dialysate concentrate. A built-in conductivity meter continuously monitors the solution before it reaches the dialyzer. Newer machines may have special proportioning and monitoring systems for different types of dialysate (e.g., variable bicarbonate, variable sodium). The dialysate solution for other machines is prepared by the simple “batch” method, but enough solution for the entire procedure must be mixed before the start of dialysis. Portable conductivity meters are used to check batch mixtures of dialysate solution. The formulation of the dialysate solution is prescribed by the physician and may be varied to meet each patient’s needs. The dialysate circuit may be housed in a single-patient unit or divided between a central unit and a number of bedside stations. A central unit may allow the bedside apparatus to be smaller and less costly than single-patient units. However, a central unit does not permit individual prescription of dialysate solution concentration. Depending on the unit used, monitoring devices in the dialysate circuit may sense dialysate temperature, conductivity, flow rate, negative pressure, ultrafiltration rate, and blood circuit leaks. Some monitors and alarms include fail-safe controls that interrupt the dialysis procedure to prevent injury. For more detailed information on dialysis, consult the Health Devices citations, particularly the 1980 evaluation of hemodialysis machines and the improper dialysate hazard, as well as Review of Hemodialysis for Nurses and Dialysis Personnel (Gutch CF, Stoner MH, Corea AL. 5th ed. St. Louis, MO: C.V. Mosby, 1993).

2

Citations from Health Devices Single-patient hemodialysis machines [Evaluation], 1980 Feb-Mar; 9:87-130. Update: Gambro dialysis unit, 1980 Apr; 9:162. Reusing dialyzers and tubing sets: Pros and cons, 1980 Nov; 10:22-4. Improper dialysate [Hazard], 1983 Oct; 12:315-8. Electrical safety of subclavian catheters used in hemodialysis, 1983 Nov; 13:18-20. Peritoneal dialysis compared with hemodialysis, 1986 Feb-Mar; 15:34-5. Hemodialysis water purification [User Experience NetworkTM], 1988 Aug; 17:247. Cobe Centry 2 and Centry 2Rx hemodialysis units [Hazard], 1988 Oct; 17:313-4. Air embolism associated with hemodialysis [Hazard], 1989 Nov; 18:406-7. Technical overview: Hemodialysis machines, 1991 Jun; 20:187.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter Thermometer accurate to at least 0.1°C over a range of at least 30° to 45°C; a temperature monitoring device made of a thermometer sealed into one leg of a Y or T connector may also be used (similar fixtures are used for hypothermia unit testing, although a separate fixture should be used for dialysis testing to avoid possible contamination) Stopwatch or watch with a second hand Syringe of the type used in the heparin pump Syringe (at least 30 cc) to generate pressure of 300 mm Hg Pressure gauge or meter capable of reading vacuum and pressure over a range of about -600 to +400 mm Hg; accuracy should be at least 5 mm Hg over the -100 to +100 mm Hg range and 5% over the remainder; necessary range depends on type of hemodialysis unit being inspected Graduated cylinder with a 1,000 mL capacity for checking flowmeter and blood pump Conductivity meter, accurate to at least 1% or standard solution to check concentration monitor


Hemodialysis Units Expendable supplies for the device being inspected, including isolators or fluid barriers for pressure gauges or meters, blood lines, syringes, clamps, dialyzers, and dialysate solution (some of these supplies are expensive; to reduce costs, a single set of expendable supplies can be used repeatedly for inspections, except for units dedicated for isolation patients or that are suspected of having been used on patients with hepatitis or AIDS; expendables used with such units should be properly disposed of after use)

Some components covered by the following procedure (e.g., blood pump) are not built into certain older models of dialysis machines but are accessories that must be supplied by the user. Note the serial numbers of these components on the inspection form.

Assorted fittings for connecting tubing and gauges


Vacuum cleaner

1.1

For some hemodialysis units, especially the more sophisticated ones, it will be impossible to perform quantitative checks on all monitoring and alarm circuits. Refer to the service manual for suggestions when the procedures described below cannot be carried out in a straightforward manner.

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Dialysate has a high salt concentration that will corrode and tarnish.

1.2


Dialysis-grade water should be used for all inspection and preventive maintenance procedures.

1.3


1.4

AC Plug/Receptacles. Examine the AC power plug for damage from abuse. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

Record the time elapsed indicated on the hour meter, if so equipped. This will help indicate appropriateness of preventive maintenance frequency and what preventive maintenance procedures to do.

pH meter or standard test solutions if unit under test has pH monitor

Special precautions

CAUTION: For protection against HBV and HIV, wear rubber gloves, a long-sleeved gown, and safety glasses or goggles when disassembling or testing dialysis units. Contact the infection control practitioner responsible for the hemodialysis unit to review institutional policies and procedures regarding protection from HIV and HBV. Treat machines as though they were contaminated, and consider maintaining separate, dedicated tool sets for servicing. To minimize the chance of oral contamination, do not eat or smoke in the test area. (For more information on infection control during IPM activities, see the article in this binder titled “IPM Safety.”)

Hospital Grade plugs are strongly recommended for hemodialysis units. Base selection of plugs on their resistance to fluid infiltration; Hospital Grade plugs molded onto the line cord might be considered.

Since there may be water on the floor of maintenance areas, consider using ground fault circuit interrupters for electric shock protection in areas where this equipment will be tested and serviced.

If the device has electrical receptacles for accessories, insert an AC plug into each and check that it is held firmly. If accessories are frequently plugged and unplugged, consider a full inspection of the receptacle. Check for corrosion.


1.5



3



1.7


1.8

1.9

Tubes/Hoses. It may be necessary to disassemble the unit to examine all tubing and connectors to ensure that they fit correctly. The tubing should not be kinked or mounted near rotating components, sharp edges, and fastener ends. If deaerators are used, check them for proper fluid levels and venting. Check that all seals, grommets, gaskets, and couplings are in good condition and are correctly installed. Tubing and fluid connectors should not show signs of aging, fatigue, or stress (e.g., discoloration, cracks); should not contain foreign material; and should not leak. Look for signs of leaks (e.g., corrosion or dried dialysate near a connector). Make repairs if any of the above defects are present. Ensure that all fluid path components are securely mounted to the unit. Cables. Inspect the cables (e.g., sensor) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Examine all gas and liquid fittings and connectors, as well as all electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Color-coded or special connectors may be used to avoid inappropriate connections (e.g., a “bicarbonate” dialysate concentrate to a “sodium” concentrate circuit). Verify that these safeguards have not been ignored or violated by the use of adapters. 1.11 Transducers. Confirm that any necessary transducers are on hand, and check their physical condition. 1.12 Filters. Check the condition of all liquid and gas (air) filters. Clean or replace and indicate this on Line 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of

4

them appear inordinate (e.g., a conductivity or flow control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, check that each control and switch performs its proper function. 1.14 Heater. Examine the heater for physical condition (e.g., corrosion of its sheath, deteriorated insulation). Operate it to ensure that its controls function properly (e.g., that a variable temperature control does, in fact, determine the amount of heating; that on/off controls work). 1.15 Motor/Pump/Fan. Check all pumps (e.g., dialysate, recirculating, drain, proportioning, blood, heparin) for proper operation. Make sure they deliver fluid properly and are not excessively hot to the touch while operating. Motors should have smooth and free-running bearings and should not be excessively noisy. Check for leaks around pump seals and coupling, and make sure that pump heads and motors are clean. Clean and lubricate pumps, fans, motors, and other moving parts according to manufacturer’s recommendations, and note this on Lines 3.1 and 3.2 of the form. On batch-type units, make sure the drain screen of the dialysate delivery pump is intact and clean. Replace it if damaged. 1.16 Fluid Levels. Check all fluid levels. Test the water-loss alarm by momentarily turning off the water while the unit is running. 1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. The power-loss alarm should sound if the plug is pulled out during operation or when the unit is off and is then turned on. Check power-loss alarm batteries. When it is necessary to replace a battery, label it with the date.


Hemodialysis Units 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, flowmeters, temperature/pressure gauges or meters, and visual displays or indicators on the unit and charger, if so equipped. Ensure that all segments of any digital displays function.

2.2

1.20 Alarms/Interlocks. Operate the device in such a way as to activate each audible and visual alarm. Check that any associated interlocks function. If the device has an alarm-silence feature, check that it silences the alarm only for the period of time specified by the manufacturer.

Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

Verify that venous line clamps apply enough force to completely occlude the line. 1.21 Audible Signals. Operate the device to activate all audible signals. Confirm appropriate volume, as well as the operation of a volume control.

Hemodialysis is sometimes performed through a subclavian catheter. Ideally, any hemodialysis machine connected to a subclavian catheter should have an isolated patient connection due to the risk of microshock from accidental migration of the catheter tip into the heart. However, most units are not designed for this application; thus, we have not included a test of fluid path isolation. For subclavian hemodialysis, we recommend using hemodialysis units with leakage current levels below 50 µA or modified units with redundant grounding or an isolation transformer.

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Verify that an emergency hand crank for the blood pump is supplied with the unit. 1.24 Deaeration. It is difficult to quantitatively assess deaeration ability in dialysis machines. One of the primary components of the deaeration system is the deaeration (vacuum) pump; deterioration of its performance can adversely affect deaeration. To check vacuum pumps used in deaeration systems, we suggest measuring the vacuum generated by the pump with a pressure gauge or meter. Consult the manufacturer for the best measuring point and acceptable vacuum levels or for other recommended tests.

2.3

2. Quantitative Tests 2.1

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. Verify that a low resistance exists from the ground pin to various points on the unit, including all accessory modules, to ensure that interconnections are adequate. We recommend a maximum of 0.5 Ω. If the device has an accessory outlet, check its grounding to the main power cord.

Leakage Current. Measure chassis and patient lead leakage current to ground with the grounding conductor temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Obtain a reading with the heater cycled on and with it cycled off. Chassis leakage current should not exceed 300 µA.

Air/Foam (Blood-Level) Detector. Check this detector for proper operation. Ensure that all visual and audible alarm indicators operate properly. Clean sensors according to manufacturer’s recommendations, and follow the suggested test procedure. Other interlocked functions (e.g., venous line clamp, shutoffs, bypasses) should operate properly when an alarm is indicated. Check sensitivity based on manufacturer’s information, and verify proper operating range. If the unit has an alarm-test switch, check that it works correctly, but be aware that it does not test the sensor. Some blood-level, air, or foam detectors may require opaque fluid in the lines in order to function. Check the manufacturer’s recommendations for testing these units.

2.4

Blood-Leak Detector. Check this detector for proper operation. Ensure that all visual and audible alarm indicators operate properly. Clean sensors according to manufacturer’s recommendations, and follow the suggested test procedure. Other interlocked functions (e.g., venous line


5

Inspection and Preventive Maintenance System perature, and compare alarm temperatures with the manufacturer’s specifications. (On units where this cannot be done, it may be possible to test temperature alarms qualitatively by infusing a bolus of hot or cold water into the dialysate line.) Verify proper function of high-temperature indicators and any other interlocked function (e.g., dialysate bypass). Return the temperature control to the normal operating temperature.

clamp, shutoffs, bypasses) should operate properly when an alarm is indicated. Check sensitivity based on manufacturer’s information, and verify proper operating range. If the unit has an alarm-test switch, check that it works correctly, but be aware that it does not test the sensor. On some units, the blood-leak alarm can be tested by injecting air or milk past the photocell detector. Check the manufacturer’s recommendations for testing these units. 2.5

2.6

Temperature. Accuracy. Set the temperature to 37°C on units with a temperature control. Set the flow rate to 500 mL/min or according to manufacturer’s recommendations. Record the reading of the unit’s temperature indicator and that indicated by the precision thermometer (actual temperature) after the unit equilibrates. On units with a coil dialyzer, measure the temperature of the dialysate in the canister. For units with parallel-flow or hollow-fiber capillary dialyzers, connect the temperature monitoring device to the dialysate line at the entrance to the dialyzer (a T connection allows dialysate to keep flowing during the measurement). When the heaters are initially turned on, the temperature in some units may overshoot the desired setting and trigger a high-temperature alarm. Allow 15 min for temperature stabilization. Remember that dialysate cools between the heater and the dialyzer; some units may compensate for this cooling by increasing the temperature of the dialysate in the unit above the set temperature. The temperature control and/or indicator should be accurate within 0.5°C or within the manufacturer’s specifications.

6

Conductivity. CAUTION: Incorrect dialysate conductivity may be fatal (see Health Devices 1983 Oct; 12:315). Accuracy. Examine and clean the conductivity probe, and ensure that the monitor is mounted correctly according to the manufacturer’s recommendations. Although conductivity readings can be most accurately verified by laboratory tests, this is inconvenient on a routine basis. Comparison to a conductivity meter or standard solutions is an acceptable alternative. The conductivity meter used for this test should have an accuracy of at least 1% and should be checked frequently against a standard solution. Monitors are calibrated in milliequivalents/L of chloride (although they measure total ionic concentration), percent deviation, or milliohms/cm. If the unit is calibrated in percent deviation, be aware that this corresponds to only one concentration of dialysate. If physicians at your hospital prescribe other concentrations, check for appropriate deviation readings.

Alarms. Keep the precision thermometer in the same position as it was for the previous test. Test low-temperature alarms by turning the heaters off and allowing the dialysate to cool or by adjusting the limits to cause an alarm. Record the temperature at which the alarm occurs. Verify the operation of the low-temperature alarm and any other interlocked functions.

While the unit is running at normal operating temperature, use the manufacturer’s recommended method to take samples. Be sure to flush the conductivity meter several times with the solution to be tested before taking readings, and take the average conductivity of three samples. If the conductivity monitor error is greater than the manufacturer’s specification, verify that it is not due to temperature effects before adjusting the conductivity meter. A fill line should be marked on the batch tank. If not, establish the line and mark it on the tank.

Test the high-temperature alarm functions by setting the temperature control to a value higher than the alarm limits or by the overshoot when the heaters are initially turned on (see Accuracy). Record the actual alarm tem-

Alarms. Verify that low- and high-conductivity alarm indicators function properly. See the instruction or service manual on how to conduct this test, or test the high-conductivity alarm by infusing a bolus of dialysate into the water line


Hemodialysis Units and test the low alarms by disconnecting the dialysate supply. Verify that all other interlocked alarms function properly. 2.7

Blood Circuit Pressure. Monitor. Check the accuracy of blood circuit pressure monitors by connecting an accurate pressure gauge or meter and the existing pressure monitor to a T or Y connector (see Sphygmomanometers Procedure/Checklist 424). Connect the sphygmomanometer bulb to the remaining port of the connector, increase the pressure, and read the pressure on both the monitor and the test gauge or meter. The monitor should be tested at three different pressures to ensure that it is accurate over the entire range. The monitor should be accurate within 10 mm Hg or 10% of the reading, whichever is greater, or within manufacturer’s specifications. If there is more than one monitor, repeat the test for the other monitors. Alarms. With the pressure gauge or meter still connected, verify that the appropriate audible and visual alarms function when the low and high blood pressure alarm limits are reached. Confirm that other interlocked functions operate properly. Record the values at which the alarms occur, and check that they are within the manufacturer’s specifications.

2.8

2.9

Heparin Pump. Check heparin pump accuracy with a saline-, water-, or heparin-filled syringe of the type actually used with the unit. Set the pump to a rate typical of actual use, and operate it for a measured time interval. Calculate the delivery rate from the syringe graduations. Accuracy should be within 10%. Check that the pump alarms and turns off when the plunger reaches the end of its travel. Blood Pump Occlusion. Check tube occlusion by connecting a T fitting to the outflow end of the tubing. On one side of the T connect a pressure gauge or meter. Occlude the tubing segment with one roller of the pump, and pressurize the tubing to 300 mm Hg with a syringe attached to the remaining port of the T or Y fitting. Any drop in pressure should be within the manufacturer’s specifications. Repeat this procedure for the other roller.

2.10 Blood Pump Flow Rate. Check rollers to make sure that they function smoothly and that there are no unusual noises from the bearings or other indications of excessive bearing wear. With cor-

rect size tubing in the pump, immerse both ends of the tubing in a tank of saline solution or water and start the pump. Check the accuracy of the pump at a mid-range flow rate by setting it to deliver 200 to 250 mL/min and collecting the volume in a 1,000 mL graduated cylinder for a specified interval. Also check operation at low and high flow settings. Flows should be accurate to within 10% or the manufacturer’s specifications. On pumps without direct reading of flow rate, it may be useful to draw a graph of flow rate versus dial setting and placard it on the pump. Indicate tubing size and brand on the graph. Ensure that an emergency hand crank is attached to the unit. Disconnect the power and verify that the hand crank will turn the pump. 2.11 Dialysate Flow Rate. Check that all markings are legible. Check the accuracy of the flowmeter by setting it to deliver a known flow rate (vol/min) and collect the dialysate flow via the drain line in a 1,000 mL graduated cylinder for a specified period. Machines with fixed flow rates or single-pass converters may be checked similarly. Check dialysate flow rate at low (minimum), medium, and high (maximum) flow settings. Flowmeter accuracy should be within 10% or within the manufacturer’s specifications. 2.12 Negative Pressure. Monitor. Check the negative pressure monitor at low, medium, or high levels with a vacuum gauge or pressure meter and a Y or T connector (some units have a sampling port in the dialysate line that can be used). The reading should be accurate within 10 mm Hg or within the manufacturer’s specifications. Refer to the manufacturer’s manual to determine where to place the gauge or meter for this test. The position of the gauge or meter relative to the dialyzer is important, since elevation errors are approximately 20 mm Hg/ft. To prevent contamination, use a standard transducer protector (isolator) when making these measurements. Alarms. Verify that the appropriate audible and visual alarms function when the dialysate pressure exceeds the preset high and low limits. Verify that other interlocked functions operate properly.


7

Inspection and Preventive Maintenance System 2.13 Additional Features. Test additional features (e.g., ultrafiltration [UFR], variable sodium and bicarbonate features, pH meters, single-needle controllers) according to the manufacturer’s specifications. If quantitative testing of UFR meters is not possible, confirm that they are functioning. Testing of the ultrafiltration control is essential for high-flux machines. Test the pH monitor in a manner similar to Item 2.6. The variable sodium and bicarbonate features may be inconvenient to test, but both of these parameters of prepared dialysate may be compared to values obtained by a laboratory blood gas/electrolyte analyzer. (Use reverse side of inspection form to record test results.)


8

Clean the exterior and interior of the unit. Vacuum air vents and cooling fans, if so equipped. Clean or replace fan filters. Clean flowmeters, if required, according to the manufacturer’s instructions.

3.2

Lubricate where appropriate. Lubricate motor and pump heads according to the manufacturer’s specifications.

3.4

Replace any tubing segments or other items according to the manufacturer’s recommendations. Replace lights if necessary.


Before returning to use Disinfect the device as recommended by the manufacturer. Make sure controls are set at normal positions and alarm volumes, if adjustable, are set loud enough to be heard in the clinical use area. Place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before use.



Ho:YAG Surgical Lasers Used For: Lasers, Surgical, Holmium:YAG [16-943]

Also Called: Ho:YAG lasers, YAG lasers (incorrectly), holmium lasers, surgical lasers, arthroscopic lasers, urology lasers, angioplasty lasers, thulium:YAG lasers, orthopedic lasers Commonly Used In: Operating rooms, short procedure areas, cystoscopy rooms, catheterization laboratories, endoscopy laboratories, orthopedic operating rooms Scope: Applies to general-purpose holmium:YAG surgical lasers that include contact and/or noncontact flexible fiberoptic delivery systems (either reusable or disposable), emit near-infrared energy at 2,100 nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and high-power holmium:YAG surgical lasers that are typically used for general surgery, orthopedic surgery, urology, cardiovascular surgery, gastroenterology, bronchopulmonary, neurosurgery, gynecology, and ENT surgery procedures; does not apply to holmium:YAG lasers used solely for ophthalmic surgery; also does not apply to other ophthalmic lasers or to CO2 lasers, Nd:YAG lasers, argon lasers, or other surgical lasers; however, many of the tests listed herein can be used or modified for these other lasers Risk Level: ECRI-recommended, High; Hospital assessment, Type

ECRI-Recommended Interval Used

Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Ho:YAG lasers are normally checked before each use by the laser’s power-on self-test and by user examination of the aiming beam and the delivery system to be used. This minimizes the need for frequent additional periodic testing. Manufacturers or outside service vendors often maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be coordinated with these outside services. Failure of a Ho:YAG surgical laser can cause patient or staff injury, abrupt interruption of a surgical procedure, or damage to the laser system. These lasers must be meticulously maintained to ensure proper and safe operation. Ho:YAG surgical lasers affect tissue by delivering invisible, mid-infrared energy at a sufficient power


Interval By Hospital

Time Required

density to cause vaporization and/or coagulation. The 2,100 nm, mid-infrared Ho:YAG energy is preferentially absorbed by water and is typically absorbed within 0.5 mm of the tissue surface. Ho:YAG surgical laser fibers are most often used in contact with or close to tissue to cause vaporization. Moving the fiber tip away from the tissue lowers the power density, causing less tissue to be vaporized and allowing some coagulation effect. In addition, Ho:YAG lasers emit a train of energy pulses; both the energy per pulse and pulse rate are user settable. Cutting hard tissue may require high energy per pulse, while a smooth cut may require a fast pulse rate. However, the range of energy per pulse and the number of pulse rate combinations are limited by the laser’s power capability. The output power of the laser is the product of the energy per pulse times the


●


Inspection and Preventive Maintenance System pulse rate — for example, 0.5 J × 10 Hz and 1.0 J × 5 Hz are both 5 watts. A 5-watt laser may allow both of these settings, but not 1.0 J and 10 Hz, which would require a 10-watt laser. This differs from most other lasers, which deliver a range of power through a variable energy and fixed pulse rate that is faster than Ho:YAG’s.

beam pattern introduced by an accessory would be apparent by examining the visible aiming beam.

Citations from Health Devices Laser use and safety [Guidance article], 1992 Sep; 21:306-10.

General-purpose Ho:YAG surgical lasers have a laser cavity that houses an yttrium-aluminum-garnet (YAG) crystalline rod doped with holmium (Ho). (In most Ho:YAG lasers, the YAG crystal is also doped with thulium [Tm] and chromium [Cr], which improve the laser’s efficiency.) Energy leaving the laser tube through a partially reflecting mirror is typically directed into a flexible optical fiber that transmits the laser energy to the tissue. The fiber may be used with additional devices (e.g., through an endoscope), with special tips, and/or with a laser handpiece or a laser micromanipulator (used to interface the laser with the surgical microscope). These attachments can be used to focus the energy into a small spot size at a known working distance and or a specific beam direction to accomplish a special task (e.g., focused energy emission at a right angle to the fiber for sclerostomy).

Ho:YAG surgical lasers [Evaluation], 1995 Mar; 24:92122.

Because the mid-infrared energy emitted by the Ho:YAG laser is invisible, a second, nontherapeutic aiming helium-neon (He-Ne) laser or laser diode, which emits visible light (typically red), simultaneously traverses the fiber and is coincident (i.e., travels the same path) with the Ho:YAG laser beam.

Vise with padded jaws or ring stand with padded clamp

Like most lasers, Ho:YAG lasers are inefficient in converting electrical energy into laser energy. As a result, excess heat is generated in the laser cavity, requiring a cooling system. Most Ho:YAG lasers use water/air cooling systems that are self-contained, connected to a freestanding chiller system, or connected to a water supply and drain.

Grounding strap (optional)

With Ho:YAG lasers, unlike those lasers that use mirror delivery systems (e.g., articulating arms on CO2 lasers), it is not necessary to periodically verify coincidence of the aiming and therapeutic beam or to assess the therapeutic beam pattern (e.g., TEM00) within the beam or spot. Since the therapeutic and aiming laser beams are transmitted through a single optical fiber, these two beams are coincident as they exit the fiber. Any beam pattern distortion at the fiber entrance would be eliminated as the laser beams travel through the fiber because of internal reflections within the fiber. Misalignment of the beam at the fiber entrance would result in decreased power output or loss or distortion of the aiming beam. In a well-aligned system, any significant problem with the therapeutic

2

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter New, unused fiber delivery system Black Delrin block 1⁄2″ or more thick, 1″ or more wide, about 3″ to 4″ long; tongue depressors; or firebrick Laser radiometer (power meter) Laser safety signs Laser safety eyewear specifically designed for use with Ho:YAG surgical lasers and of sufficient optical density to protect the wearer’s eye from laser injury

Pressure gauges and coolant system tee fitting Outlet test fixture (optional) Insulating gloves, high voltage (optional)

Special precautions Inspecting and maintaining lasers is a dangerous as well as necessary process, and far greater care is required than with most devices. Personnel who inspect or service lasers should receive special training from the manufacturer or from a qualified alternative training source. Laser energy can cause serious injury, particularly when the internal interlock is overridden or in any other situation in which the energy does not diverge significantly over long distances. Under some circumstances, the beam may not diverge significantly, even a full room length or more away from the laser (and can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser beam is accessible. Area security and use of personnel protective devices and practices should be consistent with hospitalwide laser safety procedures and/or should be approved by the laser safety committee.


Ho:YAG Surgical Lasers In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas. Users should wear appropriate laser safety eyewear at all times whenever the laser is in the Operating mode. WARNING: Laser safety eyewear does not protect the wearer from the aiming system light. Do not stare directly into the aiming system beam or the therapeutic laser, even when wearing laser safety eyewear. Avoid placing the laser beam path at eye level (i.e., when kneeling, sitting, or standing). Do not perform these procedures when a patient is present or clinical staff is working, and do not aim the laser across a path that a person might normally use as a thoroughfare. Furthermore, at minimum, post doors to the room with appropriate laser safety signs stating that the laser is in use and that it is unsafe to enter the room without authorization by the service person performing the procedure. A second person should be present, especially during procedures of recognized risk, to summon help in case of an accident. The laser should remain in the Off position when not in use. When in use, it should be in the Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser operation key and store it in a controlled location.

enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to measure, drain, or insulate high voltages carries the appropriate insulation rating (e.g., above 20 kV). Where possible, perform tests with the unit turned off. Because of the presence of high voltage, perform the Grounding Resistance test (Item 2.1) before any other test that requires operation of the laser. Report any laser accident immediately to the laser safety officer or equivalent, as well as to the hospital risk manager.



General. Verify that the key has not been left in the laser. (Remove it if it has been, and inform users of the importance of storing the key in a controlled location.) Examine the exterior of the unit for cleanliness and general physical condition. Be sure that all housings are intact and properly aligned, that assembly hardware is present and tight, that any retractable parts slide easily and lock in place if so constructed, that there are no signs of spilled liquids or other evidence of abuse, and that there are no obvious signs of water or oil leakage.

Do not use the laser in the presence of flammable anesthetics or other volatile substances or materials (e.g., alcohol), or in oxygen-enriched atmospheres, because of the serious risk of explosion and fire. Remove from the working area or cover with flame-resistant opaque material all reflective surfaces likely to be contacted by the laser beam. Whenever possible, use a firebrick or other nonflammable material behind the target material (e.g., black Delrin) when the laser is to be activated. Target materials will ignite when exposed to high laser energies; use short durations when practical. A CO2 fire extinguisher should be readily available. Some surgical lasers use high voltages (e.g., 20 kV), which can be lethal. Capacitors may store charges long after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and avoid contact with any portion of the high-voltage circuit until you are certain that the charge has been drained. In such cases, a good ground must be present; preferably, use a redundant ground strap if you must

Chassis/Housing.

Shutters. If manual shutters for the aiming system or the therapeutic laser are accessible, ensure that they operate smoothly and correctly. Be sure to leave the shutter in the proper position for normal operation. 1.2

Mounts/Holders. Check that mounts or holders intended to secure the fiber to the fiber support (to protect the fiber when in use) are present, in good working order, and being used. Similarly,


3


1.3

check mounts or holders for other devices (e.g., external power meters, footswitch).

Electrical contacts should be straight, clean, and bright.


There should be no visible dirt or residue in the optical path of the laser aperture. Ensure that any mechanism to close off the laser aperture (fiber port) is clean, operates smoothly, and is in use.

Casters/Brakes. Check that the casters roll and swivel freely. Check the operation of brakes and swivel locks.

1.4

AC Plug/Receptacle. Examine the AC power plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug, and listen for rattles that could indicate loose screws. If you suspect damage, open the plug and inspect it.

1.5

Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.6


1.7


1.8

Tubes/Hoses. Check the condition of all coolingsystem hoses and any other hoses or tubing the laser may have (e.g., drain). Check that they are of the correct type; that they have not become cracked and do not show other signs of significant abuse; that they are connected correctly and positioned so that they will not leak, kink, trail on the floor, or be caught in moving parts; and that they are secured adequately to any connectors.

1.9


1.10 Fittings/Connectors. Examine all optical (e.g., fiber), liquid, and electrical fittings and connectors for general physical condition. Liquid fittings should be tight and should not leak.

4

1.12 Filters. Check the condition of all liquid and air filters. Some Ho:YAG surgical lasers require deionized water, and most require special filtration. Measuring the pressure drop across a liquid filter can be helpful in determining whether the filter should be replaced. Clean or replace filters according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi), and indicate this in the preventive maintenance section of the inspection form. Clean or replace air filters and radiators that are obviously dirty. 1.13 Controls/Switches. General. Before moving any controls, check and record their positions. If any position appears inordinate, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical condition, secure mounting, and correct motion. If a control has fixed-limit stops, check for proper alignment as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from fingernails, pens, surgical instruments). If you find such evidence, notify users to avoid using tape and sharp instruments. During the inspection, be sure that each control and switch works properly. Remote. Examine the exterior of the control for cleanliness and general physical condition. Be sure that housings are intact, that assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. If the remote control is attached by cable to the laser, ensure that the cable and any connectors are in good condition. Examine all controls and switches for general physical condition, secure mounting, correct motion, and intended range of settings. Where a control should operate against fixed-limit stops, check for proper alignment as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs properly.


Ho:YAG Surgical Lasers Footswitch. Examine the footswitch for general physical condition, including evidence of spilled liquids. Footswitches for lasers include an internal switch that activates according to the depth of pedal depression. It is usually possible to feel the vibration caused by closure of the switch, even through a shoe. Check that the internal switch is operating and that the footswitch does not stick in the On position. Some footswitches include two internal switches; in this case, verify the operation of both. During the procedure, check to be sure that the laser activates consistently when the footswitch is depressed. Flex the cable at the entry to the switch, and using an ohmmeter, check for internal wire breaks that cause intermittent operation. Confirm that strain reliefs are secure. Examine the male and female connectors for attaching the footswitch to the laser cabinet to be sure that no pins are bent and that no other damage is present. Ensure that the connector secures acceptably to the laser cabinet. 1.15 Motors/Pumps/Fans/Compressors. Check the physical condition and proper operation of these components, if present. If lubrication is required, note this in the preventive maintenance section of the inspection form. Clean any obvious dust from these components. 1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the manufacturer’s recommendations, and note this in the preventive maintenance section of the inspection form. 1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible. If a remote control or display is battery powered, check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, verify proper operation of all lights, indicators, meters, gauges, and visual displays on the unit and remote control. Ensure that all segments of a digital display function. Note any error messages displayed during the power-on self-test.

If primary and remote-control indicators and displays can be used at the same time or if control can be switched from one to the other during the course of a procedure, verify that the same information (e.g., settings, displays) is indicated on both control panels during laser operation. If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated energy counter), ensure that each display provides the information expected. Ensure that user prompts occur in the proper sequence. Store some sample information, and verify that it is correct. If a feature to manually reset this information is available, ensure that it works. 1.19 Laser Delivery System Calibration. Some holmium:YAG surgical lasers include a user-accessible calibration port or power meter that allows output calibration and/or testing of the laser fiber. This feature is provided because transmission of laser energy through a fiber may change as a result of fiber use. Based on the measurement from the calibration power meter, the laser may automatically recalibrate itself and/or adjust the displays so that the power indicated to be delivered to the patient will be correct, or it may require the user to do this manually. Verify that this feature is functioning by using the manufacturer’s recommended calibration procedure to test one delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. A good-quality (e.g., >85% transmissibility, undamaged sheath) fiber or handpiece should be used for this test. 1.20 Alarms/Interlocks. Operate the device in a manner that will activate the self-check feature, if present, and verify that all visual and audible alarms activate according to the manufacturer’s documentation. If no self-check feature is present, operate the laser in a manner that will activate each audible and visual alarm; be sure to test only those alarms that will not cause damage to the laser or present an unnecessary risk of laser beam exposure to yourself or bystanders. If a door or window interlock is used, ensure that it deactivates the laser properly. (Do not disassemble major parts of the laser to test internal interlocks.) After deactivating the laser and reclosing the door or window, check to be sure that the laser will restart. Be sure to check


5

Inspection and Preventive Maintenance System the interlocks in all locations where the laser is used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.) If the laser is equipped with an emergency “kill” switch, test this feature to be sure that it deactivates the laser and that the laser will subsequently restart. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., laser emission, setting change). Check for proper operation, and verify that the signal can be heard in the environment in which the laser will be used. 1.22 Labeling. Check that all placards, labels, and instruction cards noted during acceptance testing (see Item 4.3) are present and legible. Check to see that an instruction manual is kept with the laser or is readily available. 1.23 Accessories. General. Verify that all necessary accessories are available and in good physical condition. Set up reusable accessories with the laser to ensure compatibility and proper functioning. Checking all fibers or accessories during a single inspection and preventive maintenance procedure is unnecessary as long as accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are sterile and require resterilization before use, making the laser potentially unavailable. Be sure to check with the person responsible for scheduling the use of the laser before beginning the procedure. Fibers. For the test fiber or before each use, examine the connector, cable, and tip of each fiber to be used, as well as the fiber support, for cleanliness and general physical condition. Be sure that all hardware (e.g., coolant channels) is present, in good condition, and firmly attached. Ensure that the connector properly seats into the laser aperture of the laser cabinet. Examine the distal end of fibers to ensure that any connecting mechanisms (e.g., threads) are in proper working order. If a fiber appears to be dirty or damaged, remove it from service. If a fiber is reusable, notify the person(s) responsible for fiber repair. The fiber should be repaired and/or cleaned according to the manufacturer’s recommendations. Verify fiber performance.

6

Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness and general physical condition. Examine individually only those components that are intended for removal during normal use and storage. (Do not remove other parts that are press-fit or attached by screws, bolts, or snaprings.) If lenses are detachable, be sure not to touch the lens surface; handle lenses by the edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean lenses. Ensure that major subcomponents of the handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the handpiece(s) to the fiber are in good working order and that they reliably secure each handpiece to the fiber. Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness and general physical condition. Be sure to handle it by the main body; do not hold it by the joystick, and do not touch the reflecting surfaces or lenses in the body. Inspect micromanipulators provided by both the laser manufacturer and the laser accessory manufacturer. Ensure that the reflecting surfaces and lenses are intact and clean. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean reflecting surfaces and lenses. Examine the joystick to ensure that it is firmly attached and that it freely moves the reflecting lens. If a finger rest is present, ensure that it is firmly attached and properly oriented. If a zoom focus feature is present, be sure that it turns easily and does not slip. Examine each objective lens to ensure that it is intact and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean the objective lenses. Carefully insert each lens into the micromanipulator, and ensure that it fits snugly. Inspect the mechanism used to attach the micromanipulator to the microscope to ensure that all parts are present and that it is in good working order. Connect the micromanipulator to the microscope to check for a secure connection.


Ho:YAG Surgical Lasers Safety filters. Verify operation of safety filters in the microscope and endoscope delivery systems.

However, if the laser power meter does not measure pulse duration, use the following less preferable alternative.

1.24 Aiming Beam. Activate the aiming beam (without the therapeutic beam), and verify that it produces a round, uniformly bright spot, with no halo. For handpieces that provide adjustable spot sizes, verify that the spot size changes as expected and still remains uniform. Check that the intensity control, if present, does change the brightness of the aiming beam. Similarly, check pulsing controls to verify that the aiming beam can be pulsed. If several color choices are available for the aiming beam, verify that each color is present and working properly.

Place and secure the laser fiber, handpiece, or micromanipulator with the aiming system focused on the target material (e.g., black Delrin or a tongue depressor). With the laser set to about 10 W and the exposure set at minimum duration, activate the laser and create a burn. Carefully move the target material to expose a clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this process until you have tested all exposure settings, except continuous, and have developed a series of burns. Compare the burns to verify that progressively larger burns occurred as the exposure duration increased.

1.25 Laser Aperture. WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser aperture. It should be clean and undamaged; clean or replace if needed. There should be no visible dirt or residue in the optical path of the laser aperture.

2.4


2.2


If your laser power meter cannot be used for this test, use the following alternative test method. Set the laser to about 10 W and a 0.1 sec exposure duration with the fiber, handpiece, or micromanipulator attached, and verify that the repeat pulse feature operates as expected by moving the target material slightly between each pulse. Be extremely careful to keep hands out of the laser beam path. If the number or duration between repeat pulses is adjustable, test that setting changes made throughout the range result in the expected performance.


2.3

Exposure Duration. Some laser power meters can measure pulse duration. If the power meter can react to pulse duration (this is the preferred circumstance), test the laser at each setting.

Repeat Pulse. If the unit includes a Repeat Pulse feature, which repeats the pulse at a fixed or adjustable rate, test this feature with the laser set at the minimum, median, and maximum repeat pulse settings, if adjustable. Some laser power meters can react quickly enough to be used to test this feature of the laser. If you are using such a power meter, test the laser to be sure that the correct power is repeatedly delivered over the correct time period.

2.5


2.6

Pulse Rate. This test can be done in conjunction with power output measurements with some power meters. Should your power meter be incapable of measuring pulse rates, output from a high-speed IR photodiode circuit and oscilloscope


7

Inspection and Preventive Maintenance System can be used to measure the number of pulses per second. Alternately, low-power illumination of thermal paper in a chart recorder will create marks on the paper that can be compared to the laser pulse rate. With the laser set at minimum and maximum pulse rates and at one mid-range setting between the minimum and maximum pulse rates, activate the laser at its minimum power setting for a sufficient period to acquire acceptable readings. Compare the reading with the pulse rate display of the laser; the measured and displayed values should all be within 10% of one another. In addition, compare the reading obtained with the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. 2.10 Power Output. Select one delivery system (e.g., fiber, handpiece, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at the appropriate distance from the detector of the laser power meter to meet spot-size requirements specified in the instructions for the meter. (Do not focus the beam to a small spot on the power meter. Some power meters require that the unfocused or a defocused laser beam be projected into the detector to cover the majority of the absorber surface. If the laser beam is focused on the detector, it may be damaged.) WARNING: Accessing the unfocused laser beam may require defeating internal interlocks. Because of the heightened risk associated with an unfocused, nondiverging laser beam, exercise great care if the interlocks are to be defeated. With the laser set at low (e.g., 10% of full scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient period to acquire acceptable readings. (Power meters use different time constants to acquire an acceptable reading, and you must know and meticulously follow the power meter’s instructions for use.) Compare the reading with the power display of the laser; the measured and displayed values should all be within 10% of one another. In addition, compare the reading obtained with the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the laser includes a low-power (e.g., mW) feature, test it in a similar fashion with a power meter of appropriate resolution in the low-power range.

8


Clean the exterior. Clean accessible optical components (e.g., blast shield, microscope lenses), if necessary, using techniques and cleaning solutions recommended by the manufacturer.

3.2


3.3

Calibrate/adjust any components (e.g., printer) according to the manufacturer’s recommendations. Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses and tubes are tight.

3.4

Replace filters if needed. Check all fluid levels, and supplement or replace fluids if needed.

4. Acceptance Tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. WARNING: Lasers may be damaged by switching between normal and reverse polarity while the device is on. If reverse-polarity leakage current measurements are made, turn off the unit being tested before switching polarity. Also, lasers powered by three-phase electrical systems may be damaged if proper electrical phase connections are not made initially and maintained thereafter. Thus, do not switch conductor connections or wiring configuration for any tests, including leakage current measurement. Do not conduct electrical leakage current tests with reversed-polarity wiring. Also test the ability of the laser to deliver laser energy as expected in all configurations and with all provided laser accessories. In addition, perform the following tests. 4.1

Areas of Use. Visit the area(s) in which the laser is to be used, and ensure that laser signs, eyewear, and window coverings are available and being used and that safety interlocks for doors or windows, if present, are functioning properly.

4.2

Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over when pushed or when a caster is jammed on an obstacle (e.g., a line cord, threshold), as may occur during transport. If the device is designed


Ho:YAG Surgical Lasers to rest on a shelf, ensure that it has nonslip legs or supports. 4.3

4.4

4.5

4.6

Labeling. Examine the unit and note the presence, location, and content of all labels. Labeling information is typically found in the laser’s operator manual. Electrical Wiring Configuration. Ensure that the branch circuits and the outlets for the laser are properly wired and rated for use with the laser. Examine the receptacles at each location where the laser is to be used to ensure that the proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.

4.7


4.8

Power Range. Using the technique described in the Power Output test, test the power output accuracy at several low, medium, and high settings.

4.9

Laser Delivery System Calibration. Use the manufacturer’s recommended calibration procedure to test each new reusable delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. Note the fiber transmission for each delivery system tested if this information is provided by the laser. Or you can calculate it using the following formula: % Transmission =





Be sure to return controls to their starting position, and place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using the unit.



9


Hypo/Hyperthermia Units Used For: Hyperthermia Units, Circulating-Fluid [17-648] Hypothermia Units [12-078] Hypo/Hyperthermia Units, Central [12-074] Hypo/Hyperthermia Units, Mobile, General-Purpose [12-075] Hypo/Hyperthermia Units, Mobile, Heart-Lung Bypass [17-206]

Also Called: Hypothermia units, hyperthermia units, heating pads, heater/cooler units Commonly Used In: Special care units, operating rooms, general medical/surgical areas, emergency departments Scope: Applies to mobile units that provide both heating and cooling; adaptable for devices that provide heat only and for central hypo/hyperthermia units; does not apply to smaller circulating-fluid pump/heating pad units, which should be inspected using Circulating-Fluid Pumps Procedure/Checklist 412 Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

*Flush and refill reservoir, if necessary, at a six-month interval.

Overview Hypo/hyperthermia units are used primarily to raise the body temperature of victims of accidental hypothermia, maintain normal temperature (normothermia) in patients during and after surgery, lower the body temperature for certain surgical procedures, and lower and stabilize the body temperature of febrile patients. The utility of hypo/hyperthermia units for some of these applications has been questioned. Hypo/hyperthermia units can typically operate in the following two modes: Manual. The operator selects the temperature of fluid to be delivered to the blanket for heating or cooling the patient. The selected and actual fluid temperatures are displayed. Some units also monitor patient temperature.


Automatic (servo). The operator selects the desired patient temperature. The machine senses the actual patient temperature through a rectal, skin, or esophageal temperature probe and delivers heated or cooled fluid accordingly. The machine displays actual and selected patient and fluid temperatures in this mode. (See Health Devices 1988 Nov; 17:320-46 for additional information on applications and operation of hypo/ hyperthermia units.) Hypo/hyperthermia units are relatively complex devices. They are among the heaviest and bulkiest pieces of mobile hospital equipment and are often subjected to rough handling. The water or antifreeze solutions used in them can corrode interior parts if the units are treated carelessly. All too often, patients being heated or cooled by units that use an automatic control mode are not observed as carefully as those whose temperature is being controlled manually.


●


Inspection and Preventive Maintenance System Thus, accurate and reliable operation of hypo/ hyperthermia units, particularly in the automatic mode, is crucial.

Such a device does not normally limit water temperature to a clinically safe level, but it should not be deactivated since unit damage can result.

Hypo/hyperthermia units have been implicated in a number of cases of patient injury or death. Investigation of these incidents reveals that some could have been avoided with adequate inspection and maintenance.

Some of the items in this procedure differ from most other procedures in that they may require opening the unit and temporarily modifying the wiring. We hesitate to recommend such wiring modifications as part of a routine inspection procedure because unskilled personnel may inadvertently damage the unit; however, there is no other way to determine whether the backup thermostats are functional. Personnel responsible for inspecting hypo/hyperthermia units who lack the technical expertise to perform this test must recognize their own limitations and seek qualified help. Performing the fluid temperature indicator test (Item 2.10) after the high- and low-temperature protection tests (Items 2.3 and 2.4) will help ensure that the device has been correctly returned to its proper operating condition.

Citations from Health Devices Hypo/hyperthermia machines and blankets [Evaluation], 1988 Nov; 17:320-46.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Calibration thermometer, accurate to at least ±0.3°C over the range of the hypo/hyperthermia unit’s electronic thermometer, and cups of hot and cold water (a temperature probe simulator suitable for use with the hypo/hyperthermia unit to be inspected may be used instead of the thermometer and the cups of water, but the water and the thermometer will be required to check temperature probes) Temperature-monitoring device that consists of an accurate dial thermometer to check the temperature of the circulating fluid, some clear tubing, and appropriate connectors for installing the device in series with the blanket. (These devices, sometimes referred to as shunt thermometers, are available from some hypo/hyperthermia unit manufacturers, or they can be constructed; see User-constructed Test Equipment behind the Test Equipment and Supplies Tab.) Hydrometer with scales suitable for the type of antifreeze used in the unit (required only if the unit circulates an alcohol or ethylene glycol solution through the blanket); inexpensive antifreeze testers are available from automotive parts suppliers.



Chassis/Housing. Examine the exterior of the unit for overall condition. The chassis should be clean and free of rust and corrosion. Exterior screws should be tight.

1.2

Mount. If the unit is mounted on a stand or cart, examine the condition of the mount.

1.3

Casters/Brakes. If the unit moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4

AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug, and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the

Short-circuited patient temperature probe plug (required only if the unit has an automatic control mode and circulates an alcohol or ethylene glycol solution through the blanket) Cup of saline solution and strip of aluminum foil for measuring probe leakage current (acceptance testing only)

Special precautions Some units have undertemperature and/or overtemperature protection to avoid damage to the heating element compressor or other parts of the unit.

2


Hypo/Hyperthermia Units damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

function properly (e.g., that a variable temperature control does, in fact, determine the amount of heating; that on/off controls function).

1.6


1.7

Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely. If the unit is protected by an external fuse, check its value and type (as well as those of any spares provided) against that marked on the chassis.

1.15 Motor/Pump/Fan/Compressor. Check the physical condition, and verify proper operation of these components. Lubricate them if required, and note this on Line 3.2 of the form (but do not check 3.2 until you have completed all necessary lubrication).

1.8


1.10 Fittings/Connectors. Attach a blanket to each pair of connectors on the unit to ensure that the unit operates smoothly and does not leak. Examine all fittings and connectors, as well as all electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Probes. Confirm that patient temperature probes are on hand, and check that they are clean and are not cracked, brittle, or otherwise deteriorated. 1.12 Filters. Check the condition of the fluid filters, if so equipped. Clean or replace them as needed, and indicate this on Line 3.1 or 3.4 of the inspection form. 1.13 Controls/Switches. Before moving any controls or alarm limits, check their positions. If any of them appear inordinate (e.g., a temperature control that is at the end of its range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails or pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.14 Heater. Examine the heater for physical condition (e.g., corrosion of its sheath, deteriorated insulation). Operate it to verify that its controls

1.16 Fluid Levels. Check the circulating fluid level in the reservoir with a blanket connected, and add fluid as needed. Consult the operator’s manual to determine the proper level. If fluid is needed, add distilled water or the manufacturer’s recommended alcohol-and-water or antifreeze-andwater mixture. If the unit uses distilled water, add a disinfectant according to the manufacturer’s instructions. If it uses antifreeze, check its specific gravity with a hydrometer, with the fluid at about room temperature. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function. 1.20 Alarms. Operate the unit in such a way as to activate each audible and visual alarm. Check that any associated interlocks function. If the unit has an alarm-silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It will not be possible to check out all alarms at this time, since some of them require abnormal operating conditions that will be simulated later in Items 2.3 and 2.4. 1.21 Audible Signals. Operate the unit to activate any audible signals. Confirm appropriate volume, as well as the operation of the volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Blankets. Check each reusable blanket for leaks, connector operation, and general cleanliness. Since blankets do not usually have serial numbers on them and may be interchanged between units, it is not possible to associate the blanket inspection with any one unit. Nevertheless, the hospital should know how many


3

Inspection and Preventive Maintenance System the maximum reading of the temperature-monitoring device, and note any overheating or hightemperature alarms. If the unit has a secondary backup device, bypass the primary high-temperature backup and repeat the test. The maximum temperature(s) should agree with the manufacturer’s specification for the primary (and secondary) backup device, but should not exceed43°C.

reusable blankets it owns and should inspect each one regularly. Check for leaks with the blanket connected to an operating hypo/hyperthermia unit because this produces the highest pressure within the blanket tubing. Blankets that pass inspection should be tagged “Inspected,” with the date and inspector’s initials noted. Roll, rather than fold, stored blankets to prolong their life.

Caution: Remove any bypasses installed for this test.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. If a redundant ground is provided, either as a second plug or an alligator clip, check its resistance to the chassis. We recommend a maximum of 0.5 Ω. If the device has an accessory outlet, check its grounding to the main power cord.

2.2

Leakage Current. Measure the maximum leakage current between the chassis and ground with the ground wire temporarily opened and any redundant ground removed. Check the following operating modes with the grounding conductor interrupted: off, manual cooling, manual heating, and circulate only. Record the highest leakage current; it should not exceed 300 µA.

2.3

High-Temperature Protection. This test confirms the operation of the high-temperature backup (and secondary backup, if present) and should be performed on all units regardless of the type of circulating fluid. Identify the backup thermostats or other devices. If the unit does not have an automatic mode, consult the manufacturer to determine how to test backup protection. If the unit has an automatic mode with two backup high-temperature cutoffs, check both. Install a jumper across the thermostat; check the service manual for information on how to do this. Operate the hypo/hyperthermia unit in the automatic mode with a temperature-monitoring device connected in series with the input line to the blanket. Set the control temperature to room air, and expose the patient temperature probe to a value above room ambient temperature. The hypo/ hyperthermia unit should heat the circulating fluid until it is limited by the backup cutoff. Record

4

Repeat the test with the patient temperature probe unplugged. The temperature should go no higher than before; some units will indicate the failure with a Probe Open alarm, and the unit will not operate. 2.4

Low-Temperature Protection. This test is similar to Item 2.3, except that it confirms the operation of the primary low-temperature backup (and secondary backup, if present) and should be performed only if the unit circulates alcohol or ethylene glycol through the blanket and has an automatic control mode. Low-temperature backup cutoffs are intended to protect the patient against excessive cooling if the temperature-control circuitry or probe fails. Before performing this test, obtain a schematic of the hypo/hyperthermia unit and determine whether the unit has low-temperature backup protection (a thermostat or other cutoff). Install a jumper across the main thermostat. Check the service manual for information on how to do this. Operate the hypo/hyperthermia unit in the automatic mode with a temperature-monitoring device connected in series with the input line to a blanket. Set the control temperature to its lowest value, and expose the patient temperature probe to room air. The hypo/hyperthermia unit should cool the circulating fluid until it is limited by the backup cutoff. Record the lowest temperature indicated by the temperaturemonitoring device, and note any alarms. If the unit has a secondary low-temperature backup, bypass the primary low-temperature backups and repeat the test. The recorded temperature(s) should agree with the manufacturer’s specification for the primary backup (and secondary backup) device (usually ≥1°C). Repeat the test with a shorted patient temperature probe plug substituted for the probe itself. Observe the operation of a Probe Shorted


Hypo/Hyperthermia Units cup of 41°C water used in the last test, and operate the unit in the automatic mode with the temperature-monitoring device in the input line to a blanket and the control point set to 37°C. The temperature of the circulating fluid should drop to the low level recorded in Item 2.10. Next, transfer the patient temperature probe to the cup of cooler water saved from the previous test (it is not necessary to recheck the temperature of that water), and observe both the temperature indicator and the Heat and Cool indicators (if so equipped) on the unit. Note the reading on the patient temperature indicator when the unit switches from cooling to heating. It should be within 0.5°C of the 37°C set-point temperature. If the unit lacks indicators for the heating and cooling modes, listen for a change in sound as the cooling compressor stops. The circulating fluid temperature should equilibrate at the high value recorded in Item 2.10. This test can also be performed using a patient temperature probe simulator, if available.

alarm, if so equipped. If the machine operates at all, the minimum fluid temperature should be limited by the primary backup cutoff. Caution: Remove any bypasses installed for this test. 2.10 Fluid Temperature Indicator. Operate the unit in the manual mode with the temperature-monitoring device in the input line to the blanket. Select the lowest blanket temperature setting, and wait until the temperature stabilizes (this should take 3 to 10 min). Record the setting of the control knob, the reading of the fluid temperature indicator, and the reading of the temperature-monitoring device; it should not drop below 1°C. The first two should be within 1°C of the temperature-monitoring device. Repeat this test with the manual control set at its highest temperature; it should not exceed 43°C. 2.11 Patient Temperature Indicator and Probe. This test applies only to units with an automatic mode of operation. Fill a cup with tap water at about 30°C, as measured with the calibration thermometer. Be sure that the thermometer is immersed to an adequate depth to provide an accurate reading. Place the calibration thermometer and the unit’s patient temperature probe in the water near each other. Record the two readings on the form. (It may be necessary to operate the unit in order to read the thermometer.) Repeat the test with cups of water at temperatures of about 37°C and 41°C. The temperatures, in all cases, should be within 1°C. Repeat this test with each probe. Save the warmest and coldest cups of water for the next test. A patient temperature probe simulator, if available, is more convenient for determining the accuracy of the patient temperature indicator. However, because the simulator tests only the circuitry and not the probe itself, probe accuracy must also be verified. A convenient test method is to dip all probes simultaneously into one bodytemperature water bath, allow them to equilibrate, and successively plug each into the same pretested temperature unit or module. All probes should give the same temperature reading. (Some variation is normal because the water temperature varies slightly with location in the bath and the water gradually cools with time.) 2.12 Automatic Controller Switching. This test applies only to units with an automatic mode. Keep the patient temperature probe immersed in the


Clean the exterior, interior, and fluid filter, if necessary. Remove dirt that has accumulated in vents and cooling fans within the unit with a vacuum cleaner or compressed air hose. This will usually require removal of a chassis panel.

3.2

Lubricate the circulating pump, if required.

3.3

Calibrate, if needed.

3.4

Flush/refill the reservoir and replace the fluid filter, if necessary.


Probe Leakage Current. If the unit has a patient temperature probe, measure leakage current from all available probes in every operating mode. Wrap the probe loosely with aluminum foil, clip the lead from the leakage current meter to the foil, and immerse the probe and foil in a salt water solution (normal saline or about a teaspoon of table salt per cup of water). Leakage current greater than 100 µA suggests a damaged probe. Alternatively, measure probe circuit leakage current directly from each probe electrical lead contact (using an appropriate plug) on units that


5

Inspection and Preventive Maintenance System do not use ground-referenced probe circuits. If the leakage current to ground from each lead of the connector is less than 100 µA in each operating mode, then it is unnecessary to check leakage current from the probe itself. (An appropriate resistance to simulate the thermistor may be required on some units that have protective circuits to turn off heater power in the event of a probe malfunction.) However, thoroughly examine the probe for defects (Item 1.11). 4.2

Hysteresis. This test will determine the difference between the set-point temperature and the reset temperature of the high-temperature thermostat. This test need be performed only in the manual mode. If a problem is found in this mode, it would consequently also be present in the automatic mode. Connect a blanket and/or test hose shunt to the unit. (Some units require that fluid circulate while the unit is operating.) Allow the unit to warm up for at least 15 min in the manual mode with the water temperature set to 40°C. After warm-up, set the water temperature selector to its highest setting. The Heat light should come on, indicating

6

that the water is being warmed. Watch the water temperature indicator and the Heat light, and record the water temperature reading at which the Heat light goes out. This is the setpoint temperature of the primary high-temperature thermostat. This temperature should agree with the manufacturer’s specification. Allow the unit to continue running in the manual mode with the water temperature selector set to its highest setting. The water temperature will begin to slowly drop. Observe the water temperature indicator, and record the temperature at which the Heat light comes back on; this is the reset temperature of the thermostat. The difference between the set-point temperature and the reset temperature is the hysteresis. The maximum hysteresis should be 3°C. Thus, the reset temperature range will typically be 39° to 41°C.

Before returning to use Verify that any control circuits that were bypassed or deactivated for testing purposes have been returned to their normal operating conditions.



Infant Incubators Used For: Incubators, Infant, Mobile [17-432] Incubators, Infant, Transport [12-114]

Commonly Used In: Delivery rooms, neonatal ICUs, nurseries, ambulances, and aircraft Scope: Does not apply to radiant warmers or transport radiant warmers (see Procedure/Checklist 419) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

NA*

months

.

hours

Time Required

* Minor intervals for transport incubators should be every 3 months.

Overview Infant and transport incubators provide warmth to help an infant maintain a normal body temperature and are often essential for an infant’s survival. Most incubators warm the infant by a forced or natural flow of heated air. One type, no longer in production, supplements air convection with radiant infrared energy from heated bassinet and hood walls. Infant incubators are designed primarily for in-hospital use at specific locations, operate on AC line power in a temperature-controlled indoor environment, and rest on relatively high movable stands. Transport incubators provide thermal support during transfer within the hospital or by car, ambulance, or aircraft to another hospital. Transport incubators are both portable and mobile; operate from a variety of power sources, including self-contained batteries; have stands that are relatively low or adjustable in height to fit into vehicles with restricted overhead clearance; and may be required to operate in ambient conditions much colder than those found in a hospital. Deaths and injuries to neonates have occurred in incubators. Reports include thermostat failures that caused incubator overheating and infant hyperthermia, malfunctions or design defects that produced fires


and presented electrical shock hazards, and poor transport incubator performance or power failure due to improperly maintained batteries or unreliable battery-charge-level indicators. Because incubators are bulky and mobile, they routinely receive rough handling (especially transport units) that may degrade performance and physical condition. Periodic inspection may reveal hazardous deficiencies that could harm patients.

Citations from Health Devices Mercury contamination in incubators and elsewhere, 1981 Dec; 11:65-8. Transport incubators [Evaluation], 1982 May; 11: 179-91. Infant incubators [Evaluation], 1982 May; 11:191-9. Update: Transport incubators, 1982 Sep; 11:301. Air-Shields C-300-1, C300-2, and TI-100 infant incubators [Hazard], 1986 Jul; 15:212-3. Air-Shields Vickers C100 and C200 infant incubators [Hazard], 1987 Jul; 16:253-4. Air-Shields C-86, C-100, and C-200 infant incubators [Hazard], 1987 Nov; 16:376-7.


●


Inspection and Preventive Maintenance System Air-Shields Vickers C-86 infant incubators [Hazard], 1988 Oct; 17:314-5. Mallinckrodt incuTemp 4 skin temperature probes and Air-Shields Vickers C-100 incubators [Hazard], 1990 Jul; 19:245. Thermometer holders detaching from hoods of Ohmeda Air-Vac transport incubators, 1994 Oct-Nov; 23:457-8.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Patient-probe simulator capable of simulating a range of temperatures as well as open- and shortcircuited probe conditions (for incubators that use patient temperature probes) Plastic 6 to 8 oz cup Source of varied-temperature water; a temperature simulator will simplify some device tests, but at least one cup of water will be needed to verify probe accuracy and probe leakage current

operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. If it is necessary to inspect several incubators that have patient probes, it may be convenient to use a patient-probe simulator to test indicator accuracy and temperature control effectiveness of all probes simultaneously. The procedure is essentially the same as that used in Temperature Monitors Procedure/Checklist 425. It may be necessary to use different connectors to accommodate the probes of the incubators being inspected. If an incubator to be inspected is in use, ask clinical personnel if they can use a temporary substitute, or request that they notify you when the incubator is free for inspection.


Calibrated glass or electronic thermometer accurate to within 0.1°C in the clinical range Oxygen source and flowmeter Hot-air gun or hair dryer For transport incubators with lead-acid batteries: hydrometer to measure specific gravity of the batteries; float markings should cover the range from 1.240 to 1.280 to within 0.001 accuracy (available from any scientific apparatus supplier) (Note: automotive hydrometers that indicate only GOOD or BAD without numerical specific gravity indications are not suitable.)

The hood condition is important for proper control of the infant’s environment. Ensure that the hood is free of cracks, warping, or other signs of deterioration. Determine whether any parts are missing or incorrectly assembled. Examine all ports for proper alignment and sealing. Consult the instruction manual for a general exploded diagram of the incubator; remove the hood, bed, baffle, main deck, and other parts and thoroughly inspect the interior for foreign objects, deterioration, or misassembly of internal components that could interfere with performance. Look for contamination of the air supply and blocked air and/or humidity passages caused by improper placement of the humidity tray or gaskets.

Special precautions Examine all mercury-in-glass thermometers and high-temperature thermostats. If broken, replace and clean the unit carefully using appropriate precautions for mercury spills (see Health Devices 1981 Dec; 11:65 and the “IPM Safety” article behind the Guidance Tab in this binder). ECRI recommends replacing all mercury-containing components in infant incubators.

Examine the humidity apparatus for deterioration, contamination, and missing or incorrectly assembled parts.

CAUTION: Mercury and its vapors are toxic. Do not allow mercury to contact an open cut. 1.2

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to

2

Chassis/Housing. Examine the overall exterior condition of the chassis. Check that the control unit is clean, that all labels and markings are legible, and that no adhesive tape or tape residue is present. Remove any tape. Check all rubber or plastic gaskets in the incubator for signs of deterioration (e.g., cracks).

Mount/Fasteners. Check that all screws, nuts, and fasteners are tight. Sometimes a loose screw may not be easy to detect visually. Use a screwdriver and systematically try to tighten every screw on the hood.


Infant Incubators Operate iris-type port closures to ensure proper function. Examine the iris diaphragms and port sleeves for tears. A torn or otherwise damaged iris reduces the integrity of the closedchamber system. Consult the manual to determine if the irises are disposable types that should be discarded after each incubator use. You need not replace torn disposable irises, since they will be routinely replaced when the interior is sterilized for the next incubator application. Verify with clinical personnel that this practice is enforced and that disposable irises are not reused. 1.3

1.4

Casters/Brakes. If the device moves on casters, check their condition. Remove accumulations of lint and thread from around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks if the unit is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture in an area. AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacle.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one. Check line cords of battery chargers.

1.6


1.7

Circuit Breaker/Fuse. If the device has a circuit breaker, check that it operates freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not cracked, kinked, or dirty. Inspect all oxygen orifices to

make sure that they are clear and free of foreign matter. 1.9

Cables. Inspect the cables (e.g., sensor, electrode, remote control) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Probes. Examine all patient probes to ensure that they are clean and are not cracked, brittle, or otherwise deteriorated. If the hospital has more than one type of infant incubator, ensure that probe labels clearly identify the associated units. Improperly interchanged probes of different types or from different manufacturers may adversely affect temperature control. 1.12 Filters. Inspect the air filter for signs of clogging; if the filter looks dirty, replace it and note this on Line 3.4 of the inspection form. Check the air-filter assembly to ensure that airflow is unimpeded. Clogged or improperly installed filters can raise the oxygen concentration above safe levels. Change filters regularly according to the manufacturer’s recommendations, and record the date you install a new filter. Attach an oxygen source with a flowmeter to each oxygen port and use your hand to feel that gas is flowing into the chamber. Vary the oxygen flow and check that manufacturer-specified maximum and minimum flow rates can be achieved. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a temperature control turned to the end of its range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be


3

Inspection and Preventive Maintenance System sure to check that each control and switch performs its proper function. 1.14 Heater. Disassemble the heating unit enough to expose the heating element. Examine the element for severe discoloration or foreign deposits. Heating elements normally change color with use, but dark, distinct surface spotting may indicate that material has come into contact with the element, possibly after falling through the air duct. Foreign matter touching the hot surface could cause a fire or the generation of noxious fumes. If you find such discoloration, examine the control unit compartment for signs of overheating (e.g., darkening, blistering). If screw terminals connect the heating element to the control circuitry, check that they are tight. Operate the heater to verify that heater controls function properly (e.g., that a variable temperature control does, in fact, cycle the heater off and on as the set point is varied). 1.15 Motor/Fan. Inspect the fan blades for deterioration or damage, such as melting (if plastic), warping, or lost blades. Ensure that the fan is securely attached to its drive shaft and that the coupling is present and intact. Check that clearance between the fan and its housing is adequate by looking for signs of rubbing. In some cases, an improperly inserted control module and heater assembly in the incubator base has bent and disabled the fan, preventing air circulation and causing overheating. Check the service manual to determine if the fan motor requires lubrication. Oil as recommended and note on Line 3.2 of the inspection form. Check the sound level inside the incubator; noisy operation may indicate that the fan motor or housing assembly needs service. In some incubators, the fan is visible at the back of the control module if the module is removed. If possible, expose the fan and operate it, and watch for wobbling or excessive vibration. If possible, spin the fan with your finger (with the power off) and make sure that it turns smoothly. 1.16 Fluid Levels. Check all fluid levels, including those in lead-acid batteries. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily accessible. Check operation of battery-operated power-loss alarms if so equipped. Each battery should have an identification number and an

4

accurate log of operating time, recharges, service, and inspections to permit early detection of deteriorating performance. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check remaining battery capacity by activating the battery test function. Check the condition of the battery charger, and to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date. A liquid-electrolyte lead-acid battery located in the same case as the charging circuitry can cause problems unless the battery is kept clean. Wash off acid and other materials that may collect on top of the battery. If there is electrolyte or a yellow-white powder on the battery, check for contaminating deposits on components of the charging circuit; these may cause rapid deterioration. Wipe components clean, or replace the charging circuit if it appears corroded. Check for obstructions in the vent caps and associated venting system. If necessary, clear the venting system with a stiff wire, or blow out the tubes through a straw inserted into the vent hole. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger, if so equipped. Verify that all segments of a digital display function. 1.19 User Calibration/Self Test. Verify operation of these features, where applicable. 1.20 Alarms. Operate the device in such a way as to activate each audible and visual alarm. Check that any associated interlocks function. Check the action of the disconnected-probe alarm, if the unit is so equipped. Also, if it has alarms for open- or short-circuited patient temperature probes, test these with open- and shortcircuited probe plugs. If the device has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as operation of volume controls. 1.22 Labeling. Check that labels clearly and concisely identify the functions of all controls, switches, and connectors. Because incubators may administer supplemental oxygen, they


Infant Incubators should carry a WARNING — FIRE HAZARD placard, since textiles, oils, and other combustibles ignite easily and burn intensely in oxygenenriched air. Exposing an infant to high oxygen concentrations may cause retrolental fibroplasia and possible blindness. Thus, incubator labeling should also include the following: WARNING: EXPOSING INFANTS TO ELEVATED OXYGEN CONCENTRATIONS MAY CAUSE BLINDNESS.

If the device has an accessory outlet, check its grounding to the main power cord. 2.2

1.23 Accessories. Hood thermometer. Check the hood thermometer for cracked glass and separation of the liquid column. If the liquid column has separated, it might be possible to consolidate it by removing the thermometer and carefully dipping it in hot water. If the thermometer has an expanded space at the top, the liquid will pool in the small reserve chamber. When the gap in the column disappears into the pool, cool the thermometer and recheck it for column separations. Repeat the process if necessary. If the thermometer does not have reserve space at the top, the heated liquid will expand until it completely fills the thermometer, after which pressure will build up. The pressure may eliminate the column separation, but it may also break the thermometer. Even with a reserve space, overheating the thermometer may break it. In either case, do not heat the thermometer too fast or to too high a temperature while attempting to consolidate the column. Replace the thermometer if it is cracked. Mattress. If the mattress position is adjustable, check the ease of motion and security of the locking mechanism. Examine the mattress for cleanliness. If the unit is to be used in the presence of flammable anesthetics, check that a conductive mattress cover is being used.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular, verify grounding of the mainframe and each module.

Leakage Current. Measure the leakage current to ground from the incubator chassis and, if the unit has a battery charger, from the charger chassis in all operating modes, including off, and during battery operation. Measure while all accessories (e.g., examining and phototherapy lamps) are operating. Chassis leakage should not exceed 300 µA. (Note that the chassis leakage of transport incubators may vary with the state of battery charge.) Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”), so that all are grounded through a single line or extension cord.

2.3

Temperature Control. Check the action of the primary and safety thermostats with the incubator fully assembled. Although this is time-consuming, it is essential, since proper thermostatic operation depends on the presence of normal airflow patterns. Test the thermostats according to the manufacturer’s instructions, and record on the form the temperature at which the safety or backup thermostat turns off the heater. If the manufacturer does not provide instructions, use the following methods, which test both manual and automatic temperature controls. In the manual mode, the primary thermostat cycles the heater on and off or provides proportional heating to maintain a constant hood temperature. The operator can adjust the temperature by changing a setting. In the automatic mode, a patient probe senses the infant’s skin temperature, and electronic circuits control the heater to keep the skin temperature constant at a clinically desirable level. To test manual controls, position the calibrated glass or electronic thermometer 10 cm (4 in) above the center of the mattress, close the hood, set the temperature control to mid range, allow the incubator to warm up to thermal equilibrium, and record the hood thermometer reading and the true mid-hood air temperature in Item 2.7. Then, alternately raise and lower the temperature setting. If the primary thermostat


5

Inspection and Preventive Maintenance System is because the safety thermostat is often at some distance from the mid-hood area, downstream in the airflow, so that its temperature lags behind the mid-hood air temperature. Also, avoid blowing hot air directly at the thermometers. If a blower is used, deliver intermittent bursts of heat and pause for thermal stabilization. Reconnect the primary thermostat that had been disabled in the above procedure (consult the operator’s manual to determine the necessary procedure).

is operating properly, the heater will turn on and off, respectively. To check automatic controls, first test the accuracy of the patient-probe temperature indicator. Place the probe and a calibrated thermometer into a cup of water preheated to approximately 35°C. Stir to reduce temperature gradients, allow the temperature readings to stabilize, and record the patient-probe temperature indication and the true bath temperature in Item 2.8. If the two readings do not agree within 0.3°C, the probe may be defective. Substitute a probe known to be accurate, and repeat the test. If the two readings still disagree, the measuring circuit or meter is defective and requires recalibration or repair.

2.6

Confirm the operation of the temperature control circuit by alternately dipping the probe into cold and hot water, well below and above the skin-temperature set point, respectively. The heater should activate when the probe is cold and turn off when the probe is hot. 2.4

Skin-Temperature Alarms. If the incubator is equipped with high and low skin-temperature alarms, verify that these alarms function. Adjust the skin temperature set point to 36°C. Place the sensor in the incubator and allow the temperature to stabilize. Remove the sensor from the incubator, and verify that the low skin-temperature alarm activates. To verify the high skin-temperature alarm, place the sensor in a water bath set at 36°C and gradually increase the water bath temperature. Note the point at which the high alarm responds.

2.5

6

Safety Thermostat To test the operation of the safety thermostat and the high-temperature alarm, disable the primary thermostat or disconnect it from the control circuit (consult the manual to determine the necessary procedure) so that the heater remains on continuously. In some cases, this can be achieved by turning the temperature control to its maximum setting. It is possible to speed up the air-temperature rise by supplementing the incubator heater output with a hot-air gun or hair dryer. Record the hood thermometer indication and the true mid-hood air temperature at which the safety thermostat and high-temperature alarm respond. Be careful not to heat the hood air too rapidly with the hot-air blower, or the mid-hood air temperature at the alarm point will be erroneously high. This

Air-Temperature Alarms. If the incubator is equipped with high and low air-temperature alarms other than those that are controlled by a secondary temperature controller, verify that the alarms are functional. Adjust the air-temperature set point to 36°C and allow the air temperature to stabilize. Verify that the low air-temperature alarm (if so equipped) activates when the incubator hood is opened. To verify the high air-temperature alarm, set the air-temperature set point to 36°C and slowly increase the air temperature with an external heat source (e.g., hair dryer or heat gun). Note when the high alarm responds.

2.7

Hood Air Temperature. The mid-hood air temperature and hood thermometer readings taken in Item 2.3 should agree within 1°C.

2.8

Patient Probe. The patient-probe temperature indication and true water bath temperature, also recorded during performance of Item 2.3, should agree within 0.3°C.

2.9

Portable Power Supply (transport incubators only). The portable power supply usually consists of a rechargeable battery, a recharging circuit, and associated wiring and connectors. It is essential to keep all parts in good condition to ensure the safe, effective operation of the transport incubator. Battery types vary, and each requires a different inspection and preventive maintenance procedure. Types commonly used are lead-acid with a liquid or sealed gelled-electrolyte, nickel-cadmium, and alkaline batteries. Sealed batteries require less maintenance than types to which fluid must occasionally be added to compensate for evaporation. Measure the specific gravity of lead-acid batteries with a hydrometer, but not while the battery is charging. If the battery is charging at


Infant Incubators inspection time, disconnect the charger and wait at least 15 min before testing the battery. Before taking a reading, rapidly fill and empty the hydrometer several times to thoroughly mix the electrolyte, taking care to avoid splashing or spilling. The specific gravity of a fully charged battery should be 1.265. (It may be necessary to check the electrolyte level and measure the specific gravity of lead-acid batteries as frequently as every two weeks, depending on use and age of battery.) If the liquid level is low, add distilled or demineralized water to bring the level to the split ring in each cell. Do not overfill. Excess water may boil over and damage the battery case and nearby charging circuits. If the battery has been on a constant trickle charge and the specific gravity is too low and battery voltage is lower than 12.6 V, then the battery is defective or the charger circuit is at fault. The charging circuit may need readjustment. If the incubator uses nickel-cadmium or gelled-electrolyte lead-acid batteries, turn the

heater on after the batteries are fully charged, and measure the voltage under load initially and after 15 min of operation. Record the two values. If the voltage decreases more than 10% during this period, replace the battery.


Clean the exterior and interior.

3.2

Lubricate the fan assembly if required.

3.3


3.4

Replace filter and battery if needed.


Before returning to use Set all controls to their normal positions.


7


Infusion Devices Used For: Infusion Controllers [11-010] Infusion Pumps, Ambulatory [16-491] Infusion Pumps, General-Purpose [13-215] Infusion Pumps, Micro [16-722] Infusion Pumps, Multichannel [17-634] Infusion Pumps, Patient-Controlled Analgesic [16-924] Infusion Pumps, Syringe [13-217] Pumps, Enteral Feeding [13-209]

Commonly Used In: All patient care areas, homes Scope: Applies to most types of electromechanical devices that regulate the delivery of fluids to a patient, including general-purpose infusion pumps, multichannel pumps, microinfusion pumps, patient-controlled analgesic (PCA) pumps, syringe pumps, ambulatory pumps, enteral feeding pumps, infusion controllers Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Infusion devices are often used when accurate delivery rates are required over long periods of time. Generalpurpose infusion pumps and controllers are used for many of the same applications and have similar alarm features. However, infusion pumps infuse under pressure, whereas controllers regulate a gravity infusion. Most general-purpose infusion pumps have a flow range of 1 to 999 mL/hr, while most controllers regulate flow in a range of 3 to 300 mL/hr. Multichannel infusion devices consist of two or more general-purpose pumps and/or controllers within one chassis. Microinfusion pumps are similar to general-purpose pumps but have greater flow resolution and lower flow settings; they are commonly used in neonatal critical care areas. PCA pumps deliver pain medication on patient demand by handswitch activation; they are programmed for drug concentration and dose volume, lockout interval, and maximum dose. Syringe pumps are typically used to



Time Required

infuse small volumes at rates less than 100 mL/hr by depressing the plunger or sliding the barrel of a conventional syringe installed in the pump. Ambulatory pumps are small and do not rely on line power or gravity for operation. They are commonly used to infuse antibiotics, analgesics, chemotherapeutic agents, and total parenteral nutrition solutions. Enteral feeding pumps are typically used to deliver enteral solution or food mixtures to a patient’s stomach or small intestine through an enteral feeding tube.

Citations from Health Devices Enteral feeding pumps [Evaluation], 1984 Nov; 13:9-30. Infusion controllers [Evaluation], 1985 May; 14:219-56. Undetected upstream occlusions in volumetric infusion pumps [Hazard], 1986 Jun; 15:182-4. Syringe infusion pumps [Evaluation], 1987 Jan; 16:3-32.


●


Inspection and Preventive Maintenance System Ambulatory insulin infusion pumps [Evaluation], 1987 Nov; 16:351-76.


Chassis/Housing. Examine the unit for overall condition. The chassis should be clean and free from IV or enteral solution residue, especially near moving parts (e.g., thumbwheel switches, pump or controller mechanisms). Also check for dried solution deposits on accessible air-in-line sensors, pressure sensing mechanisms, and infusion set/cassette locking mechanisms. Check that labels and markings are legible.

1.2

Mount. Screws and brackets that attach the unit to an IV pole should be secure and functioning. If the device is mounted on a stand or cart, examine the condition of the mount. Also examine the pole, stand, or cart.

1.3

Casters/Brakes. If the unit is mounted on a dedicated IV pole, stand, or cart that moves on casters, check their condition. Look for accumulations of lint and thread around the casters and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

Patient-controlled analgesic pumps [Evaluation], 1988 May; 17:137-66. General-purpose infusion pumps [Evaluation], 1989 Mar-Apr; 18:92-133. Ambulatory infusion pumps [Evaluation], 1991 Sep; 20:324-58. IV free-flow — still a cause for alarm [Perspectives], 1992 Sep; 21:323-8. ECRI responds to FDA Public Health Advisory on IV free-flow [Hazard], 1994 Jun; 23:256-7.

Test apparatus and supplies General: Ground resistance ohmmeter Leakage current meter or electrical safety analyzer At least one IV tubing set, cassette, syringe, and/or other disposable specified for the pump or controller being inspected Fluid container of outdated (i.e., clinically unusable) IV solution or degassed water IV pole Pressure meter (0 to 50 psi)

If the device or its IV pole has electrical receptacles for accessories, inspect them by inserting an AC plug into each and checking that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacle.

U-100 insulin syringe and needle For determining flow accuracy at settings ≥1 mL/hr: 50 mL graduated cylinder with 1 mL graduations and stopwatch or watch with a second hand, or Infusion pump analyzer

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, either replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire the new power cord or plug with the correct polarity.

1.6


1.7

Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely. If the unit is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare fuse is provided.

1.9

Cables. Inspect drop sensors and remote air-inline detector cables for general condition. Examine cables carefully to detect breaks in the

For determining flow accuracy at settings <1 mL/hr: Electronic balance with a 200 g range and resolution to 0.1 mg and small beaker, or 10 mL pipette with 0.1 mL graduations and vertical mounting stand


2


Infusion Devices insulation. Ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. 1.10 Fittings/Connectors. Examine any electrical cable connectors (e.g., drop sensor, nurse call) for general condition. Electrical contact pins or surfaces should be straight and clean. Check any spill-protection connector caps for signs of damage. 1.13 Controls/Switches. Before moving any control switches, dials, or knobs, check their positions. If any appear inordinate (e.g., volume-infused counter or audible alarm level at the end of its range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls (e.g., occlusion pressure limits) that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery. Inspect the physical condition of batteries and battery connectors, if readily accessible. Operate the unit on battery power during its entire inspection to check that the battery has been charged and can hold a charge. If a low-battery alarm occurs, check to ensure that it is properly displayed and then continue the inspection using line power. Note how long the unit has been operating and the conditions under which the low-battery alarm occurred. Fully charge the battery before returning the unit to use. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, visual displays, and display backlighting, if so equipped. Be sure that all segments of a digital display function. (Many infusion devices automatically check indicator and display function when turned on or during a manually activated self-test.) 1.20 Alarms. Many of the alarm capabilities of infusion pumps and controllers can be checked qualitatively. The following procedures include tests for the most common alarm conditions. Check

the instruction manual to see how the alarm should work. When an alarm occurs, check to see that both audible and visual alarms are activated and that flow stops or is reduced to a keep-vein-open rate (e.g., <5 mL/hr). Confirm appropriate alarm volume, as well as the operation of any volume control. Set up the infusion device according to the manufacturer’s instructions, using an IV pole, a container of outdated IV solution or degassed water, and the specified IV set. Be sure that the set is properly primed and that bubbles are removed. Air-in-line. In some units, this alarm is the same as the empty-container alarm. Test its function by introducing a small air bubble into the system by righting the fluid container briefly or by injecting air into an injection port of the IV tubing with a syringe between the container and the air-in-line detector. (Sensitivity to air volumes of less than 50 µL is likely to result in nuisance alarms; most devices will trigger an alarm for greater than 100 µL air; 50 and 100 µL volumes can be approximated by 5 and 10 units, respectively, from a U-100 insulin syringe.) Empty container. Simulate an empty fluid container while the device is infusing. The simulation method will depend on the type of sensor that is used in the alarm system. For most units, turning the fluid container upright will cut off the supply, empty the tubing leading from the container, and trigger the alarm. For units that rely on a drop sensor or an empty container detector to determine fluid depletion, simply remove the sensor detector from the drop chamber. Occlusion. See Item 2.11. Infusion complete. If the total volume to be infused can be preset, set it to a low volume (e.g., 10 mL), and operate the pump at a high-flow setting. Open door/misloaded infusion set. Check this alarm during setup and operation. Nurse call. Some pumps have a relay contact closure that activates a nurse-call system when an alarm condition occurs. This requires a special cable that connects the pump to the nurse-call system. If the unit has this capability and it is used in any clinical location, connect the cable, and simulate one or


3

Inspection and Preventive Maintenance System more of the above alarm conditions to determine whether they activate the nurse call. Alternatively, use an ohmmeter to check that a change in resistance (either low to high or high to low) occurs between the two conductors of the cable when an alarm condition is created. 1.21 Audible Signals. Operate the device (e.g., press rate switches) to activate any audible signals. Confirm appropriate volume, as well as the operation of the volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Check the condition of external airin-line and drop sensors, if so equipped. Clean sensors according to the manufacturer’s instructions. After cleaning the drop sensor, confirm operation by passing a pen or finger between the sensor while watching for activation of the drop indicator, if present. 1.24 Flow-Stop Mechanism(s). Turn the power off with the infusion set primed and loaded in the device. With all tubing clamps open and the fluid container two feet or more above the device, verify that no fluid flows out of the set. If the device incorporates a mechanism that automatically closes the set or requires the set to be manually closed before it is removed from the device, verify the operation of this mechanism. 1.25 Lockout Interval. (This test applies only to PCA pumps.) Program the unit for its minimum lockout interval (typically 1 to 5 min). Activate a dose, and then verify that a second dose cannot be activated until the programmed lockout time has elapsed.


Grounding Resistance. Measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis with an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms. We recommend a maximum of 0.5 Ω. If the device or its IV pole has an accessory outlet, check its grounding to the main power cord.

4

2.2

Leakage Current. Measure leakage current between the chassis and ground with the grounding conductor temporarily opened. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord. Chassis leakage current to ground should not exceed 300 µA.

2.10 Flow Accuracy. It may be desirable to record the type of tubing, pump chamber or syringe brand and size (where user selectable), solution used, and any other test variables to facilitate the comparison of results with those obtained during future inspections. Flow settings ≥1 mL/hr: Use an infusion pump analyzer or collect the output in a graduated cylinder. Determine the flow accuracy at two or more typical clinical flow settings (e.g., 10 and 100 mL/hr). (Choose the correct fluid code when testing volumetric controllers.) Use a stopwatch or a watch with a second hand to time the delivery into the graduated cylinder until at least 10 mL is collected. Record the time interval and volume collected, and calculate the delivery rate in mL/hr. Flow settings <1 mL/hr: If an electronic balance is available, gravimetrically determine device accuracy by weighing a small beaker (covered with a film of plastic wrap to minimize evaporative losses) before and after collecting a mass of at least 1.5 g. Convert the mass to volume (1 g H2O = 1 mL; 1 g/mL can be used for most other test solutions [e.g., normal saline], although the mass per unit volume of some fluids may differ significantly). Divide the calculated volume by the collection time in hours (e.g., 1.5 mL ÷ 15 hr = 0.1 mL/hr). Follow this procedure to determine bolus volume accuracy of PCA pumps; for pumps programmed in volume units (e.g., mL), collect and determine the average value of three 1.5 mL boluses; for pumps programmed in mass units (e.g., mg), select a concentration of 1.0 mg/mL and a 1.5 mg bolus, and then collect and determine the average value of three boluses.


Infusion Devices alarm pressure(s). The maximum pressure of newer pumps is typically 20 psi or less.

If an electronic balance is not available, use a small length of rubber hose to connect the infusion set to the base of a vertically mounted, graduated 5 mL pipette (resolution to 0.1 mL). Divide the collected volume (1.5 mL, minimum) by the collection time to calculate the infusion rate.

Connect the distal end of the primed administration set to a pressure meter, and start the infusion. Test alarm pressures at two commonly used flow settings (e.g., 10 and 100 mL/hr). If the pressures are outside the unit’s specifications, consult the service manual for making the necessary corrections. For units that have adjustable occlusion alarm pressures, test at high and low settings.

To calculate flow error, use the following formula: % Error =

Actual rate − Desired rate × 100% Desired rate

Exercise extreme care during measuring to ensure accurate test results. Although most intravenous infusion pumps are specified to deliver within 5% of the flow setting, 10% is acceptable for most applications; for critical applications, the error should not exceed 5%. (Note: Negative and positive flow error represents underdelivery and overdelivery, respectively.) Expect greater delivery errors (up to 15%) with enteral feeding pumps. Infusion controllers are typically specified to deliver within 10% of the flow setting or drop rate. Be sure that infusion devices are used appropriately (e.g., infusion controllers should not be used for critical intravenous infusions). If the unit is designed to count drops and the delivery rate can be set only in drops/min, do not attempt to convert to mL/hr. Converting drops to milliliters is complex and only grossly assesses the device’s ability to deliver fluid volumes. Instead, operate the device for 3 to 5 min at a midrange rate setting, and then count the drops falling into the drip chamber for 2 min. Operate the device for several more minutes, and repeat the count. Calculate the number of drops per minute for each trial, and average the two rates if they are different. (Slight variations may be due to the control circuitry correcting for errors.) 2.11 Maximum Pressure/Occlusion Alarms. (Exclude infusion controllers from these tests because of their inherently low operating pressures.) Determine the unit’s specified downstream occlusion

If the device delivers from an external fluid container, verify upstream occlusion detection by activating infusion with the tubing clamped just below the container. (Some pumps do not have this capability; see Health Devices 1986 Jun; 15:182-4.)


Clean the exterior and the interior of the unit, if required. Pay particular attention to solution deposits on mechanical infusion control mechanisms, drop and air-in-line detectors, and occlusion or pressure-sensing mechanisms.

3.3

Calibrate per the manufacturer’s specifications.

3.4

Replace the battery, if necessary.


Flow Accuracy. Determine flow accuracy at minimum and maximum flow settings, following the procedures in Item 2.10.

Before returning to use Ensure that the unit’s battery is fully charged and that the case is properly reassembled to minimize the risk of fluid entry.


5


Intra-Aortic Balloon Pumps Used For: Circulatory Assist Units, Intra-Aortic Balloon [10-846]

Also Called: IABPs, counterpulsation units Commonly Used In: Critical care units, catheterization labs, operating rooms Scope: Applies to all intra-aortic balloon pumps; ECG and pressure monitors in these units should be inspected using the appropriate Inspection and Preventive Maintenance Procedures Risk Level: ECRI Recommended, High; Hospital Assessment,

Type



Major

6 months

months

.

hours

Minor

NA

months

.

hours

Time Required

Intra-aortic balloon pumps [Evaluation], 1987 May; 16:135-76. (See also 1987 Jun; 16:216.)

Overview An intra-aortic balloon is placed in the descending aorta and controlled by a complex electromechanical system in an attempt to lower the pressure the heart has to work against and to provide better coronary and systemic perfusion.

Inaccurate blood pressure readings on IABP patients [Hazard], 1989 Mar-Apr; 18:138.


Intra-aortic balloon pumps have been used for several types of heart disease. Their most frequent and successful use has been with cardiac surgery, applied as a preoperative, intraoperative, or postoperative aid to open-heart surgery; for patients with unstable angina who are not responding to medication and who may be helped by revascularization surgery; as a precaution before revascularization surgery after arteriography has indicated a coronary lesion; in high-risk patients (patients with left main coronary artery occlusion or poor left ventricular function); and for weaning patients with low cardiac output from cardiopulmonary bypass.

Aortic simulator (see the “Test Equipment” section of this binder)


Leak-detecting solution

Intra-aortic balloon pumps [Evaluation], 1981 Nov; 11:3-39.

Transducer connector (may be required to gain access to monitor terminals) (acceptance inspection only)


Transducer simulator (or pressure transducer and accurate pressure source); these devices were evaluated in Health Devices 1980 Jan; 9:59 ECG simulator Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Expendable supplies such as a stopcock and syringe and other tubing and fittings for connecting test equipment


●


Inspection and Preventive Maintenance System Isolation test supply; this feature may be included in some electrical safety analyzers (acceptance inspection only)

accessories are plugged and unplugged often, consider a full inspection of the receptacle. 1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one. Also check line cords of battery chargers.

1.6


1.7


1.8

Tubes/Hoses/Moisture. Check the condition of all tubing in the unit. Be sure that tubing is not cracked, kinked, or dirty. Check that tubing is secured away from any elements that may become hot and that it has proper strain relief. Clean or replace as necessary.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Since available intra-aortic balloon pumps differ considerably and are relatively complicated life-support devices, be familiar with the operation of the unit to be inspected. Inspection test methodology and criteria may vary from unit to unit; customize this procedure as required. For specific instructions on how to perform tests or inspections, consult the operator’s manuals or manufacturers. Record the hour meter reading and (when applicable) note the software version before beginning the inspection.



1.2

Mount/Fasteners. If unit components (e.g., ECG, blood pressure monitors) are independent modules on the console, check mounting of modules to ensure that they are securely attached.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture in an area.

1.4

2

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, insert an AC plug into each and check that it is held firmly. If

Be sure no moisture has accumulated in the pneumatic pathway. Inspect the patient isolation system, where applicable, for moisture. If the isolation system is not transparent, briefly operate the balloon pump with the tubing attached to determine if there is moisture in the unit. See the operator’s manual for specific instructions on how to clear moisture. If moisture is in the tubing, either dry it or replace the tubing. After clearing moisture, inform IABP users that moisture has accumulated during use and instruct them to clear the system of moisture after each use. 1.9

Cables. Inspect ECG electrode and pressure transducer cables and any interconnecting cables between modules for neat and secure routing, condition, and strain reliefs. If additional cables are provided for slaving pressure or ECG signals to other units, check their function and condition. Spare ECG and pressure cables should be kept with the unit. Check cable (ECG and blood pressure ports) on consoles to ensure that connectors are in good condition (e.g., no bent pins or cracked connectors).

1.10 Fittings/Connectors. Check the condition of all gas manifolds, fittings, and connectors in the pneumatic pathway. Examine all gauges and


Intra-Aortic Balloon Pumps valves for general condition. If leaks are suspected, check tubing and high-pressure regulator connections for leaks using a leak-detecting solution. If pneumatic systems pass near electronic portions of the units, be careful not to spill or drip the solution on electronic components.

may prove to be cost-effective, since it eliminates most battery failures and the problems of unscheduled battery replacement. This is particularly true for transport models.) Where appropriate, check the specific gravity of leadacid batteries.

1.11 Electrodes/Transducers. Verify that ECG electrodes and pressure transducers and disposable domes, if used, are on hand and in good physical condition.

Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check that charging lights or battery status meters are operative. Verify automatic switchover to battery power, if provided. Check the condition of the battery charger, and to the extent possible, confirm that it charges the battery. When not in use, always leave the unit plugged in so that batteries may charge. The unit should be placarded LEAVE PLUGGED IN AT ALL TIMES.

1.12 Filters. Check the condition of air filters in the pneumatic pathway associated with the compressor or vacuum pump and filters associated with fans for cooling electronic components. Clean or replace as required and indicate this on Lines 3.1 and 3.4 of the form. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate, consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.15 Motor/Pump/Fan. Inspect and confirm the physical condition and proper operation of vacuum and pressure pumps, drive solenoids, and cooling fans. Replace pump diaphragms, valves, or gaskets, lubricate as required, and note this on Lines 3.2 and 3.4 of the inspection form. 1.16 Fluid Levels. Check fluid levels in lead-acid batteries where appropriate. Check the fluid level in the dome and syringe of the Mansfield (now Boston Scientific) unit, and refill with distilled or sterile water, if necessary. (The dome should be full when the syringe is empty.) 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Check the battery date code, if provided, for expiration. (Depending on how heavily your hospital relies on rechargeable batteries for IABP operation, annual battery replacement

To further assess rechargeable battery capacity, most of the inspection procedure can be performed with the unit operating on battery power. Before operating the unit on battery power for a prolonged period, be sure there is adequate time for recharging or that an alternate unit is available. If required, replace the batteries during the inspection procedure (unless the operator’s manual requires more frequent replacement). When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays. If the unit has digital displays, be sure that all segments of the display function properly. Examine all regulators and pressure gauges or meters for signs of damage or abuse. 1.19 User Calibration. Confirm that the ECG and pressure monitors’ calibration functions operate properly. 1.20 Alarms/Interlocks. Operate the device in such a way as to activate audible and visual alarms (e.g., heart rate, leak detectors, trigger loss, vacuum or pressure loss, trigger change, balloon disconnect). Check the function of any associated interlocks (e.g., balloon deflation). 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as operation of the volume control, if so equipped. If audible alarms have been si-


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Inspection and Preventive Maintenance System that the diameter of the orifice through the Tpiece is not significantly smaller than the catheter diameter; otherwise, the back pressure created by the restriction may trigger alarms on some units. The test method will vary with the model being tested. The following describes tests appropriate for units currently in common use.

lenced, alert clinical personnel to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, timing adjustment charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of safety chambers, patient isolator, and magnet (i.e., for Mansfield [now Boston Scientific] “Telewire” transmitter).

Aries and Datascope pumps. Operate in Auto mode. (Operation of the Aries in Manual and the Datascope 90 in Manual-fill mode will disable leak alarms.)

1.24 Gas Supplies. Check pressure of gas tanks; make sure that the location of spares is placarded on the unit. If helium pressure is below 250 psi or if the IABPs indicate that the gas is low, replace the gas tanks with full tanks and arrange to have them refilled. If CO2 is used with your unit, tanks should be replaced if the pressure is below 850 psi. (Since CO2 maintains a constant pressure of 850 psi at room temperature until all the liquid is converted to gas, a pressure of less than 850 indicates that replacement is required.) Recheck the pressure after a new tank is installed to verify that it is full and that the gauge or meter is functioning properly.

Datascope and Mansfield (now Boston Scientific) pumps. Withdraw gas in 1 cc increments until a leak alarm sounds. Typically, 11 to 12 cc of gas must be withdrawn before the units will alarm. The Aries leak alarm circuitry is designed to trigger if the system detects a gas leak rate exceeding 3 cc per min. Test the unit by withdrawing gas at a rate of approximately 4 cc per min to verify that the alarm is operating. (At leak rates of 3 cc per min or less, the Aries will automatically compensate for the gas loss by repriming the system with helium. Kontron IABPs are also designed to detect leakage by leak rate; contact Kontron or consult the operator’s manual to determine the appropriate rate for the model being tested.)


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular, verify grounding of the mainframe and each module. If the device has an accessory outlet, check its grounding to the main power cord.

2.2

Leakage Current. Measure chassis current to ground with the grounding conductor temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Leakage current should be 300 µA or less.

2.3

Pressure Monitor. Follow Item 2.10 in Blood Pressure Monitors Procedure/Checklist 434.

2.4

ECG Monitor. Follow ECG Monitors Procedure/ Checklist 409. (If a pacemaker is incorporated and is intended to be used, also follow External Pacemakers Procedure/Checklist 418.)

2.5

Leak Detector. Using the aortic simulator, insert a T-piece in the balloon catheter and connect a 25 cc syringe to the third port on the T. Be sure

4

2.6

Frequency Weaning. Check the operation of the weaning control by applying a simulated ECG signal and setting the unit for 1:1 pumping; observe the response when the setting for pumping frequency is changed to alternate settings (e.g., 1:2, 1:3). Verify that the frequency is what is indicated on the control knob position.

2.7

Triggering/Timing. Using the aortic simulator and an ECG simulator, confirm the proper operation of the controls for timing and triggering of the balloon pumping on each unit. Set the ECG simulator to a heart rate of 90 bpm and observe the ECG signal on a monitor. Set timing controls for several settings and confirm changes in the balloon inflation point, inflation duration, and the deflation point.

2.8

Driving System. Using a 40 cc balloon in the aortic simulator, confirm proper vacuum and pressure levels during operation at high heart rates. Balloon should completely deflate and inflate (depending on timing control position) even at high rates (e.g., 120 bpm).

2.10 Volume Displacement. Set the IABP to fully inflate the 40 cc balloon in the simulator. Leave


Intra-Aortic Balloon Pumps the chamber open to the atmosphere, start the pump, and observe the fluid displaced in the simulator. It should be within 10% of the setting. Check displacement again at volumes of 30 and 20 cc. (Run the test with a low trigger rate to aid in measuring the displacement.) Close the chamber to the atmosphere and increase pressure in the simulator to 40 and then to 60 mm Hg. Observe the displaced volume when fully inflating the balloon. If significant decreases in displaced volume occur (40%), the unit may not pump effectively. Contact the manufacturer.


Clean the exterior.

3.2

Lubricate per the manufacturer’s instructions.

3.4

Replace pump diaphragms, valves, gaskets, gas line filters, ventilation filters, safety chambers, and diaphragm isolators, if needed.

Check the number of hours of use since the last inspection and the hours of use on safety chambers (Datascope), VLDs (Aries), or diaphragm isolators (Mansfield/Boston Scientific). Replace these according to the manufacturer’s recommendations (Aries every 2,000 hours or every year; Datascope every 1,000 hours or by the expiration date; Mansfield/Boston Scientific every 250 hours). On the inspection form, note the date installed and the hour meter reading at installation. Be sure clinical personnel know how to change these components.

4. Acceptance tests In addition to the tests described in the major inspection procedure, conduct the appropriate tests in the General Devices Procedure/Checklist 438 and acceptance tests for ECG and blood pressure monitors and pacemakers (ECG Monitors Procedure/Checklist 409, Blood Pressure Monitors Procedure/Checklist

434, External Pacemakers Procedure/Checklist 418). In addition, perform the following test. 4.1

Compatibility with ECG and BP monitors. We have received several reports of difficulties users have experienced when trying to interface monitors with IABPs. While we generally recommend against slaving IABPs off separate patient monitoring systems, we recognize that this is a relatively common practice. If your hospital interfaces IABPs with monitors, verify that the IABPs purchased are compatible with the monitors to which they may be connected. Using an ECG or arterial pressure waveform simulator, connect IABPs to monitors as they are commonly connected in your hospital and attempt to trigger the pump. (This type of test will not guarantee equipment compatibility, but should identify units that are grossly incompatible. As further verification, contact the IABP manufacturer to obtain its recommendations.)

Before returning to use Make sure controls are set at normal positions and that alarm volumes, if adjustable, are set loud enough to be heard in the clinical setting. Verify that cooling fans are drawing air through the console housing once the panels are back in place. Be sure that the battery is charged or the unit is charging. (Note: After running the unit on battery during this inspection procedure, it is prudent to allow the IABP to fully recharge before returning the unit to use. Be sure that an alternate IABP is available during the interim for clinical use.) Place a CAUTION tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using. If any gas hoses were removed or replaced during inspection or servicing, be sure to verify that the unit works properly by attaching and pumping a 40 cc balloon in the aortic simulator.


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Isolated Power Systems Used For: Isolated Power Systems [15-817] Line Isolation Monitors [12-361]

Also Called: Isolated power centers Commonly Used In: Operating rooms and special care areas Scope: Applies to isolated power systems with dynamic line isolation monitors; in addition, most items are applicable to older static ground fault detectors, which usually do not have meters to monitor the total hazard index but which will give audible and/or visual indication after the limit has been exceeded (exceptions noted in the text) Risk Level: ECRI Recommended, Low; Hospital Assessment, Type


Major

6 months

months

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hours

Minor

NA

months

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hours

Isolated power systems are nonspecialized power distribution systems in which neither load conductor is directly grounded and a detection device (a line isolation monitor [LIM] or ground fault detector) is incorporated to determine the extent of degradation of isolation. These systems have been widely installed in operating rooms and may also be found in other areas of the hospital (e.g., critical care units, special procedures laboratories, emergency rooms). Until recently, codes and standards have required their installation in all anesthetizing locations. Although appropriate applications of isolated power systems continue to be debated, these systems are currently required in operating rooms only if the operating room is not designated as a nonflammable anesthetizing location. Isolated power systems or alternative protective mechanisms are also required in “wet” (as defined in NFPA 99, 1993 Edition, Section 3-5.2.4) locations (such as hydrotherapy areas). Periodic inspection and appropriate record keeping is

A NONPROFIT AGENCY

Time Required

required for all installed systems, even in areas in which they are not currently required.

Overview

009081 439-0595


Once isolated power systems are installed, their performance is generally taken for granted, and degradation in isolation can go unnoticed. The front-panel test button and the alarms on many systems will indicate certain faults. However, we have examined isolated power systems in which even these features were not functioning properly. NFPA requirements call for a monthly test that can be easily accomplished using the front-panel test button. The requirements also call for a more thorough inspection when the systems are first installed, after any required maintenance, and semiannually thereafter. Our inspection procedure meets these requirements. The term “total hazard index” is used throughout this procedure to refer to the meter reading on the LIM. This term is commonly used to denote the current that the meter predicts will flow through a line-to-ground short, should one develop. The total hazard index is the greater of the currents measured when a leakage current meter


●


Inspection and Preventive Maintenance System is connected, in turn, between each load conductor and ground. The terms “Line 1” and “Line 2” are used to refer to the power-carrying (load) conductors of an isolated system. The designation is strictly arbitrary and may not appear on the wiring itself within the system. It serves merely to establish a polarity convention. In newer systems, one line is wired with orange insulated wire; the other line has brown insulation.

Citations from Health Devices Isolated power systems [Evaluation], 1974 Aug-Sep; 3:243-58. Electrical safety analyzers [Evaluation], 1988 Oct; 17:283-309. Isolated power systems [User Experience NetworkTM], 1988 May; 17:170-1. Electrical outlets in anesthetizing locations, 1993 AugSep; 22:420.

Test apparatus and supplies Isolated power system analyzer (optional for routine inspections); can be a stand-alone device or one that connects to a leakage current meter, electrical safety analyzer, or voltmeter (see Special Precautions and Health Devices 1988 Oct; 16:283-309); if used, many of the following items will not be necessary; for routine major inspections, a safely constructed test fixture with a single resistor (2W) and a three-position switch — Line 1 to ground; off; Line 2 to ground — can be used (resistance value specified in Item 7) AC voltmeter for measuring line voltage Leakage current meter or voltmeter capable of measuring 10 to 500 mV Adapters that plug into the power receptacles (e.g., parallel blade, twist-lock, explosion proof, x-ray) used in the systems to be inspected, and allow safe connection to test equipment without exposed conductive surfaces that could pose a shock hazard Adapters that plug into the power receptacles (e.g., twist-lock, explosion proof, x-ray) used in the system that have an exposed ground connection and can be hooked to a trouble light or some other load to verify the presence of AC power (120-240 V) Grounding cable that plugs into special grounding receptacles used in the system to be checked Ground resistance ohmmeter (to avoid risk to patients in the area in which testing is being conducted

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and in areas distant from the testing site, any device used to determine ground quality or grounding resistance on occupied patient care areas must limit the output to 500 mV RMS [1.4 V peak-to-peak] or 1.4 VDC; several test devices using different measurement methodologies are available; any of these special-purpose devices, or simply an ohmmeter, is satisfactory, so long as it meets the above output limits and has adequate resolution and accuracy for the test; for periodic measurement in existing construction, the measurement current can be either AC or DC; an AC measuring source is required for postconstruction tests) Parallel-blade receptacle tension tester (optional) Long lead with probe (long enough to reach from a control grounding point to all areas of the room)

Special precautions Because checking isolated power requires that measurements be made on energized power lines, it is possible for personnel to contact full line voltage. Isolated power systems deliver substantial currents through line-to-line contacts, and, depending on the condition of the system, contacts from line to ground may yield hazardous currents. Exercise the same precautions used when testing or working with a conventional grounded system. We strongly recommend that isolated power systems be inspected by a team of at least two people so that, in the event of an accident, one can summon help or begin CPR. The second person will also prove invaluable for testing remote indicator panels and circuit breakers. In the past, it was necessary to use separate meters and variable resistances that were interconnected through a variety of test leads and adapters with the isolated power system by the person(s) doing the inspection. Several manufacturers currently make devices that can be used in conjunction with electrical safety analyzers, leakage current meters, and voltmeters to inspect isolated power systems. The use of such devices significantly decreases the risk of shock, expedites the inspection process, and alleviates the need for many of the previously required extra wires and adapters. Hospitals that intend to inspect isolated power systems on a regular basis should purchase and use these types of devices. Never test isolated power supplies that serve operating rooms, catheterization labs, or special procedures rooms while procedures are underway. If it is necessary to test systems in other areas of the hospital while patients are present, check with clinical


Isolated Power Systems pivots to nominal zero. (Note: The left end of the scale corresponding to the de-energized meter may not be labeled “0.”)

personnel to ensure that tripped circuit breakers will not compromise patient support or safety in the area.

Procedure

4.

Alarms and Silencing Feature. Most LIMs have at least two buttons or switches — one to test the alarms and one to silence the audible alarms. Actuate both to verify proper function. Record the reading on the LIM when the alarm test button is actuated. This value can be helpful in diagnosing failures in the LIM (normally, it should advance to the trip level). When the alarm-silence button is actuated, there should be a visible indication either that the system is still in alarm or that the alarm is silenced. Remember to test all remote indicators. Be sure that the audible and visual alarms reset following this test. The audible alarm may or may not automatically reset upon resolution of the alarm condition.

5.

Fuses. If the LIM has accessible fuses, examine them for condition and rating. Their rating should be placarded near the fuseholder. If it is not placarded, do not assume that a fuse of the correct value is installed; check the specifications for the LIM. Be sure that the fuseholders are in good condition.

6.

Circuit Breakers. Examine and manually operate each primary and secondary circuit breaker associated with the isolated power system. If the circuit-breaker panel is usually locked, determine whether this is a necessary precaution. In most cases, especially if the breakers are located in the same room that they serve, a locked breaker panel is inappropriate because it will delay restoration of power following a fault.

7.

Confirmation of LIM Function. (Note: This test does not confirm LIM accuracy and does not need to be performed during acceptance testing when Item 10 is conducted.) Connect a 24 kΩ resistance (for 120 V system or 48 kΩ for a 240 V system) between Line 1 and ground. Repeat the test with this same resistance connected between Line 2 and ground. (An isolated power analyzer or a calibrated, adjustable resistance can be used for this test. However, it may be more convenient to make a test fixture by wiring an appropriate plug with a 24, or 48, kΩ resistor that can be switched from ground to Line 1 or Line 2.) Confirm that the visual and audible alarm indicators are activated for each of these connections. This test confirms that an alarm will occur for a fault that would result in a 5 mA hazard current. A proportionately higher resistance may be used

The Universal Inspection Form is not applicable to this procedure. Use the special Isolated Power System Form 439. For new installations, fill in the required identification information at the top of the form. This includes nameplate data on the isolated power system, location of remote indicators and alarms, and type of power receptacle. In addition, list all fixed or permanently connected equipment (e.g., overhead lighting, x-ray view boxes, clocks) that is powered by the isolated power system. A box is provided on the form to sketch the layout of the room or area served by the isolated power system to identify the location of defective components or receptacles. The sketch should provide some orientation (e.g., location of bed or operating table, doors). (An otherwise blank form, with this information filled in, can be copied for routine inspections; verify that no changes have been made since the acceptance inspection. The sketch is not required if receptacles are assigned identification numbers and labeled during acceptance testing.) Items 1 through 9 constitute a simple operational check of the system to be performed routinely. These and the remaining items constitute an acceptance procedure. Although they are listed separately for clarity, checks of several items (e.g., lights, meters, alarms) can be performed simultaneously.

Qualitative and quantitative tests 1.

Physical Condition. Check the physical condition of display and circuit-breaker panels, including indicators, meters, and circuit breakers. Verify that they are not cracked or broken, that they do not show signs of fluid entry, and that viewing and access are not obstructed.

2.

Lights. Check all indicator lights, including any remote indicators, to verify that they are functioning. It may be necessary to actuate the test feature to check certain lights. Ensure that colored lenses over the indicator lights are intact. If a light is burned out, replace it or note the type on the inspection form to facilitate replacement.

3.

Meters. Be sure that the LIM meter is in good condition. The needle should not be bent and should advance smoothly when the test button is pressed. If it is possible to disable the LIM (e.g., by removing its fuse), check that the needle


3

Inspection and Preventive Maintenance System Verify that each receptacle has power by plugging a lamp or trouble light into the receptacle (a 240 V bulb is needed for x-ray outlets). Check the grounding contact of each receptacle. A duplex to locking receptacle adapter (or duplex to x-ray) may be required. It may be possible to combine the grounding contact test with the power test if a light with an accessible grounding point is used.

for confirmation at the 2 mA level (e.g., 60 kΩ for 120 V systems, 120 kΩ for 240 V systems). If an analyzer with adjustable trip point adjustment is used, the alarm should activate at resistances at or above those specified here. If leakage readings are used, the alarm should activate at readings no greater than 5 mA (or 2 mA for 2 mA LIM). 8.

Receptacles. Check explosion-proof and x-ray receptacles. Replace chipped or broken receptacles and cracked faceplates. Parallel-blade duplex receptacles can be checked either as part of the isolated power inspection procedure or during routine inspection of duplex receptacles in that area of the hospital (see Electrical Receptacles Procedure/Form 437).

For new construction, NFPA 99 requires that the voltage limit between a reference point and grounding contact of each receptacle in the patient vicinity not exceed 20 mV. In existing construction, the voltage should not exceed 500 mV in general care areas and 40 mV in critical care areas. However, voltages in modern construction are usually <10 mV; voltages >20 mV may indicate a deteriorating condition and should be investigated. It should be understood that these limits are not precise, and differences of <20% should be considered insignificant.

It is only necessary to record any defective outlets that are found. If all outlets are satisfactory, check Pass. If the test is postponed because it will be included as part of the receptacle inspection procedure, put a line through both the Pass and Fail columns.

Measure ground potentials with a voltmeter or leakage current meter. Leakage current readings can be converted to millivolts (mV) if the leakage current meter’s impedance is known. (Most leakage current meters have a 1,000 Ω impedance at line frequency; the reading in µA is then numerically equivalent to the voltage in mV.) Connect one lead of the meter to a reference ground point that is known to be securely grounded. It is usually most convenient to use the ground contact of one receptacle, but a ground plug or structural member can also be used. Do not use the cover plate screw, because this may not be adequately grounded. Connect the other lead to the ground contact of each receptacle in turn.

Measure the retention force of parallelblade outlets with a receptacle tension tester. Be sure that withdrawal of the tester from the outlet is straight and smooth. Retention force on the ground prong must be 4 oz or more. Although measurement of retention force on the power-carrying prongs is not required, we recommend that this be measured. A retention force of 4 oz is also adequate for these prongs, and forces of 2 to 4 oz are satisfactory if the plug brand in use tends to stabilize at this value and does not continue to deteriorate. Replace any outlet with less than 2 oz retention force on any prong. (See Procedure/ Form 437 for additional information.) A quantitative test of contact quality cannot be made in most locking receptacles. Instead, make a qualitative test of the power contacts by plugging a movable floor lamp or trouble light into the receptacle, either directly or through an adapter (a 240 V bulb will be needed for x-ray outlets). Jiggle the plug and pull on it after it has been inserted and notice whether the light flickers. The insertion and removal of the plug should be smooth. If the receptacle is explosion proof, check that the lamp does not go on until the appropriate action is taken (e.g., twisting the plug in the receptacle, rotating the cover plate).

4

Measure the resistance between the grounding terminal of the receptacle (accessed through the adapter) and ground, and verify that it is <0.2 Ω (or 0.1 Ω in new construction) and does not vary as the plug is jiggled in the receptacle. 9.

Grounding Jacks. Examine all installed grounding jacks for general physical condition. Insert a cable intended for that type of receptacle to make sure that there are no obstructions (e.g., broken locking pins) in the receptacle or other damage that prevents insertion or retention of the plug.


Isolated Power Systems Check ground potentials and resistance as described in Item 8; the same criteria apply.

(24 to 48 kΩ for a 5 mA, 120 V system). If a resistance higher than this value activates an alarm, it is indicative of inadequate isolation. This can result in nuisance alarms.

Acceptance tests Items 10-14 should be done only after the system is first installed or if major modifications or repair have been performed on the system. 10.

If resistances significantly below the expected value are required to generate an alarm, then malfunction or miscalibration of the line isolation monitor is likely; this condition should be corrected before the inspection continues.

Line Voltage. Line voltage tests are not required by NFPA 99. These tests should be performed following new construction, renovations, or major repairs to the electrical distribution system to ensure that voltage taps are set correctly. Testing after typical loads are applied or testing in existing facilities may indicate poor wiring or inadequate system capacity.

Static LIMs may not alarm until the resistance is about 20 kΩ, and LIMs with other alarm levels may be encountered. Examine the specifications of these special systems; the systems should operate within those specifications. (If the hazard index is above 5 mA, do not attempt the next step [measuring total hazard current] unless your meter is protected against line voltage.) Measure the resulting total hazard current with the resistance in place on Line 1 by switching the analyzer meter to read from Line 2 to ground (the LIM meter will go to full scale). Record this current reading. This current should not exceed 2 mA (5 mA on 5 mA systems) and should agree, within 20%, with the LIM meter reading before the leakage current meter was connected. To satisfy current codes, it should not be, under any circumstances, significantly higher than 5 mA.

Measure and record the output voltage of the system between Line 1 and Line 2. The measured value should conform, within reasonable limits, to the value specified on the nameplate. Any significant deviation requires further investigation. However, it may reflect the relatively poor accuracy of many AC voltmeters, so check your meter before blaming the system. 11.

Alarm Levels. This test verifies that the alarm will function when a suitable fault from one line to ground occurs, verifies the accuracy of the LIM meter, and provides a measure of the degree of isolation from each line to ground.

Static ground fault detectors may have alarm levels above 5 mA or more and may be beyond the range of some meters. In addition, static detectors do not recognize balanced faults.

Unplug all cord-connected equipment and turn off all fixed equipment (e.g., x-ray view box) from the system. Connect the analyzer and set it to apply a resistance between Line 1 and ground. Reduce the resistance from a high value (e.g., 200 kΩ) until the alarm sounds. Record this resistance value and the total hazard index (LIM meter reading). If the analyzer does not indicate the actual resistance used during this particular test, it is not imperative that this value be obtained and recorded. However, it is important to perform the procedure for determining system leakage (Item 12) and to record system leakage values. The resistance between a single power line and ground that can cause an alarm varies, depending on the isolation of that line. The resistance required to cause an alarm and the system leakage current are both indications of the isolation of the system, and either value is sufficient. For a 2 mA, 120 V system, resistance values between 60 and 120 kΩ indicate adequate isolation

Older dynamic line isolation monitors scan between Lines 1 and 2 at rates that can introduce marked fluctuations in meter readings. When the scanning rate is slow enough that two distinct readings can be distinguished on the meter, record the greater of the two values. Otherwise, record the average current. Repeat this sequence of tests, connecting the resistance from Line 2 to ground, adjusting it until the alarm sounds, and measuring the total hazard current from Line 1 to ground with a leakage current meter. 12.

System Leakage. These measurements check system integrity and give further information on LIM meter accuracy. While not essential if Item 10 is performed, the information obtained may be helpful in assessing a new installation and in future troubleshooting. Comparing the readings


5

Inspection and Preventive Maintenance System with values obtained in previous inspections may indicate degradation of the isolation of transformers, wiring, or other components.

mA for a 120 V system (1.2 mA for a 240 V system). 13.

Record the hazard index indicated on the LIM with the isolated power system on, all cord-connected devices unplugged, and individual branch circuit breakers or switches integral to the unit turned on. Installed lighting powered by the system (e.g., overhead surgical lights, x-ray view boxes) should be turned on or off, whichever yields the higher hazard index. Measure the system leakage with the line isolation monitor connected. Connect the leakage current meter between Line 1 and ground and note the reading. This represents leakage caused by impedance from Line 2 to ground. Repeat the measurement with the meter connected between Line 2 and ground. Record the two values and compare the greater one to the reading recorded for the LIM meter. A significant difference suggests a line isolation monitor malfunction. To ensure that there will be adequate leeway on the system to cope with connected loads, this value should be <1 mA for 2 mA systems and <2.5 mA for 5 mA systems. If the fuses of the LIM can be removed, if the grounding wire of the LIM can be disconnected, or if the breaker serving the LIM can be turned off, repeat system leakage measurements. This value measures the collective leakage of installed wiring, transformer, and associated components, but without the degradation of isolation caused by the LIM; thus, it is a better indication of wiring degradation. NFPA 99 states that the isolation must be >200,000 Ω; therefore, system leakage (mA) should be <0.6

6

Grounding of Exposed Metal. NFPA 99-1993 calls for testing of installed, permanently attached, electrically conductive surfaces that might become electrically energized and that might be touched by the patient or persons touching the patient. Testing is required following significant modifications and is recommended (but not required) at one-year intervals. However, NEC (1993) no longer requires grounding of such surfaces. We recommend performing this test after new construction and significant modifications. Tests and criteria are the same as for Item 8. It is not necessary to be concerned about resistance to ground of isolated exposed metal as long as the potentials measured above are acceptably low.

14.

Circuit Breaker Function and Labeling. Determine the correspondence between circuit breakers and receptacles. Turn off all secondary circuit breakers and plug a light, voltmeter, or other indicating device into one receptacle. Momentarily turn on one breaker at a time until the breaker controlling the receptacle is identified. Repeat this for all receptacles served by the isolated power system. As you go through the area, check that the receptacles and breakers are labeled (preferably by numbering) to indicate the relationship between them. This can facilitate restoration of power should a breaker trip. If they are not labeled, arrange to permanently tag each receptacle with the number of the circuit breaker that controls it. If more than one receptacle is served by a breaker, use letter suffixes (e.g., 8A, 8B).


Isolated Power Systems


7


8



Laparoscopic Insufflators Used For: Insufflators, Laparoscopic [16-849]

Also Called: CO2 Insufflators Commonly Used In: Operating rooms, short procedure and ambulatory surgery areas Scope: Applies to pneumatically and electronically controlled insufflators intended for introduction of CO2 or N2O gas into the peritoneal space. Does not apply to insufflators for hysteroflation (i.e., insufflation of the uterus). Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Insufflators are used to establish and maintain the pneumoperitoneum during laparoscopic procedures. Gas, typically CO2, introduced into the peritoneal cavity distends the abdominal wall to provide a viewing and working space within the abdomen. The primary function of the insufflator is to act as a pressure-controlled gas flow regulator. The insufflator takes in compressed gas from a supply cylinder (700 to 850 psi) or wall outlet (50 to 100 psi) and delivers it to the patient, typically at 10 to 15 mm Hg (0.2 to 0.3 psi). In pneumatic insufflators, abdominal pressure control is accomplished by limiting the pressure of gas delivered to the patient. Electronic insufflators typically deliver gas at a pressure higher than that desired in the pneumoperitoneum; these units limit abdominal pressure by slowing and then suspending flow when intermittent abdominal pressure measurements approach and reach a user-selected pressure. For electronic insufflators to accurately measure abdominal pressure, flow is briefly suspended so that pressure in the abdomen, insufflator tubing, and the patient outlet port of the insufflator



Time Required

can stabilize, allowing the pressure in the transducer inside the insufflator to equalize with the abdominal pressure. Both pneumatic and electronic insufflators feature controls for setting the pressure and maximum flow rate. They feature displays, gauges, or other indicators for set and detected abdominal pressure and flow, volume of gas consumed, and external gas cylinder pressure or volume remaining. In pneumatic insufflators, flow is typically specified as high or low. In electronic insufflators, flow rates are specified either as a time-averaged flow or as an instantaneous flow. The maximum flow possible from a given insufflator varies depending on flow resistance introduced by inline tubing filters and by the stopcock connection through which the insufflator is connected to the patient.

Citations from Health Devices Laparoscopic insufflators [Evaluation], 1992 May; 21:143-73. Entry of abdominal fluids into laparoscopic insufflators [Hazard], 1992 May; 21:180-1.


●


Inspection and Preventive Maintenance System Fatal gas embolism caused by overpressurization during laparoscopic use of argon enhanced coagulation [Hazard], 1994 Jun; 23:257-9.

damage is near one end, cut out the defective portion. 1.6


1.7

Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis and ensure that a spare is provided.

1.8

Tubes/Hoses. Check the condition of reusable patient tubing and gas-supply hoses. Be sure that they are not cracked, kinked, or dirty.

High-flow laparoscopic insufflators [Evaluation], 1995 Jul; 24:252-85.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Pressure meter or gauge (range 0 to 75 mm Hg; mercury manometers are not suitable) Large-bore (20 ga or larger) hypodermic needle Empty 500 mL and 3 L (one each) IV and/or anesthesia solution bags with at least two ports Trocar cannula or IV stopcock Stopwatch or watch with second hand



Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Inspect the gas outlet port for evidence of fluid entry, which can indicate contamination by body fluids.

1.2


1.4


1.5

2

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the

1.10 Pneumatic Connectors. Verify that the highpressure hose is pin-indexed for the appropriate gas (e.g., CO2 or N2O). Examine all external gas fittings and connectors, as well as electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate connectors. Gas fittings should be tight and should not leak. 1.11 Electrodes/Transducers. Confirm that any necessary electrodes and/or transducers are on hand, and check their physical condition. 1.12 Filters. Check the condition of internal gas filters. Clean or replace as appropriate, and indicate this in Section 3 of the inspection form. Follow the manufacturer’s recommended interval for service of internal filters (typically 2 years) and instructions for replacement. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., a pressure control at maximum), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper


Laparoscopic Insufflators ment temporarily opened. Operate the device in all normal modes, including on, standby, and off; record the maximum leakage current.

alignment, as well as positive stopping. During the course of the inspection, be sure to check that eachcontrol andswitchperformsitsproperfunction.

Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. 1.19 User Calibration. Verify that any calibration function operates. 1.20 Alarms. Induce alarm conditions to activate audible and visual alarms. Check that any associated interlocks function. If the unit has an alarm silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions that will be simulated later in this procedure. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level.

Chassis leakage current to ground should be 300 µA or less. 2.3

Set Pressure Accuracy. Connect the insufflator to an empty 3 L solution bag. Introduce a largebore hypodermic needle through an injection port on the bag. Connect the pressure meter or gauge to the hypodermic needle, and measure the gas pressure in the bag after it has stabilized. Measurements should be taken at maximum, minimum, and a pressure setting in the range of 12 to 15 mm Hg and should be within 3 mm Hg of the pressure setting.

2.4

Displayed Pressure Accuracy. During the preceding test (Item 2.3), compare the displayed pressure with pressure measured with the pressure meter or gauge; displayed pressure should be within 3 mm Hg of the measured pressure. Manually compress the bag to produce pressure in excess of the set pressure, and verify that displayed pressure remains within 3 mm Hg or 10% of measured pressure, whichever is greater.

2.5

Pressure Relief Mechanism. An insufflator should limit delivered pressure to a manufacturer-specified maximum value. In addition to a pressure-relief valve, some units also have vents that are electronically opened if the detected pressure exceeds a threshold value (e.g., 30 mm Hg) or if the detected pressure exceeds the selected pressure by a certain value. In many cases, these vents activate after a delay of several seconds. With the insufflator connected to a filled 3 L solution bag, manually compress the bag so that pressure is slowly increased 5 mm Hg at a time until pressure relief is activated. Note the bag pressure at which pressure relief occurs as indicated by the pressure meter or gauge also connected to the bag.

2.6

High-Pressure Alarms. During the preceding two tests (Items 2.4 and 2.5), note the bag

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible.


Grounding Resistance. For line-powered units, use an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms to measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. If the device has an accessory receptacle, check its grounding to the main power cord.

2.2

Leakage Current. For line-powered units, measure chassis leakage current to ground with the grounding conductor of plug-connected equip-


3

Inspection and Preventive Maintenance System set intended for use with the insufflator, and compare it to the flow established for that unit during acceptance testing. Insufflators should have a setting that delivers flow in the range of 1 to 2 L/min. For this test, compute the flow using the following formula:

pressures at which intermittent and continuous audible alarms and visual indicators are activated. 2.10 Maximum Flow. With the insufflator set to its maximum flow setting, measure the time required to fill a 3 L solution bag to a typical pressure setting (e.g., 15 mm Hg) through the tubing/filter set intended for use with the insufflator, and compare it to the flow established for that unit during acceptance testing. For this test, compute the flow using the following formula: flow (L⁄min) =

(3 L) × (60 min) fill time (sec) sec⁄

(This measurement may differ markedly from the manufacturer’s specified maximum flow rate if it is specified as an instantaneous flow or is not adjusted for flow resistance of the tubing set and filter. It is important to minimize flow resistance in the connection between the insufflator tubing set and the reservoir bag [e.g., do not use a Veress or hypodermic needle for this connection]. If a trocar cannula or IV stopcock is used for this connection, it should be maintained as a permanent test device because flow resistance of stopcocks and cannulae varies significantly.) 2.11 Low Flow. With the insufflator set to minimum flow setting, measure the time required to fill a 500 mL IV reservoir bag to a typical pressure setting (e.g., 15 mm Hg) through the tubing/filter

4

flow (L⁄min) =

(0.5 L) × (60 sec⁄min) fill time (sec)

3. Preventive Maintenance 3.1

Clean the exterior (interior, if required).

3.2


3.3

Calibrate pressure settings, if required.

3.4

Replace filters, if required.


Before returning to use Ensure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Attach a Caution tag in a prominent position so that the user will be aware that control settings may have been changed.



Mammography Units Used For: Radiographic Units, Mammographic [12-425]

Commonly Used In: Radiology departments, breast clinics Scope: Applies to mobile and stationary screening x-ray mammography units that use a screen-film receptor; xeroradiographic and digital receptor systems are not covered here specifically, although many of the following tests will apply to these systems; biopsy systems are also not covered in this procedure Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Mammography units use x-rays to produce a film image of the breast (a mammogram) that provides information about breast morphology, normal anatomy, and gross pathology. Mammography is primarily used to detect and diagnose breast cancer, as well as to evaluate palpable masses and nonpalpable breast lesions. A mammographic radiographic system consists of an x-ray generator, an x-ray tube, a positioning assembly, a compression system, a Bucky grid to reduce scatter radiation, a radiation shield, and an image recording system. X-ray generators for mammography are usually high-frequency (they convert the 50- or 60-cycle input voltage to a frequency as high as 100 kilohertz) or constant-potential (they supply a ripplefree, continuous voltage to the x-ray tube, regardless of the input power). For screen-film mammography, the kilovoltage (kV) settings range from 20 to 35 kV; this narrow range accentuates the subtle density differences in breast tissue. X-rays are produced by the x-ray tube, which usually has a rotating anode that dissipates heat produced during exposure. A molybdenum (Mo), tungsten (W), or rhodium (Rh) target on the anode receives the electron



Time Required

beam from the cathode and emits x-rays. Mo, aluminum (Al), and/or Rh filters are placed in the path of the x-ray beam to absorb unwanted x-rays. The x-rays that pass through the filter are shaped by a collimator or by cone apertures. Currently, five target/filter combinations for screen-film mammography are available: Mo/Mo, W/Mo, W/Rh, Mo/Rh, and Rh/Rh. The target/filter combination selected for imaging depends on the thickness and density of the breast after compression. An automatic exposure control (AEC) device is used to terminate x-ray generation when a radiation sensor behind the film cassette senses the proper exposure. AEC devices can automatically compensate for technique variance and patient anatomy (breast thickness), thereby reducing radiation exposure and retakes. The positioning assembly is capable of vertical and rotational movement to adjust for different patient heights and breast sizes and to permit the acquisition of images from various angles around the breast (e.g., craniocaudal, mediolateral). A compression system, either automatic or manually operated, is used to uniformly reduce the thickness of the breast to facilitate


Inspection and Preventive Maintenance System x-ray beam penetration and maximize the amount of tissue imaged. In screen-film mammography, the image recording system uses high-detail fluorescent screens that convert x-rays to light photons and that are in contact with a single- or double-emulsion film. Xeromammography, a method of electrostatic image recording using charged photoconductive plates, is still available on some mammography units.

Citations from Health Devices Mammography units [Evaluation], 1989 Jan; 18(1):3-53. Quality assurance in screening mammography [Clinical perspective], 1990 May-Jun; 19(5-6):152. Mammography units [Evaluation], 1990 May-Jun; 19(5-6):153-98.

Test apparatus and supplies Ground resistance ohmmeter

Wear a lead apron during all radiation testing and maintain a safe distance between yourself and the x-ray tube. It should not be necessary to place hands or fingers in the x-ray beam; if this is unavoidable, wear lead gloves. For repeated exposures, as required by some of the tests in this procedure, allow adequate time between exposures to prevent the x-ray tube from overheating. Do not remove high-voltage cables from the wells with the power on. When removing them, ensure that the cables are completely discharged by repeatedly contacting the conductor to the ground as soon as the cables are removed from the wells. For tests of the AEC and of image quality, it is imperative that an optimally performing film processor be used. This film processor should be the one that is normally used to process all mammograms. Also, the technical tests should be undertaken using the same screen-film combination that is used for acquiring mammograms.


Procedure

Noninvasive mammographic kVp meter

Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

Noninvasive timer (may be included with the kVp meter) Ionization chamber with electrometer, or a combination exposure meter, capable of making exposure measurements in the mammography energy range and specifically calibrated for this purpose Five high-purity (>99%) aluminum filters measuring 10 cm × 10 cm × 0.1 cm 10 cm of stiff wire Four coins or lead markers One dozen sheets of 18 cm × 24 cm mammography film from same batch One dozen sheets of 24 cm × 30 cm mammography film from same batch One 18 cm × 24 cm mammography cassette with screen One 24 cm × 30 cm mammography cassette with screen Densitometer Ten pieces of 15 cm × 15 cm × 1 cm plexiglass American College of Radiology (ACR) accreditation mammography phantom Oscilloscope (calibration only) High-voltage divider (calibration only)

2

Special precautions

This procedure is intended to ensure adequate system performance and maintenance. It should not be construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations. Such regulations and standards may include testing beyond that provided below and may also require documentation by a certified medical physicist. For acceptance testing, we strongly recommend contracting with a medical physicist. Acceptance testing is crucial because it generates data on baseline performance of the device.


Chassis/Housing. Examine the exterior of the mammography unit for cleanliness and general physical condition. Be sure that all hardware is present and secure and that there are no signs of serious abuse. Check the movements of the Carm assembly, both for rotation and vertical movements, ensuring that all of its movements


Mammography Units are smooth and that the locks function adequately. Also check during these tests that the film cassette is retained securely but that it is not difficult to insert or remove. Check the condition of the operator shield and the patient face shield. 1.2

Mounts/Fasteners. Ensure that the mammography unit is securely mounted on the floor so that it is not likely to become unstable when a patient is leaning on the breast platform or when the technologist is moving the C-arm assembly.

1.3

Casters/Brakes. For mobile mammography units, verify that the wheels turn and swivel, as appropriate, and look for accumulations of dirt and grime around the wheels. Also, check the operation of brakes and the adequacy of the park positions of the C-arm assembly and of any other components likely to move during transport.

1.4

1.5

AC Plug/Receptacles. For line-powered mammography units, examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the unit has electrical receptacles for accessories (e.g., printers), verify the presence of line power and insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacles. Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with correct polarity. Also check line cords of battery chargers.

1.6


1.7


1.9

Cables. Inspect any cables (e.g., from the AEC detectors to the generator, cable to footswitches) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent

rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter. 1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate connectors. If keyed connectors are used, make sure that no pins are missing and that the keying is correct. Also, check the mechanical connections, particularly of the compression paddles and of the magnification platforms. Ensure that the connections permit safe and adequate attachment of these devices. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., very large preset density change or a kVp that is too low), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches (x-ray initiation, technique selection, filter selection, focal spot selection, compression and decompression switches, preset density change, etc.) for physical condition, secure mounting, and correct motion. Check that control knobs, if present, have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the inspection, be sure to check that each control and switch performs its proper function. For the radiographic exposure switches, ensure that they do not stick and that continuous pressure is required to continue exposure. Release of pressure should immediately terminate exposure. Also pay close attention to the operation of the compression and decompression switches. Ensure that, where provided, automatic decompression follows exposure. 1.15 Motor/Pump/Fan/Compressor. Check the physical condition of the motor-driven compression mechanism. Also, ensure that the cooling fan in the tube head assembly is clean and operates adequately. Clean and lubricate if necessary and note this in Items 3.1 and 3.2 of the inspection form. 1.18 Indicators/Displays. During the inspection, confirm the operation of all lamps, indicators,


3

Inspection and Preventive Maintenance System meters, gauges, and visual displays on the unit. Examples of indicators and displays are technique settings, choice of focal spots, filter in use, breast thickness, source-to-image distance (SID), and C-arm rotation indicators. Include checks of the light field in this test. 1.20 Alarms. Induce conditions to activate audible and visual alarms (for example, x-ray exposure, backup timer activation). Check that any associated interlocks (e.g., no exposure if there is no film cassette in the Bucky) function. If the unit has an alarm silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions (e.g., long exposure times). Instruct users to document activation of these alarms to ensure that they are functional.

2.2

Leakage Current. For mobile mammography units, use a safety analyzer to measure leakage current. The chassis leakage current to ground should not exceed 300 µA. Note that for existing mobile units, leakage currents of up to 500 µA are deemed not to pose a hazard, but, if the leakage current is between 300 and 500 µA, a documented maintenance schedule should be implemented to ensure the integrity of the grounding connection. Permanently wired equipment should be tested before installation. With all grounds lifted, leakage current should not exceed 5 mA.

2.3

Accuracy of kVp. Use a noninvasive kVp meter capable of making measurements in the mammographic energy range. The kVp meter should have been previously calibrated against a highvoltage divider on the type of generator that powers the mammography unit. Use the kVp meter in accordance with the recommendations of the meter’s manufacturer (e.g., the distance at which the kVp meter has to be placed).

1.21 Audible Signals. Operate the device to activate any audible signals (for example, radiographic exposure). Confirm appropriate volume.

Make measurements at a minimum of three kVp settings that span the range normally used at your facility. For units that have two focal spots, measurements should be made using each focal spot at the tube current setting appropriate for the focal spot in use. After appropriate corrections have been applied to the measured kVp readings (e.g., for filtration), the measured kVp should be within ±5% of the preset kVp.

1.22 Labeling. Check that all necessary certification labels, warning labels, technique charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories (e.g., full and spot compression paddles, grids, magnification platform, diaphragms, and cones).


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the ground pin (or the ground for hard-wired systems) and the accessible conductive surfaces on the mammography unit. The resistance should not exceed 0.5 Ω. Handswitches and footswitches that are powered from low voltages need not be grounded. Although confirmation of grounding integrity provides reasonable assurance of safety, NFPA 99 calls for voltage measurements for installed devices in the patient vicinity. Using a voltmeter, measure and record the voltage between a reference grounding point (e.g., the grounding pin of an electrical receptacle or some other known ground) and exposed (i.e., unpainted and not anodized) metal on the chassis. A voltage reading below 500 mV is acceptable for general care areas in existing construction.

4

If a consistent significant error between the preset kVp and the measured kVp is detected, further testing with a high-voltage divider may be required to identify the problem. 2.4

Timer Accuracy. Use a noninvasive timer to measure the accuracy of the time settings. If the noninvasive kVp meter also displays exposure times, it is acceptable for this test. Follow the manufacturer’s recommended technique for making time measurements. Measure at a minimum of three time settings spanning the range normally used at your facility. For all measurements, use a fixed tube voltage setting of 28 kVp. If the time settings are not displayed on the mammography unit, calculate them from the mAs values by factoring out the mA the unit uses at 28 kVp for that focal spot. Make measurements for both focal spots, where available. The difference between the measured time and the preset time should not exceed ±1 msec or ±5% of the preset time, whichever is greater.


Mammography Units 2.5

mR with no added filters in the beam. These kVp, mAs values should be held constant during the whole course of this test.

Linearity of mAs. Use an ionization chamber with an electrometer (or a combination exposure meter) to measure the exposure in mR for this test. The devices should have been specifically calibrated using mammographic energy ranges. The ionization chamber should be placed centrally in the x-ray beam, with the compression paddle removed.

Record the initial exposure value (in mR) with nothing in the primary beam (i.e., 0 mm of aluminum). Then add aluminum filters in 0.1 mm steps up to a total of 0.5 mm, and obtain an exposure reading for each 0.1 mm addition. Plot mR values against aluminum thickness on semilog paper (mR vertically on log scale). Read the amount of aluminum thickness required to drop the initial mR value by 50%. This is the HVL. The measured HVL should comply with the following equation:

Dial up a midrange kVp setting (e.g., 28 kVp). Make radiographic exposures at this fixed kVp, using a minimum of at least three mAs settings that span the range normally used. Record the exposure values (in mR) from the electrometer or exposure meter for each exposure. Calculate the mR/mAs for each exposure and average the calculations. Each individual mR/mAs value should be within ±10% of the average mR/mAs value. 2.6

Exposure Reproducibility. Use one of the above mR/mAs values at 28 kVp as the one value to be used for evaluating short-term and long-term reproducibility of the mammography unit. For the short-term test, make a minimum of four exposures at the same mAs over a span of 15 minutes. The mR/mAs values should have a coefficient of variation no larger than 5%. For long-term reproducibility, simply mark the current average mR/mAs value on a trend chart together with values recorded at previous tests.

HVL ≥ [(kVp/100) + 0.03] mm Al

For example, at 28 kVp, the HVL should be a minimum of 0.31 mm of aluminum. Previous HVL values should be compared with the current measurement; a change in HVL may indicate tube deterioration. 2.8

It is critical that identical test conditions (e.g., same chamber-electrometer, chamber at same distance from focal spot, same technique, absence of compression paddle) be maintained for accurate assessment of long-term reproducibility. Long-term reproducibility should be within ±5% of the average. 2.7

Half-Value Layer (HVL). Use high-purity aluminum filters for this test. This test should be conducted with the compression paddle in place and at a kVp setting commonly used to image a compressed breast 4 cm thick so that the derived HVL may be used to calculate the average glandular dose (see Item 2.14). Position the compression paddle as close as possible to the x-ray tube. Place the ionization chamber on the cassette table, roughly 4 cm in from the patient edge of the table. Collimate the beam so that only the sensitive area of the chamber is fully exposed. Check this with the light field. Set the mammography unit to operate at the kVp setting that would be commonly used to image a compressed breast 4 cm thick (e.g., 28 kVp). Select the mAs value that produces an exposure of around 500

Collimation. Place an 18 cm × 24 cm film cassette in the cassette tray. Place a larger nonscreen film (24 cm × 30 cm) on top of the cassette table, such that it extends beyond the patient edge of the cassette table by about 4 cm. Position a 10 cm stiff wire on the larger film such that it is aligned with the patient edge of the cassette table. Next, turn on the light field and place one coin at each of the other three sides of the field defined by the light field. The outer edges of the coins should mark the edges of the light field. Finally, place a fourth coin in the bottom left corner of the light field to provide orientation information. (See Figure 1 for wire and coin placement.) Record the SID in use on the mammography unit. Then make an exposure and process both films. On the 18 cm × 24 cm film, ensure that no area beyond the outer edges of the coins can be seen on the film. On the larger film, measure the distance from the wire edge to the edge of the x-ray field. This distance should be no greater than 2% of the SID. Note that this 2% criterion is valid only for the side that is adjacent to the patient’s chest. Repeat this test for the 24 cm × 30 cm film size in the cassette table and for all collimators in use on the system. The same criteria apply to all film sizes and for all collimators.

2.9

AEC Object Thickness Compensation. Place 4 cm of 15 cm × 15 cm plexiglass on the cassette table. Ensure that it covers the AEC detectors. Bring the


5

Inspection and Preventive Maintenance System compression paddle down to touch the top of the stack. Set the mammography unit to operate at the commonly used kVp for imaging a compressed breast 4 cm thick (e.g., 28 kVp). Use the standard screen-film combination utilized at your facility as the receptor in the cassette holder. Make an AEC-controlled exposure. Process the film on the standard film processor used to process all mammography films, having checked that it is performing optimally. Use a densitometer to measure the optical density of the phantom image at a point about 4 cm in from the edge of the phantom. The optical density should measure in the range of 1.2-1.4 OD, or some other value that the radiologists have had programmed into the unit. Periodic checks should result in optical density changes within ±0.1 OD. If the measured optical density falls within the acceptable range, repeat the test using identical setup conditions but with varying amounts of plexiglass on the cassette table. At a minimum, check the optical density at 2 and 6 cm of plexiglass. All films used in this test should come from the same batch, and for each check the film must be loaded into the same cassette for the whole test. The optical density of all processed films should agree to within ±0.3 OD of the optical density at 4 cm of plexiglass. Repeat this test using the magnification imaging mode on the mammography unit. The same criteria apply.

2.10 AEC kVp Compensation. Place 4 cm of plexiglass on the cassette table. Ensure that it covers the AEC detectors. Bring the compression paddle down to touch the top of the plexiglass stack. Load a standard film-screen cassette into the cassette holder for all checks in this test. Make a series of AEC-controlled exposures of the 4 cm thick plexiglass at different kVp values. At a minimum, use four kVp settings that span the range commonly used. For each exposure at a given kVp, process the film on an optimally performing processor. Read the optical density of the phantom image using a densitometer. The optical density of all films at all kVp settings checked should agree to within ±0.3 OD. Repeat this test using the magnification imaging mode. 2.13 Image Quality. Place the ACR accreditation test phantom on the cassette table. Bring the compression paddle down to touch the top of the phantom. Load a standard screen-film cassette into the Bucky. Dial up 28 kVp on the mammography unit (or the kVp commonly used at your facility for this thickness of compressed breast) and acquire an image using an AEC-controlled exposure. Process the film using the standard film processor used for all mammography films, having first ensured that it is performing optimally. Once processed, the film should be viewed on the viewbox normally used to display mammograms. It should be possible to see a minimum of four fibrils, three speck clusters, and three masses.

Figure 1. Collimation test setup

6


Mammography Units TABLE 1. Glandular Dose (in mrad) for 1 Roentgen Entrance Exposure to a 4.2 cm Breast Thickness — 50% Adipose/50% Glandular Breast Tissue Using a Mo/Mo or W/Al Target Filter Combination X-Ray Tube Voltage (kVp) HVL

23

24

26

27

0.23 0.24

116 121

124

0.25

126

129

131

0.26 0.27

130 135

133 138

135 140

138 142

0.28 0.29 0.30

140 144 149

143

142 146 151

144 148 153

146 150 155

0.31

154

156

157

0.32 0.33

158 163

160 165

0.34

168

0.35 0.36 0.37 0.38 0.39 0.40

25

28

29

30

147 151 156

149 153 157

154 158

159

159

160

161

162

163

164

162 166

163 168

164 169

166 170

167 171

168 173

168 173

170 174

171 175

180 185

170

171

172

173

174

175

176

177

178

179

190

174

175 179

176 181 185

177 182 186

178 183 187

179 184 188

180 185 189

181 185 190

182 186 191

183 187 191

194 199 204

190

191

192

193

194

195

195

208

196

197 201

198 202

198 203

199 204

200 204

213 217

206

207

208

208

221

211

212 215

212 216

225 230

220

234 238

0.41 0.42 0.43

31

32

33

W/Al Target-Filter Combination

170 175

0.44 0.45 Source: American College of Radiology. Mammography quality control manual. Revised ed. 1994:163.

2.14 Average Glandular Dose to Standard Breast. The average glandular dose is determined by using the HVL value measured in Item 2.7 together with the entrance exposure measured in air for imaging the ACR mammography accreditation phantom. To measure the entrance exposure, place the phantom on the cassette table, ensuring that the phantom completely covers the sensitive area of the AEC detectors. Next, set the ionization chamber at one side of the phantom such that its center is 4 cm in from the patient edge of the cassette table and also vertically in alignment with the top of the accreditation phantom. Secure the chamber in this position. Make sure that the x-ray field completely envelops both the phantom and the ionization chamber. Lower the

compression paddle so that it is just in contact with the chamber and the phantom. Set the mammography system at the kVp setting commonly used to image a compressed breast 4 cm thick (note that this kVp should match the value used for measuring the HVL in Item 2.7), and engage the AEC system. For a mammography system provided with a variable SID, record the SID together with the technique settings. Make an exposure of the phantom and record the mR value. This is the entrance exposure for the mammography phantom. Using the HVL measured in Item 2.7 and the entrance exposure measured in this test, the average glandular dose may be calculated as follows: a. Determine the target/filter combination of the system under test. If it is a Mo/Mo system


7

Inspection and Preventive Maintenance System TABLE 2. Glandular Dose (in mrad) for 1 Roentgen Entrance Exposure to a 4.2 cm Breast Thickness — 50% Adipose/50% Glandular Breast Tissue Using a Mo/Rh Target Filter Combination X-Ray Tube Voltage (kVp) HVL

25

26

27

28

29

0.28 0.29 0.30

149 154 158

151 156 160

154 158 162

31

32

159 162

163

0.31

163

164

166

166

167

167

0.32 0.33

167 171

169 173

171 175

171 176

171 176

172 176

172 176

0.34

176

178

179

179

177

180

180

180

0.35 0.36

180 185

181 186

183 187

181

181

183 187

184 188

185 188

185 189

186 190

187 191

0.37 0.38 0.39

189 193 198

190 194 199

191

191 196 200

191 196 200

192 197 201

193 197 201

193 197 202

194 198 202

195 199 203

195 199 203

200 204

0.40

202

0.41 0.42

206 211

203

204

204

205

205

206

207

208

208

208

207 211

208 212

208 212

209 213

209 213

210 214

211 215

212 216

212 216

212 217

0.43 0.44 0.45 0.46

215

216

217

217

218

218

219

219

220

220

221

220 224

220 224 228

221 225 229

221 225 229

222 226 230

222 226 231

223 227 231

223 227 232

224 228 233

224 228 233

225 229 234

0.47

233

233

234

235

235

236

237

237

238

0.48 0.49

238

238 242

239 243

240 243

240 244

241 244

241 245

242 245

242 246

247

247

248

248

249

250

251

251

252 257

253 257

254 258

254 258

255 259

261

261 265 269

262 266 270

263 267 271

264 268 272

0.56

275

276

276

0.57 0.58

279

280 284

281 285

288

289

0.50 0.51 0.52 0.53 0.54 0.55

30

0.59 0.60

33

34

35

293

Source: American College of Radiology. Mammography quality control manual. Revised ed. 1994:164.

or a W/Al system, use Table 1. For Mo/Rh and Rh/Rh systems, use Table 2 and Table 3, respectively. b. Go down the first column in the table until you find the HVL value measured in Item 2.7. c. Progress along the row at this HVL until you are in the column headed by the kVp setting used to measure the entrance exposure in this test.

8

d. The value at the intersection of the HVL row and the kVp column is the normalized glandular dose (i.e., the dose that applies to an entrance exposure of 1 R). Multiply the normalized glandular dose by the entrance exposure measured in this test. The value obtained is the average glandular dose for the system under test. The average glandular dose for the system under test should not exceed 300 mrad (3 mGy).


Mammography Units TABLE 3. Glandular Dose (in mrad) for 1 Roentgen Entrance Exposure to a 4.2 cm Breast Thickness — 50% Adipose/50% Glandular Breast Tissue Using a Rh/Rh Target Filter Combination X-Ray Tube Voltage (kVp) HVL

25

26

27

28

29

0.28 0.29 0.30

150 155 160

155 160 164

159 164 168

30

31

168 172

176

0.31 0.32

165 169

168 173

172 177

174 181

0.33

174

178

181

0.34 0.35

179 184

183 187

0.36

189

0.37 0.38 0.39

193 198 203

0.40 0.41 0.42

34

35

180 184

182 186

188

185

188

190

192

186 190

190 194

193 197

195 199

196 201

199 203

192

195

198

201

204

205

207

209

196 201 206

199 204 208

202 207 211

205 209 214

207 211 216

209 213 217

211 215 219

213 217 221

219 223

221 224

208

211

213

216

218

220

221

213 218

215 220

217 222

220 224

222 226

224 228

225 229

223

224

226

228

227 231

228 232

230 234

232 236

0.43

222

224

226

228

230

232

0.44 0.45 0.46

227 232

229 234

231 235 239

233 237 241

235 239 243

237 241 245

233

235

236

238

240

238 242 246

239 243 247

240 244 248

242 246 250

243 247 251

247 251

249 253

250 254

251 255

252 256

254 258

255 259

0.49

257

258

259

260

261

262

0.50 0.51

261

262 266

263 267

264 268

265 269

266 270

0.52

270

271

272

273

274

0.53 0.54 0.55

275

276 279 283

276 280 284

277 280 284

278 281 285

0.47 0.48

32

0.56

33

288

0.57 0.58

288

289

292 296

293 297

0.59

300

0.60

304

Source: American College of Radiology. Mammography quality control manual. Revised ed. 1994:165.

As an illustration of the above method, assume that on a Mo/Mo system, the HVL measured at 28 kVp was 0.33 mm Al and that the entrance exposure measured at 28 kVp was 500 mR (0.5 R). From Table 1, the normalized glandular dose is 170 mrad. Multiplying the normalized dose by the entrance exposure of 0.5 R provides the glandular dose value of 85 mrad.


Clean exterior and interior, if needed.

3.2

Lubricate according to the manufacturer’s instructions (e.g., clean and lubricate casters, if needed).

3.3

Calibrate the unit, if needed.

3.4

Replace items on the unit, if needed.

4. Acceptance tests Acceptance testing is typically performed by a medical physicist.


9


Before returning to use Ensure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. If the unit is being used at

10

home, ensure that all controls are set correctly before it is returned to the patient. Attach a Caution tag in a prominent position so that the user will be aware that control settings may have been changed.


Procedure/Forms 440-0595

Medical Gas/Vacuum Systems Used For: Alarms, Central Gas System [15-824] Medical Gas and Vacuum Systems [18-046] Medical Gas Outlets [17-682] Valves, Medical Gas and Vacuum [18-044]

Also Called: Piped medical gas systems, medical-surgical gas systems, nonflammable medical gas systems, vacuum systems Commonly Used In: Most patient care areas and some laboratories Scope: Applies to any piped medical gas system (including oxygen, air, and nitrous oxide) and central vacuum system; does not replace full testing according to NFPA 99, Standard for Health Care Facilities, which must be conducted following any new construction or modification; does not apply to medical air compressors, dryers, contaminant monitors, or purification systems, which must receive regular IPM for safe and reliable operation (see Medical gas and vacuum systems, Health Devices [Guidance article], 1994 Jan-Feb; 23:4-41) Type



Time Required

Major

After any renovations, modifications, and/or additions to the medical gas system

Months

Approximately 100 outlets/day in occupied areas; 250 outlets/day in unoccupied areas

Minor

12 months*

Months

Same as above

* Although we recommend that a major inspection (Items 2, 3, 5, 6, 7, and 8) be performed annually for medical gas and vacuum systems, we understand that, for some hospitals, this may not be practical. Increasing the inspection interval up to but not more than two years is acceptable in these cases. However, some frequently used outlets and inlets (e.g., in the emergency room) are subject to wear, and more frequent performance of Items 5 and 6 should be considered to ensure their safe operation. Where alarm-system test buttons are provided, audible and visual alarm indicators should be tested monthly (NFPA 99, Appendix C, Section C-4.2.17).

Overview

multiple fatalities in some institutions, in at least 15 hospitals in North America.

In an actual case, workers renovating an emergency room inadvertently cross-connected the nitrous oxide and oxygen supply lines. As a result, 20 outlets labeled “oxygen” actually delivered nitrous oxide for more than six months before the hospital’s chief anesthesiologist discovered the error. We are also aware of other cases in which similar incidents have occurred. Mix-ups in medical gas connections have caused deaths, including

Piped gas systems present certain characteristic hazards, usually related to their original construction, modification, or repair. However, problems can develop during the working lifetime of the systems, particularly in medical compressed air systems, outlets, and vacuum inlets. The hazards include plumbing errors, as described above; use and degradation of materials incompatible with the gases to be delivered;



●


Inspection and Preventive Maintenance System obstruction of flow by migration of material left in the pipelines; gas contamination by residual debris or accumulated foreign matter (e.g., scale, hydrocarbons, microorganisms, moisture, or dirt in medical compressed air pipelines); gas contamination due to chemical interaction, including fire and explosion, between the gases and pipeline components or foreign matter; and gas contamination due to a contaminated source (e.g., air intake near diesel exhausts). (See Cleaning contaminated MGVSs, Health Devices 1994 Jan-Feb; 23:34-5.) Problems related to how the system is used and maintained during its lifetime include leaking outlet seals, clogged vacuum inlets and piping (e.g., by dust or by body fluids), inadequate particulate filtration, corrosion of automatic condensate drains, wear or embrittlement of valve seals, physically damaged or loose outlets, wear of compressor or pump seals and bearings, and pressure sensor drift. NFPA 99, which is mandatory in some localities, states in Chapter 4, the section on gas and vacuum systems, that the piping systems must be tested following new construction, addition, renovation, or repair. (In this procedure, references to NFPA 99 refer to the 1993 edition, unless otherwise specified.) It specifies tests for zone-valve and alarm-system function, leaks, and cross-connections (in addition to other items) and provides specific criteria for gas analysis and monitoring. Installers are required to perform some testing of new or modified systems; independent testing of these systems before they are used for patient care is recommended. NFPA 99 also calls for the healthcare facility to develop and implement procedures for testing medical gas and vacuum systems and their related alarm systems; this IPM procedure should satisfy this requirement for piping and alarm systems testing. The standard also requires that proper medical gas concentration be verified and that the supply systems be tested after any breach of or modification to the system. Also, in its 1995 Accreditation Manual for Hospitals, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) requires that the hospital have documented plans and procedures for routine testing, inspection, and maintenance of utility systems (e.g., medical gas and vacuum systems) to ensure that these systems operate properly and will continue to operate in an emergency. The JCAHO manual also indirectly refers to NFPA 99 through NFPA 101, Life Safety Code, and the American Institute of Architects’ Guidelines for Construction and Equipment of Hospital and Medical Facilities, which base design and safety requirements on NFPA 99. Also, because medical gases are drugs, the JCAHO manual, in its section

2

on medications, requires that medications (i.e., drugs) be prepared, delivered, and administered according to appropriate laws and standards of practice, which again indirectly refers to NFPA 99. Hospitals should insist that those responsible for construction document the test methods and results as required in NFPA 99; this documentation, as well as documentation from analytical tests, should be kept on permanent record. Hospitals should also obtain documentation verifying the purity of medical gases from suppliers. In addition, the hospital should perform acceptance inspection and testing of the medical gas and vacuum systems independently of tests conducted by the installing contractor. The hospital’s facility engineering, anesthesia, clinical engineering, or respiratory therapy department may perform this testing. If adequate personnel, experience, or equipment is lacking, an independent testing organization that specializes in this type of activity can be employed. In a typical hospital, piped medical gas and vacuum systems are frequently repaired, modified, and expanded. These activities may include replacing defective outlets or inlets, valves, or piping; relocating outlets; and adding outlets to the existing system. Identification plates and other labels are often removed during this activity, increasing the probability of error. Major changes to systems (e.g., construction of a building addition) are not included in this category. ECRI knows of no procedure other than this one that enables the hospital to safely, easily, accurately, and completely inspect only the modified portion of the system. The procedures outlined in NFPA 99 are clearly intended to test newly constructed systems that have not yet been put into service. The process described by that standard requires testing at different stages of installation before proceeding with additional installation. For example, both the 150 psig pressure test (Section 4-5.1.2.1) and the blow-down (or initial purging) test (Section 4-5.1.2.2) must be performed before system components, such as pressureactuating alarm switches, alarms, manifolds, pressure gauges, and pressure relief valves, are installed.* Pressure testing and purging of the completed system must also be performed. The hospital should have the contractor who installs the system and an outside testing organization provide documentation of conformance * Pressure is measured relative to one of two reference points: standard atmospheric pressure (14.7 psia) or zero absolute pressure; psig refers to gauge pressure (i.e., the reference pressure to which the measuring device is calibrated, typically standard atmospheric pressure), and psia refers to absolute pressure (i.e., reference pressure of zero).


Medical Gas/Vacuum Systems with all portions of NFPA 99, Chapter 4, for all new medical gas and vacuum system construction.

Pressure measuring devices, 0 to 100 and 0 to 400 psig, with 5% accuracy

Performing certain portions of the NFPA 99 testing procedure requires a complete shutdown of the system. Thus, the hospital must provide a large number of alternative gas or vacuum sources (e.g., cylinders with regulators, portable suction systems) and may need to minimize gas or vacuum usage (e.g., by rescheduling surgery) to test the entire medical gas or vacuum system following modifications.

Flowmeter, 0 to 250 L/min, with 5% accuracy (flowmeter manufacturers usually supply calibration curves for a range of common gases with each instrument); alternatively, if a flowmeter calibrated for the gas being measured is not available, use the following formula:

Because of the difficulty and expense entailed and the possible compromise of patient care, hospitals are reluctant to fully test modified systems, except after major modifications or additions. However, failure to fully test systems can allow serious problems (e.g., cross-connections, which are usually thought of as problems associated only with new systems) to go undetected.

Flow control valve(s)

ECRI has developed a simple technique that permits testing and inspection both of existing systems and of modified portions without affecting the entire hospital at once; this procedure also allows detection of most problems that can develop during system modification or system operation.


Corrected Flow = Indicated Flow

 √ Density (Design Gas) Density (Test Gas)

Test equipment that combines the functions of the above test devices or that automates the testing described in this procedure is available and may be substituted. Also, portable pneumatic calibrators or anesthesia machine calibrator/analyzers may be suitable alternatives. Note: Medical gas systems may contain contaminants that may affect test instruments; periodic cleaning, in addition to calibration, may be needed. Source of oil-free dry nitrogen with a pressure regulator to supply a test gas (see the section on compressed gases in “IPM Safety” behind the Guidance Tab of this binder)

Restricted draw in Schrader-type vacuum inlets [User Experience NetworkTM], 1993 Aug-Sep; 22:426-7.

Hoses and adapters to connect the pressure or vacuum measuring device and test gas cylinder to each gas outlet

Color-coded compressed medical gas hose changes color [Hazard], 1986 Apr; 15:106-7.

Hand tools, such as screwdrivers, wrenches (including Allen wrenches), and pliers

Medical gas and vacuum systems [Guidance article], 1994 Jan-Feb; 23:4-41. Should vacuum pump effluent be treated? [User Experience NetworkTM], 1994 Jul; 23:310. Use of filters on medical gas system outlets and vacuum system inlets [User Experience NetworkTM], 1994 Dec; 23:494-5. Soldered medical gas piping [User Experience NetworkTM], 1995 Mar; 24:127.

Test Apparatus and Supplies Oxygen analyzer that will remain accurate in the presence of and not be damaged by nitrous oxide (analyzers used with anesthesia units are probably satisfactory) Vacuum measuring device, 0 to 30 inches of mercury (in Hg; 0 to 760 mm Hg), with 5% accuracy

Labels, such as “Do Not Use” and “System Under Test” Sampling bottles and filters for collecting samples for analysis; typically, these are obtained from the laboratory that will conduct the analysis

Special Precautions General. Before testing, alert clinical personnel, and ensure that an adequate supply of appropriate gas cylinders and/or vacuum sources is available in the immediate area as a backup for piped gases. Provide ample preparation time, especially if a system or zone must be shut down for testing. Never disconnect or test any medical gas outlet, vacuum inlet, or system serving a patient or patient care area without the approval of clinical personnel. Do not perform any test that may interfere with the gas supply to patients (e.g., turn off zone valves, pressurize with another gas or to a pressure different


3

Inspection and Preventive Maintenance System from the usual supply pressure) while that section of the system is in use for patients. Never use oxygen as a test gas (e.g., pressure test) — use only oil-free dry nitrogen. Do not allow smoking or other open sources of ignition in the immediate test area, especially in the presence of nitrous oxide or oxygen. Because of high pressure, take special care when inserting and disconnecting adapters from the outlet under test. Also, before testing, make certain that the adapter is securely locked into the outlet. Never pressurize (i.e., apply a test gas to) a vacuum system with gauges in the section of the system to be pressurized; this could damage the vacuum gauges. Overpressurizing compressed gas lines, as required for certain sensors (e.g., newly installed or modified systems), can also damage certain sensors, alarm switches, and outlets in these systems. Certain pressure tests must be conducted before these components are installed in the system per NFPA 99, Section 4-5.1.2.1. Purging. When using the test gas (oil-free dry nitrogen) to inspect an alarm panel or to pressurize a piping system, purge the test gas from the system before using it for patients. With the appropriate zone valve closed, open an outlet to depressurize the system. After depressurization, close that outlet; then open the zone valve and each outlet in the zone in order, starting with the outlet nearest the zone valve. You can turn off an outlet before opening the next outlet in the line. Where appropriate (e.g., with oxygen and medical compressed air pipelines), use an oxygen analyzer to verify proper oxygen content at each outlet, or flush each outlet with its labeled gas for approximately 1 min (except nitrous oxide — see the precautions below — and also note that an oxygen analyzer, by definition, will not detect nitrogen or nitrous oxide). Nitrous Oxide. Take special precautions when testing or purging nitrous oxide systems to minimize exposure to the exhausted gas. Although occasional acute exposure to nitrous oxide, which might occur during annual testing, has not been shown to be hazardous, we recommend that you still take reasonable precautions to minimize exposure. For example: Women of childbearing age should not routinely perform this procedure or be in the area during the procedure. Use a length of corrugated tubing (about one inch in diameter) to direct the exhausted gas away from personnel and, where practical, into a ventilation return duct or out a window.

4

Limit purging and flow measurement times from each outlet to 10 sec. (About 200 ft of piping can be purged in this time; correspondingly shorter purge times can be used for shorter piping runs.) Purge the nitrous oxide system last, and leave the room after turning off the outlets. Restrict personnel from entering the room to allow the exhausted gas to dissipate. In a typical operating room, 15 min is adequate. In smaller rooms with lower ventilation room-air exchange rates, such as delivery rooms, dissipation may require 1 hr. Restrict unnecessary entry into the room during this time; the room may be used if essential for patient care.

Procedure This procedure was developed to help hospitals find and correct hazards associated with existing and modified piped medical gas and vacuum systems. It does not replace the full testing required by NFPA 99; it confirms safe operation and is recommended for use by the hospital for independent confirmation of safety and performance only after the construction, tests, and inspection per NFPA 99 have been completed and on an annual basis thereafter. You must perform all items in the procedure on any portion of the system that is repaired or modified before that portion of the system is put into service. Before beginning the inspection, carefully read this procedure; be sure you understand how the gas system and associated equipment are intended to operate, the significance of all controls and indicators, and the alarm capabilities. Begin the inspection procedure by identifying the area to be tested. This may be a room, a special care area, or an area with many outlets. We recommend that each gas outlet be identified with a numbered label or an engraved number on the faceplate. One systematic numbering method consists of starting to the left of a given doorway from a position facing into the room and proceeding clockwise, numbering the outlet stations in the room (see Figure 1). Include ceiling columns (e.g., as in an operating room), as well as surface-mounted stations. Each outlet at a given station is then numbered from left to right. Disconnect equipment from each outlet before performing the inspection of that outlet station. If you are inspecting a system that is already in operation, consult clinical personnel before disconnecting any patient care equipment being used. Inspect every outlet at each station in the area. Because the Universal Inspection Form is not applicable, use the special three-part Medical Gas and


Medical Gas/Vacuum Systems 1.

When all components of the system have been installed and the system is ready to be used, pressurize the appropriate section of the medical gas or vacuum system to 100 psig with oil-free dry nitrogen. On additions and modifications, close the appropriate zone valve before pressurizing so that the section to be tested is isolated from the rest of the system. We recommend using 100 psig (instead of 150 psig, as required by NFPA 99 during the initial pressure test) for testing to reduce the risk of damaging system components. (Verify that components [e.g., pressure sensors] will not be damaged by this test pressure.) However, this does not substitute for pressure testing according to NFPA 99 during installation. Measure the pressure immediately after pressurization to 100 psig and again 1 hr later. After correcting for any temperature changes, confirm that there has been no change in line pressure after the 1 hr period. To correct for temperature changes, use the following formula:

Figure 1. Sample room with 6 stations, numbered clockwise from left, and 18 outlets. Vacuum System Inspection Form provided. Part A of the form is for alarm-panel and zone-valve inspections, and Part B is for medical gas outlet and vacuum inlet inspections. Part C is for documenting medical gas purity analysis. On the appropriate part of the inspection form (on Parts A and B), record the test data and the actions needed and taken. If deficiencies detected during the inspection are serious enough to preclude using an outlet until it is repaired, check both the Action Needed and the Do Not Use columns; label the outlet so that it will not be used and so that it can be quickly identified for future repairs. If the outlet is in an area being used, inform clinical personnel, and make sure that an adequate alternative gas supply is available. If the outlet is usable, check only the Action Needed column. To clearly identify defective outlets on the inspection form, circle unacceptable values, or note specific defects in the Comments section at the bottom of the form. The Status box in the upper right corner of each form provides a quick indication of the condition of the outlets or alarms and valves listed. Check the appropriate box after completing the inspection. If even one outlet, alarm, or valve on the sheet requires servicing, check the Service Required box. The individual who completes the repairs should record the date and his or her initials in the Action Taken column; check the OK column after confirming the satisfactory condition and performance of that item. Check the Passed box in the Status area only after all repairs for all items on that form are complete.

Pressure Testing. All new or modified systems should be pressure tested per NFPA 99, Sections 4-5.1.2.1 and 4-5.1.2.3. We recommend that the following acceptance test be performed by the hospital or an independent agency before a new system or modified portion of the existing system is put into use.

PFinal =

PInitial × TFinal TInitial

where T = absolute temperature measured in kelvins or degrees Rankine* 2.

Area Pressure Alarms. Area pressure alarms should be activated when line pressure varies 20% from normal system pressure. To test the high-pressure alarm, close the appropriate zone valve, and apply oil-free dry nitrogen through a pressure measuring device to one outlet in the zone until the alarm is activated. Measure and record the alarm pressure. To test the low-pressure alarm, bleed system pressure with the zone valve closed until the low-pressure alarm is activated. Measure and record the alarm activation pressures on the top portion of Part A of the Medical Gas/Vacuum Systems Inspection Form. (Note: This test can be performed in conjunction with Item 3.) Check area signal panels, remote indicators (if present), and appropriate gauges for proper

* To obtain a temperature in kelvins or degrees Rankine, add 273.2 to degrees Celsius and 459.7 to degrees Fahrenheit, respectively.


5

Inspection and Preventive Maintenance System With appropriate adapters (which should match outlet labels), check each individual outlet of each gas and vacuum system to determine that test gas is not present at any outlet other than the one connected to the pressurized supply. Disconnect the source of the test gas, and reduce the first system to atmospheric pressure. Repeat this test by pressurizing each additional piping system, one at a time, including vacuum (unless gauges are present). Purge all tested systems in accordance with NFPA 99, Section 4-5.1.3.9, and the special precautions noted previously.

labeling and function or accuracy. Also check audible alarm-silence systems during alarm activation — a visual alarm light should remain on. In addition, check signal panels for deactivation after returning the system to normal pressure. Before placing the system in service, purge it as described in the Special Precautions section and in accordance with NFPA 99, Section 4-5.1.3.9. (Other testing may be completed with the test gas before purging; see the precautions regarding nitrous oxide.) If the alarm panel has test buttons, retesting of audible and visual alarms should be done monthly. 3.

Zone Valves. Zone valves are tested to ensure that the branch served by the zone valve will be closed and isolated in the event of an emergency. Check each zone valve for a label or placard that lists the gas it controls and the area it serves. Also check that a line-pressure gauge is present downstream of the zone valve and that it correctly reads the system pressure by comparing it with a pressure measuring device at an outlet in that area. Close the valve, and bleed the branch to zero pressure. Confirm that the system gauge and pressure measuring device read zero. Record findings on the bottom portion of Part A of the Medical Gas/Vacuum System Inspection Form. Perform a leakage test on all threaded components of the pressurized zone valve using a test solution listed as safe for use with oxygen.

4.

Cross-Connection Testing. This test should only be performed on new systems or following any system modifications. The test must be performed after all outlets are completely installed, including labels, cover plates, and fittings. This will ensure that outlets are connected to and labeled for the appropriate gas system. Do not rely on testing done before final attachment of labels and other identification plates that identify gas outlets. To test new systems or major modifications to existing systems where gas sources can be shut down without disrupting existing patient care, use the following procedure. Reduce all pipelines to atmospheric pressure. Disconnect all sources of test gas from all of the systems with the exception of the one system to be checked. Pressurize this system to 50 psig with oil-free dry nitrogen to avoid disruption to and possible contamination of the existing services.

6

To avoid disrupting patient care when testing modifications to existing systems that are in use, use the oxygen concentration measuring procedure described in Item 5. 5.

Medical Gas Outlets (medical compressed air, nitrogen, nitrous oxide, oxygen, carbon dioxide, and other gases if piped). Examine the condition of the outlet. Check that each outlet is properly labeled with the name of the dispensed gas and that its cover plate is securely fastened. Ensure that color coding is consistent with standards for the gas supplied to each outlet (e.g., green for oxygen, yellow for medical compressed air). Make sure that the adapter specific for the gas dispensed locks securely into the outlet, that the outlet does not leak with the adapter installed, that the adapter is easily removed, and that the valve closes when the adapter is removed. Listen for leaks before and after inserting adapters. Leaks may be corrected by replacing seals (e.g., O-rings, gaskets) in the valve assembly. Attach an oxygen analyzer, a pressure measuring device, and a flowmeter or pneumatic analyzer to the outlet; measure and record the flow and pressure at that flow on Part B of the Medical Gas/Vacuum System Inspection Form. NFPA 99 requires that piping systems be able to deliver flows at the pressures listed in Table 1, Recommended Pressures and Flows. Open the flow-control valve until a flow of 100 L/min is seen. Pressure at that outlet should not Table 1. Recommended Pressures and Flows* Medical Gas

Pressure, psig

Flow, L/min

Oxygen Nitrous Oxide Medical Air Carbon Dioxide Nitrogen

50 to 55 50 to 55 50 to 55 50 to 55 ≥160

≥100 ≥100 ≥100 ≥100 ≥145

*Pressures and flows per NFPA 99, Section 4-5.1.3.8.


Medical Gas/Vacuum Systems drop below 50 psig for all gases except nitrogen, which should not drop below 160 psig at a flow of at least 145 L/min. Some older systems may not be able to meet these requirements. However, if the pressure drops to below 80% of the listed values in older systems or below the required values in newer systems or if the required flows cannot be obtained, corrective action is required. Unacceptable pressure or flow may indicate a blockage in either the distribution piping or the outlet check valve(s). Blowing the piping clear with the outlet removed and cleaning the outlet check valve(s) will usually resolve this problem. (Minimize exposure to nitrous oxide; see Special Precautions.) If the above measures do not resolve the problem, the outlet may have to be replaced or, depending on the severity of the restriction, a portion of the system may need to be modified. Consult with clinical staff to determine the minimum acceptable flow for clinical needs, including the safe operation of life-support equipment. Also consider whether simultaneous use of multiple outlets will further degrade performance. ECRI can provide advice on the most appropriate action to take should a flow-restriction problem exist.

label. This problem may also arise if you use extension hoses to connect equipment to a wall or ceiling outlet. Recheck each time service personnel remove a hose for repair, maintenance, or replacement. Gas hoses should have appropriate connectors for attachment to equipment. Avoid using special adapters for connecting hoses (e.g., DISS to quick-connect fittings) to minimize problems such as gas leaks at the connectors. Color-coded hoses are recommended for this application to reduce the risk of misconnection. Be aware that the color of gas hoses can change over a period of time (see Color-coded compressed medical gas hose changes color [Hazard], Health Devices 1986 Apr; 15:106-7.) Replace any hoses that have changed color or faded. 6.

Vacuum Inlets (vacuum and evacuation vacuum). Inspect the condition of each inlet, as described in Item 5.

Measure and record (on Part B of the Medical Gas/Vacuum Systems Inspection Form) the oxygen concentration to determine that the outlet is delivering the proper medical gas. The oxygen concentration should be 100% at oxygen outlets and 21% at medical compressed air outlets. NFPA 99, Section 4-5.1.3.9, requires the use of gas-specific analyzers for initial testing of new and renovated systems, but for routine testing of installed systems, nitrogen, nitrous oxide, and carbon dioxide outlets should read 0% on an oxygen analyzer. Note that, in an operating system, nitrogen will be at a higher pressure than nitrous oxide. This test can also serve to check for cross-connection in existing systems.

Attach the vacuum measuring device to an inlet and a flowmeter to an adjacent inlet. Measure and record the pressure and flow on Part B of the Medical Gas/Vacuum System Inspection Form. NFPA 99, Section 4-11.2.1.3, requires that the vacuum pressure be at least 12 in Hg (305 mm Hg) while 85 L/min (3 standard cubic feet per minute) flow is being drawn at an adjacent inlet. We recommend that, where practical, the two inlets be on the same branch and that the pressure be measured at an inlet beyond the inlet at which the flow is established. In addition, we recommend noting the maximum flow. Most newer systems will be able to provide 85 L/min at an inlet, although such high flows may not be required for many applications. Some older systems may not be able to meet these criteria; it is then necessary to determine whether corrective action (e.g., cleaning the pipeline) is required to meet clinical needs.

In some hospitals, hoses extend from ceiling connectors to outlets that are suspended at a lower, more accessible height. Although the ceiling connector and suspended outlets may have proper labels and unique fittings for each gas to prevent incorrect connections, the end connections of the hoses and the pipelines to the gas fittings and outlets may be identical. Thus, it may be possible to attach an outlet or connector to the wrong hose. If you have such an installation, make sure that the ceiling connector and outlet linked by a given hose have the same gas

For inlets that have reduced vacuum draw, inspect the interior of each vacuum inlet for accumulated dust or other debris from leaking seals or poor suctioning procedures. Clean the inlet, if necessary, by removing the inlet valve assembly and washing it in warm soapy water (see the section on infection control in “IPM Safety” behind the Guidance Tab in this binder). Using a piece of tubing, suck about a liter of the wash water into the disassembled inlet to clean debris from the inlet section of the pipeline. Rinse the inlet valve assembly with clean water


7

Inspection and Preventive Maintenance System and reassemble the inlet. Remeasure vacuum pressure and flow at the cleaned inlet. Inadequate flow may indicate other problems in the vacuum system (e.g., a clogged pipe). 7.

8.

Master Alarm Panel. Refer to NFPA 99, Section 4-4.1.1.2 and Appendix C-4, for required components and recommended test intervals. Section 4-6.2.3.9 of NFPA 99 requires periodic retesting of audible and visual alarms to determine whether they are functioning properly, and Section C-4.2.16 recommends annual testing of all components of warning systems if testing can be performed without changing system line pressure. Refer to the manufacturer’s instructions for component testing. Medical Gas Analysis. Acceptance testing of medical gas purity is not usually required if purity testing required by NFPA 99 is conducted by an independent test organization when the system is completed. Obtain certificates of purity showing all testing performed by the gas manufacturer for each shipment of gas. For oxygen, nitrous oxide, nitrogen, and carbon dioxide, verify that certificates of purity have been received and filed for each gas shipment, and note this on the Confirmation of Purity section of the inspection form. Include the source of any certificate of purity and the date of the certificate. After installation of a new system, the piping system for these gases should also be tested for gaseous and liquid hydrocarbons, as well as for particulates and gas concentration. We recommend taking gas samples from an outlet nearest the gas source and at the outlet most remote from the source. Refer to Table 2 for recommended maximum allowable levels of contaminants for these gases. NFPA 99, Section 4-3.1.9.8, requires that the quality of the medical compressed air generated on-site be monitored continuously for dew point and carbon monoxide. A gas sampling port downstream of the system pressure regulators is used for this purpose. Reciprocating (oil-less)

8

compressors must also be monitored for liquid (continuously) and gaseous (quarterly) hydrocarbons. Piped medical compressed air systems should also be tested annually for particulates. Independent dew point and carbon monoxide tests should be conducted at least annually for all medical compressed air systems, preferably in the summer when these contaminants are most prevalent, to verify monitor performance. More frequent analyses may be warranted in hospitals with medical compressed air problems until those problems are resolved. For medical compressed air analysis, obtain sampling bottles (as well as instructions for their use) from an analytical laboratory. For annual inspections, sampling can be done at an outlet close to the source. To determine the cause of any problem, it may be necessary to monitor the quality of the outside air at the medical air compressor intake. For all other analyses, take a sample at the farthest outlet locations from the compressor in the piped medical compressed air system. Enter the results of the medical air analysis on Part C of the inspection form. Compare the results to the values listed in Table 2, in which most allowable values meet or exceed the contaminant limits of most of the various concerned agencies. ECRI chose the values listed in the table because we believe they are reasonable to obtain and safe for the particular gas and contaminant based on our review of the several documents that define the composition of medical gases. Judging the level of a particular contaminant relative to this table should be done with caution. Such factors as the measurement accuracy, the sampling location, the sampling technique, and the contaminant itself will affect what should be done. Regardless, a second test, independent of the first, should be made to verify any suspected contamination. Determination of the source of the contamination will direct the course of corrective action (e.g., change of source, purge of pipeline).


Medical Gas/Vacuum Systems


9


10


Medical Gas/Vacuum Systems


11


12



Mobile C-arms Used For: Radiographic/Fluoroscopic Units, Mobile [11-758]

Also Called: Portable C-arms, surgical C-arms Commonly Used In: Critical care areas, emergency departments, and operating rooms Scope: Applies to mobile C-arms capable of fluoroscopy and radiography Risk Level: ECRI Recommended, High; Hospital Assessment, Type

ECRI-Recommende Interval

Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview C-arms provide radiographic and fluoroscopic imaging in surgical, orthopedic, critical care, and emergency care procedures. They are used to image patients in radiolucent beds, stretchers, or tables when it is not feasible to transport the patient to the radiology department. The fluoroscopic feature allows real-time imaging, which permits quick diagnoses and minimal patient time under anesthesia during surgical procedures. C-arms are used in a variety of general surgical, cardiac, and neurological applications, including aneurysm repair, pacemaker implantation, hip replacement, fracture reduction, foreign-body location, needle biopsy, catheter placement, percutaneous lithotripsy, and brachytherapy. These devices also enable special studies, such as the diagnosis of swallowing disorders in patients who cannot readily sit on a standard fluoroscopic table or stand on a footboard. Mobile C-arms can also be equipped with a variety of digital hardware and software options for use in angioplasty, interventional neuroradiology, neurosurgery, and trauma care. Compact, scaled-down fluoroscopic imaging systems called mini C-arms are designed for extremity imaging in the emergency room, the operating room,



Time Required

the physician’s office, the industrial site, and the athletic field. The user can quickly acquire projections of the patient’s anatomy from various angles while continuously viewing the fluoroscopic images. Radiographic imaging capability may not be provided.

Citations from Health Devices Mobile C-arm units [Evaluation], 1990 Aug; 19: 251-91. International Medical Systems Exposcop Plus mobile C-arm system [Evaluation], 1993 Mar; 22:103-21. FluoroScan Mini C-arm unit [Evaluation], 1995 Feb; 25:44-70.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Noninvasive kVp meter (compatible with the x-ray generator being inspected) Noninvasive timer (may be included with kVp meter) Ionization chamber with electrometer or a combination exposure meter


Inspection and Preventive Maintenance System Five filters of 10 cm × 10 cm × 1 mm Type 1100 aluminum

maintenance procedures or frequencies are recommended by the manufacturer.

Ruler with leaded 1 cm or 1⁄2″ markers

This procedure is intended to ensure adequate system performance and maintenance. It should not be construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations. Such regulations and standards may include testing beyond that provided below and may also require documentation by a certified medical physicist.

Large-format x-ray film (30 cm × 30 cm) Patient simulator material (e.g., 8 pieces of 30 × 30 × 2.5 cm plexiglass, or appropriate thickness of aluminum or copper) to bring the unit to midrange technique under automatic brightness stabilization (ABS) control Six pieces of 30 cm × 30 cm × 1 mm lead High-contrast resolution line-pair phantom to 5 lp/mm minimum Low-contrast phantom consisting of two 3/4″ (2 cm) aluminum plates, 7 × 7″ (18 × 18 cm), and one sheet of 1.0 mm aluminum, 7 × 7″ (18 × 18 cm), with two sets of four holes of the following sizes: 1/16″, 1/8″, 3/16″, and 1/4″ (1.0, 3.0, 5.0, and 7.0 mm) (using an alternative low-contrast phantom is acceptable provided that it can be reproducibly used for assessing long-term performance; use the criterion applicable to the phantom selected)

For acceptance testing, we strongly recommend contracting with a medical physicist. Acceptance testing is crucial because it generates data on baseline performance of the device.


Oscilloscope (calibration only) High-voltage divider (calibration only of rotating anode type x-ray tubes)

Check the mechanical operation of the C-arm, including up/down motion, rotation, and wig/wag, ensuring that all movements are smooth; ensure that the arm locks securely at each position.

Special precautions Wear a lead apron and thyroid shield at all times during x-ray exposure. Maintain the greatest possible reasonable distance from the x-ray source and all scattering material. It should not be necessary to place hands or fingers in the x-ray beam; if unavoidable, wear lead gloves. Keep x-ray exposure time to a minimum. Do not remove the high-voltage cables from the wells with the power on. Ensure that high-voltage cables are completely discharged by repeatedly touching the conductor to ground as soon as it is removed from the well. Wear rubber gloves or other appropriate protection when exposed to blood or other body fluids.

1.3

Casters/Brakes. Verify that the casters turn and swivel freely. Check the ease of steering of the C-arm stand and the display cart. Ensure that caster brakes secure the stand from movement.

1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug, and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

For repeated exposures, allow adequate time between exposures to prevent overheating of the x-ray tube.

If the device has electrical receptacles for accessories, verify the presence of line power. Insert an AC plug into each receptacle, and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacles.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instructions and service manuals; ensure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive

2

Chassis/Housing. Examine the exterior of all components of the C-arm for cleanliness and general physical condition. Be sure that all hardware is present and tight and that there are no signs of spilled liquids or other serious abuse. External collimators should be checked for pooling of blood and be cleaned, if necessary. The grid and image intensifier housing should be checked for blood and cleaned, if necessary.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective


Mobile C-arms proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. For the fluoroscopic and radiographic exposure switches, ensure that they do not stick and that continuous pressure is required to continue exposure. Release of pressure should immediately terminate exposure.

portion. Ensure that the remaining length is adequate. Be sure to wire a new power cord or plug with correct polarity. 1.6


1.7

Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.9

Cables. Inspect any cables (e.g., between the C-arm stand and display cart, from the C-arm, connecting the footswitch) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing cables for the display near each end and looking for erratic operation. For units with rotating anode tubes, the highvoltage cables should be removed from the wells, and the ends and the wells should be cleaned, coated with high-voltage compound, reinserted, and tightened securely.

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate connectors. If keyed connectors are used, make sure that no pins are missing and that the keying is correct. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any setting appears inordinate (e.g., high mA setting), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches (x-ray initiation, collimation, image manipulation, technique selection, size of image, etc.) for physical condition, secure mounting, and correct motion. Check that control knobs, if present, have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Examples of indicators and displays are technique settings, image modes, fluoroscopic exposure time, x-rays on, display monitor text, and image storage numbers. 1.20 Alarms. Induce conditions to activate audible and visual alarms (e.g., x-rays on). Check that any associated interlocks (e.g., fluoroscopy inhibition) function. If the unit has an alarm silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions (e.g., long exposure times). Instruct users to document activation of these alarms to ensure that they are functional. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., radiographic exposure, boost or high-level control fluoroscopy). Confirm appropriate volume. If audible alarms have been silenced or the volume set too low, adjust alarm volume to the appropriate level. 1.22 Labeling. Check that all necessary certification labels, warning labels, technique charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories (e.g., film cassette holder, digital acquisition systems, multiformat cameras, video printers).


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between common ground and exposed metal on the C-arm, the control stand, and the display cart. We recommend a maximum resistance of 0.5 Ω. The footswitch does not need to be grounded if it operates from low voltages.


3


2.3

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, during exposure, and off; record the maximum leakage current. Chassis leakage current should be 300 µA or less. For older Carms, leakage current up to 500 µA is acceptable, provided that a documented maintenance schedule is established to ensure grounding integrity; a three-month interval is a nominal period, but may be adjusted depending on intensity of use and previous experience.

Timer Accuracy. Use a noninvasive timer to measure the accuracy of the timer settings available on the C-arm system when it is operated in the radiographic mode. Most noninvasive kVp meters also display exposure times. Follow the manufacturer’s recommended technique for making time measurements. Cover the image intensifier with 6 mm thick lead plate to protect the image intensifier and TV camera system. Once the unit has been appropriately set up, dial up a midrange kVp setting (e.g., 70 kVp). The mobile C-arm may have a display only of mAs rather than exposure time. If this is the case, consult the C-arm manuals to find out what mA is being used at 70 kVp in the radiographic mode. The exposure time readings can then be

4

2.5

Accuracy of kVp. Use a noninvasive kVp meter that has previously been calibrated against a high-voltage divider on the type of generator that powers the C-arm system. Use the kVp meter in accordance with the recommendations of the manufacturer of the kVp meter. (These may include the kind of filters to use and the distance at which the kVp meter has to be placed. Some meters require that the user specify the type of generator being tested and the amount of filtration present in the primary x-ray beam.) Take measurements in the radiographic and fluoroscopic modes of operation of the C-arm at low, medium, and high settings (e.g., 60, 80, and 100 kVp). After the appropriate corrections have been applied to the measured kVp readings (e.g., for filtration), the difference between the measured kVp and the preset kVp should not exceed 5% of the preset kVp. If a consistent significant error between the preset kVp and the measured kVp is detected, further testing with a high-voltage divider may be required to identify the problem.

2.4

calculated from the mAs values. Conduct measurements at typically used low, medium, and high time settings. As a general rule, the difference between the measured time and the preset time should not exceed 1 ms or 5%, whichever is greater. Linearity of mAs. Use an ionization chamber with an electrometer (or a combination exposure meter) to measure the exposure in mR for this test. The ionization chamber should be placed centrally in the x-ray beam. The image intensifier should be covered with a lead plate to protect it from excessive radiation. Dial up a midrange kVp setting (e.g., 80 kVp) with the C-arm set to operate in the radiographic mode. Make radiographic exposures at this fixed kVp, and record the exposure values (in mR) from the electrometer or exposure meter at a minimum of three settings that span the range typically used. Calculate the mR/mAs at each setting, and average the calculations. Each individual mR/mAs value should be within 10% of the average. 2.6

Exposure Reproducibility. Use one of the above mR/mAs values as the one value to be used for evaluating short-term and long-term reproducibility of the x-ray tube and the generator combination. For the short-term test, make a minimum of four exposures at the same mAs over a span of approximately 15 minutes. The mR/mAs value should have a coefficient of variation no larger than 10%. For long-term reproducibility, simply record the current average mR/mAs value from the four values above and compare this with the value recorded during the preceding inspection. It is critical that identical test conditions be used for assessing reproducibility. For example, the same chamber-to-source distance should be used, and the technique (kVp, mAs) should be the same. Long-term reproducibility should be within ±10% of the average.

2.7

Half-Value Layer (HVL). Use an ionization chamber, electrometer, and Type 1100 aluminum filters for this test. Place the ionization chamber on the image intensifier or at about 60 cm from the focal spot. Under fluoroscopic guidance, adjust the collimation on the C-arm so that the x-ray field just encompasses the ionization chamber. Set the C-arm to operate in the radiographic mode at 80 kVp. Select a midrange mAs value.


Mobile C-arms These kVp and mAs values should be held constant during the whole course of this test. Record the initial exposure value (in mR) with nothing in the primary beam (i.e., 0 mm of aluminum). Then record the exposure reading with aluminum thickness of 2 mm and 4 mm. The thickness of aluminum required to reduce the initial exposure reading by half is the half-value layer of the beam. The HVL is most accurately read by plotting the measurements on semilog graphing paper. Plot the exposure values on the logarithmic scale against the thickness of aluminum on the linear scale. At 80 kVp, the HVL should be a minimum of 2.3 mm of aluminum. The HVL measurement should be compared to measurements from previous inspections, since a change in HVL may indicate tube deterioration. 2.8

Collimation. Place a ruler with leaded 1 cm or 1/2″ markers on the image intensifier housing, and measure the visual field size (length and width) of the image intensifier on the display monitor during a fluoroscopic exposure using the largest available mode on the image intensifier. Next, place a large-format x-ray film (30 cm by 30 cm minimum) on the image intensifier housing and make a fluoroscopic exposure, still using the largest available mode on the image intensifier. A fluoroscopic exposure of about five seconds is likely to provide sufficient film darkening. After the film has been processed, ensure that the dimensions of the x-ray beam measured on the film do not differ from the dimensions of the fluoroscopic image measured with the lead ruler by more than 3% of the source-to-image distance (SID).

2.11 Standard Fluoroscopic Exposure Rate. In addition to verifying that the unit meets exposure requirements, this test also verifies functioning of the ABS system. Use an ionization chamber with an electrometer (or a combination exposure meter) capable of measuring exposure rate. Place the chamber or the meter 30 cm above the image intensifier input plane. Place sufficient patient simulator material on the image intensifier that the technique tracks to about midrange (e.g., 70 kVp) in the automatic fluoroscopic mode. Run a fluoroscopic exposure, and record the exposure rate. Check for consistency of the exposure rate with those made during previous

inspections. The typical exposure rate is 1 R/min (with a range of 0.5 to 2.0 R/min). If the exposure rate has increased from that of previous inspections, further testing should be performed to determine the reason for the required increase in radiation. 2.12 Maximum Fluoroscopic Exposure Rate. Use an ionization chamber with an electrometer (or a combination exposure meter) capable of measuring exposure rate. Place a thick lead plate (at least 6 mm thick) over the image intensifier housing. Ensure that the whole input face of the image intensifier is covered by the lead plate. Place the ionization chamber 30 cm above the image intensifier input plane. Record the exposure rate on the electrometer or exposure meter during a fluoroscopic exposure in the automatic mode, as well as in the manual mode at the highest technique. If the C-arm also has a “boost” or “high-level” control mode, record the exposure rate during a fluoroscopic exposure in this mode. For units that have only manually selectable kVp and mA settings, the exposure rate at the highest settings should not exceed 5 R/min. For units that have automatic kVp and mA control, the exposure rate should not exceed 10 R/min. There are no governmental regulations that limit exposure rates under boost mode for devices in use now. However, for devices manufactured in 1996 and after, the exposure rate in the boost or high-level control mode should not exceed 20 R/min. 2.13 Image Quality. High-Contrast Resolution. Place the line-pair phantom on the grid. It should be placed at a 45-degree angle to the grid lines and raster lines of the TV system. At low kVp (ABS with nothing other than the line-pair phantom in the field), determine the maximum line-pair resolution for all available field sizes. It may be necessary to alter the brightness and contrast settings on the TV monitor to optimize the display for the visualized object. Resolution should be at or above 1.2 lp/mm for a 22 cm (9″) field of view (FOV) and 1.7 lp/mm for a 15 cm (6″) FOV. Low-Contrast Resolution. Ensure that the 1 mm piece of aluminum is next to the grid. Place the low-contrast phantom on the grid. The thicker aluminum pieces should be on top of the 1 mm


5

Inspection and Preventive Maintenance System thick plate. Initiate a fluoroscopic exposure under ABS control. On the 15 cm (6″) FOV, the three smallest holes should be visible. It may be necessary to alter the brightness and contrast settings on the TV monitor to optimize the display for the visualized object.


Clean the exterior, as well as the interior if needed.

3.2


3.3

Calibrate per the manufacturer’s instructions. Adjust caster brakes and arm locks, if needed.

6

4. Acceptance Tests Acceptance testing is typically performed by a medical physicist.




Mobile X-ray Units Used For: Radiographic Units, Mobile [13-272]

Also Called: Mobile radiographic systems, portable x-ray machines Commonly Used In: Patient rooms, surgical suites Scope: Applies to portable radiographic systems powered from or charged by a standard 115 VAC receptacle Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Mobile x-ray units are used for radiographic imaging of patients who cannot be moved to the radiology department and who are in areas, such as intensive care units or emergency rooms, that lack standard, fixed radiographic equipment. These units consist of an x-ray generator, an x-ray tube and tubestand, collimators, and a film cassette storage drawer. Batterypowered units also contain a battery and charging system, and self-propelled units contain a motor drive. One of three different types of x-ray generators can be used: a line-powered transformer, a capacitor-discharge generator, or a battery-powered transformer. Line-powered transformers use 120 or 220 VAC for x-ray production. A step-up transformer increases the voltage, and a rectifier converts the AC to the DC required by the x-ray tube. In a capacitor-discharge generator, 110 or 220 VAC power is fed into a step-up transformer; the output is then rectified and used to charge a large capacitor or group of capacitors, which are then discharged through a grid-controlled x-ray tube. Because the capacitors are charged to the same potential, each exposure begins at the same peak kilovoltage (kVp), but the kV will decrease during exposure as the capacitor discharges. At the end of each



Time Required

exposure, the capacitor(s) must be recharged. In a battery-powered generator, line power is used to charge lead-acid batteries; the fully charged unit can then be operated independently of an outside power source until the batteries need to be recharged. Battery-powered generators supply a constant kV and current throughout the exposure. The x-ray tube assembly, which includes the x-ray tube and collimator, is attached to a tubestand that can be rotated about its base or moved horizontally and vertically. The x-ray tube anode is either stationary or rotating. Filters are placed in the path of the x-ray beam to absorb the less penetrating x-rays. After the beam passes through the filters, a set of collimators confines the primary beam to the size and shape that will cover the area of diagnostic interest. Because of design constraints, tube current in mobile units is often lower than in stationary radiographic systems. Therefore, radiographs taken with mobile units are usually of poorer quality. Furthermore, because patient positioning and film placement are more difficult with bedside radiography, the overall image quality is lower, as well. Mobile radiographic units are designed for use only when patient transport is contraindicated; the radiology department, with


●


Inspection and Preventive Maintenance System fixedradiographic equipment, offers a more controlled, optimal setting for imaging.

maintenance procedures or frequencies are recommended by the manufacturer.


This procedure is intended to ensure adequate system performance and maintenance. It should not be construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations. Such regulations and standards may include testing beyond that provided below and may also require documentation by a certified medical physicist.

Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Noninvasive kVp meter (compatible with the x-ray generator being inspected) Noninvasive timer (may be included with the kVp meter) Ionization chamber with electrometer or a combination exposure meter Five filters of 10 cm × 10 cm × 1 mm Type 1100 aluminum Collimator alignment template marked in centimeters or inches

For acceptance testing, we strongly recommend using a medical physicist. Acceptance testing is crucial because it generates data on baseline performance of the device.


Chassis/Housing. Examine the exterior of all components of the portable x-ray unit for cleanliness and general physical condition. Be sure that all hardware is present and tight, and that there are no signs of spilled liquids, deep scratches, dents, or other serious abuse. Check the mechanical operation of all moving parts to include any film storage compartment, as well as all movements of the x-ray tube, x-ray tube support, and collimator, ensuring that all movements are smooth with no binding or undue resistance.

1.3

Casters/Brakes. Verify that the casters turn and swivel freely. Look for accumulations of dirt and grime around the casters. Check the ease of steering. Check the brake or locking device for each movement of the x-ray tube, x-ray tube support, and collimator. Ensure that all locks function properly and hold securely.

1.4

AC Plug/Receptacles. Examine the AC power plug for damage and ensure that the AC plug is clamped securely to the line cord. If you find evidence that the plug is being removed from the receptacle by pulling on the cord, caution users against this practice. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Ensure that the remaining length is adequate. Be sure to wire a new power cord or plug with correct polarity.

Medium-format x-ray film (25 cm × 30 cm or 10″ × 12″) Ten pieces of 30 cm × 30 cm × 2.5 cm plexiglass (or another patient-simulating material for testing the automatic exposure control [AEC]) Densitometer Oscilloscope (calibration only) High-voltage divider (calibration only)

Special precautions Wear a lead apron and thyroid shield. Maintain the greatest possible reasonable distance from the x-ray source and all scattering material during all x-ray exposures. It should not be necessary to place hands or fingers in the x-ray beam. If this is unavoidable, wear lead gloves. Do not remove the high-voltage cables from the wells with the power on. Ensure that high-voltage cables are completely discharged by repeatedly touching the conductor to ground as soon as it is removed from the well. Wear rubber gloves or other appropriate protection when exposed to blood or other body fluids. Allow adequate time between repeated exposures to prevent overheating of the x-ray tube.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; ensure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive

2


Mobile X-ray Units 1.6


1.7


1.9

Cables. Inspect any cables (e.g., collimator cables, high-voltage cables) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. For cables other than high-voltage cables, verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation. Use an ohmmeter if a problem is suspected. High-voltage cables should be removed from the wells (at the x-ray tube ends), cleaned, coated with high-voltage compound, reinserted, and tightened securely. The high-voltage transformer end should not require routine inspection if the wells are vertical and high-voltage oil is used.

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. If keyed connectors are used, make sure that no pins are missing and that keying is correct. 1.12 Filters. Check the condition of any air filters present in the systems. Clean or replace as needed. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., high mA setting), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches (x-ray initiation, collimation, technique selection, etc.) for physical condition, secure mounting, and correct motion. Check that control knobs, if present, have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the inspection, be sure to check that each control and switch performs its proper function. Ensure that radiographic exposure switches do not

stick, that continuous pressure is required to continue exposure, and that release of pressure immediately terminates exposure. Ensure the proper operation of the two-position exposure switch (i.e., ensure that the x-ray exposure is not released by the first trigger only), if present. 1.17 Battery/Charger. Using a multimeter, measure the battery voltage. (Consult the manufacturer’s documentation for appropriate measuring points.) Verify that the level of charge is accurately represented by the level-of-charge indicator on the operator’s panel. Verify that the battery charger automatically stops charging when the appropriate state of charge is reached. Ensure that any cooling or ventilation fans operate properly. 1.18 Indicators/Displays. During the inspection, confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Examples of indicators and displays are technique settings, exposure time, and x-ray on. Inspect the source-to-image distance (SID) indicator (usually a tape measure). Ensure that it is present, operates smoothly, and is accurate. 1.20 Alarms. Induce conditions to activate audible and visual alarms (e.g., x-ray on). Check that any associated interlocks (e.g., x-ray tube park) function. If the unit has an alarm silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions. Instruct users to document activation of these alarms to ensure that they are functional. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., radiographic exposure, audible signal during motorized drive if applicable). Confirm appropriate volume. If audible alarms have been silenced or the volume set too low, adjust alarm volume to the appropriate level. 1.22 Labeling. Check that all necessary certification labels, warning labels, technique charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories (e.g., film cassette holder). 1.24 Drive Mechanism (for motor-powered units only). Ensure that the drive system operates smoothly, does not pull to one side or the other, and makes no unusual noises (e.g., apparent binding, squeaking). If there are variable-speed controls


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Inspection and Preventive Maintenance System been appropriately set up, dial up a midrange kVp setting (e.g., 80 kVp). The unit may have a display only of mAs rather than exposure time. If this is the case, consult the instruction and service manuals to find out what mA is being used at 80 kVp. The exposure time readings can then be calculated from the mAs values. Conduct measurements at typical low, medium, and high settings. The difference between the measured time and the preset time should not exceed ±1 msec or ±5%, whichever is greater.

present, test their operation. Verify that the bumper switches disable the drive circuitry for both forward and reverse motions. Verify that any interlocks associated with the drive circuitry are functional (e.g., that an x-ray tube not in park position allows slow drive only, that the main drive handle must be depressed or squeezed to allow movement).


2.2

2.3

2.4

4

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between common ground and exposed metal on the portable x-ray unit. We recommend a maximum resistance of 0.5 Ω. Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, exposure, and off, and record the maximum leakage current. Chassis leakage current should be 300 µA or less. For older portable x-ray units, up to 500 µA is acceptable, provided that a documented maintenance schedule is established to ensure grounding integrity; three months is an acceptable interval, but may be adjusted depending on the intensity of use and on previous experience. Accuracy of kVp. Use a noninvasive kVp meter that has previously been calibrated against a highvoltage divider on the type of generator that powers the portable x-ray unit. Use the meter in accordance with the manufacturer’s recommendations. (These may include the kind of filters to use and the distance at which the kVp meter has to be placed. Some meters require that the user specify the type of generator being tested and the amount of filtration present in the primary x-ray beam.) Make measurements at low, medium, and high settings (e.g., 60, 80, 100 kVp). After the appropriate corrections have been applied to the measured kVp readings (e.g., for filtration), the difference between the measured kVp and the preset kVp should not exceed ±5% of the preset kVp. Timer Accuracy. Use a noninvasive timer to measure the accuracy of the time settings available on the unit when it is operated in the radiographic mode. Most noninvasive kVp meters also display exposure times. Follow the manufacturer’s recommended technique for making time measurements. Once the unit has

2.5

Linearity of mAs. Use an ionization chamber with an electrometer (or a combination exposure meter) to measure the exposure in mR for this test. The ionization chamber should be placed centrally in the x-ray beam at a known standard distance from the focal spot (e.g., 100 cm). Dial up a midrange kVp setting (e.g., 80 kVp). Make radiographic exposures at this fixed kVp and record the exposure values (in mR) from the electrometer or exposure meter at a minimum of three mA settings that span the range commonly used for a generator with variable mA. Also use three mAs settings for constant mA generators. Calculate the mR/mAs at each setting and average the calculations. Each individual mR/mAs value should be within 10% of the average.

2.6

Exposure Reproducibility. Use one of the above mR/mAs values as the one value to be used for evaluating short-term and long-term reproducibility of exposure. For the short-term test, make a minimum of four exposures at the same mAs over a span of 15 minutes. The mR/mAs values should have a coefficient of variation no larger than 10%. For long-term reproducibility, simply record the current average mR/mAs value, and compare it with the value recorded during the preceding inspection. It is critical that identical test conditions be used for assessing reproducibility. For example, the same chamber-to-source distance should be used, and the technique (kVp, mAs) should be the same. Long-term reproducibility should be within ±10% of the average.

2.7

Half-Value Layer (HVL). Use an ionization chamber, electrometer, and Type 1100 aluminum filters for this test. Place the ionization chamber in the center of the x-ray beam at about 100 cm from the focal spot. Collimate so that the x-ray field just encompasses the ionization chamber. Set the unit to operate at 80 kVp. Select a midrange mAs value. These kVp, mAs values should be held constant during the whole


Mobile X-ray Units course of this test. Record the initial exposure value (in mR) with nothing in the primary beam (i.e., 0 mm of aluminum). Then record the exposure reading with aluminum thicknesses of 2 mm and 4 mm. The thickness of aluminum required to reduce the initial exposure reading by half is the HVL of the beam. The HVL is most accurately read by plotting the measurements on semilog graphing paper. Plot the exposure values on the logarithmic scale against the thickness of aluminum on the linear scale. At 80 kVp, the HVL should be a minimum of 2.3 mm of aluminum. The HVL measurement should be compared to measurements from previous inspections since a change in HVL may indicate tube deterioration. 2.8

Collimation. Place a medium-format x-ray film (25 cm × 30 cm or 10″ × 12″), at an SID of 100 cm (40″). Ensure that the x-ray film is perpendicular to the x-ray beam. Precisely center the collimator alignment tool on the cassette. Turn on the collimator light and collimate to an area of 20 cm × 20 cm. Ensure that the light beam is exactly centered on the collimator alignment tool. Note the exact readout of the exposure area size indicators. Record the exact size of the illuminated boundaries from the collimator alignment tool. Make an x-ray exposure (for a film/screen speed of 400, a technique of 55 kVp and 5 mAs should be sufficient), and process the x-ray film. Congruence of the light field to the x-ray field. Measure the distances L1, L2, W1, and W2 on

the processed film. The sum of W1 + W2 + L1 + L2 is the total misalignment between the light field and the x-ray field. This sum must not exceed 2% of the SID; that is, at an SID of 100 cm, the misalignment should not exceed 2 cm. See Figure 1. Field size indicators versus actual exposed area. Measure the length and width of the exposed area on the exposed film. Compare the actual size of the exposed area to the readout of the exposure area size indicators noted earlier. The dimensions of the exposed area must be within 2% of the SID — that is, 2 cm at an SID of 100 cm. 2.9

AEC Object Thickness Compensation (for units provided with an AEC system). This test is to be conducted on each available radiographic image receptor holder (e.g., spot-film, table Bucky, wall Bucky). Place 20 cm of 30 cm × 30 cm plexiglass on the table or support it up against the wall Bucky. (It is acceptable to use another patient simulating material for AEC tests, such as aluminum.) Ensure that the plexiglass covers the AEC detectors. Set the unit to operate at 80 kVp (or some other setting commonly used to image a medium-sized patient). Load a cassette of a size commonly used with the standard film used at the facility, and place this into the receptor holder being tested. Then make an AEC-controlled exposure. Process the film on a processor that has previously been verified as operating optimally.

″

″

Figure 1. Schematic showing misalignment of the light field with respect to the x-ray field


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Inspection and Preventive Maintenance System Use a densitometer to measure the optical density of the radiograph in the center of the image. If the optical density falls within the range chosen by the radiologists (typically 1.2-1.4 OD), repeat the test using identical setup conditions but with varying amounts of plexiglass in the beam. At a minimum, check the optical density at 15 cm and 25 cm of plexiglass. All films used in this test should come from the same batch, and only one cassette is to be used for all exposures. The optical density of all the processed films should agree to within ±0.3 OD of the optical density at 20 cm. 2.10 AEC kVp Compensation (for units provided with an AEC system). This test should also be conducted on each available radiographic image receptor holder (spot-film, table Bucky, and wall Bucky). Place 20 cm of plexiglass (or some other patient simulating material) on the table or support it up against the wall Bucky. Ensure that the AEC detectors are covered by the plexiglass. Use the most common size of films in the same cassette holder for all checks in this test. Make a series of AEC-controlled exposures of the 20 cm of plexiglass at different kVp values. At a minimum, use three kVp settings (e.g., 60, 80, 100 kVp). For each exposure, process the film on an optimally performing processor. Read the optical density of the radiograph using a densitometer.

6

The optical density of the films at all kVp settings checked should agree to within ±0.3 OD.


Clean the exterior and interior. Take precautions when dealing with body fluids.

3.2


3.3

Calibrate the system to ensure performance within the manufacturer’s specifications, at intervals recommended by the manufacturer or as indicated by inspection results. Adjust all brakes and locks to ensure proper performance.

3.4

Replace components if needed.

4. Acceptance Tests Acceptance testing is typically performed by a medical physicist.

Before returning to use Ensure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Attach a Caution tag in a prominent position so that the user will be aware that control settings may have been changed. Recharge battery-powered devices or equip them with fresh batteries, if needed.



Nd:YAG Surgical Lasers Used For: Lasers, Surgical, Nd:YAG [16-943]

Also Called: YAG lasers (incorrectly), continuous-wave YAG lasers, surgical lasers, urology lasers, angioplasty lasers, bronchopulmonary lasers, gastroenterology lasers, neurosurgical lasers, photocoagulator lasers Commonly Used In: Operating rooms, short procedure areas, cystology rooms, catheterization laboratories, endoscopy laboratories, radiology areas Scope: Applies to general-purpose Nd:YAG surgical lasers that include contact (e.g., sapphire tip) and/or noncontact flexible fiberoptic delivery systems (either reusable or disposable), emit near-infrared energy at 1,064 nm, and can provide sufficient power output to coagulate and vaporize tissue; applies to low- and high-power Nd:YAG surgical lasers that are typically used for general surgery, urology, cardiovascular surgery, gastroenterology, bronchopulmonary, neurosurgery, gynecology, ENT, and plastic surgery procedures; applies to the Nd:YAG portion of units that combine the Nd:YAG wavelength with other wavelengths (e.g., KTP or CO2); does not apply to ophthalmic Nd:YAG lasers or to Nd:YAG lasers that are, for example, frequencydoubled and do not emit energy for delivery to the patient at 1,064 nm (frequency-doubled units are covered in Procedure/Checklist 464); also does not apply to CO2 lasers, argon lasers, or other ophthalmic lasers; however, many of the tests listed herein can be used or modified for these other lasers Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Nd:YAG lasers are normally checked before each use by the laser’s power-on self-test and by user examination of the aiming beam and calibration of the system with the delivery system to be used. This minimizes the need for frequent additional periodic testing.


Time Required

sers must be meticulously maintained to ensure proper and safe operation.

Manufacturers or outside service vendors often maintain lasers for hospitals. The extent and frequency of inspection by hospital personnel should be coordinated with these outside services.

Nd:YAG surgical lasers affect tissue by delivering invisible near-infrared energy at a sufficient power density to cause photocoagulation, thermal denaturation, and/or vaporization of tissue. The 1,064 nm Nd:YAG energy is not well absorbed by any tissue and is typically scattered over a 5 mm depth within tissue. Nd:YAG surgical lasers are frequently used to cause photocoagulation or thermal denaturation of tissue in the noncontact mode or with quartz or sapphire contact tips.

Failure of an Nd:YAG surgical laser can cause patient or staff injury, abrupt interruption of a surgical procedure, or damage to the laser system. These la-

General-purpose Nd:YAG surgical lasers have a laser cavity that houses an yttrium-aluminum-garnet (YAG) crystalline rod that is doped with neodymium



●


Inspection and Preventive Maintenance System (Nd). Energy leaving the laser tube through a partially reflecting mirror is typically directed into a flexible optical fiber that transmits the laser energy to the tissue. The fiber may be used with additional connectors (e.g., through an endoscope), with contact tips or contact-tip fibers connected, and/or with a laser handpiece or a laser micromanipulator (used to interface the laser with the surgical microscope) connected. These attachments can focus the energy into a small spot size at a known working distance or a specific beam pattern to accomplish a specific task. In a few cases (e.g., the Trimedyne Laserprobes SLT contact tips), the laser energy is transformed into thermal energy to heat a catheter tip, which then causes the clinical effect; in this case, no or very little direct laser irradiation of tissue occurs. Because the near-infrared energy emitted by the Nd:YAG laser is invisible, a second, nontherapeutic aiming helium-neon (He-Ne) laser — which emits visible red light — a red diode laser, or a xenon lamp with filters to emit white or blue light simultaneously traverses the fiber and is coincident (i.e., travels the same path) with the Nd:YAG laser beam. Like most lasers, Nd:YAG lasers are inefficient in converting electrical energy into laser energy of 0 to 140 W. As a result, excess heat is generated in the laser tube, requiring a cooling system. Some Nd:YAG lasers use internal water/air cooling systems, while others require external connection to a water source and drain or to a freestanding cooling system. Most Nd:YAG laser fibers require gas or liquid cooling as well for certain applications. As a result, gas compressors/regulators and/or fluid pumps are typically integral or attached to these lasers. Because Nd:YAG laser fibers may be used in body cavities (e.g., during gastroscopy), some lasers may include a gas recirculation system that inserts gas to cool the fiber and/or insufflate the cavity and withdraw gas to limit pressure and avoid distension. With Nd:YAG lasers, unlike those lasers that use mirror delivery systems (e.g., articulating arms on CO2 lasers), it is not necessary to periodically verify coincidence of the aiming and therapeutic beam or to assess the therapeutic beam pattern (e.g., TEM00) within the beam or spot. Since the therapeutic and aiming laser beams are transmitted through a single optical fiber, these two beams are coincident as they exit the fiber. Any beam pattern distortion at the fiber entrance would be eliminated as the laser beams travel through the fiber because of internal reflections within the fiber. Misalignment of the beam at the fiber entrance would result in decreased power output or loss or distortion of the aiming beam. In a well-aligned system, any significant problem with the therapeutic

2

beam pattern introduced by an accessory would be apparent by examining the visible aiming beam.

Citations from Health Devices Lasers in medicine: An introduction, 1984 Jun; 13:151-78. Lasers as investigational devices: Appendix A, 1984 Jun; 13:167-9. Lasers: Model policy and procedures statement: Appendix B, 1984 Jun; 13:169-71. Loss of metal nozzle on Nd:YAG surgical laser fibers [User Experience NetworkTM], 1987 Mar-Apr; 16:115. Fatal gas embolism associated with intrauterine laser surgery [Hazard], 1989 Sep; 18:325-6. Surgical lasers [Evaluation], 1991 Jul-Aug; 20:239-316.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter New, unused fiber delivery system Black Delrin block ≥1⁄2″ thick, ≥1″ wide, about 3″ to 4″ long; tongue depressors; or firebrick Laser radiometer (power meter) Laser safety signs Laser safety eyewear specifically designed for use with Nd:YAG surgical lasers and of sufficient optical density to protect the wearer’s eyes from laser injury Vise with padded jaws or ring stand with padded clamp Pressure gauges and coolant system tee fitting Outlet test fixture (optional) Insulating gloves, high voltage (optional) Grounding strap (optional) Calibrated flowmeter

Special precautions Inspecting and maintaining lasers is a dangerous as well as necessary process, and far greater care is required than with most devices. Personnel who inspect or service lasers should receive special training from the manufacturer or from a qualified alternative training source. Laser energy can cause serious injury, particularly when the internal interlock is overridden or in any other situation in which the energy does not diverge


Nd:YAG Surgical Lasers significantly over long distances. Under some circumstances, the beam may not diverge significantly, even a full room length or more away from the laser (and can harm tissue or burn material even at this distance). Therefore, exercise great care whenever a laser beam is accessible. Area security and use of personnel protective devices and practices should be consistent with hospitalwide laser safety procedures and/or be approved by the laser safety committee. In addition, windows should be covered with nonreflective material to prevent transmission of laser energy to other areas. Wear appropriate laser safety eyewear at all times whenever the laser is in the Operating mode. WARNING: Laser safety eyewear may not protect the wearer from the aiming system light. Do not stare directly into the aiming system beam or the therapeutic laser beam, even when wearing laser safety eyewear. Avoid placing the laser beam path at eye level (i.e., when kneeling, sitting, or standing). Do not perform these procedures when a patient is present or clinical staff is working, and do not aim the laser across a path that a person might normally use as a thoroughfare. Furthermore, at minimum, post doors to the room with appropriate laser safety signs stating that the laser is in use and that it is unsafe to enter the room without authorization by the service person performing the procedure. A second person should be present, especially during procedures of recognized risk, to summon help in case of an accident.

Some surgical lasers use high voltages (e.g., 20 kV), which can be lethal. Capacitors may store charges long after the device has been disconnected from line voltage. Consult the manufacturer’s recommended procedures for servicing high-voltage laser circuits, and avoid contact with any portion of the high-voltage circuit until you are certain that the charge has been drained. In such instances, a good ground must be present; preferably, use a redundant ground strap if you must enter the laser cabinet. When possible, disconnect the laser from line voltage before entering the laser cabinet, and use insulated gloves for those procedures in which contact with a high-voltage source is possible (and the gloves are not otherwise contraindicated). Ensure that equipment intended to be used to measure, drain, or insulate high voltages carries the appropriate insulation rating (e.g., above 20 kV). Where possible, perform tests with the unit turned off. Because of the presence of high voltage, perform the Grounding Resistance test (Item 2.1) before any other item that requires operation of the laser. WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch, talc) on its inside surface because the agent could contaminate the gas recirculation system of the laser and ultimately contaminate a patient wound during a subsequent procedure. Report any laser accident immediately to the laser safety officer or equivalent, as well as to the hospital risk manager.

Procedure The laser should remain in the Off position when not in use. When in use, the laser should be in the Standby/Disabled mode. Do not switch it to the Operating mode until the procedure is about to begin and the laser and its delivery system are properly positioned. If the procedure must be interrupted, disconnect the laser from line voltage, and remove the laser operation key and store it in a controlled location.

Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and service manual; be sure that you understand how to operate the equipment, the significance of each control and indicator, and precautions needed to ensure safety and avoid equipment damage. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

Do not use the laser in the presence of flammable anesthetics or other volatile substances or materials (e.g., alcohol), or in an oxygen-enriched atmosphere, because of the serious risk of explosion and fire. Remove from the working area or cover with flame-resistant opaque material all reflective surfaces likely to be contacted by the laser beam. Whenever possible, use a firebrick or other nonflammable material behind the target material (e.g., black Delrin) when the laser is to be activated. Target materials will ignite when exposed to high laser energies; use short durations when practical. A CO2 fire extinguisher should be readily available.


Chassis/Housing. General. Verify that the key has not been left in the laser. (Remove it if it has, and inform users of the importance of storing the key in a controlled location.) Examine any external gas tanks that may be in use with the laser, and ensure that they have been turned off after the last use. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that all housings are intact


3

Inspection and Preventive Maintenance System and properly aligned, that assembly hardware is present and tight, that any retractable parts slide easily and lock in place if so constructed, that there are no signs of spilled liquids or other evidence of abuse, and that there are no obvious signs of water or oil leakage. Shutters. If manual shutters for the aiming system or therapeutic laser are accessible, ensure that they operate smoothly and correctly. Be sure to leave the shutter in the proper position for normal operation. 1.2

1.3

Mounts/Holders. Check that the mounts securely contain any gas cylinders that may be in use. Be sure that mounts or holders intended to secure the fiber to the fiber support (to protect the fiber when in use) are present, in good working order, and being used. Similarly, check mounts or holders for other devices (e.g., external power meters, footswitches). Casters/Brakes. Check that the casters roll and swivel freely. Check the operation of brakes and swivel locks.

1.4

AC Plug/Receptacle. Examine the AC power plug for damage. Wiggle the blades to determine whether they are secure. Shake the plug, and listen for rattles that could indicate loose screws. If you suspect damage, open the plug and inspect it.

1.5

Line Cords. Inspect line cords for signs of damage. If a cord is damaged, replace the entire cord, or, if the damage is very near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.6


1.7


1.8

4

Tubes/Hoses. Check the condition of all cooling-system hoses and any other hoses or tubing the laser may have (e.g., drain, gas). Check that they are of the correct type; that they have not become cracked and do not show other signs of significant abuse; that they are connected correctly and positioned so that they will not leak,

kink, trail on the floor, or be caught in moving parts; and that they are secured adequately to any connectors. 1.9


1.10 Fittings/Connectors. E xam ine all optical (e.g., fiber), gas, liquid, and electrical fittings and connectors for general physical condition. Gas and liquid fittings should be tight and not leak. Electrical contacts should be straight, clean, and bright. There should be no visible dirt or residue in the optical path of the laser aperture. Ensure that any mechanism to close off the fiber laser aperture (fiber port) is clean, operates smoothly, and is in use. If external gas tanks or wall-supply outlets can be used, gas-specific connectors should be present. Be sure that no pins are missing from yokes and that the keying and indexing of connectors for each gas to be used is correct. A laser that connects to a central piped medical gas system or to a freestanding medical gas system should have the matching DISS or quick-connect fitting for the gas that it is to be used with. Verify that suitable connectors are supplied so that adapters are not required. 1.12 Filters. Check the condition of all liquid and air filters. Some Nd:YAG surgical lasers require deionized water, and most require special filtration. Measuring the pressure drop across a liquid filter can be helpful in determining whether the filter should be replaced. Clean or replace filters according to the manufacturer’s recommendations (e.g., replace if the pressure drop is >5 psi), and indicate this in the preventive maintenance section of the inspection form. Clean or replace air filters and radiators that are obviously dirty. 1.13 Controls/Switches. General. Before moving any controls, check and record their positions. If any position appears unusual, consider the possibility of inappropriate use or of incipient device failure. Examine all controls and switches for physical condition, secure mounting, and correct motion. If a control has fixed-limit stops, check


Nd:YAG Surgical Lasers for proper alignment, as well as positive stopping. Check membrane switches for tape residue and for membrane damage (e.g., from fingernails, pens, surgical instruments). If you find such evidence, notify users to avoid using tape and sharp instruments. During the inspection, be sure that each control and switch works properly. Remote. Examine the exterior of the control for cleanliness and general physical condition. Be sure that housings are intact, that assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. If the remote control is attached by cable to the laser, ensure that the cable and any connectors are in good condition. Examine all controls and switches for general physical condition, secure mounting, correct motion, and intended range of settings. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the inspection, be sure to check that each control and switch performs properly. Footswitch. Examine the footswitch for general physical condition, including evidence of spilled liquids. Footswitches for lasers include an internal switch that activates according to the depth of pedal depression. It is usually possible to feel the vibration caused by closure of the switch, even through a shoe. Check that the internal switch is operating and that the footswitch does not stick in the On position. Some footswitches include two internal switches; in this case, verify the operation of both. Some footswitches also include a switch to operate the liquid- or gas-cooling system. Check to be sure that this switch operates reliably.

1.15 Motors/Pumps/Fans/Compressors. Check the physical condition and proper operation of these components, if present. If lubrication is required, note this in the preventive maintenance section of the inspection form. Clean any obvious dust from these components. 1.16 Fluid Levels. Check all fluid (e.g., coolant) levels. Refill or change the fluid according to the manufacturer’s recommendations, and note this in the preventive maintenance section of the inspection form. If an external water supply is in use, ensure that the water pressure is properly regulated and at the appropriate pressure and that the supply and drain system is properly configured (e.g., filters are oriented for proper flow, drain hoses are positioned in a sink or drain). 1.17 Battery. If a remote control or display is battery powered, check or replace the battery (periodic prophylactic battery replacement is often preferred to risking battery failure during use). Other batteries, such as those used to provide additional power for 110 VAC Nd:YAG lasers, should be inspected according to the manufacturer’s recommendations. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, verify proper operation of all lights, indicators, meters, gauges, and visual displays on the unit and remote control. Ensure that all segments of a digital display function. Note any error messages displayed during the power-on self-test. If primary and remote-control indicators and displays can be used at the same time or if control can be switched from one to the other during a procedure, operate the laser in a way that will verify that the same information (e.g., settings, displays) is indicated on both controls.

During the procedure, check to be sure that the laser activates and deactivates consistently when the footswitch is depressed and that the fiber-coolant system operates properly when the fiber-coolant switch is activated and deactivated. Flex the cable at the entry to the switch, and, using an ohmmeter, check for internal wire breaks that cause intermittent operation. Confirm that strain reliefs are secure.

If display screens or digital displays are provided for user prompts or for viewing accumulated information (e.g., pulse or accumulated energy counter), ensure that each display provides the information expected. Ensure that user prompts occur in the proper sequence. Store some sample information, and verify that it is correct. If a feature to manually reset this information is available, ensure that it works.

Examine the male and female connectors for attaching the footswitch to the laser cabinet to be sure that no pins are bent and that no other damage is present. Ensure that the connector secures acceptably to the laser cabinet.

1.19 Laser Delivery System Calibration. Nd:YAG surgical lasers typically include a user-accessible calibration port leading to an internal power meter that allows output calibration and testing of the laser fiber. This feature is provided because transmis-


5

Inspection and Preventive Maintenance System sion of laser energy through a fiber can change in response to fiber use. Based on the measurement from the calibration power meter, the laser may automatically recalibrate itself and/or adjust displays so that the power indicated to be delivered to the patient will be correct; or it may require the user to do this manually. Verify that this feature is functioning by using the manufacturer’s recommended calibration procedure to test one delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. (Contact tips cannot be calibrated using the laser’s calibration power meter.) 1.20 Alarms/Interlocks. Operate the device in a manner that will activate the self-check feature, if present, and verify that all visual and audible alarms activate according to the manufacturer’s documentation. If no self-check feature is present, operate the laser in a manner that will activate each audible and visual alarm; be sure to test only those alarms that will not cause damage to the laser or present an unnecessary risk of laser beam exposure to yourself or bystanders. If a door or window interlock is used, ensure that it properly deactivates the laser. (Do not disassemble major parts of the laser to test internal interlocks.) After deactivating the laser and reclosing the door or window, check to be sure that the laser will restart. Be sure to check the interlocks in all locations where the laser is used. (For some lasers, the function of the interlocks can be checked using an ohmmeter.) If the laser is equipped with an emergency “kill” switch, test this feature to be sure that it deactivates the laser and that the laser will subsequently restart. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., laser emission, setting change). Check for proper operation, and verify that the signal can be heard in the environment in which the laser will be used. 1.22 Labeling. Check that all placards, labels, and instruction cards noted during acceptance testing (see Item 4.3) are present and legible. Check to see that an instruction manual is kept with the laser or is readily available. 1.23 Accessories. General. Verify that all necessary accessories are available and in good physical condition.

6

Set up reusable accessories with the laser to ensure compatibility and proper functioning. Checking all fibers or accessories during a single inspection and preventive maintenance procedure is unnecessary as long as accessories are routinely checked by the person(s) responsible for laser setup and operation. In addition, many of the accessories are sterile and would require resterilization before use, making the laser potentially unavailable. Be sure to check with the person responsible for scheduling the use of the laser before beginning the procedure. Fibers. For the test fiber and before each use, examine the aperture connector, cable, and tip of each fiber to be used, as well as the fiber support, for cleanliness and general physical condition. Be sure that all hardware (e.g., laser gas tubing channels) is present, in good condition, and firmly attached. Ensure that the aperture connector properly seats into the laser aperture of the laser cabinet. Examine the distal end of fibers to ensure that any connecting mechanisms (e.g., threads) are in proper working order. If a fiber appears to be dirty or damaged, remove it from service. If a fiber is reusable, notify the person(s) responsible for fiber repair. The fiber should be repaired and/or cleaned according to the manufacturer’s recommendations. Verify fiber performance. Contact tips. Examine each tip that may be used with the laser fibers for cleanliness and general physical condition. Be sure that the mechanism to connect a tip to a fiber is in proper working order and forms a secure connection. If a tip appears to be dirty or damaged, remove it from service and notify the person(s) responsible for tip repair or replacement. Some tips may look dirty after a single use, but remain acceptable for use; if you are unsure about the need to clean or repair a tip, consult with the person(s) responsible for tip repair or replacement and with the manufacturer, if necessary. Handpieces. Examine each handpiece component (e.g., body, tips, lenses) for cleanliness and general physical condition. Examine individually only those components that are intended for removal during normal use and storage. (Do not remove other parts that are press-fit or attached by screws, bolts, or snap-rings.) If


Nd:YAG Surgical Lasers brightness of the aiming beam. Similarly, check pulsing controls to verify that the aiming beam can be pulsed. If several color choices are available for the aiming beam, verify that each color is present and working properly.

lenses are detachable, be sure not to touch the lens surface; handle lenses by the edges only. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean lenses. Ensure that major subcomponents of the handpiece, when assembled, are secure. Ensure that the mechanisms used to connect the handpiece(s) to the fiber are in good working order and that they reliably secure each handpiece to the fiber. Microscope micromanipulator. Examine the microscope micromanipulator for cleanliness and general physical condition. Be sure to handle it by the main body; do not hold it by the joystick, and do not touch the reflecting lenses in the body. Inspect micromanipulators provided by both the laser manufacturer and the laser accessory manufacturer. Ensure that the reflecting surfaces and lenses are intact and clean. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean reflecting surfaces and lenses.

1.25 Laser Aperture. WARNING: Make this inspection with the laser powered off. Remove and inspect the protective window (e.g., blast shield) behind the laser aperture. It should be clean and undamaged; clean or replace if needed. There should be no visible dirt or residue in the optical path of the laser aperture. 1.26 Gas Regulators. Examine any gas regulators for cleanliness and general physical condition. Ensure that the gauges on the regulators are not broken. During the procedure, ensure that the regulator and the gauge operate as expected. Verify that the correct gas is attached to each regulator. Be sure that a key or wrench to facilitate changing the gas supply is with the unit or readily available. If the laser includes a gas recirculation system, ensure proper operation by allowing it to control the gas supply into and out of a sealed plastic bag.

Examine the joystick to ensure that it is firmly attached and that it freely moves the reflecting lens. If a finger rest is present, ensure that it is firmly attached and properly oriented.

WARNING: Do not use an anesthesia or other similar bag that may have a mold-release agent (e.g., starch, talc) on its inside surface because the agent could contaminate the gas recirculation system of the laser and ultimately contaminate a patient wound during a subsequent procedure.

If a zoom focus feature is present, be sure that it turns easily and does not slip. Examine each objective lens to ensure that it is intact and clean. Do not touch the lens surface. Consult the manufacturer’s recommendations for the procedures and cleaning agents to use to clean the objective lenses. Carefully insert each lens into the micromanipulator, and ensure that it fits snugly. Inspect the mechanism used to attach the micromanipulator to the microscope to ensure that all parts are present and that it is in good working order. Connect the micromanipulator to the microscope to check for a secure connection. Safety filters. Verify operation of safety filters in microscope and endoscope delivery systems. 1.24 Aiming Beam. Activate the aiming beam (without the therapeutic beam), and verify that it produces a round, uniformly bright spot, with no halo. For handpieces that provide adjustable spot sizes, verify that the spot size changes as expected and still remains uniform. Check that the intensity control, if present, does change the

If proper operation is questionable, consider using a calibrated flowmeter to measure actual gas flow.

2. Quantitative tests WARNING: In general, do not use liquid fiber cooling for tests unless specifically described in the item. Use of this kind of cooling rather than gas fiber cooling may damage test equipment or cause erroneous test results. 2.1



7


Pulse feature operates as expected by moving the target material slightly between each pulse. Be extremely careful to keep hands out of the laser beam path. If the number or duration between repeat pulses is adjustable, test that setting changes made throughout the range result in the expected performance.


2.3

Exposure Duration. Some laser power meters can measure pulse duration. If the power meter can react to pulse duration (this is the preferred circumstance), test the laser at each setting. However, if the laser power meter does not measure pulse duration, use the following less preferable alternative. Place and secure the laser fiber, handpiece, or micromanipulator with the aiming system focused on the target material (e.g., black Delrin or a tongue depressor). With the laser set to about 10 W and the exposure set at minimum duration, activate the laser and create a burn. Carefully move the target material to expose a clean area, maintaining the same distance. Adjust the exposure setting in increments of 0.1 sec or the next longest duration, and activate the laser at each setting. Continue this process until you have tested all exposure settings, except continuous, and have developed a series of burns. Compare the burns to verify that progressively larger burns occurred as the exposure duration increased.

2.4

Repeat Pulse. If the unit includes a Repeat Pulse feature, which repeats the pulse at a fixed or adjustable rate, test this feature with the laser set at the minimum, median, and maximum Repeat Pulse settings, if adjustable. Some laser power meters can react quickly enough to be used to test this feature of the laser. If you are using such a power meter, test the laser to be sure that the correct power is repeatedly delivered over the correct time period. If your laser power meter cannot be used for this test, use this alternative test method. Set the laser to about 10 W and a 0.1 sec exposure duration with the fiber, handpiece, or micromanipulator attached, and verify that the Repeat

8

2.5


2.10 Power Output. Select one delivery system (e.g., fiber, handpiece, micromanipulator), and perform the manufacturer’s recommended user calibration procedure. Secure the delivery system at the distance from the laser power meter to meet spot-size requirements specified in the instructions for the meter. (Do not focus the beam to a small spot on the power meter. Some power meters require that the unfocused or a defocused laser beam be projected into the power meter to cover the majority of the absorber surface. If the laser beam is focused on the receiver of such meters, the meter may be damaged.) WARNING: Accessing the unfocused laser beam may require defeating internal interlocks. Because of the heightened risk associated with an unfocused, nondiverging laser beam, exercise great care if the interlocks are to be defeated. With the laser set at low (e.g., 10% of full scale), medium (e.g., 50% of full scale), and maximum output, activate the laser for a sufficient period to acquire acceptable readings. (Power meters use different time constants to acquire an acceptable reading, and you must know and meticulously follow them.) Compare the reading with the power display of the laser; the measured and displayed values should all be within 10% of one another. In addition, compare the reading obtained with the reading taken on incoming acceptance testing, at the last preventive maintenance procedure, or after the last service procedure. If the laser includes a low-power (e.g., mW) feature, test it in a similar fashion with a power meter of appropriate resolution in the low-power range.


Clean the exterior. Clean cooling system fibers and accessible optical components (e.g., blast


Nd:YAG Surgical Lasers shield, microscope lenses), if necessary, using techniques and cleaning solutions recommended by the manufacturer. 3.2


3.3

Calibrate/adjust any components (e.g., printer) according to manufacturer recommendations. Only appropriately trained personnel should attempt laser adjustments. Ensure that all hoses and tubes are tight.

3.4

4.4

Electrical Wiring Configuration. Ensure that the branch circuits and the outlets for the laser are properly wired and rated for use with the laser. Examine the receptacles at each location where the laser is to be used to ensure that the proper electrical configuration (e.g., proper neutral and ground connections, proper phase rotation) has been installed. Connect the laser to each receptacle and confirm that the laser operates properly, specifically confirming that motors are operating in the proper direction.

4.5


4.6


4.7


4.8

Power Range. Using the technique described in Item 2.10, test the power output accuracy at several low, medium, and high settings.

4.9

Laser Delivery System Calibration. Use the manufacturer’s recommended calibration procedure to test each new reusable delivery system (e.g., fiber, handpiece) that the manufacturer indicates can be acceptably calibrated using these procedures. (Contact tips cannot be calibrated using the laser’s calibration power meter.) Note the fiber transmission for each delivery system tested if this information is provided by the laser. Or, you can calculate it using the following formula:

Replace filters if needed. Check all fluid levels and supplement or replace fluids if needed.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. WARNING: Lasers may be damaged by switching between normal and reverse polarity while the device is on. If reverse-polarity leakage current measurements are made, turn off the unit being tested before switching polarity. Also, lasers powered by three-phase electrical systems may be damaged if proper electrical phase connections are not made initially and maintained thereafter. Thus, do not switch conductor connections or wiring configurations for any tests, including leakage current measurement. Do not conduct electrical leakage current tests with reversed-polarity wiring. Also test the ability of the laser to deliver laser energy as expected in all configurations and with all provided laser accessories. In addition, perform the following tests. 4.1

4.2

4.3


% Transmission =


Casters/Mounts/Holders. Ensure that the assembly is stable and that the unit will not tip over when pushed or when a caster is jammed on an obstacle (e.g., a line cord threshold), as may occur during transport. If the device is designed to rest on a shelf, ensure that it has nonslip legs or supports.



Be sure to return controls to their starting position, and place a Caution tag in a prominent position so that the next user will be careful to verify control settings, setup, and function before using the unit.

Delivery systems with less than the manufacturer-recommended transmission (typically 80%) should be discarded if they are disposable, or repaired if they are reusable and intended for repair.


9


Oxygen-Air Proportioners Used For: Oxygen-Air Proportioners [12-876]

Also Called: Oxygen blenders, oxygen controllers, oxygen-air mixers Commonly Used In: Critical care units, NICUs; occasionally used in operating rooms and most other patient care areas Scope: Applies to external oxygen-air proportioners; can be adapted for proportioners that are built into ventilators Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Oxygen-air proportioners are designed to mix compressed air and oxygen to user-selectable oxygen concentrations varying from 21% to 100% at high- or low-output flows. Their mixed-gas output is often passed through a humidifier or a nebulizer and delivered to patients through ventilators, tracheostomy tubes, endotracheal tubes, oxygen tents, oxygen hoods, or masks at flows ranging from 1 to more than 100 L/min. Oxygen-mixing devices are built into ventilators or supplied as stand-alone units. This procedure covers the stand-alone units but can be adapted for other units. Oxygen-air proportioners operate by receiving air and oxygen from central gas pipelines in the hospital or from other compressed-gas sources, such as tanks or portable air compressors. Ideally, the two input gas sources are regulated at equal pressures (usually 50 psi). However, because this is often not the case, proportioners have their own pressure-regulating mechanisms to match input supply pressures or adjust



Time Required

them to preset levels at or below inlet supply levels. At these matched or preset pressures, air and oxygen enter a mixing valve that regulates their proportions as they flow out of the unit. When input pressures drop too low or differ greatly, proportioners cannot deliver accurate concentrations. For this reason, proportioners have built-in reed alarms that sound when there are large pressure differentials at the gas inlets or when there are low inlet or outlet pressures. The most common problems related to these units involve the contamination of oxygen or air sources due to backflow of the other gas and the delivery of inaccurate oxygen concentrations. These problems are most often caused by buildup of moisture or particulates inside the units from the compressed-gas lines. Along with regular preventive maintenance schedules, hospitals can maintain accuracy and reliability by installing water-trap filters at the gas inlets and using gas filtration and drying systems at compressed-gas sources.


●



Citations from Health Devices Oxygen-air proportioners [Evaluation], 1985 Jul; 14:263-76. Using a double flowmeter assembly in lieu of an oxygen blender [User Experience NetworkTM], 1985 Nov; 14:401. Inaccurate O2 concentrations from oxygen-air proportioners [User Experience NetworkTM], 1989 Oct; 18:366.

Test apparatus and supplies Although this procedure can be performed using only the common tools and materials listed below, some manufacturers sell special service kits for their units. This procedure, as well as service and repair, may be facilitated by these kits; consult your service manual to determine if a kit is available. See Figure 1 for a typical test setup. High-flow flowmeters with a range of 0 to 100 L/min (accurate to within 10% of reading) Flowmeters with ranges of approximately 0 to 50 mL/min and 1 to 15 L/min with 10% accuracy Hoses and adapters for connecting pressure gauges and flowmeters to equipment being inspected Cylinders of oxygen and air with pressure gauges that can be regulated between 0 and 100 psi; cylinder pressures should be at least 1,000 psi Nondisposable corrugated breathing hose (disposable tubing may be used only if it provides reliable connections) Oxygen analyzer with at least ±3% accuracy and with a “T” adapter for sensor head Flow-control valve Teflon tape Cleaning solvent recommended by the manufacturer Lubricant specified by the manufacturer

Special precautions

Figure 1. Typical test setup the equipment, the significance of each control and indicator, and the alarm capabilities. Also, determine if any special inspection or preventive maintenance procedures are recommended by the manufacturer.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all connectors are present and tight, and that there are no signs of spilled liquids or other serious abuse.

1.2


All testing should be done with pressure gauges and flowmeters specified for oxygen or medical gas use only. Turn off all pressurized gas sources when they are no longer in use.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate

2


Oxygen-Air Proportioners 1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not cracked, kinked, or dirty and that they do not leak.


Maximum Flow Rate. Using a high-flow flowmeter, measure the maximum flow rate out of the proportioner. If the proportioner has two outlets, measure the flow from its high-flow outlet. Unless designed specifically to deliver low flows (e.g., below 15 L/min), the proportioner should be able to deliver at least 80 L/min from its high-flow outlet when the concentration is set at 60%. Also, measure the maximum flow rate when the concentration is set to 21% and 100%. The flows at these concentration settings should not differ by more than 10 L/min. Flow differences greater than 10 L/min indicate a restriction at one of the inlets and probably the need to replace an inlet filter.

2.4

Alarms. Adjust input pressures to the proportioner’s specified alarm conditions. Verify that the alarms can be heard clearly and that the unit delivers accurate concentrations before the alarm sounds.

2.5

Flow with Loss of an Input Source. Turn off one of the input supplies and verify that the unit continues to alarm and deliver adequate flows at all concentration settings. With the loss of an input source, the proportioner should be able to deliver at least 30 L/min from its high-flow output and 15 L/min from its low-flow output. Note that not all proportioners have the same alarm conditions; check the manufacturer alarm specifications.

2.6

Check-Valve Leakage. Apply 5 psi to one input source and attach a flowmeter to the second source. With the output disconnected, no more than 0.1 L/min should leak from the second input source. Repeat this procedure with the other input source.

1.10 Fittings/Connectors. Examine the condition of all gas fittings. They should be tight and should not leak. If keyed connectors (e.g., DISS gas connectors) are used, make sure that the keying is correct. 1.12 Filters. Clean or replace inlet gas filters where appropriate, and indicate this on Lines 3.1 and 3.4 of the form. Replace filters if their time of use has exceeded the manufacturer’s recommended interval or if the proportioner’s performance indicates that they need to be changed (see Item 2.3). Use Teflon tape to ensure sealing when replacing any pipe-thread fittings that were removed for filter replacements. 1.13 Controls/Switches. If the proportioner has adjustments for anything other than O2 concentration (e.g., alarm limits, output pressure), check their positions. If they appear to be set to unusual values, consider the possibility of inappropriate clinical use. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all gauges and visual displays on the unit. 1.22 Labeling. Check that all necessary placards and labels are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories, including high-pressure hoses, flowmeters, and water-trap filters. High-pressure hoses should be supplied with the appropriate oxygen and air DISS fittings to match their outlet fittings. Water-trap filters should be clean and drained of all fluid. 1.24 Low-Flow Bleeds. Some proportioners have lowflow continuous bleeds to the atmosphere to improve accuracy. Inspect the proportioners to ensure that the bleed outputs are not blocked or clogged by tape or dirt.

2.10 Accuracy. Adjust input pressures to 50 psi; using an oxygen analyzer, measure the concentration from the proportioner output at settings of 21%, 60%, and 100% with the flowmeters adjusted to deliver flows over the range that would typically be used (e.g., 5 and 30 L/min). Accuracy should be within 3%.



3.2

Lubricate per the manufacturer’s instructions. Never use lubricants that will react with oxygen.

3.3

Calibrate per the manufacturer’s instructions.


3


Replace tubing, hoses, dirty filters, and damaged components if needed.


4

Before returning to use Depressurize all external gas supplies and make sure that alarms and controls are set to appropriate levels. Where appropriate, attach a Caution tag in a prominent position to alert users that alarm or control settings may have been changed.



Oxygen Analyzers Used For: Oxygen Analyzers [12-858] Oxygen Monitors [12-863]

Also Called: Oxygen monitors Commonly Used In: Operating rooms and critical care units Scope: Applies to oxygen analyzers/monitors intended to monitor the level of oxygen being delivered to a patient, which may be measured at or near the airway (e.g., endotracheal tube) or in the oxygen delivery device (e.g., oxygen hood); also applies to devices used to calibrate or verify the oxygen concentration in certain medical gases, and to devices used to calibrate and verify performance of oxygen-mixing devices (see Oxygen-Air Proportioners Procedure/Checklist 444) Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview For several years, ECRI has recommended that all anesthesia patient circuits incorporate oxygen concentration analyzers/monitors (hereafter referred to simply as oxygen analyzers) with alarms. We consider this essential to protect patients from hypoxia, since the analyzer senses the oxygen concentration in the inspiratory line of the patient circuit rather than at the oxygen flowmeter or common gas outlet of the anesthesia unit where oxygen concentration may be higher than in the patient circuit. Use of a properly functioning oxygen analyzer in conjunction with the anesthesiologist’s educated hand (on the reservoir bag) and ear (listening to breath sounds) greatly increases the likelihood that an adequately oxygenated mixture will be directed into the patient’s lungs. Continuous monitoring of oxygen concentration may also be required in applications of critical care ventilators or other oxygen administration equipment. For example, when ventilating some infants, it is often



Time Required

essential to collect and store data on the concentration of inspired oxygen and the total time duration at each level. An oxygen analyzer should also be used regularly to check the accuracy of ventilator settings. Most oxygen analyzers for breathing circuits operate on electrochemical principles and use polarographic electrodes or galvanic cells. Some paramagnetic oxygen analyzers are also used. Oxygen analyzers can accurately measure oxygen concentrations, as demonstrated in our evaluations of the devices. However, anesthesiology departments need to realize that the instruments require more care and maintenance than the anesthesia machines on which they are used. The devices are too often found with their batteries or sensors depleted. Daily checks by the user are essential to ensure accuracy and response. The reliability of oxygen sensors can also be affected by other factors. Nitrous oxide can be reduced by a polarographic electrode, but at a higher voltage than that required by oxygen. In the past, some analyzers


●


Inspection and Preventive Maintenance System exhibited a sensitivity to nitrous oxide immediately before battery depletion. (The voltage of mercury batteries peaks just before depletion and is then high enough to cause the reaction to proceed with nitrous oxide at the electrode.) Such interference resulted in indications of a higher-than-actual oxygen concentration, but was corrected by limiting cell voltage to a value where nitrous oxide interference was insignificant. Early galvanic cells were also structurally distorted by nitrous oxide and lost calibration. Newer galvanic cell designs resist this distortion and can be used with anesthetic gas mixtures. Halothane can also be reduced by polarographic electrodes and, if permitted to enter the cell, may generate significant error signals that increase over the duration of anesthesia administration.

Citation from Health Devices

1.4


1.5


1.6


1.7

Fuse. If the device is protected by an external fuse, check its value and type against that marked on the chassis and ensure that a spare fuse is provided.

1.9

Cables. Inspect the cables (e.g., sensor) and their strain reliefs for general condition. Examine carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

Oxygen analyzers for breathing circuits [Evaluation], 1983 Jun; 12:183-97.

Test apparatus and supplies Ground resistance ohmmeter (for line-operated units only) Leakage current meter (for line-operated units only) Oxygen source capable of providing about 4 L/min flow Gas manifold or T adapter Stopwatch or watch with a second hand

Special precautions Do not touch or puncture the membrane surface.

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures are recommended by the manufacturer.



1.2

Mount/Fasteners. Check the security of the mounting mechanism.

2

1.10 Fittings/Connectors. Examine all gas fittings and connectors, as well as all electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Confirm that the transducer fits tightly into the manifold fittings. 1.11 Electrodes/Transducers. Examine the sensor for salt accumulation that might indicate electrode leakage. Check the condition and placement of O-rings. Check electrolyte level of polarographic electrodes; replenish it if needed and note this on Line 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a calibration control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixed-limit


Oxygen Analyzers stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery/Charger. Inspect the physical condition of all batteries and battery connectors. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check remaining battery capacity by activating the battery test function or measuring the output voltage. Check the condition of the battery charger if so equipped and, to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date.



2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Leakage current should not exceed 300 µA.

2.3

Accuracy. The analyzer should indicate the oxygen level in a dry gas mixture in the circuit to within 3% oxygen. Check the accuracy at 21% (room air) or 100% oxygen concentration, whichever was not used in adjusting the unit’s calibration (in Item 1.19). Use the gas manifold if 100% oxygen is needed.

2.4

Response Time. Analyzers should rapidly indicate changes in oxygen concentration. The response time, including alarm delay, should be within the manufacturer-specified time, but with a time constant (time for 63% of a change) of less than 20 sec.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, and visual displays on the unit. Be sure that all segments of a digital display function. 1.19 User Calibration. Confirm that the calibration function operates. Calibrate the unit before proceeding to the quantitative tests. If it cannot be adjusted according to manufacturers’ instructions, it may need sensor replacement or renewal or battery replacement or recharging. Replace as needed and note this on Line 3.4 of the form. 1.20 Alarms. Operate the unit in such a way as to activate each audible and visual alarm. Where the device has an alarm-silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. An oxygen analyzer for continuous monitoring should have a low alarm that cannot be set below 18% oxygen. If the device has a lower alarm limit, alert the user to this condition and consider replacing the unit. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control. 1.22 Labeling. Check that all necessary labels are present and legible. 1.23 Accessories. Verify that replacement sensors, membranes, batteries, and electrolyte solution or gel are available. Confirm that the expiration date is current and that all packages are properly sealed.

An excessively long time constant usually indicates that the sensor needs replacement or renewal. With low alarms set at 50% oxygen, circulate 100% oxygen until the reading stabilizes, then terminate oxygen flow, remove the sensor, and expose it to room air. (The 50% alarm setting represents approximately 63% of the change from 100% to 21% oxygen.) Measure the time to indicate the change to 50% and alarm with a stopwatch or watch with a second hand and record this value. 2.10 Alarms. Alarms should activate when the indicated oxygen level is within 2% oxygen of the set alarm value for the range 15% to 40% oxygen, which is most critical for patient safety, and within 5% oxygen for the range 40% to 100% oxygen. Vary the indicated oxygen concentration (by varying the calibration adjustment) above or below the alarm settings of 21% (low-alarm setting) and


3

Inspection and Preventive Maintenance System 50% (high-alarm setting) oxygen and record whether the alarm points are within the required limits. If the unit’s design does not allow the above method to be used, then check the low alarm by increasing the alarm setting from 21% (with the sensor exposed to room air) until the alarm is activated. Test the high alarm similarly, but expose the sensor to 100% oxygen in the manifold and decrease the alarm setting from 100%.


Clean the exterior.

3.3

Calibrate if required.

3.4

Replace the battery and sensor, if needed.

4


Before returning to use If there are indications of improper daily maintenance, misuse, or nonuse (e.g., deteriorated sensor, depleted battery, low alarm set below 20%), alert appropriate clinical personnel (users and/or chief of anesthesiology). Stress the importance of daily maintenance and monitoring oxygen concentrations whenever inhalation anesthesia is administered. Patient deaths have occurred that could have been averted if a properly operating oxygen analyzer had been used.



Pacemakers, External Invasive Used For: Pacemakers, Cardiac, External Invasive [12-912]

Also Called: Temporary pacemakers, transvenous pacemakers Commonly Used In: Critical care units, emergency rooms, operating rooms, electrophysiology labs Scope: Primarily applies to single- and dual-chamber external (transvenous) pacemakers used for temporary demand or asynchronous pacing; does not apply to noninvasive (transcutaneous) pacemakers (see Pacemakers, External Noninvasive Procedure/Checklist 460) Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview The heart has its own pacemaker — a group of specialized cells that produces a rhythmic train of electrical pulses. These pulses are carried by specialized conducting cells to cardiac muscle cells in the atria and ventricles, stimulating them to contract at the proper times. In some patients, the intrinsic pacemaker or the conduction network fails. Unless the heart muscle is stimulated by some other means, the heart may beat erratically or stop. A pacemaker is used to control these arrhythmias (irregular heart rhythms) by applying a repetitive electrical stimulus to the heart. Temporary external pacing is used to control the heart until it reverts (or is reverted through other therapy) to a satisfactory rhythm or until a permanent pacemaker can be implanted. Temporary pacing is also used when patients with a history of certain cardiac disturbances must undergo major surgery. The most common method of temporary pacing is through an electrical lead, or catheter, positioned in the heart. The lead, which is usually inserted in a vein in the arm or neck, has a metal tip and a metal ring that act as electrodes to deliver a stimulus produced by a



Time Required

battery-powered external pulse generator. An epicardial lead can also be placed during open-heart surgery. In the asynchronous, or fixed-rate, pacing mode, the pacemaker emits a stimulus at regular intervals, regardless of cardiac activity. Asynchronous pacing is often used when a pacemaker is initially connected, or is used periodically to confirm that the signal amplitude is adequate to capture, or pace, the heart. The asynchronous mode is also used for continuous pacing when the heart is unlikely to spontaneously revert to a normal sinus rhythm during pacing. If an asynchronous pacemaker is used, and the heart reverts to its own rhythm, competition may occur between the pacemaker stimuli and the natural cardiac signals. This may cause ventricular fibrillation or a decrease in cardiac output. To avoid this possibility, the demand, or ventricular inhibited, mode of operation can be used. In this mode, the pacemaker circuitry senses the heart’s intrinsic electrical signal and attempts to pace the heart only if the intrinsic signal is too infrequent or absent. Although most temporary pacing is performed with demand or asynchronous ventricular pacing,


●


Inspection and Preventive Maintenance System dual-chamber pacemakers are also available for atrialventricular (A-V) sequential pacing. In addition, some pacemakers are capable of fast-rate pacing for overriding certain cardiac rhythms.

Citations from Health Devices External pacemakers [Evaluation], 1974 Feb; 3:75-90. External pacemakers [Evaluation], 1974 Aug-Sep; 3:268-74. Undetected pacemaker spike signals in IABP patients [Hazard], 1989 Dec; 18:441.

Procedure

500 Ω resistor

Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator, as well as the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

Connector or connector pins to attach leads to pacemaker


Test apparatus and supplies A variable amplitude and rate ECG simulator with at least several millivolts QRS output amplitude and range of rates to 75 pulses per minute

Oscilloscope (to be used to determine the rate accuracy of the pacemaker and thus requiring an accurate sweep speed verified by periodic calibration; an ECG monitor or electrograph should not be used to determine the output amplitude of a pacemaker, since the limited frequency response of these instruments may distort the waveform and result in erroneous amplitude readings) Pacing system analyzer (optional) Note: A pacing system analyzer, used to test pacemakers and leads during an implantation procedure, has features that greatly facilitate inspection of external (invasive) pacemakers. It may be possible to borrow a pacing system analyzer from the cardiology or surgery department for this inspection. Of course, a unit must always be available for their use. As an alternative, a pacing system analyzer may be purchased (see Health Devices 1993 May-Jun; 22:260). Pacemaker device analyzers (for external pacemakers only) will perform many of the qualitative tests and some of the quantitative tests in this procedure and may be useful for quick confirmation of a pacemaker’s performance. Although they may not directly perform all of the recommended tests, they may be equipped with an oscilloscope output to facilitate these tests.

Special precautions Before performing an inspection, notify clinical staff if the pacemaker will be removed from its normal storage area or if the unit will be out of service for even a few minutes. While the results of a specific test may

2

indicate a deficiency, they may not justify removing the pacemaker from use unless a replacement unit is readily available. (For example, if the rate is inaccurate but still covers the necessary range, notify the clinical staff of the problem, suggest that another unit be used if possible, and contact the manufacturer to arrange for repair or replacement. However, if the unit cannot be inhibited in the ventricular inhibited mode, immediately remove it from use.)

1.1


1.9

Cables. Extension leads (cables) are sometimes used to allow more remote placement of the pacemaker (e.g., during a surgical procedure). A cable may be kept with the pacemaker, or all extension cables may be kept in one central location. Inspect the cables and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain. The cable connectors should provide an insulated connection. Replace older, noninsulated connectors, and avoid using alligator clip connectors. If cables are sterile, ensure that they are inspected with each use and have them resterilized.

1.10 Terminals. Inspect the output terminal insulation for cracks or signs of deterioration. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a maximum rate setting), consider the possibility of inappropriate clinical use or of incipient device failure. Record


Pacemakers, External Invasive simulator to the pacemaker output terminal, adjust the ECG rate higher than the pacing rate, observe the sensing indicator, and note the cessation of the pacing indicator.

the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery. Inspect the physical condition of batteries and battery connectors. Open the battery compartment and examine it for signs of corrosion. If corrosion residues are apparent, or if there is evidence of spilled liquid in the battery compartment, clean the compartment and replace the battery.

1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Verify that limb straps, a spare battery, and a screwdriver (if one is needed to replace the battery) are readily accessible for each unit. A sterile catheter and an extension cable may also be kept with each unit. Insulating caps to cover the lead connectors when the pacemaker is disconnected should also be included. Check that straps are clean and untangled. Do not store spare batteries in areas with high temperatures or where the terminals could be shorted.

Discuss appropriate battery replacement intervals and procedures with users. If the battery has been in use for the maximum recommended time, or if it is time for routine replacement, install an appropriate new battery. Label it with the date, if appropriate. Most manufacturers recommend alkaline, mercury, or lithium batteries, although some manufacturers state a preference.

1.24 Battery Test Feature. Check the battery condition with the battery test feature of the unit. This may be either a meter reading obtained by pushing a button or an observation that the pacing indicator is functioning when the unit is turned on. Check the unit’s instruction manual for details.

Battery connectors should be clean and shiny. If they are dirty, clean them with a paper towel or a rubber pencil eraser, and wipe them afterward with a clean, soft cloth. Do not use emery cloth, steel wool, or liquids to clean the contacts because this may leave conductive residues that could interfere with pacemaker function. Check that battery connectors securely grip the battery and correct, if necessary.

If a dual-chamber pacemaker is being tested, record appropriate quantitative results for both pacemaker channels.

2. Quantitative tests

2.3

1.18 Indicators/Displays. Verify that all indicators and markings are easy to read. The pacing indicator should indicate pacing pulses when the pacemaker is turned on. Verify that the pacing indicator rate varies as the pacing rate control is adjusted. If the indicator is designed to show only pulse currents delivered to the heart, provide a complete current path by either connecting the pacemaker to the 500 Ω load or short-circuiting the output terminals of the pacemaker. If a shorted lead is used, remove it following the test. To verify that the QRS sensing indicator functions, set the pacemaker to its maximum sensitivity (lowest setting). Connect an ECG

Pulse Width. Use the test setup shown in Figure 1, or connect the pacemaker to a pacemaker analyzer to determine the pacemaker output pulse width. Set the pacemaker to approximately 5 mA (2.5 V) at 60 bpm. The oscilloscope sweep speed should be about 0.2 msec per division, and the trace should be set to trigger at the beginning of the pacemaker pulse so that the waveform covers most of the oscilloscope’s viewing area. Use consistent start and end points (i.e., manufacturer’s specifications or 90% amplitude points) when measuring pulse width. Typical pulse widths are 0.5 to 2.0 msec. If pulse widths are user adjustable, select maximum and minimum settings and verify that they are within 10% of the manufacturer’s specifications.

2.4

Atrial-Ventricular Delay. For dual-chamber units with A-V delay, check the delay. Use the test setup shown in Figure 1 with the atrial and ventricular outputs connected together, or use a


3

Inspection and Preventive Maintenance System pacing system analyzer with this capability. Using the same output settings as in Item 2.3, measure and record the time delay between the start of the atrial pulse output and the start of the ventricular pulse output. If the delay is adjustable, confirm that minimum and maximum are within specification (±10%); record this additional result as Item 2.5 on the inspection form. 2.6

Direct Current Leakage. Connect a 500 Ω load across the output terminals of the pacemaker as shown in Figure 1. With the pacemaker turned off, measure the DC voltage with a voltmeter across the 500 Ω load; it should not exceed 5 mV. Turn the pacemaker on and, using an oscilloscope, measure the voltage across the 500 Ω load during the nonpaced activity period just before the output pulse. Again, it should not exceed 5 mV. These tests should be repeated for both the atrial and ventricular channels in dual-chamber pacemakers.

Rate accuracy within 5% is considered to be satisfactory. 2.11 Amplitude Accuracy. Using the test setup shown in Figure 1, set the pacemaker rate to about 60 bpm and the output amplitude to 1 mA (0.5 V on those units calibrated in volts). Verify that pulses are of the correct polarity. Calculate the average amplitude as indicated in Figure 2. Record either voltage or current amplitude. Repeat this test with the pacemaker set to 5 mA (2.5 V) and 10 mA (5 V) or maximum. Amplitude accuracies should be within 10%. 2.12 Sensing Sensitivity. This test will determine the pacemaker sensitivity to an externally applied pulse. The external ECG test signal is not equivalent to the intracardiac electrical signal that would appear on the pacemaker catheter; therefore, pacemaker response may not be identical to

Additionally, for dual-chamber units, connect two 500 Ω loads between the positive and negative output and connect a third 500 Ω load between the A+ and V+ terminals. Set the pacing mode to DDD, and measure the voltage across this third resistor during the nonpaced activity period using an oscilloscope; it should not exceed 5 mV. 2.10 Rate Accuracy. Use the pacemaker analyzer or test setup shown in Figure 1. Set the pacemaker output to approximately 5 mA (2.5 V) in the asynchronous mode. Most pacemakers should be checked at rates of 60 and 120 bpm (corresponding to periods of 1.0 and 0.5 sec), although special-purpose high-rate units should be checked at higher rates. Measure and record either the actual rate or period of the pacemaker. To determine the rate, divide 60 by the period (i.e., 60/period [sec]).

Figure 1. Pacemaker pulse width, rate, and amplitude setup.

4

Figure 2. Pulse amplitude calculation.


Pacemakers, External Invasive that obtained during actual use. A 40 or 20 msec sine-squared pulse is often used (in pacing system analyzers) to provide a standard signal for comparison among units or between results of tests at two different times; however, a variableamplitude ECG simulator is also adequate for inspection purposes. Because ECG waveforms may differ among simulators, note the model of the simulator used, and use the same model simulator when testing this and other pacemakers in the future. With the pacemaker in the ventricular inhibited mode and at maximum sensitivity, connect the ECG simulator output to the pacemaker, and monitor the signal on the oscilloscope (see Figure 3). Allow the oscilloscope sweep to free-run (automatic trigger) at 1 sec per division. The pacemaker should be set at approximately 60 bpm and 5 mA output. The ECG simulator should be set for a 75 bpm rate. Slowly increase the simulator output from zero until the pacemaker is completely inhibited (pacemaker output is not observed on the oscilloscope or pacemaker output indicator). From the oscilloscope display, measure and record the QRS peak amplitude by the scope at the pacemaker terminals. Repeat the test at a midrange sensitivity to ensure that the sensing control is functioning. Pacemaker sensitivity should meet the manufacturer’s specifications. At maximum sensitivity, most units will begin to sense at 1 to 2 mV. Some units have sensitivity knobs graduated in millivolts; these are usually only approximate because of the poor resolution provided. To test units with a ventricular synchronous mode of operation, instead of looking for the pacemaker pulse to disappear, look for the pacemaker pulse to coincide with each pulse generator pulse, and record the amplitude of the pulse generator

Figure 3. Pacemaker sensitivity test setup. pulse. It may be necessary to turn the pacemaker off to accurately measure the pulse amplitude.


Clean the exterior.

3.4


4. Acceptance tests Conduct major inspection tests for this procedure. If a pacing system analyzer with appropriate test functions is available, test the following feature. 4.1

Refractory Period. Follow the analyzer manufacturer’s instructions for performing this test.

Before returning to use Ensure that all controls are set properly in their normal pre-use positions. Attach a Caution tag in a prominent position on life-support equipment or any other device for which the user must be aware that control settings may have been changed. Either recharge the battery, or equip the device with fully charged batteries.


5


Pacemakers, External Noninvasive Used For: Defibrillator/Monitor/Pacemakers [17-882] Pacemakers, Cardiac, External Noninvasive [16-516]

Also Called: Noninvasive pacemakers, temporary pacemakers, transcutaneous pacemakers, transthoracic pacemakers Commonly Used In: Critical care units, emergency rooms, operating rooms, ambulances Scope: Applies to pacemakers used for temporary pacing through adhesive electrodes applied to the skin; includes pacemakers that are integral to a defibrillator/monitor; does not apply to implanted, transesophageal, or transvenous pacemakers. (See Procedure/Checklist 418 for Pacemakers, External Invasive.) This procedure is intended to be used in conjunction with the procedures for ECG monitors and defibrillator/monitors. For noninvasive pacemakers with an integral monitor, see ECG Monitors Procedure/Checklist 409. For noninvasive pacemakers that are integral to a defibrillator/monitor, see Defibrillator/Monitors Procedure/Checklist 408. Risk Level: ECRI Recommended, High; Hospital Assessment, Type

ECRI-recommended Interval

Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview The heart has its own pacemaker — a group of specialized cells that produce a rhythmic train of electrical pulses. These pulses are carried by specialized conducting cells to cardiac muscle cells in the atria and ventricles, stimulating them to contract in a coordinated pumping action. In some patients, the intrinsic pacemaker or the conduction network fails. Under these circumstances, unless the heart muscle is stimulated by some other means, the heart may beat erratically, slow down, or stop. A pacemaker is used to control these arrhythmias (irregular heart rhythms) by applying a repetitive electrical stimulus to the heart. Temporary external pacing is used to control the heart until it reverts (or is reverted through other therapy) to a satisfactory rhythm or until a permanent pacemaker can be



Time Required

implanted. Temporary pacing is also used when patients with a history of certain cardiac disorders must undergo major surgery. In addition, it can be used to induce cardiac stress during diagnosis of cardiac ailments. Noninvasive pacemakers conduct pacing current through the patient’s thorax using a pair of adhesive electrodes placed on the chest or on the chest and back. These are connected to the pacemaker with a cable. Most noninvasive pacemakers are integrated into a defibrillator/monitor. In the fixed-rate pacing mode, the pacemaker emits a stimulus at regular intervals, regardless of cardiac activity. Fixed-rate pacing is sometimes used when a pacemaker is initially set up to confirm that the signal amplitude is adequate to capture, or pace, the heart.


●


Inspection and Preventive Maintenance System If fixed-rate pacing is used and the heart reverts to its own rhythm, competition may occur between the pacemaker stimuli and the natural cardiac signals. This may cause ventricular fibrillation or a decrease in cardiac output. To minimize this possibility, the demand, or ventricular-inhibited, mode of operation is usually used. In this mode, the pacemaker circuitry senses the heart’s intrinsic electrical signal and attempts to pace the heart only if the intrinsic signal is too infrequent or absent. When the heart rate is above the set pacing rate, pacemaker output is inhibited.

Citations from Health Devices Pace*Aid Model 50C external transcutaneous pacemaker [Evaluation], 1983 Nov; 13:3-13.

defibrillator/monitor/pacemaker units. While the results of a specific test may indicate a deficiency, they may not justify removing the pacemaker from use unless a replacement unit is readily available. For example, if the rate is inaccurate but still covers the necessary range, notify the clinical staff of the problem, suggest that another unit be used if possible, and arrange for repair or replacement. However, if the unit cannot be inhibited in the demand mode, immediately remove it from use. Caution should be used when the unit is delivering output. Noninvasive pacemakers can typically generate impulses of up to 300 V.

Transcutaneous pacemakers [Guidance article], 1988 Feb; 17:39-47.

Do not monitor through multifunction electrodes during demand-mode and sensitivity tests. Monitoring through the output electrodes is not possible during pacing because the impulses will saturate the monitor.

Defibrillator/monitors and external noninvasive pacemakers [Evaluation], 1993 May-Jun; 22:213-94.

Procedure

Noninvasive pacemaker testers, 1993 May-Jun; 22:260-1.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Noninvasive pacemaker tester (optional) Note: Pacemaker analyzers can be used to perform many of the tests in this procedure and may be useful for quick confirmation of a pacemaker’s performance. For some tests, it may be necessary to use an oscilloscope. Analyzers intended for implantable or transvenous pacemakers are not suitable for testing noninvasive pacemakers unless specifically designed with this capability. The items listed below may not be required if an analyzer is available. ECG simulator with variable amplitude (≤0.5 mV) and rate settings (from 30 to 200 ppm)

Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Determine whether any special IPM procedures or frequencies are recommended by the manufacturer. Many units have self-test or service-mode functions that allow supplemental performance verification.

1. Qualitative Tests 1.1


1.2

Mount/Fasteners. If the device is mounted on the wall or on a stand, IV pole, or cart, examine the condition of the mount. Verify that the mounting apparatus is secure and that all hardware is firmly in place. Check for weld cracks. Ensure that the assembly is stable.

1.3

Casters/Brakes. If the device moves on casters, check their condition and make sure they roll and swivel freely. Check the operation of brakes and swivel locks.

1.4

AC Plug. Examine the AC power plug for damage. Attempt to wiggle the blades to determine if they are secure. Shake nonmolded plugs, and listen for rattling, which could indicate loose

Adapters for connecting pacing cable leads to test equipment (these can be easily made using the connectors of an electrode pair) 200 to 1,000 Ω noninductive load, 5 W (see manufacturer’s specifications) Oscilloscope

Special precautions Before performing an inspection, notify clinical staff if the pacemaker will be removed from its normal storage area or if the unit will be out of use for even a few minutes; this is particularly crucial in the case of

2


Pacemakers, External Noninvasive screws. If damage is suspected, open the plug and inspect it. 1.5

Line Cord. Inspect all line cords, including the battery charger line cord, for signs of damage or inappropriate repairs (e.g., taped sections). If replacement is necessary, be sure to wire the new power cord or plug with the correct polarity.

1.6


1.7

Circuit Breaker/Fuse. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check the fuse’s current rating and type against that marked on the chassis. If the unit has a spare fuse holder, verify that a fuse of the same rating and type is provided. If the spare fuse is missing, advise clinical personnel that it is important to have a spare fuse to expedite the return of the device to operation when a fuse blows. They should also be advised to notify clinical engineering or another appropriate department whenever a fuse is blown so that the appropriate personnel can investigate the cause and provide another spare fuse.

1.9

Cables. Inspect the cables and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain. The cable connectors should provide an insulated connection. Replace damaged cables (e.g., loose connectors).

controls that should be returned to their original positions following the inspection. It is most appropriate to set the output current (mA) and rate (ppm) controls of noninvasive pacemakers to zero or their minimum values to minimize the risk of inadvertent activation. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check controls that should operate against fixedlimit stops for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. For units with internal batteries, open the battery compartment, and examine it for signs of corrosion. If corrosion residues are apparent or if there is evidence of liquid spillage in the battery compartment, clean the compartment and replace the battery. Consult the unit’s service manual for battery condition self-tests. Verify that the unit or charger is plugged into line power and that all batteries are either charged or charging. Discuss appropriate battery cycling and replacement intervals and procedures with users. For units with removable batteries, verify that an adequate number of batteries are being maintained at full charge. If the battery has been in use for the maximum recommended time or if it is due for routine replacement, install an appropriate, fully charged, new battery. Label it with the date, if appropriate.

1.10 Connectors. Inspect the pacing output energy port for insulation and signs of deterioration. Connect the pacing and/or multifunction cables to the appropriate output ports, and verify easy and secure connection to the unit.

1.18 Indicators/Displays. Verify that all visual indicators and displays, including power, mode, pace indicator, and leads-off message, are working. Verify that control labels and markings are easy to read.

1.11 Electrodes. Confirm that an adequate supply of ECG and pacemaker electrodes is available. Check the expiration dates of electrodes and replace as necessary.

Connect the monitoring leads to an ECG simulator or pacemaker analyzer. Connect the pacing cable to an appropriate test load or a pacemaker analyzer, start the pacemaker, and print a strip. Verify that a pacing pulse marker appears on the monitor and strip. Verify that the pacing marker rate varies as the pacing rate control is adjusted.

1.13 Controls/Switches. Before adjusting any controls and alarm limits, check their positions; these settings will sometimes be stored in a setup menu. If any of them appear inordinate (e.g., a maximum rate setting), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those

1.19 User Calibration/Self-Test. Activate self-test or service-mode functions that allow supplemental performance verification.


3

Inspection and Preventive Maintenance System 1.21 Audible Signals. Activate all audible signals, including QRS detector, heart-rate alarm, and lead faults. Verify that the signal can be easily heard in the environment in which the device will be used. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.24 Demand-Mode Activation/Inhibition. The pacemaker should inhibit demand-mode pacing whenever a heart rate greater than the set pacing rate is detected. With a test load across the pacemaker output, use an ECG simulator to apply a normal sinus rhythm to the ECG input. Verify that pacing is inhibited when the simulated heart rate (bpm) exceeds the set pacing rate (ppm) and that pacing activates when the simulated heart rate falls below the set pacing rate. A difference of up to 10 bpm between inhibition and activation rates is common.

2. Quantitative Tests 2.1

2.2

2.3

4

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum grounding resistance of 0.5 Ω. Chassis Leakage Current. With the grounding conductor of plug-connected equipment temporarily opened, measure chassis leakage current to ground. Operate the device in all normal modes, including on, standby, and off; record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA. Pulse Width. To determine the pacemaker output pulse width, either use the test setup shown in Figure 1 or connect the pacemaker to a pacemaker analyzer. Set the pacemaker to approximately 100 mA at 60 bpm. The oscilloscope sweep speed should be at least 5 msec per division, and the trace should be set to trigger at the beginning of the pacemaker pulse so that the waveform covers most of the oscilloscope’s viewing area. Use consistent start and end points (i.e., manufacturer’s specifications or 90% amplitude points) when measuring pulse width. Typical pulse widths are 20 and 40 msec. A pulse width within 10% of the device’s specified width is satisfactory.

2.10 Rate Accuracy. Use the pacemaker analyzer or test setup shown in Figure 1. Set the pacemaker output to approximately 100 mA in the fixed-rate mode; for demand-mode-only units, either connect ECG leads to an ECG simulator set to a rate lower than the set pacing rate or short all monitoring leads together, which will simulate asystole. Pacemakers should be checked at their maximum and minimum rates and at 60 ppm. Measure and record either the actual rate or period of the pacemaker. To determine the rate in pulses per minute, divide 60 sec/min by the period in sec/cycle (i.e., rate [in ppm] = 60/period [in sec]). Rate accuracy within 5% is considered to be satisfactory. 2.11 Amplitude Accuracy. Use the pacemaker analyzer or the test setup shown in Figure 1. Set the pacemaker rate to about 60 ppm and the output amplitude to 50 mA. If viewing the output on an oscilloscope, also verify that no DC voltage is present. Record the peak amplitude and either voltage or current amplitude. Repeat this test with the pacemaker set to 100 mA and its maximum current. Amplitude accuracies should be within 10%.


Clean the exterior.

3.3

Calibrate per the manufacturer’s specifications.

3.4


4. Acceptance Tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following test. 4.1

Demand-Mode Sensitivity. Pacemaker sensitivity should meet the manufacturer’s specifications;

Figure 1. Pacemaker pulse width, rate, and amplitude setup.


Pacemakers, External Noninvasive most units will begin to sense an ECG waveform with a QRS complex of 0.5 mV or less. Therefore, a variable-amplitude ECG simulator that generates waveforms with R-wave amplitudes less than or equal to 0.5 mV should be used. Because ECG waveforms may differ on different simulators, note the model of the simulator used, and use the same model when testing all pacemakers, both in the present and in the future. Using the setup in Figure 1, connect the ECG cable to the simulator with its output set to minimum amplitude or asystole. Set the pacemaker for demand mode, and adjust the monitor for maximum sensitivity or gain. Set the pacemaker to a rate lower than that of the simulated heart rate, and start pacing. Verify pacing output on the oscilloscope and pacing markers on the monitor and recorder. Gradually increase the amplitude of the

simulated ECG waveform, and note the amplitude at which pacing is inhibited.

Before returning to use Ensure that all controls are set properly. Set alarms loud enough to attract attention in the area in which the device will be used. Other controls should be in their normal pre-use positions. It is most appropriate to set the output current (mA) and rate (ppm) controls of noninvasive pacemakers to zero or their minimum values to minimize the risk of inadvertent activation. Attach a Caution tag in a prominent position on life-support equipment or any other device for which the user must be aware that control settings may have been changed. Either recharge the battery, or equip the device with fully charged batteries.


5


Peritoneal Dialysis Units Used For: Peritoneal Dialysis Units [11-226]

Also Called: Peritoneal dialysis cyclers, PD cyclers Commonly Used In: Dialysis units, patient homes Scope: Applies to automatic peritoneal dialysis cyclers that can be used in dialysis units and in the home Risk Level: ECRI Recommended: High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Peritoneal dialysis (PD) is one of several therapies used to remove metabolic wastes from the blood in the treatment of renal failure. The purpose of dialysis is to partially replace kidney function. Although dialysis does not perform the endocrine functions of healthy kidneys and does not promote kidney function or healing, it slows down the deterioration of other organ systems by ridding the blood of metabolic wastes and excess water. In PD, dialysate is infused directly into the peritoneal cavity through a catheter and a sterile disposable tubing system. Usually, a permanently implanted catheter provides access to the peritoneal cavity for a series of dialysis sessions, although temporary catheters are used for acute dialysis. Diffusion of metabolic wastes from the blood occurs within the abdominal cavity through the pores and intracellular channels of the peritoneum, the membrane covering the abdominopelvic walls and organs. PD is based on the principles of diffusion and osmosis. Through diffusion, solutes (e.g., toxic metabolic wastes, electrolytes) readily move from an area of greater concentration (the blood) to an area of lesser concentration (the dialysate) until equilibrium is reached. Through



Time Required

osmosis, solvents (e.g., water) move across the semipermeable peritoneal membrane from an area of lesser solute concentration to one of greater solute concentration. To provide a concentration gradient for diffusion and osmosis, the dialysate contains no metabolic wastes and a higher concentration of solute molecules (e.g., dextrose) than the blood. PD can be administered by manual or automated means. Manual PD can be self-administered and is gravity dependent. Using aseptic technique, the patient instills dialysate into the peritoneal cavity. The dialysate remains in the peritoneum for 30 min to 8 hr, depending on selected treatment protocol, and is then drained by positioning the bag lower than the abdomen. Automated PD requires the use of a PD unit, but is still gravity dependent. This device consists primarily of a dialysate heater and timing mechanisms to actuate valves that start and stop the flow of fluid into and draining from the peritoneal cavity. Most current units include additional features, such as electronic scales, drain alarms, temperature alarms, and flow alarms.

Citations from Health Devices Peritoneal dialysis cyclers [Evaluation], 1986 FebMar; 15:31-59.


●


Inspection and Preventive Maintenance System there are no signs of spilled liquids or other serious abuse.

Baxter PAC-X automated PD cyclers [User Experience NetworkTM], 1988 May; 17:169.


1.2

Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount. Also examine the stand or cart, including examination of the height-adjustment mechanism, if present.

1.3

Casters/Brakes. If the device is mounted on a stand or cart that moves on casters, check their condition. Verify that they turn and swivel, as appropriate, and look for accumulations of lint and thread around the casters. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug properly. Also check line cords of battery chargers, if present.

1.6


1.7

Circuit Breaker/Fuse. If the device has a switchtype circuit breaker, check that it operates freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.9

Cables. Inspect any cables (e.g., from heating unit to main unit) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Thermometer accurate to at least 0.5°C over a range of 30° to 43°C, or a temperature monitoring device made of a thermometer sealed into one leg of a Y or T connector (see the Test Equipment and Supplies Tab in this binder) Stopwatch or watch with a second hand Large graduated cylinder (2 L capacity preferred) Consumable supplies as required by machine type, including a tubing set, one or two 2 L bags of dialysate solution (can be expired), and two drain bags (3 L or larger). (To reduce costs, a single set of consumable supplies can be used repeatedly for inspections. If expired dialysate solution is not available, an empty dialysate bag can be filled with 2 L of tap water. This may require the use of a funnel connected to a piece of tubing with a spike on one end. Place the spike into the empty dialysate bag, and connect the other end of the tubing to the funnel. The water can then be poured easily into the bag. After the bag is filled, clamp it at the top, then remove the tubing and funnel. Conspicuously mark the bag so that it will not be used for a patient.) Tubing clamp

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. In some units, especially the more sophisticated ones, it will be impossible to perform quantitative checks on all monitoring and alarm circuits. Refer to the manufacturer’s service manual for suggestions when the procedures described below cannot be carried out in a straightforward manner.


2

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all hardware is present and tight, and that

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. If keyed connectors (e.g., pin-indexed gas connectors) are used, make sure that no pins are missing and that the keying is correct. Verify that tubing segments from disposable tubing sets fit securely in pinch valves.


Peritoneal Dialysis Units 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection.

alarm by unplugging the device at any point during the PD cycle. If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions that will be simulated later in this procedure.

Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level.

1.14 Heater. Examine the heater for physical condition (e.g., corrosion of its sheath, deteriorated insulation). 1.15 Motor/Pump. Check the physical condition and proper operation of these components, if present. Clean and lubricate as required, and note this on Lines 3.1 and 3.2 of the inspection form. (However, do not check 3.1 and 3.2 until all necessary cleaning and lubrication are completed.) 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check battery condition by activating the battery test function or measuring the output voltage; for lead-acid batteries, measure the specific gravity. Check the condition of the battery charger if present, and to the extent possible, confirm that it does, in fact, charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function. Record the reading of an hourmeter if present. 1.20 Alarms. Induce alarm conditions to activate audible and visual alarms. Check that any associated interlocks function. Test the power-failure

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.24 Pinch Valves. If pinch valves are present, check them for mechanical integrity. Make sure they move freely, are clean, and properly occlude the tubing when activated. Check occlusion pressure as recommended by the manufacturer. Pinch valves on some devices may need to be calibrated or checked with a calibration kit supplied by the manufacturer. If so, obtain the kit and follow the manufacturer’s recommended interval for calibration or calibration checks.



2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Set the thermostats so that the heater operates while taking measurements. Chassis leakage current to ground should not exceed 300 µA.


3


2.4

Fluid Temperature. Set up the PD unit according to the manufacturer’s instructions, using the 2 L dialysate bag filled with expired dialysate or tap water (at room temperature) and the tubing set. Connect the thermometer or temperature measuring device to the end of the dialysate line using a T connector, and place the open end of the T into an empty graduated cylinder. Set the infusion volume at a volume typical of the unit’s clinical usage (e.g., 2 L for adult use, 500 mL or 1 L for pediatric use). After a dialysate warming period (15 to 30 min), the patient fill line will open, and the dialysate will flow from the bag, through the tubing, and into the graduated cylinder. Record the temperature of the dialysate as it flows past the thermometer in the T connection. The temperature should be 32° to 37°C.

(expired dialysate or tap water). Set the infusion volume to 1 L and dwell and drain times to minimal values. After a dialysate warming period, the solution will flow from the dialysate bag, through the tubing, and into the “patient” bag. Using a stopwatch or watch with a second hand, measure the dwell time and drain time (time from end of dwell to next fill). Cycle time should be within ±10% of set times. 2.7

Ultrafiltration Monitor (if present). After completion of the cycle-timing procedure described above, allow all of the fluid to collect in the drain bag. The ultrafiltration monitor should display a volume within 5% of the known volume of fluid added to the “patient” bag at the beginning of the cycle-timing procedure. Alternatively, ultrafiltration accuracy can be verified by confirming the accuracy of the infusion volume and drain scales. Overall, ultrafiltration accuracy should be within 10%. Individual scale accuracies, if used for determining ultrafiltration, should be within 5%.

2.8

Fill Alarm. This alarm can be tested in the second cycle, following the cycle-timing procedure described above. While the fluid is flowing from the dialysate bag into the “patient” bag, clamp the tubing between the two bags to occlude the flow. (Note: Fill and drain alarms may work along with a timing mechanism — the alarm may occur only if the proper volume of fluid fails to reach a specific point in a given period of time. As a result, the alarm may not occur until several minutes after the tubing is occluded.)

2.9

Drain Alarm. The drain alarm can similarly be tested when the fluid is flowing from the “patient” bag to the drain bag. Clamp the tubing between the two bags to occlude the flow.

Infusion Volume Accuracy. Measure the volume of fluid collected in the graduated cylinder during the dialysate temperature measurement described above. Be sure to wait until the infusion cycle is completed before measuring the volume. Alternatively, infusion volume accuracy can be verified using calibrated weights rather than fluid on some PD units. Scale accuracy verification procedures may be described in the operator’s or service manual. A 10% fill volume accuracy appears to be acceptable for safe and effective treatment; however, a maximum error of 5% is needed if fill and drain volumes are used to calculate ultrafiltration (UF).

2.5

2.6

4

Temperature Alarm. The high-temperature alarm can be tested using the same testing configuration used for the temperature control testing described above, but use warm tap water (about 40°C or consistent with manufacturer’s specifications), instead of room-temperature dialysate or tap water. Verify that dialysate cannot be delivered to the patient in a high-temperature alarm condition. A low-temperature alarm is usually not present because dialysate at room temperature is adequately warmed during the heating phase to prevent patient discomfort. This has already been checked in Item 2.3. Cycle Timing. Set up the unit according to manufacturer’s instructions using a 2 L dialysate bag filled with expired dialysate or water, the tubing set, and the two drain bags, one simulating the patient’s peritoneal cavity and the other the drain. To the “patient” bag, add a known volume (e.g., 500 mL) of additional fluid


Clean the exterior and interior, if needed. Pay particular attention to solution deposits. Vacuum the air vents and cooling fans, if needed.

3.2


3.3


4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following tests.


Peritoneal Dialysis Units 4.1

Leakage Current from Dialysate Line to Ground. If the chassis leakage current measured in Item 2.2 exceeds 50 µA, measure the leakage current from the patient dialysis line to ground. Test with the unit in all normal operating modes and with the unit off. If the device housing is not grounded, measure leakage currents from the patient dialysis line to the housing.

4.2

lysate has not heated sufficiently. This feature can be tested by the same testing configuration described in Item 2.3 but using cold (refrigerated) water instead of room-temperature water.

Before returning to use Set alarms loud enough to alert personnel in the area in which the device will be used.

Leakage current from the patient dialysis line should not exceed 50 µA.

Attach a Caution tag in a prominent position so the user is aware that control settings may have been changed.

Cold-Fluid Protection. Most units have a mechanism that prevents infusion if the dia-

Recharge battery-powered devices or equip them with fresh batteries if needed.


5


Phototherapy Units Used For: Phototherapy Units, Visible Light, Hyperbilirubinemia [17-515]

Also Called: Bili-lights, phototherapy lamps (lights), blue lamps (lights) Commonly Used In: Neonatal intensive care units, hospital nurseries, homes Scope: Applies to phototherapy units with overhead lamps or fiberoptic pads and phototherapy lights integral with incubators or radiant warmers Risk Level: ECRI Recommended, Medium; Hospital Assessment, Time Type



Required

Major

12 months*

months

.

hours

Minor

NA

months

.

hours

* For overhead lamps with fluorescent tubes, the spectral irradiance may need to be measured at more frequent intervals, depending on the level of use and the types of tubes used. However, other tasks of this IPM procedure typically need not be performed on a more frequent basis.

Overview Hyperbilirubinemia is characterized by elevated levels of bilirubin (a pigment in the blood derived from hemoglobin). The condition is typically associated with jaundice — a yellowish skin discoloration that affects many newborns. Phototherapy units are used to reduce bilirubin levels in the blood. These units emit visible light, which photodegrades bilirubin into excretable photoproducts. Blue light (420 to 480 nm) is considered most effective. Overhead phototherapy lamps can be one of two types: a bank of fluorescent tubes or a tungsten-halogen spotlight. Fluorescent tubes that are typically used include (1) wide-spectrum white light (e.g., daylight, cool white), (2) regular wide-spectrum blue light (designated F20T12/B), or (3) narrow-spectrum blue light (e.g., Special, or Super, Blue; F20T12/BB). Tungsten-halogen bulbs are filtered for maximum light output within the blue spectrum. Light intensity can be controlled by changing the distance between the patient and the light source.


Fiberoptic phototherapy systems apply therapeutic light using a plastic pad. The light is delivered from a tungsten-halogen bulb through a fiberoptic cable and is emitted from the sides and ends of the fibers inside the pad. Filters are used to maximize light output within the blue spectrum. Some systems provide light intensity controls to adjust the irradiance levels of the light sources. Any ultraviolet (UV; 280 to 400 nm) or near-infrared (IR; 780 to 1,400 nm) radiation that is emitted by these light sources must be filtered because both UV and IR radiation, at high enough levels or for long exposure periods, can damage the eyes (retina and cornea) and the skin. Fluorescent tubes emit mostly UV; in units with fluorescent tubes, the UV is blocked by the Plexiglas cover. Tungsten-halogen bulbs emit UV and IR; in units with these bulbs, the radiation is blocked by UV/IR filters or heat-reflecting mirrors. Radiometers are used to measure the light performance of phototherapy units in a clinical setting. These devices take a single measurement across a relatively


●


Inspection and Preventive Maintenance System wide band of wavelengths concentrated in the region considered most therapeutically effective. The readings (displayed in units of µW/cm2/nm) are intended to provide an effective irradiance measurement that users can relate to the light’s ability to degrade bilirubin. No standards currently specify phototherapy treatment levels. However, a minimum average spectral irradiance of 4 µW/cm2/nm in the range of 425 to 475 nm has been suggested. Most medical textbooks recommend average levels in the range of 6 to 12 µW/cm2/nm.

operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.



1.2


1.3

Casters/Brakes. If the device moves on casters, check their condition. Verify that they turn and swivel, as appropriate, and look for accumulations of lint and thread around the casters. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture in an area.

1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion.

1.6


1.7


1.8

Fiberoptic Pads/Cables. Inspect any fiberoptic pads and cables associated with the phototherapy

Citations from Health Devices Freestanding phototherapy units [Evaluation], 1981 Apr-May; 10:133-51. Fiberoptic phototherapy systems [Evaluation], 1995 Apr; 24:134-52.

Test Equipment and Supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Radiometer that measures spectral irradiance across the wavelength band of 425 to 475 nm Note: A radiometer’s reading depends on the unique spectral response characteristics of each model phototherapy device and radiometer. Therefore, only irradiance readings for a particular light source/radiometer combination can be compared. Readings from different manufacturers’ radiometers for the same light source cannot be compared. It is not necessary to use a phototherapy unit manufacturer’s radiometer.

Special precautions Plexiglas covers, for phototherapy units with fluorescent tubes, must be put back in place after tube replacement. ECRI has received reports of inappropriate replacement of fluorescent phototherapy tubes with UV tubes. Although these UV light sources may emit some blue light and may have the same pin bases and dimensions as the correct tubes, they are not intended for phototherapy of hyperbilirubinemia and may expose infants to hazardous levels of UV radiation. Do not touch the glass of tungsten-halogen bulbs. Hold the bulb with a cloth during installation.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to

2


Phototherapy Units unit for general condition. Check that there are no unusual dark spots across the pad when the light unit is turned on. Carefully examine insulation of cables for broken fibers.


1.10 Fiberoptic Cable Connector. Verify that the fiberoptic cable is firmly gripped by its cable connector. 1.12 Filters/Heat-Reflecting Mirrors. In phototherapy units with tungsten-halogen bulbs, check the condition of the IR/UV filter for any noticeable scratches or flaking. Clean with manufacturer-recommended solutions. In phototherapy units with fluorescent tubes, check that the Plexiglas cover (UV filter) is clean and in place. 1.13 Controls/Switches. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.14 Heater. If the unit is integral with a radiant warmer, refer to the Radiant Warmers Procedure/Checklist 419. 1.15 Fan. Check the physical condition and proper operation of the fan, if so equipped. Clean and lubricate as required, and note this on Line 3.1 and 3.2 of the inspection form. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all indicators on the unit. Be sure that all segments of a digital display function. Record reading of an hourmeter, if present. 1.20 Alarms. Induce alarm conditions to activate audible and visual alarms. 1.21 Audible Signals. Operate the device to activate any audible signals. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Verify that user-operated radiometers are returned for manufacturer calibration at least annually.

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. If the device has an accessory receptacle, check its grounding to the main power cord.

2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off; record the maximum leakage current. If the unit has heating and cooling modes, set the thermostats so that each operates while taking measurements. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord. Chassis leakage current to ground should be 300 µA or less.

2.10 Spectral Irradiance. Measure spectral irradiance with a radiometer, and determine an average of at least three measurements. Use the same model radiometer and sensor head with the same phototherapy unit and the same method of measurement as used to obtain baseline readings during acceptance testing (see Item 4.1). Compare the average irradiance with the average value determined during acceptance inspection. Replace fluorescent tubes if light has dropped 20% to 30% below the baseline value (the selected level should be no lower than 4 µW/cm2/nm) or after the manufacturer-specified number of operating hours. When the spectral irradiance level is marginal, it may be desirable to determine that it is not due to low line voltage


3

Inspection and Preventive Maintenance System (i.e., below 105 VAC). Replace fluorescent tubes having output below acceptable levels, as well as tungsten-halogen bulbs when they have burned out, and indicate this on Line 3.4 of the inspection form.


Clean the exterior (interior, if appropriate).

3.2

Lubricate the fan, if necessary.

3.4

Replace tube(s)/bulb, if necessary.

4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438. In addition, perform the following test: 4.1

4

Baseline Spectral Irradiance. Measure spectral irradiance with a radiometer and determine an average of at least three measurements. Units with variable intensity should be adjusted to the maximum setting. Measure and record line voltage supplied to the phototherapy unit and, for

units with fluorescent tubes, note the type of tube(s) and tube combinations that are used. Also, record the model of the radiometer and identification (control and/or serial number) of the sensor head. To ensure consistent measurements in future inspections, it is important to describe the position of measurement in relation to the light source (a diagram may be useful) and the method of averaging data. Otherwise, measure at a normal operating distance (e.g., 20 in) from an overhead lamp, along a line that marks the central axis. For fiberoptic phototherapy systems, measure irradiance on the surface of a pad at a central position. Determine if the manufacturer recommends inspection and/or tube/bulb replacement at a specified interval.

Before returning to use Ensure that all controls are set properly. If the unit is being used at home, ensure that all controls are set correctly before it is returned to the patient.



Physical Therapy Ultrasound Units Used For: Ultrasound Units, Physical Therapy [11-248] Ultrasound Units/Neuromuscular Stimulators, Physical Therapy [17-908]

Also Called: Therapeutic Ultrasound Commonly Used In: Physical therapy departments and clinics Scope: Tabletop, portable, and cart- or wall-mounted therapeutic ultrasound units and combination ultrasound/neuromuscular stimulator units Risk Level: ECRI Recommended, Low; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Output power should be tested following any user report that a transducer has been dropped, has been operated without proper coupling to a patient, or is generating heat. It is also generally necessary to calibrate output power following transducer replacement or repair to the ultrasound unit.

Overview Therapeutic ultrasound units convert electromagnetic energy to high-frequency (i.e., 1 or 3 megahertz [MHz]) sound waves that penetrate tissues to produce pain relief through thermal and nonthermal physiologic reactions. This conversion of energy occurs in the transducer, or sound or treatment head, of the machine. Ultrasound as a modality can be used independently or in conjunction with a neuromuscular stimulator to enhance pain-relief mechanisms. A therapeutic ultrasound unit has two basic components — a generator and a transducer. The electrical output of the generator is applied through a flexible cable to a piezoelectric crystal in the transducer. The electrical energy is converted into sound energy through the reverse piezoelectric effect: as the voltage alternates across it, the crystal expands and contracts, creating vibrations. This sound energy exits the transducer in a collimated beam pattern. A special coupling gel is used to facilitate transmission of the ultrasound beam from the transducer to the patient’s


skin. Not using gel or using an inadequate amount will cause heat at the transducer/skin interface instead of the underlying tissues, possibly burning the patient. Most units allow selection of a continuous mode, in which the output power is constant, or a pulsed mode, in which the output is switched on and off; the pulse rate is typically 60 to 120 pulses per second (pps), although some units operate at a higher or lower rate. Pulsed waves are further characterized by the duty cycle, the percentage of time that ultrasound waves are present during a pulsed period. Typical duty cycles range from 20% to 50%. Because the output power of a pulsed waveform averaged over the on and off phase of the cycle is lower, it causes less heating than a continuous output on the same setting. Since there is no direct indicator of internal tissue temperature, the operator depends on patient feedback to adjust the intensity of the treatment and prevent burns. The operator can, however, estimate the output strength by knowing the transducer’s effective radiating area (ERA), the sound wave frequency,


●


Inspection and Preventive Maintenance System and the length of treatment. Ultrasound units specify output as power (watts) and/or as intensity (power divided by a transducer’s ERA in cm2 [watts/cm2]. The maximum output of most units does not exceed 20 watts. Some units have an automatic shutoff that discontinues therapy and stops the unit’s treatment timer when there is insufficient coupling between the transducer and the patient; they can also have an audible and/or visible alarm to alert the user to the problem. Some units also accommodate the use of two transducers at a time, either to treat two separate areas on one patient or to treat two patients at once. In addition, some vendors offer watertight transducers for use in underwater therapy. In a neuromuscular electrical stimulator, an electronic generator transmits pulses of energy through the sound head, which acts as the active electrode, and into the tissue. Pulse waveforms are monophasic (either positive or negative) or biphasic; typically, a biphasic waveform is used in conjunction with the ultrasound therapy. The pulse rate is variable; generally, 80-150 pps are used therapeutically. The pulse amplitude is adjusted separately for each modality, allowing the maximum benefit from both modalities while maintaining patient comfort. Neuromuscular stimulation produces some local thermal and chemical changes in the patient; however, it is most often used to create a muscle contraction. When electrical stimulation is used in conjunction with ultrasound, the active electrode can be manipulated to produce a rhythmic contraction/release episode in the muscle or muscle group that is most affected by the injury. The contraction/release acts as a pump and promotes the removal of metabolic by-products, which helps reduce spasm and pain.

and service manuals; be sure that you understand how to operate the equipment and know the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Note: To prevent damage to the transducer, it must be connected to the load of the power meter/balance any time that the ultrasound unit is operating during this procedure (e.g., for leakage current or timer accuracy measurements). Reliable ultrasound power measurements require a significant amount of user technique to properly position and couple the transducer to the test device. Most test devices require degassed water (water with less than 5 ppm dissolved oxygen) for a coupling medium. In hospitals, this requirement can frequently be met by using sterile distilled water prepared by most central sterile supply/materials management departments (the water should be sealed in an airtight container immediately after preparation). Water is usually sufficiently degassed after boiling for 30 minutes and sealing the container. Boiling the water in a flask makes it easy to seal and cool in a refrigerator. (Some users find it convenient to store and transport degassed water in 2 L plastic soft drink bottles.) Gently pour the degassed water into the test cavity of the power meter/balance, avoiding turbulent flow.



1.2


1.3


1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Stopwatch Ultrasound power balance or meter (1 to 30 watts, 5%) 50 to 500 mL degassed water Manufacturer-specified test load (for units with neuromuscular stimulators) Oscilloscope (for units with neuromuscular stimulators)

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction

2


Physical Therapy Ultrasound Units Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function.

If any damage is suspected, open the plug and inspect it. 1.5


1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), we recommend that the cord be affixed to the unit so that it cannot be removed by the operator.

1.7

Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it operates freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis.

1.9

Cables. Inspect any cables (e.g., sensor, electrode, remote control) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate connectors. If keyed connectors are used, make sure that no pins are missing and that the keying is correct.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. 1.19 User Calibration. Verify that the calibration function operates, if so equipped. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories, such as ultrasound coupling gel (check the expiration date), different size/frequency transducers, and neuromuscular stimulator electrodes and probes.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double-insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value.

2.2

Leakage Current. For units that are not doubleinsulated, measure chassis leakage current to ground with the grounding conductor temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Chassis leakage current to ground should be 300 µA or less.

2.3

Timer. Connect the transducer to the power meter/balance. At a timer setting of 1 minute and at

1.11 Transducers/Electrodes. Confirm that any necessary transducers and/or electrodes are on hand and check their physical condition. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion.


3

Inspection and Preventive Maintenance System tive load specified by the stimulator manufacturer (commonly, a precision 1,000 Ω, ≥1⁄4-watt resistor) and to an oscilloscope. At maximum, midrange, and low stimulator output settings, determine the voltage from the oscilloscope for the corresponding waveforms. Compare the voltages or derived currents (voltage ÷ test load resistance) to those set on and/or displayed by the stimulator at each setting. Refer to the manufacturer’s accuracy specification, although the measured output for most units can be expected to be within 10%.

maximum output, verify that output is switched off (i.e., the power meter/balance indicates no output) in 1 min ±10 sec. (At settings above 5 min, timers should be accurate to within 10%.) 2.10 Ultrasound Power. Identify the power meter/ balance used for this test and its specified test error in the “Notes” section of the inspection form, and carefully follow all manufacturer directions for its use. With the ultrasound unit selected for continuous output, measure output power at maximum, midrange, and low settings (e.g., 20, 10, and 5 watts). (If the unit has output indicated and displayed only in units of intensity [watts/cm2], it will be necessary to convert to watts by multiplying each intensity setting by the value of the transducer’s area. For example, at an intensity setting of 5 watts/cm2, a 4 cm2 transducer should emit 20 watts.) Measured values should be within 20% at each setting (25% would be acceptable, allowing for a test error of 5%). If the unit has more than one transducer and/or frequency, perform this test at both frequencies for each transducer, recording the transducer serial number and the selected frequency for each test. 2.11 Stimulator Voltage or Current. Connect the leads of the neuromuscular stimulator to a resis-

4



3.3



Before returning to use Make sure that power controls are set to zero output level.



Pneumatic Tourniquets Used for: Tourniquets, Pneumatic [14-074]

Also Called: Surgical tourniquets, automatic tourniquets, arterial tourniquets Commonly Used In: Operating rooms Scope: Applies to pneumatic tourniquets used during limb surgery Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Time Required

Overview

must remain inflated until the infused agent has been sufficiently absorbed.

Pneumatic tourniquets are primarily used to occlude blood flow and maintain a bloodless surgical field during limb surgery. Inflating the tourniquet cuff to a suprasystolic pressure compresses the arteries and arrests circulation. The fundamental objective of a pneumatic tourniquet is to reliably maintain the minimum pressure necessary to stop blood flow in the limb.

Nerve damage, although rarely permanent, is the most common tourniquet-related injury. Injury is likely to result from extended application time and/or excessive cuff pressure. Tourniquet literature suggests that the application period be limited to 1 hr on arms and 11⁄2 hr on legs.

These devices have four basic components: a cuff that is usually applied around the proximal portion of a limb, a means for inflating the cuff bladder (e.g., compressed gas, hand or electric pump), an indicator for monitoring cuff pressure, and a means of regulating this pressure. Some tourniquet controllers also have a timer or elapsed-time meter. In addition to providing a bloodless surgical field, a pneumatic tourniquet used during intravenous regional anesthesia (IVRA) prevents infused local anesthetic (e.g., lidocaine) from flowing out of the limb until most of the infusion has been absorbed by limb tissues (about 20 min). This technique usually employs a dual-bladder cuff and a control valve for interfacing a standard tourniquet controller with the dual-bladder cuff. Because the various anesthetics used for IVRA are potentially toxic, at least one of the two bladders


Sudden depressurization — such as would occur if a connector came loose — or insufficient pressure from a slow leak may also cause injury. If cuff pressure falls below the patient’s systolic pressure during the first 20 min of IVRA, serious adverse reactions (e.g., cardiovascular collapse, convulsions, coma) or death can result from the anesthetic entering the circulatory system. Venous congestion or edema may also occur if cuff pressure falls between systolic and diastolic. Tourniquets inflated with oxygen or nitrous oxide present a fire risk. Nevertheless, we continue to see oxygen routinely used for this purpose, and some tourniquet manufacturers sanction oxygen inflation in their operator’s manuals and sell oxygen fittings. We emphasize that tourniquets should never be inflated with oxygen or nitrous oxide; rather, compressed air or nitrogen should be used.




1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug observing correct polarity.

1.6


1.7


1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not stretched, cracked, kinked, or dirty. If the device has hose barbs, ensure that tubing/hoses fit tightly and are not stretched at these sites. Because serious consequences can result from sudden cuff depressurization, replace any questionable hoses.

Pneumatic tourniquets [Evaluation], 1984 Oct; 13:299. Maintaining pneumatic tourniquets: Who is responsible? 1984 Oct; 13:316.

Test apparatus and supplies Leakage current meter or electrical safety analyzer (line-powered units only) Ground resistance ohmmeter Pressure gauges or meter to ≥1,000 mm Hg Hoses, T fittings, and adapters for connecting squeeze bulb and pressure gauge or meter Cylindrical object to simulate an arm (1 lb coffee can or a pipe with 3 to 4 in outer diameter) Squeeze bulb with bleed valve Stopwatch or watch with a second hand

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Although most units are gas powered and have few (if any) alarms, we have included electrical safety and electronic component functional tests for use on those units, where appropriate.



1.2

Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount.

1.3


2

1.10 Fittings/Connectors. Examine all fittings and connectors for general condition. Gas fittings should lock tightly and should not leak. If keyed connectors (e.g., pin-indexed gas connectors) are used, make sure that no pins are missing and that the keying is correct. Gas source connectors should not be compatible with oxygen or nitrous oxide supplies. 1.13 Controls/Switches. Before moving any controls or alarm limits, check their positions. If any of them appear inordinate (e.g., a cuff pressure set at maximum), consider the possibility of inappropriate clinical use or of incipient device failure. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. If a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.


Pneumatic Tourniquets operate properly and hold securely. Velcro-type fasteners should be clean, since excessive dirt or lint may affect their ability to fasten securely.

1.15 Motor/Pump. Check the proper operation of these components (line-powered units only). 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for a minimum of 15 min to check that the battery is charged and can hold a charge. (The inspection of controller stability [Item 2.4] or timer [Item 2.5] may be carried out simultaneously on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function, if so equipped. Check the condition of the battery charger, and to the extent possible, confirm that it does, in fact, charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function and that gauges read zero with no pressure applied. 1.20 Alarms. Where possible, induce alarm conditions (e.g., kinked tube, cuff underpressure and overpressure) to activate audible and visual alarms. Disconnect the cuff to simulate underpressurization, and squeeze the inflated cuff to produce an overpressure. If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. 1.21 Audible Signals. Operate the device to activate any audible signals, including elapsed time indicators. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level.

Test the cuffs for leaks by wrapping each around a cylindrical object and connecting it to pressure gauge or meter with a T fitting. Use a squeeze bulb to inflate the cuff to 300 mm Hg. Cuff pressure should remain unchanged after 1 min. (This procedure may be performed simultaneously with Item 2.4 or 2.5.) Leak test both bladders of dual-bladder cuffs. 1.24 Dual-Bladder Control Valve. Verify that tubing and connectors are secure and in good condition. Check that fittings are secure and do not leak and that tubing is not stretched, cracked, kinked, or dirty. Connect the control valve to the tourniquet controller and a dual-bladder cuff. Verify correct functioning of the control valve, including ability to sequentially have one cuff (proximal) inflated, both cuffs inflated, and one cuff (distal) inflated.



2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Check the unit while on and off, and record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA.

2.3

Maximum Cuff Pressure. Disconnect the cuff from the tourniquet controller, and in its place connect a T fitting attached to the pressure gauge or meter and a squeeze bulb. Adjust the controller for maximum cuff pressure, then attempt to exceed this pressure with the squeeze bulb. Verify that the maximum pressure does not exceed 550 mm Hg or is within 50 mm Hg of the manufacturer’s specified maximum pressure. While we recommend that maximum pressure not exceed 550 mm Hg, many units are designed to allow higher pressures.

2.4

Controller Stability. When testing pressure indicator accuracy (Item 2.10), observe each pressure reading for 2 min to verify that the pressure

1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of all cuffs. Verify that fittings lock securely and that the bladders and tubing are not stretched, cracked, kinked, or dirty. The covers should be clean, and the fastening mechanisms should


3

Inspection and Preventive Maintenance System remains stable. Because experience indicates that the Kidde Model 400 may develop a valve leak that permits excess reservoir pressure into the cuff, verify the stability of this controller. Using the same setup as used in the previous test, adjust the gauge or meter pressure to 400 mm Hg from 0 mm Hg. This pressure should not vary more than 10 mm Hg after 15 min. 2.5

Elapsed-Time Meter/Timer. Verify the accuracy of a timing mechanism, where present, using a stopwatch or watch with a second hand for a period of 15 min. The error should not exceed 2 min.

2.10 Cuff Pressure Indicator Accuracy. With the controller still connected to the pressure gauge or meter, verify indicator accuracy at settings of 200 and 450 mm Hg. Observe each pressure reading for 2 min. The cuff pressure indicator should be accurate to within 5%.

4


Clean the exterior, if needed.

3.2


3.3

Calibrate per manufacturer’s specifications.

3.4

Replace tubing, hoses, cuffs, and batteries, if needed.


Before returning to use Return controls to their preinspection or normal pre-use settings. Either recharge batteries or equip battery-powered devices with fresh batteries.



Portable Ventilators Used For: Ventilators, Portable [17-423]

Also Called: Respirators, home care ventilators Commonly Used In: Home care and hospital or emergency vehicle transport Scope: Applies to ventilators that are physically compact, totally powered by battery or AC line cord and that have an internal chamber in which a piston driven by an internal motor pressurizes air that is delivered to the breathing circuit; these ventilators may use external O2 source attachments for delivering supplemental O2 therapy, external positive end-expiratory pressure (PEEP) valves, heated humidifiers, and external monitors or remote alarms; does not apply to anesthesia units and critical care ventilators (see Procedure/Checklists 461 and 458, respectively) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

6 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Inspection and preventive maintenance intervals should be scheduled according to the manufacturer’s recommendations, which may be related to hours of use. However, units should have a major inspection at least every six months. Pre-use checks should be performed by a respiratory therapist or respiratory equipment technician.

Overview As technological advances continue to prolong life for critically ill patients and make life possible for both children and adults with otherwise fatal conditions, a large, rapidly growing patient population needs longterm ventilatory support. To meet these needs, some hospitals have special care areas, such as intermediate care or prolonged respiratory care units, where stable ventilator-dependent patients can remain indefinitely or be cared for until they are weaned from ventilatory support, moved to another facility, or sent home. These patients do not need to be in an ICU and do not require complex critical care ventilators and are instead placed on portable ventilators. Mechanical ventilators are used to compensate for deficiencies in normal breathing by aiding or augmenting


spontaneous breathing or by completely regulating a prescribed breathing pattern for a patient who cannot breathe without assistance. Dependence on the amount and type of mechanical support varies according to the disorder and the presence of any pulmonary complications; therefore, ventilation needs may range from occasional ventilator use to complete ventilator dependency. Patients who require long-term mechanical ventilation include adults and children who have impaired or total loss of ventilatory function resulting from a variety of etiologies, such as neuromuscular diseases, restrictive and chronic obstructive lung diseases, and spinal cord injuries, as well as children who were born with premature or neonatal lung disease. Portable ventilators are available with varying degrees of sophistication to meet the spectrum of needs


●


Inspection and Preventive Maintenance System of long-term ventilator users. For example, to control costs, some ventilators have limited capability for patients with limited needs. Other ventilators have additional features for pediatric use and for patients who may be more difficult to treat. Thus, portable ventilators offer some features that are usually available only on critical care ventilators (e.g., nonphysiologic breathing patterns, such as inverse inspiratory:expiratory [I:E] ratio), while retaining simplicity of operation, portability, and low cost.

Citations from Health Devices Leaving ventilator-dependent patients unattended [Hazard], 1986 Apr; 15:102-3. Remote alarms for ventilators and other life-support equipment, 1986 Dec; 15:323-4.

charged, the inspection can be carried out on battery power to help confirm adequate battery capacity. Manufacturers’ recommended procedures for inspection and preventive maintenance of mechanical ventilators vary in both methods and required accuracy. In addition, ventilation modes, controls, and algorithms for calculated variables vary greatly according to manufacturer and model. This procedure provides the basic framework for complete ventilator inspection and preventive maintenance. Manufacturers’ recommended procedures should be added where appropriate. References to specific pages of the manufacturer’s manual should be added to the checklist. (The checklist includes blank spaces for the insertion of these page references.)

Disposal breathing circuits [Evaluation], 1993 Jul; 22:311-31.

IPM Task ManagerTM, the software component of the Inspection and Preventive Maintenance System, enables easy production of customized procedures and checklists for specific ventilator models and clinical needs. Items performed by outside vendors can be excluded from the checklist; a separate checklist for use by outside vendors can be produced to ensure that those items agreed upon are performed by the vendor.



Portable volume ventilators [Evaluation], 1988 Apr; 17:107-31. Portable volume ventilators [Evaluation], 1992 Aug; 21:255-89.

Lung simulator with expandable bellows Pressure gauge or meter with 2 cm H2O resolution from -20 to +120 cm H2O

1.1


1.2

Mount/Fasteners. If the device is mounted on a bracket or wheelchair tray, examine the condition of the mount. If it rests on a shelf, check the security of this attachment. Check the mounting security of all components (e.g., supplemental O2 equipment, heated humidifiers) or attached monitors.

1.4


1.5


Syringe with a volume of at least 1.5 L or a volume monitor Stopwatch Ventilator tester (optional) Various breathing circuit adapters, including a connector that can occlude the breathing circuit’s exhalation port Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Additional items as required for a specific manufacturer’s procedures

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. If the battery is fully

2


Portable Ventilators 1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), affix the cord to the unit so that it cannot be removed by the operator. (See Health Devices [Hazard], 1993 May-Jun; 22:301-3.)

1.7


1.8


1.9

Cables. Inspect any cables (e.g., remote alarm cable) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are securely gripped in the connectors at each end, which will prevent rotation or other strain. Where appropriate, verify that there are no intermittent faults by flexing cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all gas fittings and connectors for general condition. Gas fittings should be tight and should not leak. Connectors to hospital central piped medical gas systems for delivering supplemental oxygen should have the appropriate DISS or quick-connect fitting to eliminate the need for adapters. 1.12 Filters. Check the condition of gas (e.g., air-inlet) filters. Check for corrosion residue indicative of liquid, gaseous, or solid particle contaminants in the gas supply; advise appropriate personnel if found. Clean or replace if appropriate, and indicate this on Lines 3.1 and 3.4 of the inspection form. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Investigate questionable control settings on a home care unit. Consult with the patient’s physician to determine correct settings. The patient or caregiver should receive additional training, if required. Record the settings of those controls that should be returned to their original positions following the inspection.

Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.15 Fan/Motor. Check the physical condition and proper operation of these components. Clean and lubricate if required, according to the manufacturer’s instructions, and note this on Lines 3.1 and 3.2 of the form. 1.17 Power Sources/Internal Battery Charger. Inspect the physical condition of the internal battery and battery connectors. Verify that, the ventilator operates on AC power and that the AC power indicator is lit. Disconnect the device from AC power. If an external battery is connected, verify that the ventilator switches to its external battery and continues to operate without interruption. Verify that the external power and power switchover indicators light and that the audible alarm activates. Usually, this is a continuous alarm that can be reset by pressing the alarmsilence button. Disconnect the external battery. Verify that if no external battery is connected or if the external battery is disconnected, the ventilator switches to its internal battery and continues to operate without interruption. Verify that the internal battery and power switchover indicators light and that the audible alarm activates. Usually, this is a continuous alarm that can be reset by pressing the alarm-silence button. Operate the unit on internal battery power. Check battery condition by activating the battery test function or measuring the output voltage. Verify that the battery is charged and can hold a charge and that the device operates for at least 20 minutes. Reconnect the external battery, if available, then plug the ventilator back to AC power, and verify that the ventilator switches from internal to external battery and then to AC power.


3

Inspection and Preventive Maintenance System Turn the ventilator off and verify that the battery charging indicator is lit. A battery charging control may need to be set on some models.

1.23 Accessories. Confirm the presence and condition of accessories, including the humidifier (see Heated Humidifiers Procedure/Checklist 431) and the nebulizer.

Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date.

Verify that all external devices are connected into the breathing circuit or to the ventilator correctly. Verify that all breathing circuit components (including filters) are compatible with the ventilator according to the manufacturer’s recommendations (see Health Devices 1988 Apr; 17:109). Check that all breathing circuit components that were retained are assembled correctly.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. Record the reading of an hour meter, if present. 1.20 Alarms/Interlocks. Induce the high- and lowpressure alarms as described below and any other alarm conditions to activate audible and visual alarms. Check that any associated interlocks function. If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. Verify that the remote alarm indicator functions properly.

1.24 Modes. Set the ventilator to operate in control mode. Verify that the ventilator can deliver breaths to the test lung. Set the ventilator to operate in the intermittent mandatory ventilation (IMV) mode, if so equipped, and verify that the ventilator delivers breaths to the test lung. Set the ventilator to operate in Assist/Control mode (or Assist mode) and simulate spontaneous breaths by expanding the bellows of the test lung. Verify that an assisted breath is delivered in response to a breathing effort when the breathing circuit exceeds the sensitivity setting. Adjust the sensitivity control to 1 cm H2O above the end-expiratory pressure, and verify that the ventilator autocycles.

Disconnect the breathing circuit at the tracheostomy tube connector to activate the lowpressure alarm. Verify that the low-pressure alarm activates audibly and visually and that the alarm activates within the manufacturer’s specified time delay. Reattach the breathing circuit and verify that the indicator remains lit until manually reset.

Set the ventilator to operate in synchronized IMV (SIMV) mode. Simulate several breathing efforts. Verify that a single assisted breath is delivered followed by spontaneous unassisted breaths.

To activate the high-pressure alarm, adjust the high-pressure alarm limit to 5 cm H2O below the peak inspiratory pressure (PIP). Verify that the high-pressure alarm activates audibly and visually and that the displayed pressure does not exceed the high-pressure alarm limit. Return the high-pressure alarm limit to its original setting and verify that the indicator remains lit until manually reset. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, and instruction cards are present and legible.

4

Set the ventilator to operate in pressure-cycled mode, if available, and set the high-pressure alarm limit 5 cm H2O below the peak airway pressure. Verify that the ventilator cycles to exhalation when the breathing circuit pressure on the ventilator’s display reaches the high-pressure alarm limit.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components,


Portable Ventilators Record the tidal volume measured by the volume monitor at the outlet of the exhalation valve or the PEEP valve, if used. (Volume can also be confirmed by calculating the delivered tidal volume from the product of the test lung and breathing circuit compliance [C] and the PIP [V = C × PIP]. To determine the compliance, deliver a set volume [same volume that the ventilator is set to deliver] to the breathing circuit and test lung with a large syringe, and record the resultant change in pressure at the inlet of the test lung. The compliance is the delivered volume divided by the recorded pressure.) The measured volume should be within 10% of the set tidal volume.

verify grounding of the mainframe and each module or component. 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

Press the sigh button, if available, to activate the sigh mode and verify that the sigh indicator illuminates. Record the delivered sigh volume and verify that it is within 10% of the volume specified by the manufacturer for the set sigh volume.


System Leakage. Refer to the manufacturer’s manual for ventilator settings. To check that there are no leaks in the breathing circuit or in the tubing within the ventilator, occlude the exhalation port and verify that the pressure does not fall more than 10 cm H2O below the PIP between breaths. If the ventilator fails this test, detach the breathing circuit and repeat the test while covering the ventilator’s air outlet with a gloved hand.

2.4

Pressure Display. Record the PIP from the ventilator’s pressure display and from the pressure gauge or meter at the inlet of the test lung. The ventilator display should be the within 10% or ±3 cm H2O (whichever is greater) of the pressure measured at the test lung. Verify that both pressure readings return to zero during exhalation.

2.5

Control Settings. Check the operation and accuracy of ventilation controls. Typically, these tests are performed by attaching the ventilator to a lung simulator and comparing measured values to settings on the ventilator. The manufacturer should recommend the appropriate ventilator settings (e.g., tidal volume, rate, inspiratory time) to verify proper operation and accuracy (generally within 10%). The procedures for checking the tidal volume and respiration rate control are listed below. A ventilator tester or some other method to record the pressure and flow waveform is required to verify the accuracy of the other controls, which may include inspiratory time, expiratory time, I:E ratio, % O2 concentration, or flow.

Record the number of breaths delivered during a 1-minute period. Verify that the measured rate is within 1 breath/min of the set respiration rate (may be ±2 breaths/min at high set rates). 2.6

Pressure-Relief Mechanism. If the ventilator has an adjustable pressure-relief valve, adjust the control to its maximum setting. Remove the test lung. Check for proper operation of the ventilator’s internal pressure-relief mechanism by occluding the breathing circuit’s exhalation port and measuring the resulting peak pressure on the pressure gauge. The pressure should not exceed the value specified by the manufacturer. Remove the occlusion from the exhalation port and reattach the test lung. Decrease the adjustable pressure-relief setting to its lowest setting during delivery of a machine breath and verify that the breathing circuit pressure lowers.


Clean the exterior, interior, and components, if needed.

3.2

Lubricate the fan and/or motor, if required.

3.3

Calibrate according to the manufacturer’s instructions.

3.4



5

Inspection and Preventive Maintenance System 4. Acceptance tests Conduct major inspection tests for this procedure and the appropriate tests in the General Devices Procedure/Checklist 438.

normal pre-use positions. If the unit is being used at home, ensure that controls are set correctly before it is returned to the patient.


Attach a Caution tag in a prominent position so that the user will be aware that control settings may have been changed.

Ensure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their

Recharge battery-powered devices or equip them with fresh batteries, if needed.

6



Pressure Transducers Used For: Transducers, Pressure [14-119]

Commonly Used In: Special care units, emergency rooms, operating rooms, cardiac catheterization laboratories Scope: Applies to reusable pressure transducers used for blood pressure and other physiologic pressure monitoring; can be adapted for the purpose of verifying performance of disposable pressure transducers Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* If users routinely use an external pressure source to verify the performance of each transducer/monitor pair before use on a patient and if transducers are well maintained during use and processing, periodic inspection may not be required or may be reduced to qualitative checks only.

Alternative in-use calibration techniques, 1982 Nov; 12:24.

Overview Pressure transducers are used in conjunction with physiologic monitors to sense a pressure and convert it into an electrical signal that is processed by the monitor and displayed on a digital or waveform display. Blood pressure transducers are generally used with a fluidfilled catheter to transmit the pressure from a point in the circulatory system to the transducer located outside the body. Catheter-tip transducers that are placed within the body and have electrical leads that leave the body through the catheter are also available.

Disposable pressure transducers [Evaluation], 1984 Sep; 13:268. Electrical isolation of blood pressure channels [User Experience NetworkTM], 1986 Dec; 15:331. Disposable pressure transducers [Evaluation], 1988 Mar; 17:75. Pre-use pressure transducer calibration procedure, 1988 Sep; 17:278.

In addition to being used to monitor blood pressure, transducers are also used to monitor uterine and intracranial pressure.

Disposable pressure transducers and multipressure channel physiologic monitors [User Experience NetworkTM], 1988 Nov; 17:357.



Physiological pressure transducers [Evaluation], 1979 Jul; 8:199.


Air embolism during calibration of invasive blood pressure monitoring systems [Hazard], 1982 Nov; 12:22.

Pressure gauge or meter (range to 300 mm Hg)


Ground resistance ohmmeter Sphygmomanometer squeeze bulb


●


Inspection and Preventive Maintenance System Proper calibration and use of test equipment will increase the quality of testing.

Y connector Accurate pressure monitor Mating connector for the transducer or small-diameter probe to gain access to transducer connector terminals (acceptance testing only; may be part of an electrical safety analyzer)


Chassis/Housing. Examine the exterior of the transducer for cleanliness and general physical condition. Be sure that plastic housings are intact, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Examine — but do not touch — the surface of the sensing diaphragm for nicks or dents. The transducer should be stored with a dome attached or in such a way that the transducer diaphragm is protected from damage.

1.2

Mount. If the transducer is mounted on a stand or IV pole, examine the condition of the mount.

1.9

Cables. Inspect the cable for cracks, cuts, or pinching. Examine the strain reliefs at both ends of the cable; be sure that they hold the cable securely.

Container of 0.9% saline solution

Special precautions The transducer diaphragm is extremely delicate and easily damaged. Do not touch the diaphragm or allow any tools to contact it. We recommend against the use of a mercury manometer for pressure measurements because of the associated mercury contamination risks.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. We recommend assigning each transducer a separate equipment control number independent of the monitor, since any particular transducer may be used with more than one monitor. (Because it is difficult to permanently tag a transducer, the serial number may be used instead of an assigned control number.) Testing the accuracy of blood pressure monitors and transducers presents a practical problem. Clinical requirements for blood pressure measurements call for an accuracy of 5% on arterial pressure ranges and ±2 mm Hg on venous or pulmonary pressure measurements. Because the criteria apply to the measurement system, the individual components must have greater accuracy. Thus, we recommend using a pressure simulator to verify the accuracy of the pressure monitor to be used to test the transducer. For efficiency, first test all of the monitors in one area with a transducer simulator or one transducer that is known to be accurate. Then, test all the transducers in that area using one monitor. Record the control number of the monitor used to test the transducer. As long as the transducer/monitor combination is accurate to within 5% or ±2 mm Hg of a given static pressure, the monitor and transducer can be considered acceptably accurate. Most pressure monitor and transducer problems result in complete failure of the unit or relatively large errors.

2

1.19 User Calibration. Connect the transducer to a monitor that has been inspected and is known to be accurate. Perform any necessary zero and calibration functions. The pressure reading with no pressure applied should be within 2 mm Hg of zero (and will usually read exactly zero). If the monitor has a calibration function, it should give a pressure reading within 5 mm Hg of the pressure specified by the monitor manufacturer. 1.23 Accessories. Confirm that monitoring kits are available or that adequate stopcocks, tubing, connectors, and continuous flushing devices are available. Metal stopcocks and connectors provide a conductive pathway to the saline in the catheter, which, in turn, could provide a conductive pathway to the heart. Advise users to replace any metal connectors and stopcocks with plastic ones. If the transducer is used with disposable domes, make sure that an adequate supply of sterile domes is available. If the transducer has a metal case and is not isolated, use disposable diaphragm domes where blood pressure measurements are made (see Health Devices 1979 Jul; 8:206).

2. Quantitative tests 2.10 Pressure Accuracy. Connect the transducer to a monitor that has been inspected and is known to be accurate. Connect the stem of the Y connector to the transducer; connect the sphygmomanometer squeeze bulb and the pressure gauge or meter


Pressure Transducers to the arms of the Y connector. Be sure to attach the transducer dome (especially a disposable diaphragm dome) to the transducer according to the manufacturer’s recommendations. Carefully zero the transducer. Test the transducer at 20, 100, and maximum (or 200) mm Hg. Use the monitor’s mean arterial pressure range for the higher measurements and the venous range for the lower measurements. The transducer and monitor combination should be accurate to within ±2 mm Hg or 5%, whichever is greater, for a given pressure.

The diaphragm is very delicate. Do not contact it directly with a probe. Some transducers have metal cases that are in continuity with the sensing diaphragm and can be easily contacted without danger of damaging the diaphragm. Otherwise, it is necessary to make electrical contact through saline solution. This is most conveniently done by suspending the transducer so that the diaphragm is immersed in a nonconductive pan or cup of saline solution. The site where the cable enters the transducer case should be kept out of the solution.

If the transducer is being tested as part of a monitor/transducer pair, replace this test with Items 2.10 and 2.11 in the Blood Pressure Monitors Procedure/Checklist 434.

The test setup is shown in Figure 1. Connect the saline solution to the grounded side of the isolation test supply to minimize the hazard to the inspector. CAUTION: To avoid electric shock, do not touch any part of the transducer, transducer connector case, saline solution, or exposed wires or probes. To simplify testing, a connector may be made with all terminals and the connector shell shorted together and attached to a single lead; this lead can then be connected to the isolation test supply. Measure the current flow when 120 volts are applied to the lead of this adapter cable. Flow through an isolated transducer should be less than 20 µA.


Clean the transducer case and cable, if necessary, with a damp cloth. Do not attempt to clean the diaphragm other than by soaking and rinsing according to the manufacturer’s instructions.


Isolation. Disposable diaphragm domes, if used, provide electrical isolation and may eliminate the need for checking transducer isolation. This test should be performed on isolated transducers only.

Before returning to use Submit the transducer for disinfection or sterilization according to the hospital’s standard policy. (This is not usually required if disposable diaphragm domes are used.)

Figure 1. Transducer isolation test


3


Pulmonary Resuscitators, Gas-Powered Used For: Resuscitators, Pulmonary, Gas-Powered [13-366]

Also Called: Pulmonary resuscitators, oxygen-powered resuscitators, demand valves Commonly Used In: Critical care areas, recovery rooms, emergency rooms, patient care areas, ambulances Scope: Applies to manually cycled, pressure-limited gas-powered resuscitators; does not apply to manually operated resuscitators (see Procedure/Checklist 422); also does not apply to pressure-cycled gas-powered resuscitators, which are considered inappropriate for use during cardiopulmonary resuscitation (CPR) by the American Heart Association (AHA) and the National Research Council (NRC) because these units can be triggered into exhalation by regular chest compressions Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

NA

months

.

hours

Time Required

*

These units should be routinely checked (see Items 1.1 and 1.25) following each use (after cleaning and reassembly).

Overview Pulmonary resuscitators are relatively simple devices, yet ECRI frequently receives reports of failures that have led to unsuccessful resuscitations. The failures we have investigated were caused by incorrect assembly following cleaning or repair or by mechanical failure. Because these devices are frequently needed for lifesaving procedures, users have no time and may lack the expertise to troubleshoot, repair, and reassemble units. Resuscitators must immediately function properly whenever they are needed. All earlier recommendations called for greater than 100 L/min outlet flow. However, the most recent AHArecommended maximum flow criterion for gas-powered resuscitators is 40 L/min (JAMA 1986; 255[21]:2934). Many current gas-powered resuscitators and all gaspowered resuscitators manufactured before 1985 will exceed this criterion (keep this in mind when performing


this inspection procedure). Such units should be modified to meet AHA’s recommendations. Unless instructed otherwise by the manufacturer, return the units to be modified to the manufacturer during scheduled inspection and preventive maintenance periods. Do not attempt to modify or repair gas-powered resuscitators unless instructed to do so by the manufacturer. When purchasing new gas-powered resuscitators, buy units that perform according to the criteria set forth in this procedure.

Citations from Health Devices Gas-powered resuscitators [Evaluation], 1978 Dec; 8:24-38. Gas-powered resuscitators [Hazard], 1988 Nov; 17:352-4. Gas-powered pulmonary resuscitators [Standards update], 1989 Oct; 18:362-3.


●



50 psi oxygen source capable of providing at least 100 L/min flow

Safety System) threaded body fitting. Check that the fitting threads are clean and free of burrs or metal particles. If the threaded fitting is attached to an adapter, verify that the connection is tight and that the adapter is clean and compatible only with oxygen fittings.

100 L/min oxygen flowmeter with less than 10 cm H2O back pressure (or gasometer or spirometer and stopwatch or watch with a second hand)

1.13 Controls. Examine any controls for physical condition and verify that each control performs its proper function.

Test apparatus and supplies Pressure gauge or meter (0 to 60 cm H2O) Lung simulator

Procedure CAUTION: Inspect units only after appropriate cleaning and disinfection. Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. Take appropriate precautions when working with pure oxygen (e.g., no open flames).


Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic and metal housings are intact, that necessary assembly hardware is present and fits tightly together, and that there are no signs of spilled liquids, cracks, or other serious abuse. Examine the resuscitator’s components to verify that they are not from other similar model resuscitators. Even if components appear to be similar, they may not function as the original components. For this reason, use only parts from the unit’s manufacturer. In addition, the hospital should stock only one model of manual and gas-powered resuscitators to prevent inadvertent mixing of components.

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Check all accessories stored with the resuscitator. List the accessories that should accompany each resuscitator, and check them against the list at each inspection. Examine all accessories for cleanliness and mechanical integrity. Oxygen cylinders. If the resuscitator is stored with an oxygen cylinder, check the amount of oxygen in the cylinder. Replace the cylinder when it is less than half full. A cylinder wrench should be chained to the regulator and yoke assembly. Transparent face masks. An assortment of mask sizes (e.g., adult, pediatric) should be stored with the resuscitator to allow its use with a wide range of patients. Use only transparent masks with resuscitators. If the hospital has opaque masks, order transparent replacements, but do not remove opaque masks from use until the replacement masks are in stock and the change has been discussed with users. Inspect masks and their connectors for signs of deterioration (e.g., embrittlement). Rein-flate collapsed inflatable rims, and check for leaks or damage by immersing the mask in water. Replace if necessary. 1.24 Valve Assembly.

1.2

Mount. If the unit is attached to a wall or rests on a shelf, check the security of the attachment. The unit should be available for immediate use.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses, especially at connectors. Be sure that they are not cracked, kinked, or dirty.

CAUTION: Before proceeding with this item, be certain that you are familiar with the correct valve assembly. Misassembly will likely cause the resuscitator to fail, which may result in patient death. Verify valve operation (Item 1.25) after reassembly.

1.10 Fittings/Connectors. Verify that gas-powered resuscitators are fitted with an oxygen supply hose and have an appropriate connector for an oxygen source, usually a DISS (Diameter Index

Ideally, the valve should require no disassembly for cleaning. However, some models must be partially disassembled. Therefore, disassemble the valve only to the extent recommended by the

2


Pulmonary Resuscitators, Gas-Powered manufacturer for effective cleaning. Keep parts of a unit together and separate from other units by placing each disassembled unit in its own mesh bag for machine cleaning and disinfection. After disinfecting, inspect the components for signs of wear or damage. Confirm that the flapper-valve device (present on some gas-powered resuscitators) that directs the gas flow is not torn or damaged. Carefully reassemble the valve, and verify correct assembly.

volume of gas expelled over a given time period. The outlet flow with full depression of the resuscitator trigger should be 35 to 45 L/min. (The AHA-recommended maximum flow rate is 40 L/min; we allow ±5 L/min for measurement error.) If a unit fails this test, contact the manufacturer to determine if a flow-limit modification is available. 2.5

Continuous Flow Rate. Using the flowmeter, measure the flow of inhalator-type gas-powered resuscitators that allow continuous oxygen flow to spontaneously breathing patients. On adjustable units, check minimum, middle, and maximum settings for accuracy (to ±20%).

2.6

Demand Valve Function.

Valves that are disassembled for cleaning should also be disassembled during periodic inspections to verify cleanliness, condition (as above), and correct assembly. 1.25 Operation. Connect the resuscitator to a 50 psi oxygen source capable of providing at least 100 L/min flow. A gas-powered resuscitator should fill a lung simulator of equivalent volume quickly and, upon releasing the trigger, should allow passive exhalation. If the resuscitator does not fill quickly, verify that the gas source is not at fault. Pressure regulators may not be capable of providing adequate flow because of improper calibration or varying tank pressures. Similarly, a hospital oxygen wall outlet may provide less than the necessary flow because of hidden line or outlet restrictions.


2.4

Maximum Working Pressure. Connect the resuscitator outlet to a pressure gauge or meter. Fully depress the resuscitator’s trigger, and record the maximum pressure reading. (It may be necessary to partially crimp the tubing between the resuscitator and a gauge to prevent pressure oscillation.) Pressure should be 55 to 65 cm H2O. If a unit fails to meet this criterion, return it to the manufacturer for repair. Some units tested with a low-compliance gauge attached directly to the resuscitator may generate a pressure spike before pressure limiting occurs. Test these units with a lung simulator (adult setting) to permit a more realistic delay time for pressure limiting to occur. Maximum Flow Rate. To determine the maximum flow rate, connect the resuscitator’s outlet to a flowmeter with less than 10 cm H2O back pressure at 100 L/min to the outlet (flowmeters that produce higher back pressure will affect the flow significantly). Alternatively, a gasometer or spirometer can be used along with a stopwatch or a watch with a second hand to measure the

CAUTION: Items 2.3 and 2.4 must be performed before attempting the following test. Also, be certain that the unit has been properly cleaned and disinfected. When inspecting units incorporating demand valves (a feature of some gas-powered resuscitators that supply a flow of oxygen in response to the patient’s inspiratory effort in addition to manually triggered flow), inhale deeply from the mask or patient connector with the oxygen turned on as well as turned off. With the oxygen on, it should be possible to hear the flow through the demand valve upon inhalation. When inhalation is complete, flow should cease and permit exhalation. When the oxygen is turned off (i.e., simulating an exhausted supply), it should be possible to inhale room air through the valve. In either case, minimal resistance should be felt during inhalation.

3. Preventive maintenance Cleaning, disinfecting, and parts replacement are usually conducted by central service, the respiratory therapy department, or the user department after each use and thus should not be required during periodic inspections. Resuscitator operation should always be verified after processing.


Before returning to use Return inspected units to use in a clean, clear plastic bag. Following major inspection in which contamination may have occurred (e.g., Item 2.6), the unit should be submitted for processing just as after clinical use.


3


Pulmonary Resuscitators, Manual Used For: Resuscitators, Pulmonary, Manual, Reusable [17-591]

Also Called: Pulmonary resuscitators, manual resuscitators, bag resuscitators, bag-valve-mask units, Ambu bags (Ambu is a registered trademark of Ambu of Denmark to be used only when referring to that device) Commonly Used In: Critical care areas, recovery rooms, emergency rooms, patient care areas, ambulances Scope: Applies to manually operated models; does not cover gas-powered resuscitators (use Pulmonary Resuscitators, Gas-Powered Procedure/Checklist 448) Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

months

.

hours

Minor

NA

months

.

hours

Time Required

*

These units should be routinely checked (see Items 1.1 and 1.25) following each use (after cleaning and reassembly).

Overview


Pulmonary resuscitators are relatively simple devices, yet ECRI frequently receives reports of failures that have led to unsuccessful resuscitations. The failures we have investigated were caused by incorrect assembly following cleaning or repair or by mechanical failure. Because these devices are frequently needed for lifesaving procedures, users have no time and may lack the expertise to troubleshoot, repair, and reassemble units. Resuscitators must immediately function properly whenever they are needed.

Citations from Health Devices Reprocessing and inspection of manual pulmonary resuscitators [Hazard], 1987 Nov; 16:378-9. Exhaled-air pulmonary resuscitators (EAPRs) and disposable manual pulmonary resuscitators (DMPRs) [Evaluation], 1989 Oct; 18:331-52.


Pressure gauge or meter (0 to 60cm H2O) Lung simulator Stopwatch or watch with a second hand 50 psi oxygen source with flowmeter for connection to resuscitator (for acceptance test only)

Procedure CAUTION: Inspect units only after appropriate cleaning and disinfection. Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.


●


Inspection and Preventive Maintenance System Use only transparent masks with resuscitators. If the hospital has opaque masks, order transparent replacements, but do not remove opaque masks from use until the replacement masks are in stock and the change has been discussed with users. Inspect masks and their connectors for signs of deterioration (e.g., embrittlement). Reinflate collapsed inflatable rims, and check for leaks or damage by immersing the mask in water. Replace if necessary.


Housing/Bag. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic and metal housings are intact, that necessary assembly hardware is present and fits tightly together, and that there are no signs of spilled liquids or other serious abuse. Inspect the resuscitator for overall physical condition. It should be clean and free of cracks or other signs of damage. Carefully inspect resuscitator bags, especially while compressing them. There should be no tears, holes, or flaking; they should compress easily and not leak, reexpand fully and quickly, and have no permanent set.

1.24 Valve Assembly. CAUTION: Before proceeding with this item, be certain you are familiar with the correct valve assembly. Misassembly will likely cause the resuscitator to fail, which may result in patient death. Verify valve operation (Item 1.25) after reassembly.

Examine resuscitator components to verify that there are no components from other similar model resuscitators. Even if components appear to be similar, they may not function like the original components. For this reason, use only parts from the unit’s manufacturer. In addition, the hospital should stock only one model each of manual and gas-powered resuscitators to prevent inadvertent mixing of components.

Disassemble the valve to the extent required for effective cleaning, and examine it for cleanliness, condition, and correct assembly. Inspect the components for signs of wear or damage. Confirm that the valve device that directs the gas flow is not torn or damaged. Some resuscitators have a separate valve assembly associated with their oxygen reservoir and/or air inlet. Inspect this in the same manner. Reassemble the unit.

Verify that the unit is placed in a sealed plastic bag and that if the bag seal is broken, the unit is submitted for cleaning and reinspection. 1.2

Mount. If the unit is attached to a wall or rests on a shelf, check the security of this attachment. The unit should be available for immediate use.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses, especially at connectors. Be sure that they are not cracked, kinked, or dirty.

1.10 Fittings/Connectors. Examine all gas fittings and connectors for general condition.

1.25 Operation. Compressing the bag should fill the lung simulator, and releasing the bag should allow passive exhalation. By placing your hand in front of the exhalation port to feel the flow of escaping gas, check that gas escapes from the exhalation port of the resuscitator and is not retained in the compression bag. Test the inlet valve by occluding the patient connector and squeezing the compression bag. No air should escape from the inlet valve. Operate the resuscitator connected to a lung simulator (with proper adult or pediatric settings, if adjustable) to confirm proper operation of the resuscitator, particularly its valve assembly.

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Check all accessories stored with the resuscitator. List the accessories that should accompany each resuscitator, and check them against the list at each inspection. Examine all accessories for cleanliness and mechanical integrity. Transparent face masks. An assortment of mask sizes (i.e., adult, infant) should be stored with the resuscitator to allow its use with a wide range of patients.

2


Cycling Rate. Connect the resuscitator to a lung simulator of equivalent volume, and compress it fully with one hand as rapidly as possible for 1 min while counting the number of cycles. Record the maximum cycling rate. A rate of less than 50/min for adult models or 70/min for infant models, while higher than that used during


Pulmonary Resuscitators, Manual

2.4

resuscitation efforts, indicates deterioration of the compression bag or a malfunctioning inlet valve. Check the valve for proper assembly, adequate cleaning, or any damage. After checking the valve, retest the cycling rate. If still unacceptable, replace the compression bag and verify proper operation.

therapy department, or the user department after each use and thus should not be required during periodic inspections. Resuscitator operation should always be verified after processing.

Occlude the oxygen inlet connector with your finger, and verify that room air is admitted and that there is no impediment to cycling rate or ease of bag compression.

Conduct major inspection tests for this procedure. In addition, perform the following test.

Maximum Pressure. Some units (e.g., Ambu, Hope) have pressure-relief mechanisms or popoff valves. To determine the actual operating pressure of a pressure-relief mechanism, connect the patient outlet of the nonrebreathing valve to a pressure gauge or meter, and record the maximum pressure that activates the relief mechanism as you fully compress the bag. Check the reading against the manufacturer’s specifications. The mechanism should activate at from 50 to 60 cm H2O for adult bags. (The specification for some models may be as low as 45 cm H2O.)

3. Preventive maintenance Cleaning, disinfecting, and parts replacement are usually conducted by central service, the respiratory

4. Acceptance tests

4.1

Cycling rate with High O2 Flow. In addition to performing the tests in Item 2.3, verify that the cycling rate is not affected by high oxygen flow rates. Connect a source of oxygen to the oxygen inlet (if provided), set the flowmeter to its maximum (flush) rate, and cycle the resuscitator into the lung simulator with various combinations of small, medium, or large compressions and slow, average, or fast cycling rates. The nonrebreathing valve should not jam, the maximum cycling rate should not be significantly reduced, and excess oxygen should be vented to the atmosphere. Carefully check models that have a valve assembly associated with an oxygen reservoir bag.

Before returning to use Resubmit unit for normal cleaning and processing.


3


Pulse Oximeters Used For: Oximeters, Pulse [17-148]

Also Called: Oximeters, ear oximeters, finger oximeters, oxygen saturation monitors, O2 sat monitors Commonly Used In: All patient care areas, including emergency vehicles; most commonly used in operating rooms, recovery rooms, critical care units, NICUs Scope: Applies to stand-alone pulse oximeters and to pulse oximeter modules built into patient monitoring systems, anesthesia machines, or ventilators, as well as to devices that combine pulse oximeters with other devices (e.g., capnometers) to serve as multiple-purpose respiration monitors (for capnometers and multiple medical gas monitors; see Procedure/Checklist 450) Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Through continuous, noninvasive monitoring, pulse oximetry provides rapid indication of a patient’s changing level of oxygenation, before significant hypoxia occurs. Pulse oximeters are very easy to understand and use, and have reduced the frequency of arterial blood analysis, thereby eliminating many costly procedures. Pulse oximeters use the principle of differential light absorption to determine the percent oxygen saturation of hemoglobin in arterial blood (spO2; this value is referred to as saO2 when determined from an arterial blood sample). Two different wavelengths of light are transmitted from a probe through a pulsating arterial bed, usually in the fingertip or earlobe. Both disposable (single use) and reusable probes are available; some attach to the ear, nose, or toe of adults and the hand or foot of infants. Probes that are based on reflectance (rather than transmittance) are also available and typically attach to the forehead.



Time Required

The two wavelengths of light (red and infrared) used by the pulse oximeter are differentially absorbed by oxygenated hemoglobin (O2Hb) and deoxygenated hemoglobin (HHb). The absorption characteristics of O2Hb and HHb differ markedly at the red wavelength and are more similar at the infrared wavelength. Based on the relative absorption of the two wavelengths in the measurement site, the pulse oximeter determines the relative amount of oxygenated and deoxygenated hemoglobin and displays the calculated spO2.

Pulse oximeters also display pulse rate and some indication of the amplitude or quality of the pulse signal. This is usually in the form of a flashing LED or a bar-graph display, which changes with each pulse, or a plethysmogram waveform that corresponds to the patient’s pulse waveform. The plethysmogram waveform is typically generated from the signal received (after processing) from the infrared LED. Pulse oximeters also have alarms for high and low spO2 and pulse rate and for probe disconnections.


Inspection and Preventive Maintenance System Some pulse oximeter manufacturers sell pulse waveform simulators for approximately $500 that attach to the unit to verify internal calibration. These simulators input signals that correspond to one or more specific spO2 and pulse rate values. Other pulse oximeter test devices are available for approximately $3,500 that simulate spO2 and pulse rate. These devices can be used to verify proper operation and dynamic performance of various model pulse oximeters and probes. One simulator produces various spO2 and pulse rate values at several different signal strengths, which are intended to simulate conditions such as weak pulse or motion artifact. Pulse oximeters and probes cannot be tested independently with this unit. Another simulator has independent inputs for the pulse oximeter and probe and is used to independently verify internal calibration of the oximeter and probe. Signals are input to the pulse oximeter that correspond to various spO2 and pulse rate values and waveforms. Parameters such as LED outputs are analyzed from the probe. Simulators do not test the clinical accuracy of pulse oximeters, since the signals generated by the simulators are based on pulse oximeter specifications and are not true simulations of patient conditions. Although simulators provide added convenience when performing this inspection procedure, they are expensive and are not required for this procedure.

and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.



1.2


1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, verify presence of line power; insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacles.

Citations from Health Devices Using an oxygen monitor with a pulse oximeter during anesthesia [User Experience NetworkTM], 1986 SepOct; 15:294-5.

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Also check the line cords of battery chargers.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), we recommend that the cord be affixed to the unit so that it cannot be removed by the operator. (See Health Devices 1993 MayJun; 22:301-3.)

1.7


1.9

Cables. Inspect any cables (e.g., probe) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the

Pulse oximeter interference from surgical lighting [Hazard], 1987 Feb; 16:50-1. Ambient light interference with pulse oximeters [User Experience NetworkTM], 1987 Sep-Oct; 16:346-7. Pulse oximeters [Evaluation], 1989 Jun; 18:184-230.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Pulse waveform simulator (if available from the manufacturer) spO2 and pulse rate simulator (optional)

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control

2


Pulse Oximeters connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing cables near each end and looking for erratic operation or by using an ohmmeter. 1.10 Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that probe cable connectors are firmly gripped in their appropriate connectors. If keyed connectors are used, make sure that the keying is correct.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function properly. Observe a signal on a CRT display and check its quality (e.g., distortion, focus, 60 Hz noise). Verify the function of integral or accessory printers and the quality of any output. Also verify that the unit can be set to produce an audible tone with each detected pulse, if so equipped.

1.11 Probes. If disposable probes are used, confirm that an adequate supply is available. Check the integrity of all reusable probes (see also Item 1.9). Confirm that any necessary electrodes and/or transducers (e.g., for multigas monitors) are on hand and check their physical condition.

Connect the pulse oximeter probe to your finger or earlobe (whichever is appropriate) or to a simulator, and verify that a reasonable spO2 and pulse rate are displayed. The spO2 for a healthy adult should fall between 95% and 100%. If a simulator is used, test at several spO2 and pulse rate values, if available. The displayed pulse rate should correspond to your manually palpated pulse (within 10%). If a plethysmogram waveform is displayed, confirm that the signal corresponds to waveforms displayed in the operator’s manual and that no excessive noise is present. If a pulse waveform simulator is available, verify that the oximeter displays appropriate SpO2 and pulse rates when attached to it.

1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

1.20 Alarms. Attach a probe to your finger or earlobe or to a simulator, and set pulse rate and spO2 alarm limits so that visual and audible alarms are activated. Verify that the alarm occurs within 1% spO2 or 1 beat per minute of the setting. If the unit has an alarm-silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. Remove the probe from your finger and verify that a probe disconnect or similar alarm occurs.

1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date.

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin


3

Inspection and Preventive Maintenance System of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. If the device has an accessory receptacle, check its grounding to the main power cord. 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. Chassis leakage current to ground should not exceed 300 µA.

4


Clean the exterior, if needed.


Before returning to use Make sure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions. Attach a Caution tag in a prominent position to alert the user that control settings may have been changed. Recharge battery-powered devices or equip with fresh batteries if needed.



Radiant Warmers Used For: Warmers, Radiant, Adult [13-249] Warmers, Radiant, Infant [13-250] Warmers, Radiant, Infant, Stationary [17-956] Warmers, Radiant, Infant, Transport [13-251]

Also Called: Infant warmers, Krieselman (a registered trademark to be used only when referring to that device) warming beds, warming lamps Commonly Used In: Nurseries, delivery rooms, recovery rooms, PACUs Scope: Applies to infant or adult, bassinet- or freestanding-type overhead warmers Risk Level: ECRI Recommended, High for Infant Warmers, Medium for Adult Warmers; Hospital Assessment, for Adult Warmers, for Infant Warmers Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Radiant warmers are designed to provide thermal support for patients while permitting free access to the patient for treatment and nursing care. Radiant warmers are typically overhead heating units consisting of a lamp, a skin temperature sensor, an automatic (servo) control unit, and visual and audible alarms. Some warmers are used exclusively in the manual (nonservo) mode and generally include a heating unit, a timer to limit the heating time, and an alarm to prompt reassessment of the patient’s status. Most radiant warmers with an automatic mode allow the operator to select the manual mode, as well. Typical heating elements are quartz tubes or incandescent lamps, which are broadband energy sources that generate a significant amount of radiant energy in the far infrared (IR) wavelength region (longer than three microns, to avoid damaging a patient’s retina and cornea). The radiant output of the heating unit is also limited to prevent thermal damage to the patient’s skin.



Time Required

Radiant warmers are available in four configurations: freestanding, integral bassinet, detachable, and wall or ceiling mounted. Freestanding units are designed for mobility and provide continuous thermal support for infants in conventional bassinets or during diagnostic or therapeutic treatment. The integral bassinet unit provides a total system for continuous thermal support of a sick infant and may also act as a short-term resuscitation platform in the delivery suite or operating room. The detachable unit is essentially a freestanding warmer that can be mounted on an optional bassinet. For mobility, warmers are mounted on casters, which may be equipped with brakes. Wallmounted units are situated directly over a bassinet, table, or bed; some are jointed to allow horizontal movement from a center position, as well as for retractability. ECRI does not recommend use of manually operated units except for short, closely monitored periods because of the increased danger of overheating or underheating the patient.


●


Inspection and Preventive Maintenance System Other problems with radiant warmers include failures within the unit. Mechanical failure of the heater support mechanism or the heating source can put the patient in contact with a hot surface or material that has fallen onto the mattress. Electronic circuit failure can result from metal particles falling onto a circuit board, failure of a solder run to a metal chassis support, and contaminated solder flux. In addition, fires can result from flammable objects (e.g., oxygen hoses, drapes) placed close to a radiant heat source, arcing in a laminated plastic canopy, or heat aging of wire insulation. Eliminating these hazards requires good prepurchase evaluation and selection of equipment, proper user training, and periodic inspection and preventive maintenance.


Chassis/Housing/Bassinet. Examine the exterior for overall condition. Check that the temperature control unit is clean, that all labels and markings are legible, and that no adhesive tape or tape residue is present. Remove any adhesive tape, paper, or other combustibles attached to any potentially hot surface.

1.2

Mount. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of the attachment. If the heater canopy is designed to rotate, test the security at the farthest points of travel and check for positive stopping at fixed-stop points.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture in an area (see Procedure/Form 441, Conductive Furniture and Floors).

1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to determine that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it.

Citations from Health Devices Infant radiant warmers [Evaluation], 1984 May; 13:119-44. Heat loss from infants, 1984 May; 13:130-1. Manual and automatic (skin) temperature control, 1984 May; 13:138-40. Plastic thermal blankets [Hazard], 1984 Aug; 13:261-3. Temperature probe jacks on Ohmeda infant radiant warmers [User Experience NetworkTM], 1990 Dec; 19:456.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer

If the device has electrical receptacles for accessories, insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacle.

Patient probe simulator, capable of simulating a range of temperatures as well as open- and shortcircuited probe conditions (for testing units with patient-temperature probes) Calibration thermometer, accurate to at least ±0.3°C over the range of at least 30° to 45°C

1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the same polarity as the old one. Also, check line cords of battery chargers.

1.6


1.7

Circuit Breaker/Fuses. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that

Controlled-temperature water bath or cups of water Wire or twist ties

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.

2


Radiant Warmers marked on the chassis, and ensure that a spare is provided. 1.9

Cables. Inspect the cables (e.g., sensor, electrode, remote control) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

1.10 Fittings/Connectors. Examine all pneumatic fittings and connectors, as well as all electrical cable connectors, for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Probes. Carefully examine the unit’s patient probes. If the hospital has more than one model of radiant warmer, be sure that probes are properly identified for use with the appropriate unit. Interchanging probes may result in hazardous operation. Replace probes that are cracked or deteriorating. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails or pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.14 Heating Element. If the heating element is a replaceable lamp, check that it is the correct type and wattage. Verify that filters or metallized lenses in front of the heating element are not cracked or scratched. The heating element canopy or housing, as well as all shields and protective devices, should be adequately secured. Check all plastic mounting components in the heating element and canopy for heat deformation. Check for asbestos or loose fiberglass particles that can fall on the patient when the heating element or its shield is tapped or jarred. (If asbestos is detected, contact ECRI or the manufacturer for information on health risks

associated with asbestos in medical devices.) Clean any residue or dirt from reflectors, lenses, and heating element. Operate the warmer to verify that all sections of the heater operate. 1.17 Battery/Charger. Inspect the physical condition of the batteries and battery connectors, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check the remaining battery capacity by activating the battery test function or measuring the output voltage. For lead-acid batteries, measure the specific gravity. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. The unit can be operated on battery power during performance testing to ensure adequate battery capacity. However, be sure that an alternate unit is available while the unit under test is being recharged. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, gauges, and visual displays on the unit and charger, if so equipped. Be sure that all segments of a digital display function. 1.19 Self-Test. Verify operation of the self-test function, if so equipped. 1.20 Alarms. Operate the device in such a way as to activate each audible and visual alarm. Check that any associated interlocks function. If the device has an alarm-silence feature, check the method of reset (e.g., manual, automatic) against the manufacturer’s specifications. If the unit has alarms for open- and short-circuited patient probes, check their operation by inserting open- and short-circuited probe plugs. Also check for a disconnected-probe alarm, and verify that it operates. 1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control. 1.22 Labeling. It is essential that radiant warmers include adequate placards warning of possible patient burns and other injury that can result from misuse of the equipment. If no such placard exists, make one and prominently attach it on the warmer. We suggest the following wording: WARNING: UNATTENDED OR IMPROPER USE OF THE WARMER CAN


3

Inspection and Preventive Maintenance System OVERHEAT OR BURN THE PATIENT OR RESULT IN SIGNIFICANT WATER LOSS. CHECK PATIENT TEMPERATURE AT LEAST EVERY 15 MIN. 1.23 Accessories. Inspect examination lights and phototherapy lamps for proper size, ease of positioning, and general condition. Check oxygen cylinders for adequate supply and appropriate fittings. Check flowmeters for proper operation. Inspect resuscitators and aspirators using a separate procedure if they were not tested after their last use. 1.24 Bassinet/Mattress. Examine the bassinet’s side panels for general condition and warping, and check that they can be easily raised and lowered. Check that hinges are clean and that panel latches hold the panels securely. Suspect defective latches if adhesive tape is being used to secure the panels. If the mattress position is adjustable, check the ease of motion and security of the locking mechanism. Examine the mattress for cleanliness. If the unit is to be used in the presence of flammable anesthetics, check that a conductive mattress cover is being used.


2.2

4

Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. Verify that various sections of the unit (e.g., control unit, heater, canopy, bassinet, stand) are all grounded. We recommend a maximum of 0.5 Ω. If the device has an accessory outlet, check its grounding to the main power cord. Leakage Current. Measure chassis and patient probe leakage currents in all modes of operation. Chargers of battery-powered units should be attached and plugged into line power. If the frame and chassis of the unit is not grounded through the power cord, ground them with a clip lead. Record the highest value of leakage and the operating mode with which it is associated. Check the unit in the automatic and manual heating modes and with the heater on and off. Also measure leakage with all accessories that plug into accessory outlets on the warmer (e.g., examining lamps, phototherapy lamps) on and off.

Measure chassis leakage current with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple-outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord. Chassis leakage current should not exceed 300 µA. 2.10 Temperature Accuracy. This test checks the accuracy of the patient probe and temperature readout, as well as the heater control circuit on warmers with an automatic mode. Connect the probe simulator to the warmer and set it for 34° or 35°C. If the warmer displays patient probe temperature, record the indicated reading and the simulated (actual) temperature on Item 2.10 of the form. Raise the control setpoint temperature gradually, and record the value at which the heater activates (as indicated either by a Heater On light or by slight deflection of a heater power meter). Now, lower the setpoint temperature, and record the temperature setting at which the heater turns off. (On units with proportional control of the heater power, the heater will turn off at virtually the same temperature at which it activated.) Repeat this procedure at a simulated probe temperature of 36°C, and enter these data on the form. Then set the simulator to 39°C, and check the accuracy of the display (do not check controller operation at this temperature). We have found that the patient probe temperature is generally within 0.3°C of the actual value, and the activation and deactivation points of the automatic control are well within 0.5°C of the probe temperature. Because the simulator tests only the circuitry and not the probe itself, probe operation and accuracy must still be tested for at least one temperature. A convenient method is to dip all probes simultaneously into one body-temperature water bath, allow them to equilibrate, and successively plug each into the same pretested temperature unit or module. All probes should give the same temperature reading. However, some variation is normal because the water temperature varies slightly with location in the bath and because the water gradually cools with time. If a patient probe simulator is not available, test indicator accuracy and controller switching


Radiant Warmers the automatic mode, and set the control temperature to 37°C. Add small quantities of hot water to the cup to raise its temperature, stirring the water in the cup frequently. Record the temperature at which the high-temperature alarm comes on. Be careful not to add too much hot water at once, or you will overshoot the alarm temperature.

using cups of water at about 34°, 36°, and 39°C. Tie the probe to the calibration thermometer (with wire or twist ties), and insert them into the cup to obtain the actual and indicated readings. 2.11 Alarm Accuracy. Check the high- and low-temperature alarms with the unit set to 37°C. If an appropriate temperature probe simulator is available, set it to 37°C and verify that the alarm is activated as the simulated temperature is increased or decreased beyond the alarm limits.

If the unit has a low-temperature alarm and patient-temperature display, determine the alarm point by first heating the probe until there is no alarm, and then removing it from the influence of the heater and noting the temperature at which the alarm comes on.

If a probe simulator is not available, use one of the following methods to check the high- and low-temperature alarms of warmers with automatic control. If the unit displays patient probe temperature, operate the warmer in the automatic mode with the control point set at 37°C. Place the connected patient probe on the bassinet mattress or similar surface. After the heater has been on for a minute or two, raise the probe and hold it close to the heater. Record the temperature reading at which the high-temperature alarm activates. This technique will work only because the heater has some degree of thermal inertia and continues to put out heat even after the control unit cuts off power to it. However, if the probe is not held close enough to the heater, this inertia will not be sufficient to raise the probe temperature to the alarm point. Should this happen, move the probe out of the range of the heater, and wait for it to cool off. Once the heater comes back on for a minute or two, hold the probe closer to it than before, and record the temperature at which the high-temperature alarm comes on. If the unit under test has no patient-temperature display, prepare a cup of water at about 37°C, measured with the calibration thermometer, with room in the cup to add more water. Insert the patient probe in the cup, close to the thermometer (tie them together with wire or twist ties, if necessary). Rest the cup on the mattress or hold it away from the heat, whichever is more convenient. Operate the warmer in

If the unit has a low-temperature alarm but no patient-temperature display, follow a procedure similar to that described for the high-temperature alarm limit, but add cold water to the cup. Compare the high- and low-temperature alarm thresholds against the manufacturer’s specifications. The thresholds may be fixed or may vary with the control setting. In either case, the measured values should agree with the manufacturer’s specifications, typically ≤0.5°C.


Clean the exterior, including vents and cooling fans. Clean residue or dirt from reflectors, lenses, and heating element.

3.3


3.4

Replace the battery if needed.


Before returning to use Inappropriate use of radiant warmers can cause patient burns. Any inordinate control settings or failures observed during inspection that may indicate incorrect use of the warmer should be discussed with appropriate clinical personnel.


5

Procedure/Checklist No. 472-0595

Radiographic Units, General-Purpose Used For: Radiographic Units, General-Purpose [13-271]

Also Called: General radiographic room, rad room Commonly Used In: Radiology departments, remote clinics, physicians’ offices Scope: Applies to general-purpose radiographic systems and associated components with ceiling-suspended or integrated x-ray tube supports Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview General-purpose radiographic table systems are used to perform routine diagnostic x-ray procedures. Some systems can be enhanced with optional modular components for fluoroscopy and linear tomography. A general-purpose radiographic system consists of a table, a Bucky film tray and grid, an x-ray tube with housing and suspension, and an x-ray generator. The table consists of a rectangular steel or metal alloy pedestal base or an open frame that supports a tabletop constructed of carbon fiber or plastic or wood laminate. Tableside and footplate controls allow the table to be raised or lowered for transferring patients or accommodating different imaging procedures. Table movement is usually power assisted. Some tables can be tilted without moving the patient. Most tables can also be equipped with handgrips, headrests, compression bands, footrests, and other accessories necessary during certain radiographic procedures. The Bucky film tray and grid are located under the tabletop. The grid is used to reduce scatter radiation. Bucky systems are usually fully automatic and can accommodate film cassettes up to 35 × 43 cm (14″ × 17″) in size. Most systems also include automatic exposure



Time Required

control (AEC) to automatically terminate the exposure when a sufficient x-ray intensity has reached the film cassette. The x-ray generator is usually three phase, high frequency, or constant potential, depending on the manufacturer. The x-ray tube has either a stationary or rotating anode and is housed in either an integrated tubestand or an overhead tube suspension. Beam restrictors (collimators) are used to regulate the shape and size of the x-ray beam to cover only the area of diagnostic interest.

Test apparatus and supplies Electrical multimeter Noninvasive kVp meter (compatible with the x-ray generator being inspected) Noninvasive timer (may be included with the kVp meter) Ionization chamber with electrometer or a combination exposure meter Five filters of 10 cm × 10 cm × 1 mm Type 1100 aluminum


●


Inspection and Preventive Maintenance System Collimator alignment template marked in centimeters or inches Large (35 cm × 43 cm or 14″ × 17″), medium (25 cm × 30 cm or 10″ × 12″), and small (20 cm × 24 cm or 8″× 10″) format x-ray cassette and film

is crucial because it generates data on the baseline performance of the device.


Chassis/Housing. Examine the exterior of all equipment items (e.g., table, tube support, x-ray generator console and equipment cabinets, upright cassette holders) for cleanliness and general physical condition. Be sure that all hardware is present and tight and that there are no signs of spilled liquids, deep scratches, dents, or other serious abuse. Check the mechanical operation of all moving parts on all items, including the x-ray tube, x-ray tube support, collimator, tabletop, vertical table movement if applicable, and upright cassette holders. Ensure that all movements are smooth and easy, with no binding or undue resistance.

1.3

Do not remove the high-voltage cables from the wells with the power on. Ensure that high-voltage cables are completely discharged by repeatedly touching the conductor to ground as soon as it is removed from the well.

Brakes. Check the brake or locking device for each movement of the x-ray tube, x-ray tube support, collimator, tabletop, upright cassette holders, etc. Ensure that all locks function properly and hold securely.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of all cables subjected to movement and stress. Be sure that they hold the cord securely.

Wear rubber gloves or other appropriate protection when exposed to blood or other body fluids.

1.7

Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it is accessible (not blocked by cabinets, covered with clipboards, or out of reach because of the presence of tables, counters, etc.) and operates freely.

1.9

Cables. Inspect any cables (e.g., collimator cables, high-voltage cables, exposed interconnect cables) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. For cables other than high-voltage cables, verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation. Use an ohmmeter if a problem is suspected. Highvoltage cables should be removed from the wells (at the x-ray tube ends), cleaned, coated with high-voltage compound, reinserted, and tightened securely. The high-voltage transformer end should not require routine inspection if the wells are vertical and high-voltage oil is used.

Ten pieces of 30 cm × 30 cm × 2.5 cm plexiglass (or another patient-simulating material for testing the AEC) Densitometer Oscilloscope (calibration only) High-voltage divider (calibration only)

Special precautions Wear a lead apron and thyroid shield, and maintain the greatest possible reasonable distance from the x-ray source and all scattering material during all x-ray exposures. It should not be necessary to place hands or fingers in the x-ray beam; if this is unavoidable, wear lead gloves.

Allow adequate time between repeated exposures to prevent overheating of the x-ray tube.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; ensure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. This procedure is intended to ensure adequate system performance and maintenance. It should not be construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations. Such regulations and standards may include testing beyond that provided below and may also require documentation by a certified medical physicist. For acceptance testing, we strongly recommend contracting with a medical physicist. Acceptance testing

2

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and


Radiographic Units, General-Purpose exposure). Confirm appropriate volume. If audible alarms have been silenced or the volume set too low, adjust the alarm volume to the appropriate level.

bright. If keyed connectors are used, make sure that no pins are missing and that keying is correct. 1.12 Filters. Check the condition of any air filters present in the systems. Clean or replace as needed. 1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., high mA setting), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches (x-ray initiation, collimation, technique selection, etc.) for physical condition, secure mounting, and correct motion. Check that control knobs, if present, have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function. Ensure that the fluoroscopic and radiographic exposure switches do not stick, that continuous pressure is required to continue exposure, and that release of pressure immediately terminates exposure. Ensure the proper operation of the two-position exposure switch (i.e., ensure that the x-ray exposure is not released with the first trigger only).

1.22 Labeling. Check that all necessary certification labels, warning labels, technique charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories (e.g., clamp-on devices such as handgrips for the tabletop). 1.24 Positive Beam Limitation. On units provided with positive beam limitation (automatic collimation), ensure proper operation by making visual checks of the light field with different-size cassettes in the Bucky and with the orientation of the cassettes changed. The light field should be limited to the size and orientation of the cassettes.


Grounding Resistance. Using an ohmmeter or multimeter with good resolution of fractional ohms, measure and record the resistance between common ground and exposed metal on the unit. We recommend a maxium resistance of 0.5 Ω. Handswitches and footswitches that are powered from low voltages need not be grounded. Although confirmation of grounding integrity provides reasonable assurance of safety, NFPA 99 calls for voltage measurements for installed devices in the patient vicinity.* Using a voltmeter, measure and record the voltage between a reference grounding point (e.g., the grounding pin of an electrical receptacle or some other known ground) and exposed (i.e., unpainted and not anodized) metal on the chassis. A voltage reading below 500 mV is acceptable for general care areas in existing construction.

2.2

Leakage Current. Chassis leakage current of permanently wired equipment cannot be readily measured after installation is completed. Permanently wired appliances in the patient vicinity should be tested before installation, while the equipment is temporarily insulated from ground. The leakage current from frame to ground of permanently wired appliances installed in general or critical patient care areas should not exceed 5 mA with all grounds lifted.

1.18 Indicators/Displays. During the inspection, confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Examples of indicators and displays are technique settings, exposure time, x-ray on, and field size indicators on the collimator. Inspect the source-to-image distance (SID) indicator. If a tape measure is present, ensure that it operates smoothly and is accurate. 1.20 Alarms. Induce conditions to activate audible and visual alarms (for example, x-ray on). Check that any associated interlocks (e.g., x-ray exposure is inhibited if the x-ray tube is not aligned with the image receptor) function. If the unit has an alarm silence feature, check the method of reset (e.g., manual or automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time since some may require abnormal operating conditions (e.g., long exposure times). Instruct users to document activation of these alarms to ensure that they are functional. 1.21 Audible Signals. Operate the device to activate any audible signals (for example, radiographic

*Patient vicinity is defined as a space within six feet beyond the perimeter of the patient support in its normal location and extending seven-and-a-half feet above the floor.


3


Accuracy of kVp. Perform this test on all x-ray tubes. Use a noninvasive kVp meter that has previously been calibrated against a high-voltage divider on the type of generator being tested. Use the kVp meter in accordance with the manufacturer’s recommendations. These may include the kind of filters to use and the distance at which the kVp meter has to be placed. Some meters require that the user specify the type of generator being tested and the amount of filtration present in the primary x-ray beam. Make measurements at low, medium, and high settings (e.g., 60, 80, 100 kVp). After the appropriate corrections have been applied to the measured kVp readings (e.g., for filtration), the difference between the measured kVp and the preset kVp should not exceed ±5% of the preset kVp.

2.4

Timer Accuracy. Use a noninvasive timer to measure the accuracy of the time settings. Most noninvasive kVp meters also display exposure times. Once the unit has been appropriately set up, dial up a midrange kVp setting (e.g., 80 kVp). The x-ray unit may display in mAs; if this is the case, calculate the time by factoring out the mA. Conduct measurements at typical low, medium, and high settings. The difference between the measured time and the preset time should not exceed ±1 msec or ±5%, whichever is greater.

2.5

Linearity of mAs. This test must be performed on all x-ray tubes. Use an ionization chamber with an electrometer (or a combination exposure meter) to measure the exposure in mR for this test. The ionization chamber should be placed centrally in the x-ray beam at a known standard distance from the focal spot (e.g., 100 cm). Dial up a midrange kVp setting (e.g., 80 kVp). Make radiographic exposures at this fixed kVp, and record the exposure values (in mR) from the electrometer or exposure meter at a minimum of three mA settings that span the range commonly used. Use an exposure time that is in the midrange for each mA value. Calculate the mR/mAs at each setting and average the calculations. Each individual mR/mAs value should be within ±10% of the average.

2.6

4

Exposure Reproducibility. Use one of the above mR/mAs values as the one value to be used for evaluating short-term and long-term reproducibility of the x-ray tube and generator combination. For the short-term test, make a minimum of four exposures at the same mAs over a span of 15 minutes. The mR/mAs values

should have a coefficient of variation no larger than 10%. For long-term reproducibility, simply record the current average mR/mAs value from the four measurements above, and compare this with the value recorded during the preceding inspection. It is critical that identical test conditions be used for assessing reproducibility. For example, the same chamber-to-source distance should be used, and the technique (kVp, mAs) should be the same. Long-term reproducibility should be within ±10% of the average. 2.7

Half-Value Layer (HVL). This test must be performed on all x-ray tubes. Use an ionization chamber, electrometer, and Type 1100 aluminum filters for this test. Place the ionization chamber in the center of the x-ray beam at about 100 cm from the focal spot. Collimate so that the x-ray field just encompasses the ionization chamber. Set the unit to operate at 80 kVp. Select a midrange mAs value. These kVp and mAs values should be held constant during the whole course of this test. Record the initial exposure value (in mR) with nothing in the primary beam (i.e., 0 mm of aluminum). Then record the exposure reading with aluminum thicknesses of 2 mm and 4 mm. The thickness of aluminum required to reduce the initial exposure reading by half is the half-value layer of the beam. The HVL is most accurately read by plotting the measurements on semilog graphing paper. Plot the exposure values on the logarithmic scale against the thickness of aluminum on the linear scale. At 80 kVp, the HVL should be a minimum of 2.3 mm of aluminum. The HVL measurement should be compared to measurements from previous inspections since a change in HVL may indicate tube deterioration.

2.8

Collimation. This test must be performed on all collimators and all receptor sizes. Place a medium-format x-ray film (25 cm × 30 cm or 10″ × 12″) at an SID of 100 cm (40″). Ensure that the x-ray film is perpendicular to the x-ray beam. Ensure that the x-ray tube is in the detent for alignment with the receptor or aligned using a centering light if there is no detent. Precisely center the collimator alignment tool on the cassette. Turn on the collimator light, and collimate to an area of 20 cm × 20 cm. Note the exact readout of the exposure area size indicators. Ensure that the light beam is exactly centered on the collimator alignment tool. Record the exact boundaries of the illuminated area from the collimator alignment tool. Make an x-ray exposure (for a film/screen speed of 400, a tech-


Radiographic Units, General-Purpose

″

″

Figure 1. Collimation test setup

nique of 55 kVp and 5 mAs should be sufficient), and process the x-ray film. Congruence of the light field to the x-ray field. Measure the distances of L1, L2, W1, and W2 on the processed film. The sum of W1 + W2 + L1 + L2 is the total misalignment between the light field and the x-ray field. This sum must not exceed 2% of the SID; that is, at an SID of 100 cm, the misalignment should not exceed 2 cm (see Figure 1). Alignment of the x-ray source to the receptor. Mark the exact center of the exposed area on the film by drawing diagonals from corner to corner of the exposed area. Mark the exact center of the film by drawing diagonals from corner to corner of the film. Measure the distance between the two centers; this must not be more than 2% of the SID — that is, at an SID of 100 cm, the centers should be misaligned no more than 2 cm. Also, ensure that the exposed area is square to the film. Field size indicators versus actual exposed area. Measure the length and width of the exposed area on the exposed film. Compare the actual size of the exposed area with the readout of the exposure area size indicators noted earlier. The dimensions of the exposed area must be within 2% of the SID — that is, 2 cm at an SID of 100 cm.

2.9

AEC Object Thickness Compensation. This test is to be conducted on each available radiographic image receptor holder (e.g., spot film, table Bucky, wall Bucky). Place 20 cm of 30 cm × 30 cm plexiglass on the table, or support it up against the wall Bucky. (It is acceptable to use another patientsimulating material for AEC tests, such as aluminum.) Ensure that the plexiglass covers the AEC detectors. Set the unit to operate at 80 kVp (or some other setting commonly used to image a medium-size patient). Load a cassette of a size commonly used with the standard film used at the facility, and place this into the receptor holder being tested. Then make an AEC-controlled exposure. Process the film on a processor that has previously been verified as operating optimally. Use a densitometer to measure the optical density of the radiograph in the center of the image. If the optical density falls within the range chosen by the radiologists (typically 1.2 to 1.4 OD), repeat the test using identical setup conditions but with varying amounts of plexiglass in the beam. At a minimum, check the optical density at 15 cm and 25 cm of plexiglass. All films used in this test should come from the same batch, and only one cassette is to be used for all exposures. The optical density of all the processed films should agree to within ±0.3 OD of the optical density at 20 cm.

2.10 AEC kVp Compensation. This test should also be conducted on each available radiographic


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Inspection and Preventive Maintenance System image receptor holder (spot film, table Bucky, and wall Bucky). Place 20 cm of plexiglass (or some other patient-simulating material) on the table, or support it up against the wall Bucky. Ensure that the AEC detectors are covered by the plexiglass. Use the most common size of films in the same cassette holder for all checks in this test. Make a series of AEC-controlled exposures of the 20 cm of plexiglass at different kVp values. At a minimum, use three kVp settings (e.g., 60, 80, 100 kVp). For each exposure, process the film on an optimally performing processor. Read the optical density of the radiograph using a densitometer. The optical density of the films at all kVp settings checked should agree to within ±0.3 OD.


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Clean the exterior and interior. Take precautions when dealing with body fluids.

3.2


3.3

Calibrate the system to ensure performance within the manufacturer’s specifications, at intervals recommended by the manufacturer or as indicated by inspection results. Adjust all brakes, locks, and bearings to ensure proper performance.

3.4

Replace air filters, if needed.




Procedure/Checklist No. 473-0595

Radiographic/Fluoroscopic Units, General-Purpose Used For: Radiographic/Fluoroscopic Table Systems [16-885]

Also Called: Fluoro room, R/F room Commonly Used In: Radiology, urology Scope: Applies to radiographic/fluoroscopic table systems with a spot-film tower, an overhead radiographic x-ray tube, and associated components Risk Level: ECRI Recommended, High; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

6 months

months

.

hours

Overview Radiographic/fluoroscopic (R/F) table systems are used for diagnostic radiographic and fluoroscopic examinations — for example, gastrointestinal studies, myelography, and studies that require the use of contrast media. R/F systems can be purchased in a variety of configurations. A typical R/F system includes a table, a spot-film device (SFD), an undertable and/or over-table x-ray tube and housing, an x-ray generator, an image intensifier, and a Bucky film tray and grid. The table base contains a motor drive unit for tilting the tabletop and provides support for the tabletop, the undertable x-ray tube, the SFD, and the image intensifier. Table models are generally described according to their degree of positive/negative tilting capability, such as +90/-90, +90/-45, or +90/-15. The tabletop is constructed of carbon fiber or a laminate material. Headrests, footrests, handgrips, harnesses, and other accessories for certain imaging procedures are available. The SFD usually accepts a variety of cassette sizes and is capable of variable film formatting, which allows



Time Required

a number of film images to be exposed on a single cassette. Digital photospot cameras are available from a number of manufacturers; they are used to convert x-ray images to digital format for immediate viewing and storage. X-ray tubes generally are located under the table for fluoroscopy and over the table for radiography. The overtable tube requires an overhead tube support, which allows the tube to be parked out of the way when not in use. The x-ray tube has a rotating anode to more effectively dissipate heat. Different types of x-ray generators are usually available for use with the system; three-phase, high-frequency, and constant-potential generators are most commonly used. The image intensifier is used to convert radiation to light, which it then amplifies. A television camera tube converts the light image to an electron pattern, then to an electric current that varies in proportion to the different light intensities of the original image. The electrical information is then converted for viewing on a TV monitor. Image intensifiers are described in terms of their input phosphor diameter — for example, 9″ or


Inspection and Preventive Maintenance System 12″. Different sizes are used, depending on the procedure and field of view required. Some vendors offer dual, triple, or quad mode image intensifiers. The image intensifier is mounted over the table in conventional table systems, and under the table in remote table systems. The Bucky film tray and grid are located under the tabletop. The grid is used to reduce scatter radiation. Bucky systems are usually fully automatic and can accommodate film cassettes up to 35 cm × 43 cm (14″ × 17″) in size. Most systems also include automatic exposure control (AEC) to automatically terminate the exposure when a sufficient x-ray intensity has reached the film cassette. Function controls can be located on the SFD console, at tableside, or in a remote location. Controls include x-ray exposure, cassette positioning and reloading, film format selection, rapid exposures, image intensifier mode selection, and table tilt.

Oscilloscope (calibration only) High-voltage divider (calibration only)

Special precautions Wear a lead apron and thyroid shield and maintain the greatest possible reasonable distance from the x-ray source and all scattering material during all x-ray exposures. It should not be necessary to place hands or fingers in the x-ray beam; if this unavoidable, wear lead gloves.

Noninvasive kVp meter (compatible with the x-ray generator being inspected)

Do not remove the high-voltage cables from the wells with power on. Ensure that high-voltage cables are completely discharged by repeatedly touching the conductor to ground as soon as they are removed from the well.

Noninvasive timer (may be included with the kVp meter)

Wear rubber gloves or other appropriate protection when exposed to blood or other body fluids.

Test apparatus and supplies Electrical multimeter

Ionization chamber with electrometer or a combination exposure meter Five filters of 10 cm × 10 cm × 1 mm Type 1100 aluminum Collimator alignment template marked in centimeters or inches Ruler with leaded 1 cm or 1/2″ marker Ten pieces of 30 cm × 30 cm × 2.5 cm plexiglass (or another patient-simulating material for testing the automatic exposure control) Densitometer Large (35 cm × 43 cm or 14″ × 17″), medium (25 cm × 30 cm or 10″ × 12″), and small (20 cm × 24 cm or 8″ × 10″) format x-ray cassettes and films Six pieces of 30 cm × 30 cm × 1 mm lead A medium-size box approximately 12″ × 12″ × 12″ or plastic bucket approximately 12″ to 14″ high (this will be used to support a film cassette and image quality phantoms below the spot film tower) High-contrast resolution line-pair phantom to 5 lp/ mm minimum Low-contrast phantom consisting of two 3/4″ (2 cm) aluminum plates, 7″ × 7″ (18 cm × 18 cm), and one

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sheet of 1.0 mm aluminum, with two sets of four holes of the following sizes: 1/16″, 1/8″, 3/16″, and 1/4″ (1.0, 3.0, 5.0, and 7.0 mm) (use of an alternative low-contrast phantom is acceptable, provided that it can be reproducibly used for assessment of longterm performance; use the criterion applicable to the phantom selected)

Allow adequate time between repeated exposures to prevent overheating of the x-ray tube.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; ensure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. This procedure is intended to ensure adequate system performance and maintenance. It should not be construed as providing full compliance with the requirements of all governmental regulations and accreditation standards of professional associations. Such regulations and standards may include testing beyond that provided below and may also require documentation by a certified medical physicist. For acceptance testing, we strongly recommend contracting with a medical physicist. Acceptance testing is crucial because it generates data on baseline performance of the device.


Radiographic/Fluoroscopic Units, General-Purpose 1.12 Filters. Check the condition of any air filters present in the systems. Clean or replace if needed.


Chassis/Housing. Examine the exterior of all equipment items (e.g., table, tube support, x-ray generator console and equipment cabinets, upright cassette holders) for cleanliness and general physical condition. Be sure that all hardware is present and tight and that there are no signs of spilled liquids, deep scratches, dents, or other serious abuse. Check the mechanical operation of all moving parts on all items, including the x-ray tube, x-ray tube support, collimator, tabletop, table tilt, spot-film tower, and upright cassette holders. Ensure that all movements are smooth and easy, with no binding or undue resistance.

1.3

Brakes. Check the brake or locking device for each movement of the x-ray tube, x-ray tube support, collimator, tabletop, spot-film tower, upright cassette holders, etc. Ensure that all locks function properly and hold securely.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of all cables subjected to movement and stress. Be sure that they hold the cord securely.

1.7

Circuit Breaker/Fuse. If the device has an external circuit breaker, check that it is accessible (i.e., not blocked by cabinets, covered with clipboards, out of reach behind tables, counters, etc.) and operates freely.

1.9

Cables. Inspect any cables (e.g., collimator cables, high-voltage cables, exposed interconnect cables) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. For cables other than high-voltage cables, verify that there are no intermittent faults by flexing the cables near each end and looking for erratic operation. Use an ohmmeter if a problem is suspected. Highvoltage cables should be removed from the wells (at the x-ray tube end), cleaned, coated with high-voltage compound, reinserted, and tightened securely. The high-voltage transformer end should not require routine inspection if the wells are vertical and high-voltage oil is used.

1.10 Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. If keyed connectors are used, make sure that no pins are missing and that keying is correct.

1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., high mA setting), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches (i.e., x-ray initiation, collimation, technique selection, etc.) for physical condition, secure mounting, and correct motion. Check that control knobs, if present, have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Be sure to check that each control and switch performs its proper function. Ensure that the fluoroscopic and radiographic exposure switches do not stick, that continuous pressure is required to continue exposure, and that release of pressure immediately terminates exposure. Ensure the proper operation of the two-position exposure switch (i.e., that the x-ray exposure is not released with the first trigger only). 1.18 Indicators/Displays. Confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Examples of indicators and displays are technique settings, exposure time, x-ray on, field size indicators on the collimator, cassette size, and format selection on the spot-film tower. Inspect the source-to-image (SID) indicator for the overtable tube. If a tape measure is present, ensure that it operates smoothly and is accurate. 1.20 Alarms. Induce conditions to activate audible and visual alarms (e.g., five-minute fluoroscopic alarm, no cassette in Bucky). Check that any associated interlocks (e.g., x-ray exposure is inhibited if x-ray tube is not aligned with image receptor) function. If the unit has an alarm silence feature, check the method of reset (e.g., manual, automatic) against the manufacturer’s specifications. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions (e.g., long exposure times). Instruct users to document activation of these alarms to ensure that they are functional. 1.21 Audible Signals. Operate the device to activate any audible signals (e.g., radiographic exposure). Confirm appropriate volume. If audible signals


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Inspection and Preventive Maintenance System divider on the type of generator being tested. Use the kVp meter in accordance with the manufacturer’s recommendations. These may include the kind of filters to use and the distance at which the kVp meter must be placed. Some meters require that the user specify the type of generator being tested and the amount of filtration present in the primary x-ray beam. Make measurements at low, medium, and high kVp settings (e.g., 60, 80, 100 kVp). After the appropriate corrections have been applied to the measured kVp readings (e.g., for filtration), the difference between the measured kVp and the preset kVp should, as a general rule, not exceed ±5% of the preset kVp.

have been silenced or the volume set too low, adjust alarm volume to the appropriate level. 1.22 Labeling. Check that all necessary certification labels, warning labels, technique charts, and instruction cards are present and legible. 1.23 Accessories. Confirm the presence and condition of accessories (e.g., handgrips, footrests, straps). 1.24 Positive Beam Limitation. On units provided with positive beam limitation (automatic collimation), ensure proper operation by making visual checks of the light field with different-sized cassettes in the Bucky and with the orientation of the cassettes changed. The light field should be limited to the size and orientation of the cassettes.

2.4

Timer Accuracy. Use a noninvasive timer to measure the accuracy of the time settings. Most noninvasive kVp meters also display exposure times. Once the unit has been appropriately set up, dial up a midrange kVp setting (e.g., 80 kVp). The x-ray unit may display in mAs; if so, calculate the time by factoring out the mA. Conduct measurements at typically used low, medium, and high settings. The difference between the measured time and the preset time should not exceed ±1 ms or ±5%, whichever is greater.

2.5

Linearity of mAs. This test should be performed on all x-ray tubes. Use an ionization chamber with an electrometer (or a combination exposure meter) to measure the exposure in mR for this test. The ionization chamber should be placed centrally in the x-ray beam at a known standard distance from the focal spot (e.g., 100 cm).


2.2

2.3

Grounding Resistance. Using an ohmmeter with good resolution of fractional ohms, measure and record the resistance between common ground and exposed metal on the unit. We recommend a maximum resistance of 0.5 Ω. Handswitches and footswitches powered from low voltages need not be grounded. Although confirmation of grounding integrity provides reasonable assurance of safety, NFPA 99 calls for voltage measurements for installed devices in the patient vicinity.* Using a voltmeter, measure and record the voltage between a reference grounding point (e.g., the grounding pin of an electrical receptacle, some other known ground) and exposed (i.e., unpainted and not anodized) metal on the chassis. A voltage reading below 500 mV is acceptable for general care areas in existing construction. Leakage Current. Chassis leakage current of permanently wired equipment cannot be readily measured after installation is completed. Permanently wired appliances in the patient vicinity should be tested before installation, while the equipment is temporarily insulated from ground. The leakage current from frame to ground of permanently wired appliances installed in general or critical patient care areas should not exceed 5 mA with all grounds lifted. Accuracy of kVp. Perform this test on all x-ray tubes for both radiographic and fluoroscopic modes. Use a noninvasive kVp meter that has previously been calibrated against a high-voltage

* Patient vicinity is defined as a space within six feet of the perimeter of the patient support in its normal location and extending seven and one-half feet above the floor.

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Dial up a midrange kVp setting (e.g., 80 kVp). Make radiographic exposures at this fixed kVp, and record the exposure values (in mR) from the electrometer or exposure meter at a minimum of three mA settings that span the range commonly used. Use an exposure time that is in the midrange for each mA value. Calculate the mR/mAs at each setting, and average the calculations. Each individual mR/mAs value should be within ±10% of the average. 2.6

Exposure Reproducibility. Use one of the above mR/mAs values as the one value to be used for evaluating short-term and long-term reproducibility of the x-ray tube and generator combination. For the short-term test, make a minimum of four exposures at the same mAs over a span of 15 minutes. The mR/mAs values should have a coefficient of variation no larger than 10%. For long-term reproducibility, simply record the


Radiographic/Fluoroscopic Units, General-Purpose current average mR/mAs value from the four measurements above and compare this with the value recorded during the preceding inspection. It is critical that identical test conditions be used for assessing reproducibility. For example, the same chamber-to-source distance should be used and the technique (kVp, mAs) should be the same. Long-term reproducibility should be within ±10% of the average. 2.7

Half-Value Layer (HVL). Perform this test on all x-ray tubes. Use an ionization chamber, electrometer, and Type 1100 aluminum filters for this test. Place the ionization chamber in the center of the x-ray beam at about 100 cm from the focal spot. Collimate so that the x-ray field just encompasses the ionization chamber. Set the unit to operate at 80 kVp. Select a midrange mAs value. These kVp and mAs values should be held constant throughout this test. Record the initial exposure value (in mR) with nothing in the primary beam (i.e., 0 mm of aluminum). Record the exposure reading with aluminum thicknesses of 2 mm and 4 mm. The thickness of aluminum required to reduce the initial exposure reading by half is the HVL of the beam. The HVL is most accurately read by plotting the measurements on semilog graphing paper. Plot the exposure values on the logarithmic scale against the thickness of aluminum on the linear scale. At 80 kVp, the HVL should be a minimum of 2.3 mm of aluminum. Compare the HVL measurement with measurements from pre-

vious inspections, since a change in HVL may indicate tube deterioration. 2.8

Collimation. This test must be performed on all collimators and all receptor sizes. Radiographic X-ray Tubes (overhead tubes). Place a medium-format x-ray film (25 cm × 30 cm or 10″ × 12″) at an SID of 100 cm (40). Ensure that the x-ray film is perpendicular to the x-ray beam. Ensure that the x-ray tube is in the detent for alignment with the receptor or aligned using a centering light if there is no detent. Precisely center the collimator alignment tool on the cassette. Turn on the collimator light, and collimate to an area of 20 cm × 20 cm. Note the exact readout of the exposure area size indicators. Ensure that the light beam is exactly centered on the collimator alignment tool. Record the exact boundaries of the illuminated area from the collimator alignment tool. Make an x-ray exposure (for a film/screen speed of 400, a technique of 55 kVp and 10 mAs should be sufficient), and process the x-ray film. Congruence of the light field to the x-ray field. Measure the distance L1, L2, W1, and W2 on the processed film. The sum of W1 + W2 + L1 + L2 is the total misalignment between the light field and the x-ray field. This sum must not exceed 2% of the SID; that is, at an SID of 100 cm, the misalignment should not exceed 2 cm. See Figure 1.

″

″

Figure 1. Schematic showing misalignment of the light field with respect to the x-ray field


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Inspection and Preventive Maintenance System park position. Select a 4 on 1 format. While performing fluoroscopy, using the appropriate mode on the image intensifier, measure the visual field size (length and width). The fluoro image should be square, limited by the 4 on 1 mask. Make a spot-film exposure (for a film/screen speed of 400, a technique of 55 kVp and 10 mAs should be sufficient if photo timing is not available or results in film that is too dark). After the film has been processed, ensure that the dimensions of the x-ray beam measured on the film do not differ from the dimensions of the fluoroscopic image measured with the lead ruler by more than 3% of the SID to the spot film.

Alignment of the x-ray source to the receptor. To evaluate the alignment of the x-ray source to the film receptor, mark the exact center of the exposed area on the film by drawing diagonals from corner to corner of the exposed area. Mark the exact center of the film by drawing diagonals from corner to corner of the film. Measure the distance between the two centers; this must not be more than 2% of the SID. At an SID of 100 cm, the centers should be misaligned no more than 2 cm. For this test, also ensure that the exposed area is square to the film. Field size indicators versus actual exposed area. Measure the length and width of the exposed area on the exposed film. Compare the actual size of the exposed area to the readout of the exposure area size indicators noted earlier. The dimensions of the exposed area must be within 2% of the SID (that is, 2 cm at an SID of 100 cm).

Alignment of source to receptor. Place a mediumformat x-ray film (25 cm × 30 cm or 10″ × 12″) in the spot-film tower, and place the film in the park position. Collimate to an area of approximately 10 cm × 10 cm (an area small enough that you can visualize the entire edge of the collimator blades). Ensure that the system is in the mode of operation that will allow the collimator blades to remain as positioned under fluoroscopy and that a 1 on 1 format is selected. Make a spot-film exposure (for a film/screen speed of 400, a technique of 55 kVp and 10 mAs should be sufficient if photo timing is not available or results in film that is too dark), and process the film. Mark the exact center of the exposed area on the film by drawing diagonals from corner to corner of the exposed area. Mark the exact center of the film by drawing diagonals from corner to corner of the film. Measure the distance between the centers; this must not be more than 2% of the SID. Also, ensure that the exposed area is square to the film.

Fluoroscopic X-ray Tubes (undertable tubes). Collimation to the image intensifier during fluoroscopy. Place the box or plastic bucket (upside down) on the tabletop below the spot-film tower. Place a ruler with leaded 1 cm or 1/2″ markers on top of the box, and lower the spot-film tower until the underside comes in contact with the ruler. While performing fluoroscopy, using the largest available mode on the image intensifier, measure the visual field size (length and width). Next, raise the spot-film tower, remove the leaded ruler, and replace it with a large-format x-ray film (35 cm × 43 cm) on the underside of the spot-film tower and make a fluoroscopic exposure, still using the largest available mode on the image intensifier. A fluoroscopic exposure of about 5 seconds is likely to provide sufficient film darkening. After the film has been processed, ensure that the dimensions of the exposed area measured on the film do not differ from the dimensions of the fluoroscopic image measured with the lead ruler by more than 3% of the SID. At an SID of 100 cm, the maximum deviation is 3 cm. Collimation of x-ray field size to spot film. Place a ruler with leaded 1 cm or 1/2″ markers on top of the box or plastic bucket, and lower the spot-film tower until the underside comes in contact with the ruler. Place a medium-format x-ray film (25 cm × 30 cm or 10″ × 12″) in the spot-film tower, and place the film in the

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2.9

AEC Object Thickness Compensation. This test is to be conducted on each available radiographic image receptor holder (e.g., spot-film, table Bucky, wall Bucky). Place 20 cm of 30 cm × 30 cm plexiglass on the table or support it up against the wall Bucky. (It is acceptable to use another patient simulating material for AEC tests, such as aluminum.) Ensure that the plexiglass covers the AEC detectors. Set the unit to operate at 80 kVp (or some other setting commonly used to image a medium-sized patient). Load a cassette of a size commonly used with the standard film used at the facility, and place this into the receptor holder being tested. Then make an AEC-controlled exposure. Process the film on a processor that has


Radiographic/Fluoroscopic Units, General-Purpose previously been verified as operating optimally. Use a densitometer to measure the optical density of the radiograph in the center of the image. If the optical density falls within the range chosen by the radiologists (typically 1.2 to 1.4 OD), repeat the test using identical setup conditions but with varying amounts of plexiglass in the beam. At a minimum, check the optical density at 15 cm and 25 cm of plexiglass. All films used in this test should come from the same batch, and only one cassette is to be used for all exposures. The optical density of all the processed films should agree to within ±0.3 OD of the optical density at 20 cm. 2.10 AEC kVp Compensation. This test should also be conducted on each available radiographic image receptor holder (e.g., spot-film, table Bucky, wall Bucky). Place 20 cm of plexiglass (or some other patient simulating material) on the table or support it up against the wall Bucky. Ensure that the AEC detectors are covered by the plexiglass. Use the most common size of films in the same cassette holder for all checks in this test. Make a series of AEC-controlled exposures of the 20 cm of plexiglass at different kVp values. At a minimum, use three kVp settings (e.g., 60, 80, and 100 kVp). For each exposure, process the film on an optimally preforming processor. Read the optical density of the radiograph using a densitometer. The optical density of the films at all kVp settings checked should agree to within ±0.3 OD. 2.11 Standard Fluoroscopic Exposure Rate. In addition to verifying that the unit meets exposure requirements, this test also verifies functioning of the ABS. Use an ionization chamber with an electrometer (or a combination exposure meter) capable of measuring exposure rate. The chamber position depends on the type of system being tested: For an undertable x-ray tube with a spot-film tower, place the chamber 1 cm above the tabletop. Position a box, with a cutout for the chamber, over the chamber. For an overhead x-ray tube, such as a remote imaging system, place the chamber 30 cm above tabletop, and position the tube as close as possible to the chamber. Then, for an undertable x-ray tube, place sufficient patient simulator material on the box such that the fluoroscopic kVp tracks to around 70 kVp under ABS. For an overhead x-ray tube, place the simulator material on the tabletop.

Determining the necessary amount of patientsimulating material will require some experimentation, but about 1.5 mm of copper is likely to work well. Once the type and amount of simulator material have been determined, use those for all inspections. Run a fluoroscopic exposure, and record the exposure rate. Check for consistency of the rate with exposures made during previous inspections. The typical rate is 1 R/min (with a typical range of 0.5 to 2.0 R/min). The rate will depend greatly on the image quality demands of the user. However, if comparisons to previous inspections indicate an increasing level, further tests should be performed to explain the required increase in radiation. 2.12 Maximum Fluoroscopic Exposure Rate. Maintain the test setup used for Item 2.11. However, this time, replace the patient simulator material with at least 6 mm of lead. See Figure 2. Ensure that the whole input face of the image intensifier is covered by the lead plate. Record the exposure rate on the electrometer or exposure meter during a fluoroscopic exposure, in the automatic mode as well as in the manual mode, at the highest technique. If the system also has a boost or high-level control mode, record the exposure rate during a fluoroscopic exposure in this mode. For units that have only manually selectable kVp, mA settings, the exposure rate at the highest settings should not exceed 5 R/min. For units that have automatic kVp, mA control, the exposure rate should not exceed 10 R/min. There are no governmental regulations that limit exposure rates under boost mode for devices

Figure 2. Test setup for measuring maximum fluoroscopic exposure rate


7

Inspection and Preventive Maintenance System FOV, the three smallest holes should be visible. It may be necessary to alter the brightness and contrast settings on the TV monitor to optimize the display for the visualized object.

in use now. But devices manufactured in 1996 and after will be required to limit boost exposure rates to under 20 R/min. 2.13 Image Quality. High-Contrast Resolution. Raise the spot-film tower, and place the line-pair phantom on the bottom of the spot-film surface. It should be placed at a 45° angle to the grid lines and raster lines of the TV system. Center the line-pair phantom using fluoroscopy. Lower the spot-film tower until it contacts the linepair phantom. At low kVp (ABS with nothing other than the line-pair phantom in the field), determine the maximum line-pair resolution for all available field sizes. Resolution in the 9-inch mode should be a minimum of 1.2 lp/mm. For the high-contrast resolution test, it may be necessary to alter the brightness and contrast settings on the TV monitor to optimize the display for the object being visualized. Be sure to mark and return the settings to the levels set for clinical use. Low-Contrast Resolution. Place the low-contrast phantom on the grid. Ensure that the 1 mm piece of aluminum is next to the grid. The thicker aluminum pieces should be on top of the 1 mm thick plate. Initiate a fluoroscopic exposure under ABS control. On the 15 cm (6)

8


Clean the exterior (interior if needed).

3.2


3.3

Calibrate the system to ensure performance within the manufacturer’s specifications, at intervals recommended by the manufacturer and/or as indicated by inspection results. Adjust all brakes, locks, and bearings to ensure proper performance.

3.4

Replace air filters, if needed.





Smoke Evacuators Used For: Smoke Evacuation Systems, Surgical [16-262]

Also Called: Laser smoke evacuators Commonly Used In: Operating rooms or ambulatory surgery rooms in which laser surgery is performed Risk Level: ECRI Recommended, Low; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

1 month

months

.

hours

Overview A smoke evacuator is used during surgery to remove the smoke that may result from laser or electrosurgical interaction with tissue. Smoke evacuation provides a clear view of the surgical site, in addition to removal of potential mutagens. The smoke evacuator is basically a vacuum pump with a sophisticated filtration system, which may include a charcoal filter and one or more particulate filters to remove gaseous elements and particles in the smoke. The components of the filtration system have a finite life span and must be replaced. Many manufacturers list the expected life of the filters in the operator’s manual; however, these expectations are only approximations and can vary with evacuator use. The more an evacuator is used, the more frequently its filter components must be replaced. As a particulate filter becomes loaded with particles, its flow resistance increases, which results in decreased effectiveness. Some evacuators have pressure gauges or test cycles to measure the pressure drop across the filtration system. However, few evacuators have an indicator that signals the need for filter replacement. For evacuators that lack an integral mechanism for determining filter integrity, we recommend that the hospital institute a standardized



Time Required

assessment (see Item 2.3); users experienced with this assessment may be able to identify when filter replacement is required. The assessment will also be useful in investigating operator complaints. Charcoal filters also have a finite lifetime and must be replaced after a specified time period. Because most evacuators lack hour meters, filter use must be logged, or the time must be estimated from the hospital’s average use. Filter inspection and replacement intervals should be determined by reviewing the manufacturer’s recommendations and considering the typical frequency of use. Depending on the degree of difficulty, requirement for tools, and availability of appropriate staff, filter inspection and replacement may be performed by OR or clinical engineering staff. In either case, responsibility for testing and replacement must be clearly established. When a unit includes a pressure gauge, or the manufacturer supplies a test procedure, inspection should be performed by the OR staff before each use (or at the end of each day). Clinical engineering personnel should supplement this testing on a monthly basis to ensure that it is taking place. If no simple test is available, filters should be replaced at regular intervals, according to the manufacturer’s recommendations or as determined by the procedure outlined


●


Inspection and Preventive Maintenance System above. Indicating the next date for filter replacement on a label or inspection sticker will facilitate routine replacement.

1.3


1.4


Citations from Health Devices General-purpose surgical laser smoke evacuation systems [Evaluation], 1990 Jan; 19:5-19.

Special precautions Because the charcoal and particle filters contain potentially infectious material, technicians should use infection control procedures (e.g., wearing gloves and masks) during filter replacement. Used filters should be treated as potentially infectious waste. (For more details on infection control, see the “IPM Safety” article in this binder.)

If the device has electrical receptacles for accessories, verify the presence of line power, insert an AC plug into each, and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacles.

Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter

1.5


1.6


1.7

Circuit Breaker. If the device has a switch-type circuit breaker, check that it moves freely. If the device is protected by an external fuse, check its value and type against that marked on the chassis and ensure that a spare is provided.

1.8

Tubes/Hoses. Check the condition of all hoses. Be sure that they are not cracked, kinked, or dirty.

Vacuum gauge (0 to 50 mm Hg) or pressure meter with equivalent capabilities Nozzle (e.g., an evacuation tip) for vacuum gauge or pressure meter; always use the same type of tip for inspections (results may change if the tip type is changed) “T” piece and adapters or tubing for connecting gauge (meter) and tip to evacuator



1.2

2

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that all hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount. If it is attached to a wall or rests on a shelf, check the security of this attachment.

1.15 Pump. Check the physical condition and proper operation of the pump. Clean if needed and note this on Line 3.1 of the inspection form. (However, do not check this item until all necessary cleaning is completed.) 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Record reading of an hour meter, if present. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible.


Smoke Evacuators 1.23 Accessories. Confirm the presence and condition of accessories (e.g., footswitch, aspirator tubing, adapter, canister).



Figure 1. Test setup for filter inspections. With experience, it is possible to correlate vacuum levels to the amount of use and to smoke evacuation performance during clinical use. Typically, a drop to 75% of the initial vacuum level should be considered significant. This measurement and the functioning of integral monitors would be affected by a damaged (e.g., torn) filter. Such damage may cause an abnormal or misleading reading.

If the device has an accessory receptacle, check its grounding to the main power cord. 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened with the device on and off. Maximum chassis leakage current to ground should not exceed 300 µA.

2.3

Filters. Check particle and charcoal filters according to manufacturer recommendations. For units without an integral mechanism (e.g., pressure gauge, filter test mode) for assessing the filter, use the following test to roughly quantify performance and provide a basis for comparison from one inspection to the next. (First perform the test on the unit with new filters to obtain a benchmark for future inspections.) Remove accessory tubing from the evacuator. Attach a standard nozzle, such as an evacuation tip, and a vacuum gauge or pressure meter to two ports of a “T” adapter. Connect the third port to the evacuator (see Figure 1). Set the unit to its highest flow setting and record the vacuum level.

Replace filter(s) if needed and indicate this on Line 3.4 of the inspection form. If, following filter replacement, the gauge reading does not return to the expected value, consider the possibility of other occlusions (e.g., additional filters or canisters that require replacement) or pump deterioration.


Clean exterior; clean interior if needed.

3.4

Replace filters if needed.


Before returning to use Return controls to their preinspection or normal pre-use settings.


3


Sphygmomanometers Used For: Sphygmomanometers, Aneroid [16-156] Sphygmomanometers, Mercury [16-158]

Also Called: Aneroid or mercury sphygmomanometers Commonly Used In: All patient care areas Scope: Applies to manual aneroid and mercury sphygmomanometers, including the manometer, cuff, squeeze bulb, and associated tubing; does not apply to automated or invasive blood pressure monitoring devices (see Procedure/Checklist 454 or 434, respectively) Risk Level: ECRI Recommended, Low; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview The blood pressure of a hospitalized patient is routinely measured upon admittance, throughout the day, and during and after surgery. Blood pressure is also measured in the emergency room and outpatient areas. A sphygmomanometer — the prefix “sphygmo” means “relating to pulse” — consists of an inflatable compression bag enclosed in a relatively inelastic but flexible covering called the cuff; a squeeze bulb with valves for inflating and deflating the compression bag; a manometer (pressure-measuring device); and connecting tubing. The manometer can be a mercury or aneroid (nonliquid) type. A mercury sphygmomanometer includes a narrow, vertical, constant-bore glass or plastic tube, connected at its bottom end to a large-diameter well containing mercury. When the system is unpressurized, both the well and the tube have the same mercury level, marked “0” on the tube’s graduated scale. Squeezing the bulb applies pressure to the inflatable bag and the mercury well, forcing mercury up the tube to a height indicating



Time Required

the pressure of mercury (mm Hg) on the graduated scale. Air displaced by the rising mercury column is vented at the top of the tube through a filter, which keeps the mercury from spilling out and filters the air. In an aneroid sphygmomanometer, pressure extends a bellows or flexes a diaphragm. Through a mechanical linkage, this movement rotates a pointer on a graduated dial gauge to the appropriate pressure reading. The bulbs, valves, cuffs, compression bags, and tubing of mercury and aneroid blood pressure sets are similar and have similar maintenance requirements. The manometers have basic differences in operating principles. The accuracy of a mercury manometer depends on dimensions that are fixed at the time of manufacture; on the free flow of air above the mercury column in the glass tube; on the cleanliness of the tube; and on the amount of mercury in the system. Once an initial calibration has shown the bore of the glass tube to be uniform and the graduated scale to be true, only simple maintenance is needed to ensure lifetime accuracy of the instrument.


●


Inspection and Preventive Maintenance System Aneroid gauges are dependent on deflection of a diaphragm within the meter. These units are prone to error due to overpressurization, mechanical vibration, and shock received during normal use. Their reliability is highly dependent on periodic inspection. Mercury sphygmomanometers are traditionally considered more accurate and reliable in high-use hospital settings, but newer, high-quality, wall-mounted aneroid gauges are available that are more reliable than earlier designs. Advise clinical personnel to have the units checked following abuse (e.g., an accidental drop) that might have caused damage. This will minimize the risk of spilled mercury or inaccurate aneroid gauge readings. Replacement of mercury sphygmomanometers on a high-priority basis is not cost-effective or justified if there are adequate procedures for handling mercury. However, planned elimination of mercury sphygmomanometers to reduce the risk of mercury exposure is recommended.

Citations from Health Devices Sphygmomanometers [Evaluation], 1971 Aug; 1:99-104. Sphygmomanometers [Evaluation], 1975 Aug; 4:227-39.

should remove all jewelry, especially gold or goldplated jewelry (mercury readily combines with gold) and should wear a mercury-vapor respirator and disposable gloves. In high-use areas, workers should wear disposable gowns and shoe coverings to minimize skin and clothing contamination, which can increase worker exposure and carry mercury to other areas of the healthcare facility. We recommend against hospitals cleaning and processing their own mercury, since this increases mercury exposure risks. Dirty mercury should be stored in sealed, break-resistant containers until properly disposed of or delivered to a mercury refinery. (For more information on mercury contamination and control, see the section on IPM Safety behind the Guidance Tab of this binder.)

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instructions. Also determine whether any special inspection or preventive maintenance activities or frequencies are recommended by the manufacturer.

Pressure gauge or meter (not required for testing mercury sphygmomanometers except for initial inspection or when glass tube is replaced)

Many sphygmomanometers lack serial numbers or a convenient area to place a control-number tag. The control number can be engraved on the back of the aneroid gauge or along the edge of a mercury manometer scale.

Y connector


Cylindrical object to simulate an arm (e.g., 1 lb coffee can or pipe with 3 to 4 in outside diameter)

1.1

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. Examine mercury column tubes for cracks. Remove damaged tubes from service, even if not currently leaking or affecting performance, to avoid the possibility of mercury spills. Examine aneroid gauge housings for dents and loose parts.

1.2


1.3

Casters/Brakes. If the device moves on casters, check their condition. Look for accumulations of lint and thread around the casters, and be sure that they turn and swivel, as appropriate. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where


Stopwatch or watch with a second hand Mercury column filler and mercury may be required

Special precautions CAUTION! Mercury and its vapors are toxic. All workers who use, clean, or maintain mercury sphygmomanometers should understand the properties of mercury and its associated hazards and should be instructed in safe handling procedures. Specific policies and procedures must be established for mercury spill cleanup, and specific areas should be designated for maintenance activities. The room used for sphygmomanometer calibration and repair should be well-ventilated and reserved for the exclusive task of handling mercury; traffic through the area should be limited. There should be no smoking, drinking, or eating in the room. The floor should not be carpeted, and a workbench should be equipped with troughs to collect mercury spills. Personnel

2


Sphygmomanometers appropriate, are usually done more efficiently as part of a check of all equipment and furniture in an area. 1.8

Tubes/Hoses/Bulb. Check the condition of all tubing and hoses and the bulb. Be sure that they are not cracked, kinked, or dirty. Replace loose or cracked tubing.

1.10 Fittings/Connectors. Examine all fittings and connectors for general condition. 1.12 Filters. Check the condition of mercury column filters. Replace as needed and indicate on Line 3.4 of the inspection form. 1.13 Bleed Valve. It should be possible to quickly and accurately adjust the bleed valve to a rate of 2 to 3 mm Hg/sec. Pressurize the system and check the valve to see if it can be easily adjusted to this bleed rate. A bleed valve with a damaged seat will open too quickly, and it will be difficult to adjust the rate accurately. 1.18 Indicators/Displays. Meter and scale markings should be clear and easy to read, and the cover glass on an aneroid gauge should be intact. 1.19 Zero Pressure Setting. With no pressure in the cuff, the aneroid gauge or mercury level should read zero (±1 mm Hg). If a mercury manometer does not read zero, add or remove mercury carefully until it does. Discard aneroid gauges that cannot be reset to read zero. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible.

1.24 Gauge/Column. Ensure that the pointer of an aneroid gauge falls smoothly throughout its scale and does not stick or bind. In a mercury manometer, the glass tube and mercury should be clean. Check that the mercury column rises and moves smoothly. Mercury “dancing” or “clinging” to the walls of the tube indicates a dirty tube and filter. If the tube appears dirty, remove it and clean it with an oversized pipe cleaner. Before removing the glass tube for cleaning, be sure that all the mercury is in the reservoir either by tilting the unit or, on some units, by unlatching the locking mechanism. Replace dirty mercury. CAUTION: Mercury is toxic (see Special Precautions).


Pressure Leakage. Wrap the cuff around a simulated limb (coffee can or pipe, 3 to 4 in diameter). Close the bleed valve, and inflate the cuff to about the maximum scale indication. Read the scale indicator after 1 min to determine the rate of pressure loss in mm Hg/min. This rate should not exceed 15 mm Hg/min. If it does, recheck all fittings, especially Luer taper fittings, and repeat the test.

2.10 Gauge Accuracy. Periodically check the accuracy of aneroid gauges. This test need not be done on mercury sphygmomanometers except during incoming inspection or when the glass tube has been replaced. Connect the blood pressure set to a pressure gauge or meter using a Y connector, as shown in Figure 1. Inflate the system to 200 mm Hg

1.23 Accessories. Cuffs. Use of an improperly sized cuff can cause significant measurement errors. Clinical personnel should be instructed never to substitute an improper cuff for lack of one of proper size. Record the cuff sizes that are either stored with the manometer or are readily available (e.g., at a nearby nursing station) on the inspection form. These should correspond to physical characteristics of the patients on whom the instrument is likely to be used (e.g., smaller cuffs in a pediatric area). All cuffs should be clean and in good condition with no torn stitching. Look for signs of degradation or cracking of the bladder. Check that Velcro closures hold firmly.

Figure 1. Test setup.


3

Inspection and Preventive Maintenance System on the gauge or meter and record the reading of the unit under testing. It should not differ by more than 3 mm Hg from the true pressure. Aneroid gauges should be accurate in all positions in which they are likely to be held while being read. Repeat the test for pressures of 120 and 60 mm Hg. Record pressures only when the system is at equilibrium (i.e., the pressure is not varying).


4

Clean exterior and mercury tube, if needed.

3.2

Lubricate casters, swivel wall mount.

3.4

Replace mercury column filters and mercury, if dirty.


Before returning to use Ensure that no mercury has been spilled on the device and that the cuff is reconnected to the unit.



Suction Regulators Used For: Regulators, Suction, Low-Volume [13-329] Regulators, Suction, Surgical [15-051] Regulators, Suction, Thoracic [13-332] Regulators, Suction, Tracheal [13-333]

Also Called: Vacuum regulators, suction controllers Commonly Used In: Operating rooms, short-procedure or same-day surgery areas, emergency departments, critical care units, medical-surgical units Scope: Applies to virtually all types of suction regulators used with central vacuum systems; does not apply to aspirators (see Procedure/Checklist 433) Risk Level: ECRI Recommended, High for Tracheal Suction Regulators, Medium for Surgical and Thoracic Suction Regulators, and Low for Low-Volume Suction Regulators; Hospital Assessment, for Low-Volume Suction Regulators, for Surgical Suction Regulators, for Thofor Tracheal Suction Regulators racic Suction Regulators, and Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Regulators in emergency departments, the OR, and some critical care units may require a six-month inspection interval if they are the only source of tracheal suction. It may be efficient to inspect suction regulators during the annual testing of the institution’s medical gas/vacuum system (Procedure/Inspection Form 440).

Overview

diaphragm and dictates the pressure at which the diaphragm will open or close the vacuum control valve.

Suction by means of a regulated central vacuum system (and/or aspirator) is widely used in hospitals to remove secretions such as vomitus, mucus, or blood during surgical procedures or to remove secretions in wound cavities following surgery. Clinical examples include surgical site suctioning, tracheal suctioning, wound drainage, gastric and uterine aspiration, and emergency airway clearance.

The vacuum level of a suction regulator depends on its application, as follows: thoracic suction, 0 to 45 mm Hg; low-volume (gastric) suction, 0 to 150 mm Hg; and surgical, tracheal, and uterine suction, 0 to >300 mm Hg. (The maximum vacuum of most central systems is >400 mm Hg.) Low-volume regulators typically operate intermittently, cycling between atmosphere and 120 mm Hg, but some also have a continuous-flow mode.

A suction regulator works on the same principle as a compressed gas regulator: a diaphragm that is linked to a control valve continuously senses the vacuum of the suction channel. A spring works against the sensing


Regulators generally have a tiny bleed hole in the patient port chamber that allows the suction system to respond to changing conditions. Because the bleed hole


●


Inspection and Preventive Maintenance System is typically only a fraction of a millimeter in diameter, it can be clogged by dirt, lint, or other fine particles suspended in the air; some regulators have a bleed hole filter. The bleed hole (and filter) should be examined whenever a regulator is opened for repair.

Citations from Health Devices Filters in suction lines, 1982 Jan-Feb; 11:97-8. Suction canisters [Evaluation], 1983 Apr; 12:127-49. General purpose wall vacuum regulators [Evaluation], 1985 May; 14:191-209. Should vacuum pump effluent be treated? [User Experience NetworkTM], 1994 Jul; 23:310. Use of filters on medical gas system outlets and vacuum system inlets [User Experience NetworkTM], 1994 Dec; 23:494-5.

Test apparatus and supplies Vacuum gauge, 0 to 760 mm Hg, ±3%, or pressure meter with equivalent capabilities Flowmeter, 10 to 50 L/min, ±5% Tubing and adapters for connecting vacuum gauge or pressure meter and flowmeter (a T fitting is needed)

Special precautions

service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer. It is vital to identify the type and/or application of the suction regulator to be inspected in order to define the performance criteria for the inspection. In addition, the inspector must know if the regulator has a factory-set limit that is below the operating vacuum level of the system. (A minimum system vacuum of 300 mm Hg [12 in Hg] is required, but many systems cycle between 400 and 600 mm Hg; tracheal suction regulators may have an upper limit of 200 mm Hg.) This information may be difficult to obtain because some regulators bear only a model or catalog number. Obtain device specifications from the manufacturer’s literature, previous inspection forms, or clinical personnel. Once the type of regulator has been identified or when new units are purchased, enter this information on the equipment control or inventory record so that it can be determined quickly in future applications.


Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that housings are intact, that all hardware is present and tight, and that there are no signs of spilled liquids or other abuse.

1.8

Tubes/Hoses. Check the condition of all tubing and hoses. Be sure that they are not cracked, kinked, or dirty. Replace if needed and indicate this on Line 3.4 of the inspection form.

Never place your mouth on any part of the regulator to blow or suck as a qualitative test of operation or to blow dirt out of a part. Suction regulators should be used with an overflow safety trap/filter, and most suction canisters are designed to prevent escape of suctioned material; still, contamination of the regulator can occur. Because contamination cannot be easily ascertained, the device should be sterilized before it is opened. Follow the manufacturer’s instructions for sterilization; the regulator knob will usually need to be adjusted to maximum suction setting. Check the regulator filter condition following sterilization. (Note: Gas sterilization may not be effective if there is fluid inside the regulator.) If the regulator cannot be sterilized, wear latex gloves, wrap cellophane or another nonpermeable barrier around the handles of all tools, and work on a surface that can be easily disinfected. Dispose of gloves and tool handle wrappings with infectious waste.

Procedure Before beginning the inspection, carefully read this procedure and the manufacturer’s instruction and

2

1.10 Fittings/Connectors. Examine all fittings and connectors for general condition and, where applicable, for the presence of O-rings, gaskets, etc.; verify that they are securely attached. Replace if needed and indicate this on Line 3.4 of the inspection form. Examine the patient and vacuum port connectors for liquids or residue from dried aspirant. If keyed connectors (e.g., pin-indexed gas connectors) are used, make sure that no pins are missing and that the keying is correct. 1.12 Filters. Check the condition of all filters, especially after the regulator has been sterilized. Replace if necessary and indicate this on Line 3.4 of the form.


Suction Regulators 1.13 Controls/Switches. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Verify dynamic regulator operation by adjusting for maximum suction level, occluding the catheter line until the vacuum level peaks, and then adjusting for 100 mm Hg. Check for any leaks through the regulator by turning it off and observing the gauge with the patient port occluded; if there are no leaks, the gauge needle will indicate a zero reading. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of gauges and visual displays on the unit. Ensure that the needle returns to zero when the regulator is turned off.

Suction Regulator Performance Values These performance values represent best current opinion on clinical need and typical regulator capability, not optimal design criteria. Units unable to meet these criteria should be discussed with clinical staff and scheduled for replacement or repair.

Low Volume Surgical Thoracic Tracheal Uterine

2.4

Maximum Flow. Measure the maximum free airflow with the flowmeter and compare it with recommended values in the table. (This measurement need not be made in the intermittent mode of operation.) Set the regulator for maximum suction. Perform the test with collection bottle or canister in place, but without patient catheters. Use either a direct coupling or a short

NA >30 >20 >30 >30

2.5

Maximum Vacuum. Connect the vacuum gauge or pressure meter to the collection bottle or canister patient connector with thick-walled tubing. Adjust the regulator for maximum suction and record this value. If the expected value (see the Suction Regulator Performance Values table above) is not obtained, look for air leaks, especially in the collection bottle/canister and overflow safety trap caps and hoses.

2.6

Vacuum Gauge Accuracy. Check the accuracy of the vacuum gauge by comparing it to the test measurement device at low, medium, and high settings. Readings should be within 10% of fullscale deflection.


Clean the exterior (do not immerse) and interior of the suction regulator and overflow safety trap, if needed. Overflow protection mechanisms in reusable collection bottles and safety traps are especially likely to require disassembly and cleaning. Wear latex gloves when cleaning or repairing a regulator. Verify patency of the bleed hole during repair.

3.2


3.3

Calibrate gauge and timing of intermittent mode, if needed.

3.4

Replace filter(s), O-rings, gaskets, diaphragms, if needed.

1.25 Intermittent Operation. If the regulator has an intermittent mode, verify that cyclical suction occurs (e.g., on 15 sec, off 8 sec) and that vacuum reaches the preselected level.


>40 >300 >40 >300 >300

Maximum Flow (L/min)

piece of large-diameter tubing from the flowmeter to the device, with the correct size adapters inserted at the regulator end. Any restrictions (e.g., small-bore adapters) will tend to reduce the free airflow.

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.24 Overflow Protection. Confirm the presence and condition of the overflow safety trap/filter assembly. In devices where overflow protection is provided by a hollow plastic ball, the ball will not function reliably if it is dented or cracked or has dried aspirate solids adhering to it. (To verify operation of the overflow protection, water must be aspirated into the protective device until it activates; such testing is not necessary for acceptance or routine inspections. If it is performed, clear tubing should be used between the overflow protection device and the regulator; be prepared to immediately turn off the regulator if the protective mechanism fails and fluid enters the regulator’s input tubing.)

Maximum Vacuum (mm Hg)

Type



3


Temperature Monitors Used For: Temperature Monitors [12-672] Thermometers, Electronic, Continuous [14-034] Thermometers, Electronic, Intermittent [14-035] Thermometers, Infrared, Ear [17-887]

Also Called: Electronic thermometers; infrared ear units are often referred to as “tympanic” thermometers, although most units detect ear canal temperature and do not focus on the tympanic membrane Commonly Used In: Operating rooms, nurseries, critical care units, emergency departments, patient care rooms Scope: Applies to line- or battery-powered thermometers Risk Level: ECRI Recommended, Low; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Electronic thermometer designs range from a simple temperature-sensing probe and readout to more complex systems with alarms and calibration checks. An electronic thermometer has a temperature probe that contains a sensing element (thermistor) whose resistance to the flow of electrical current varies with temperature. The resistance is measured by an electronic circuit, and the corresponding temperature is displayed on an analog or digital meter. The circuits and display may be powered by line voltage, a rechargeable battery, or a primary (nonrechargeable) battery. Many electronic thermometers use a cable with a thermistor in the tip. A disposable cover is placed over the tip or probe before each use. Cable/probe thermistor unit temperature measuring sites include the mouth, rectum, and axilla. Infrared (IR) ear thermometers utilize an optical system to focus the IR radiation emitted by the ear canal or, in some cases, the tympanic membrane onto



Time Required

a special integrated circuit (typically, a matrix of small thermocouples). Probe covers are part of the optical system and must be used for all readings because ear wax buildup will produce inaccurate readings. Some clinical applications and/or patient conditions require continuous temperature monitoring (e.g., patients under general anesthesia or suffering from any condition that depresses the body’s ability to regulate its own temperature, such as shock and septicemia). Infants whose temperature-regulating mechanisms have not fully developed are often monitored. Body temperature should also be monitored during artificial heating or cooling. Monitors may stand alone or may be incorporated into multiparameter physiologic monitoring systems, infant incubators, and hypo/hyperthermia machines. The vast majority of temperature measurements in healthcare facilities are taken periodically along with other vital signs (e.g., once or twice during an eighthour shift). Most electronic thermometers used for


●


Inspection and Preventive Maintenance System intermittent or discrete measurements are designed to reduce the time required to obtain a reading by predicting patient temperature from the rate of temperature rise after inserting the probe. For thermometers with cable/probe thermistors, predictive mode measurement time is typically within 15 to 60 sec. Some IR ear thermometers predict temperatures at alternative sites and produce a reading within 3 sec. Cable/probe thermistors are available with a variety of physical and electrical characteristics. Generally, the electrical characteristics of all probes designed for a given instrument will be similar, but probe shapes may differ to facilitate temperature measurements at various anatomic sites. Probes intended for use with different model units may not be interchangeable, even though both are designed for the same anatomic site.

whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.



1.2


1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Check line cords of battery chargers.

1.6


1.7

Circuit Breaker/Fuse. If the unit has a switchtype circuit breaker, check that it moves freely. If the unit is protected by an external fuse, check its value and type against that marked on the chassis, and ensure that a spare is provided.

1.9

Cables. Inspect cables (e.g., sensor) and their strain reliefs for general condition. Examine cables carefully to detect breaks in the insulation and to ensure that they are gripped securely in the connectors of each end to prevent rotation or other strain.

Citations from Health Devices Intermittent-use electronic thermometers [Evaluation], 1982 Nov; 12:3-20. Infrared ear thermometry [Guidance article], 1991 Nov; 20:431-41.

Test apparatus and supplies Leakage current meter or electrical safety analyzer. Ground resistance ohmmeter. Reference thermometer, accurate within 0.1°C (0.2°F) over a range of at least 30° to 45°C (86° to 113°F); an equivalent Fahrenheit thermometer can be used if the units to be tested include Fahrenheit scales. Precision mercury-in-glass thermometers traceable to the National Institute of Science and Technology (NIST) are available from chemical supply houses. Alternatively, another electronic thermometer of known accuracy may be used, but it may require more frequent calibration. Constant temperature water bath with a temperature range of 30° to 45°C. Certified emmisivity black body or the thermometer manufacturer’s dedicated calibration device (for IR ear thermometers). Patient probe simulator (optional for cable/probe thermistor thermometers).

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine

2

1.10 Connectors. Examine all electrical connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. 1.11 Probes. Check that all probes are clean and not cracked, brittle, or otherwise damaged. 1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate (e.g., a zeroing control


Temperature Monitors or alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection.

the probe. It may not be possible to verify the operation of all alarms at this time (e.g., high and low temperature), but you should know all the alarm capabilities and remember to check them at the appropriate time.

Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function.

1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Probe covers should be stored with the unit. Notify clinical personnel if the covers are missing or are stored incorrectly (e.g., in a manner that will not protect their cleanliness). A used cover should not be left on the probe after testing.

1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors, if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. Check remaining battery capacity by activating the battery test function. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. When it is necessary to replace a battery, label it with the date.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular, verify grounding of the mainframe and each module. If the device has an accessory outlet, check its grounding to the main power cord.

1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, and visual displays on the unit and charger, if so equipped.

2.2

Leakage Current. Measure chassis and patient lead leakage current to ground with the grounding conductor temporarily opened. Operate the device in all normal modes, including on, standby, and off. Leakage current should not exceed 300 µA.

Check that all digits light in digital displays either by observing the changing temperature readings as the probes warm during the water bath accuracy test or by varying the probe simulator through its range. A display of “8” in the tens and units positions will check all elements of a segmented or dot display. Confirm that a “1” can be displayed in the hundreds position of a Fahrenheit display. 1.19 User Calibration. Confirm that the calibration function operates. If the unit has an external calibration adjustment, verify that the control can be set to a point that brings the unit within calibration and that this setting is not near the end of its range. A setting near the end of its range may indicate that the unit requires battery replacement or an internal adjustment. 1.20 Alarms. Visual alarms should function properly. Confirm appropriate volume, as well as the operation of a volume control. Check the probedisconnect alarm, if so equipped, by unplugging

2.10 Temperature Accuracy (cable/probe thermistor thermometers). Predictive mode. Check approximate accuracy by taking an oral temperature. Compare the electronic thermometer reading with the reading taken with a mercury thermometer on the same person at about the same time. Expect discrepancies of several tenths of a degree Celsius with this method. Larger errors or inconsistent results may result from improper user technique with either thermometer. Improper technique may include failure to leave the mercury thermometer in place long enough (3 to 8 min), incorrect placement of the probe and/or the glass thermometer, repeating an electronic thermometer measurement before the probe has cooled sufficiently, and repeating an electronic thermometer measurement without replacing the probe cover.


3

Inspection and Preventive Maintenance System Thermometers that also allow operation in a steady-state mode facilitate assessment of the predictive mode and can be tested with a water bath. However, this steady-state test does not check all of the predictive circuitry. See the unit’s operating manual for specific instructions for activating the steady-state mode and for specifications and directions for testing. Steady-state mode. Test the accuracy of the thermometer in a water bath of known temperature or with a patient probe simulator. Check accuracy at 35°C (95°F), 37°C (98.6°F), and 39°C (102.2°F). Check thermometers intended for wide temperature range applications (e.g., hypothermia monitoring) at temperatures near the high and low extremes of the range. If a patient probe simulator is not available, use a thermostatically controlled constant temperature water bath for accuracy measurements. Alternatively, hot and cold tap water can be mixed in an insulated cup or beaker or a thermos flask to achieve the desired test temperatures. Use a precision thermometer to measure the water temperature. If a mercury-in-glass calibration thermometer is used, submerge it to the recommended depth to ensure a correct reading. Vary the temperature by adding hot or cold water as needed. Stir the water frequently and allow sufficient time for the temperature probe and the calibration thermometer to equilibrate at the water temperature before taking readings and comparing them. Fluctuating or decreasing water bath temperature may cause errors if the response times of the electronic thermometer being tested and the calibration thermometer differ greatly or if the thermometer being tested is the type that reads the maximum temperature during a measurement. When inspecting multiple units, use three vessels to establish the three test temperatures at the same time to avoid the necessity of changing the temperature. Also, if conditions permit, save time by placing the probes of all the thermometers to be tested in the same bath simultaneously. If a patient probe simulator is used, remember that the simulator tests only the circuitry and not the probe itself; therefore, probe operation and accuracy must still be tested for at least one temperature. A convenient method is to dip all probes simultaneously into one

4

body-temperature water bath, allow them to equilibrate, and successively plug each into the same pretested thermometer unit or module. All probes should give the same temperature reading. Some variation is normal because the water temperature varies slightly with location in the bath and the water gradually cools with time. Steady-state thermometers should be accurate within 0.3°C (0.5°F) or within manufacturers’ specifications, with some allowance for possible errors in the measuring system. Correct reading inaccuracies according to the manufacturer’s recommended calibration procedure. 2.11 Temperature Accuracy (IR ear thermometers). It may be necessary to put the thermometer into a calibration or “unadjusted” mode. Test measurements are made using a black body heated to temperatures in the range of 35°C to 39°C. The black body must have an orifice that mates snugly with the probe of the ear thermometer. If a black body float is used, place it in a water bath adjusted to 37°C. While agitating the bath sufficiently to ensure thermal uniformity, measure the bath temperature by positioning the calibration thermometer so that its tip is positioned near the center of the bath without touching the sides or bottom; allow one minute for a reliable reading and to ensure that the temperature has equilibrated. Insert the probe of the thermometer into the black body so that it occludes the cone of the float. IR thermometer readings should be within 0.3°C of the bath temperature or other calibration device. 2.12 Temperature Alarms. This test checks the highand low-temperature alarms of monitoring modules. Set the low-temperature alarm below 35°C and dip the probe in a 35°C water bath, or set the simulator at the equivalent resistance. Slowly increase the alarm setting until the alarm activates. Record the final alarm setting and the actual water bath temperature. They should be within 0.6°C. Set the high-temperature alarm above 39°C, and place the probe in a 39°C water bath or use the probe simulator. Slowly decrease the alarm setting until the alarm activates. Record the alarm setting and the actual water bath temperature. They should also be within 0.6°C.


Temperature Monitors 3. Preventive maintenance 3.1

Clean the exterior of all units and the probe lens of IR units, if needed.


Patient Probe Leakage Current. This test applies only to units that can operate on line power with probes that are not ground referenced. Measure probe circuit leakage current directly from each probe electrical lead contact (using an appropriate connector). If the leakage current to ground from each lead of the connector is less

than 100 µA, then it is unnecessary to check leakage current from the probe itself. If the preceding method is inconvenient or if the leakage current obtained exceeds 100 µA, measure patient probe leakage current by dipping the probe into a container of water. Do not immerse the probe above the handle or allow the solution to enter any connectors. Leakage currents should not exceed 100 µA. However, a reading above a few microamperes may indicate deterioration of the probe covering and a need to replace the probe.

Before returning to use Return alarms and other controls to their pre-inspection or normal pre-use setting. Recharge batteries or equip with fresh batteries if needed.


5


Traction Units Used For: Traction Units, Intermittent [14-106] Traction Units, Intermittent, Mobile [14-108]

Also Called: Intermittent traction units, powered traction units Commonly Used In: Physical therapy departments and clinics, orthopedic clinics Scope: Applies to powered traction units used for cervical and lumbar traction; does not apply to static traction devices consisting of pulleys and weights Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type


Major

12 months

months

.

hours

Minor

NA

months

.

hours

Overview Traction units powered by hydraulics or an electric motor apply traction to the cervical or lumbar spine by means of harnesses attached to a patient’s head or pelvic area. The traction force widens the intervertebral spaces, thus relieving nerve root compression by intervertebral disks and the associated pain and burning or tingling sensations in the neck, shoulders, and arms (when the cervical spine is involved) or in the back, buttocks, legs, and feet (when the lumbar spine is involved). Traction was traditionally provided with static weights attached to a harness worn by a patient while immobilized in bed. Research has demonstrated that considerably more force is required to widen intervertebral spaces than can be provided with such a system; however, the required forces are too high to be tolerated for long periods. Studies showed that intermittent or cycled traction provided sufficient, effective force but was relatively comfortable. Studies also proved that conventional traction applied with a pelvic belt to the lumbar region of a patient lying in bed was ineffective since friction of the lower half of the body



Time Required

against the bed dissipated all of the linear force before it could widen the lumbar intervertebral spaces. Thus, split beds were developed that allowed the lower half of the bed to roll back and forth several inches on a frame, eliminating the friction and permitting traction force to be transmitted directly to the lumbar region. Traction units usually have a timer to set treatment duration and automatically turn off the machine at the end of the treatment session; the units also have controls for adjusting cycling rate and the ratio of traction and relaxation. All units provide a method for adjusting the traction force, which is usually calibrated in pounds. Cervical traction units are typically wall mounted but can also be mounted overhead, on floor stands, or on standards associated with or integrated into special chairs. Lumbar traction units may be integrated into special beds or tables. Mobile, hydraulically powered units can be used with most beds or special tables. Universal models can be mounted overhead for cervical traction or attached to a bed or special table for either cervical or lumbar traction. The greatest safety problems are related to mounting security; ceiling- and wall-mounted units present the greatest hazard.


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Inspection and Preventive Maintenance System screws are used, verify that the stress is distributed to two or more studs. Molly bolts, plastic shield screws, wood screws, and direct mounting on plaster or drywall are unacceptable.

Most of the hazards associated with powered units involve mechanical safety. Machine components (e.g., cables, spreader bars, linkages, and scales that apply and measure traction forces) have broken or separated from their mounts and fallen on patients. Improperly secured mounts have caused entire machines to fall or topple, sometimes on patients. Foreign objects and clothing have been caught in moving parts, and fingers have been pinched.

Test the mounting integrity of vertically mounted units by hanging a 100 lb weight from the patient cable or lever several inches above the floor for 5 min, and examine mounts, fixtures, welds, and mounting surfaces for stress. While this test is under way, continue with the remainder of the visual inspection, but do not stand or sit under the unit.

Test apparatus and supplies Ground resistance ohmmeter Leakage current meter or electrical safety analyzer Weights (five 10 lb, one 50 lb), accurate to at least 5% and a connector for attaching them to the traction unit 100 lb spring scale or dynamometer, accurate to 5% (for horizontally mounted units that cannot be removed and mounted for testing in the vertical plane; optional for vertically mounted units)

1.3

Casters/Brakes. If the device moves on casters, check their condition. Check the operation of brakes and swivel locks, if the unit is so equipped.

1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damage is present, replace the entire cord, or if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity.

1.6


1.7


Stopwatch or watch with a second hand Lubricants recommended by the manufacturer

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manual; be sure you understand how to operate the equipment, the significance of each control and indicator, and the alarm capabilities. Also determine whether any special inspection or preventive maintenance procedures or frequencies are recommended by the manufacturer.


1.2

Chassis/Housing. Examine the exterior of the unit for cleanliness and general physical condition. Be sure that plastic housings are intact, that necessary assembly hardware is present and tight, and that there are no signs of spilled liquids or other serious abuse. If required, clean and lubricate (Items 3.1 and 3.2) at this time. Mount/Fasteners. Inspect the chassis and all stress-bearing members. Carefully examine the basic structure for evidence of undue stress, including metal fatigue; fractures; integrity of welds; size, condition, and tightness of fasteners; condition and characteristics of mounting substructure (i.e., wall, backing board or plate, chair structure); and corrosion. Tighten loose fasteners. Wall-mounted units should employ backing plates to spread forces over a large area. If lag

2

1.13 Controls/Switches. Before moving any controls and alarm limits, check their positions. If any of them appear inordinate, consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Where a control should operate against fixedlimit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails,


Traction Units the grounding conductor temporarily opened. Operate the unit in all normal modes, including on, standby, and off, and record the maximum leakage current. Leakage current should not exceed 300 µA.

pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.15 Motor. Confirm physical condition and proper operation. Perform lubrication, if required; note this in Item 3.2 (but do not check until all necessary lubrication has been completed). 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. 1.20 Alarms. Test the activation of alarms, if so equipped. 1.22 Labeling. Check that all necessary placards, labels, conversion charts, and instruction cards are present and legible. 1.23 Accessories. Carefully examine operating levers, cables, chains, ropes, and spreader bars used to transfer the machine’s linear motion to the patient harness. Examine ropes for wear and fraying. Cables should be clean, free of corrosion, and without fishhooks or other evidence of broken strands, sharp bends, kinks, or unstranding that would weaken the cable. Examine the integrity of cable connections, whether splices, thimbles, press sleeves, or clevis or eye fittings. Be sure that clevis or eye-fitting pins have cotter pins or bolts with stop nuts to ensure security. Check S-hooks, chain links, and spreader bars for cracks, bends, and other evidence of weakness. Tighten, repair, or replace components as necessary. 1.24 Patient Pendant Control. Examine the pendant switch housing and its electrical cable and strain relief for wear and damage. Check that the switch functions properly and that it overrides all other on/off switches and the treatment duration timer.


2.2

2.3

Timer Accuracy. Check the timer accuracy with a stopwatch or a watch with a second hand. The error should be less than 10%.

2.10 Traction Control Accuracy. The machine should deliver forces accurate to within 10% of the indicated value. Test vertically mounted traction units at 10, 50, and 100 lb by placing the appropriate weights on a chair under the unit and attaching them to a coupling device. Take into account the weight of the weight carriers, spreader bar, and other parts that contribute to the total load. Set the machine’s force control to the equivalent force in each case; set its controls for hold (dwell) and rest times for 20 sec. The machine should just lift each weight off the chair. Many table-mounted traction units can be easily removed and clamped to the top of a door for testing in the vertical plane. Alternatively, they can be left in place and tested with a spring scale or dynamometer. In either case, these units should also be tested at 10, 50, and 100 lb. Recalibrate the unit according to the manufacturer’s instructions, if necessary, and indicate this on Line 3.3 of the inspection form. 2.11 Intermittent Traction. Verify correct operation when intermittent traction is selected, using the same test setup as in Item 2.10. The rope/cable should slacken after 20 sec, setting the weight back on the chair, or causing the spring scale/dynamometer reading to fall to zero. After another period of 20 sec, the force should be resumed.


Clean the exterior.

3.2

Lubricate the gearboxes, cams, and motor according to the manufacturer’s instructions.

3.3

Calibrate, if necessary.



Leakage Current. Measure chassis and patient pendant control leakage current to ground with

Return controls to their preinspection or normal pre-use settings.

4. Acceptance tests



3


Transcutaneous O2/CO2 Monitors Used For: Carbon Dioxide Monitors, Transcutaneous [15-970] Oxygen Monitors, Transcutaneous [12-592]

Commonly Used In: NICUs Scope: Applies to devices that assess blood gas levels noninvasively from a skin-surface probe Risk Level: ECRI Recommended, High; Hospital Assessment, Type



Major

12 months

month

.

hours

Minor

NA

month

.

hours

Time Required

Overview


Transcutaneous carbon dioxide (tcpCO2) and oxygen (tcpO2) monitors provide noninvasive methods for measuring the partial pressure of carbon dioxide and oxygen at the skin surface. These measurements are not always equal to the arterial partial pressure of carbon dioxide (paCO2) and oxygen (paO2), but they can be useful indicators of changes in these values.

Transcutaneous oxygen monitors [Evaluation], 1983 Jul-Aug; 12:213-51.

Transcutaneous monitoring is done primarily on infants in the neonatal intensive care unit (NICU). Since these infants often experience respiratory distress, tcpO2 monitoring is critical for avoiding hypoxemia (low paO2, which can lead to brain damage) and hyperoxemia (high paO2, which can cause blindness). Persistent hypercapnia (high paCO2) in the infant may indicate potentially life-threatening pulmonary complications. Hypocapnia (low paCO2) might be symptomatic of infantile asthma or of a pulmonary embolism limiting blood flow to the lungs; it might also result from mechanical overventilation of the lungs, which creates an excessive minute respiratory volume (i.e., the volume of new air moving into the lungs each minute). Prenatally, tcpO2 measurements can also monitor maternal and fetal oxygenation.


Test apparatus and supplies Leakage current meter or electrical safety analyzer Ground resistance ohmmeter Manufacturer’s recommended calibration equipment Water bath or manufacturer’s patient simulator



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Inspection and Preventive Maintenance System 1.11 Probes. Confirm that any necessary probes are on hand and check their physical condition.



1.2


1.4


1.5

Line Cord. Inspect the cord for signs of damage. If damaged, replace the entire cord, or, if the damage is near one end, cut out the defective portion. Be sure to wire a new power cord or plug with the correct polarity. Also check line cords of battery chargers.

1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), we recommend that the cord be affixed to the unit so that it cannot be removed by the operator. (See Health Devices 1993 MayJun; 22:301-3.)

1.7


1.9

Cables. Inspect probes and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

1.10 Fittings/Connectors. Examine all electrical connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that probe leads are firmly gripped in their appropriate connectors.

2

1.13 Controls/Switches. Before changing any controls or alarm limits, check their positions. If any settings appear inordinate (e.g., a gain control at maximum, alarm limits at the ends of their range), consider the possibility of inappropriate clinical use or of incipient device failure. Record the settings of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. Check membrane switches for membrane damage (e.g., from fingernails, pens). During the course of the inspection, be sure to check that each control and switch performs its proper function. 1.17 Battery/Charger. Inspect the physical condition of batteries and battery connectors if readily accessible. Check operation of battery-operated power-loss alarms, if so equipped. Operate the unit on battery power for several minutes to check that the battery is charged and can hold a charge. (The inspection can be carried out on battery power to help confirm adequate battery capacity.) Check battery condition by activating the battery test function or measuring the output voltage. Check the condition of the battery charger and, to the extent possible, confirm that it does, in fact, charge the battery. Be sure that the battery is recharged or charging when the inspection is complete. When it is necessary to replace a battery, label it with the date. 1.18 Indicators/Displays. During the course of the inspection, confirm the operation of all lights, indicators, meters, gauges, and visual displays on the unit and charger (if so equipped). Be sure that all segments of a digital display function. Observe a signal on a CRT display, if present, and check its quality (e.g., distortion, focus, 60 Hz noise). 1.19 User Calibration. Verify that the calibration function operates. 1.20 Alarms. Induce alarm conditions with each procedure below, and verify that the unit operates properly and activates an audible and visual alarm for each alarm limit that has been exceeded.


Transcutaneous O2/CO2 Monitors If the unit has an alarm-silence feature, check the method of reset (i.e., manual or automatic) against the manufacturer’s specifications. Verify that reset silenced alarms reactivate within the manufacturer’s specified time. It may not be possible to check out all alarms at this time, since some may require abnormal operating conditions that will be simulated later in this procedure. Gas concentration alarms. Set the high- and low-concentration alarm limits so that they are exceeded when the probe is exposed to either ambient air or an exhaled breath. The sensor may have to be exposed to a zero gas (e.g., N2) to activate the low tcpO2 alarm. Observe alarms.

insulated, grounding resistance need not be measured; indicate “DI” instead of the ground resistance value. 2.2

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including heater on and off, standby, and off, and record the maximum leakage current. Chassis leakage current to ground should be 300 µA or less.

2.3

1.21 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped. If audible alarms have been silenced or the volume set too low, alert clinical staff to the importance of keeping alarms at the appropriate level.

Temperature Control. If a patient simulator is available from the manufacturer, secure the probe to the simulator. If a simulator is not available, a water bath can be used to simulate the patient’s skin temperature. Select a commonly used set-point temperature on the monitor. With the simulator temperature initially set at 30°C, verify that the heater indicator shows that the heater is on. Increase the temperature of the simulator. When the simulator temperature reaches the set-point temperature (within 0.1°C), the heater indicator should be off.

2.4


Temperature Display Accuracy. The surface temperature display should be within 0.1°C of the simulator temperature. Record the simulator temperature and the displayed temperature on the inspection form.

2.5

High-Temperature Alarm. Using the test described in Item 2.3, continue to increase the simulator temperature; the high-temperature alarm should activate when the simulator temperature exceeds the set point by 0.5°C.

2.6

Low-Temperature Alarm. Detach the probe from a simulator that has heated to the unit’s set temperature, and verify that the low-temperature alarm activates when the displayed temperature is 0.5°C below the set temperature.

2.7

tcpO2 Display Accuracy. Expose the probe to calibration gas containing O2 and verify that the display is within ±5 mm Hg or 10%, whichever is greater, of the actual concentration. If the display is inaccurate, calibrate the unit.

2.8

tcpCO2 Display Accuracy. Expose the probe to calibration gas containing CO2 and verify that the display is within ±5 mm Hg or 10%, whichever is greater, of the actual concentration. If the display is inaccurate, calibrate the unit.

Site-timer alarm. Verify that the site timer is operational and activates an alarm. Other alarms. If the unit indicates any other alarm condition, induce the alarm and verify that the alarm condition is indicated by the unit.

1.23 Accessories. Confirm the presence of probe application kits. 1.24 Chart Recorder. If the unit has a chart recorder, confirm that it operates smoothly, that the paper feeds evenly and does not stray from side to side, and that the trace is of good quality at all paper speeds. The trace should be dark and thin.


Grounding Resistance. Using an ohmmeter, electrical safety analyzer, or multimeter with good resolution of fractional ohms, measure and record the resistance between the grounding pin of the power cord and exposed (unpainted and not anodized) metal on the chassis. We recommend a maximum of 0.5 Ω. If the system is modular or composed of separate components, verify grounding of the mainframe and each module or component. If the device is double


3

Inspection and Preventive Maintenance System 3. Preventive maintenance

4. Acceptance tests

3.1

Clean the exterior, interior, chart recorder, and rollers if needed and the probe if recommended.


3.2

Lubricate the chart recorder paper drive per manufacturer’s instructions.


3.3

Calibrate according to the manufacturer’s recommended procedure.

Make sure that all controls are set properly. Set alarms loud enough to alert personnel in the area in which the device will be used. Other controls should be in their normal pre-use positions.

3.4

Replace filter, printer paper, battery, and calibration gas tanks, if needed.

Recharge battery-powered devices or equip with fresh batteries, if needed.

4



Ultrasound Scanners Used For: Scanners, Ultrasonic, Abdominal [16-241] Scanners, Ultrasonic, Cardiac [17-422] Scanners, Ultrasonic, Dedicated Linear Array [16-747] Scanners, Ultrasonic, General-Purpose [15-976] Scanners, Ultrasonic, Intravascular [17-746] Scanners, Ultrasonic, Mammographic [15-656] Scanners, Ultrasonic, Obstetric/Gynecologic [15-657] Scanners, Ultrasonic, Ophthalmic [11-389] Scanners, Ultrasonic, Small-Parts [18-052] Scanners, Ultrasonic, Vascular [15-957]

Also Called: Real-time scanners, 2-D scanners, duplex scanners, echocardiographs, cardiac ultrasound imagers, vascular ultrasound imagers Commonly Used In: Cardiology, diagnostic imaging, OB/GYN, ophthalmology, radiology, surgery, vascular lab Scope: This procedure covers all diagnostic ultrasound scanners, including general-purpose and dedicated systems; this procedure does not cover nonimaging diagnostic ultrasound systems such as Doppler blood-flow detectors and Doppler fetal heart monitors Risk Level: ECRI Recommended, Medium; Hospital Assessment, Type



Major

12 months*

months

.

hours

Minor

NA

months

.

hours

Time Required

* Scanners with a mechanically steered transducer should probably be inspected semiannually. It is also necessary to perform Items 2.3 to 2.8/2.9 whenever a new or repaired transducer is to be used.

Overview Ultrasound scanners provide 2-D images of soft tissue for abdominal, obstetric/gynecologic, cardiac, smallparts, and vascular examinations. With specially designed probes, they can also be used for intravascular and intraoperative applications. Ultrasound refers to sound waves emitted at frequencies above the level of human hearing. For diagnostic imaging, frequencies ranging from 2 to 10 MHz are typically used. Ultrasound waves are mechanical


vibrations that require a medium for transmission. Because they exhibit the normal wave properties of reflection, refraction, and diffraction, they can be predictably aimed, focused, and reflected. Echoes are produced whenever the beam encounters an interface of different acoustic impedances, such as the soft-tissue/ bone interface. Large differences in tissue acoustic impedance characteristics result in a high degree of reflection. A transducer, which consists of one or more piezoelectric elements, is placed on the skin after an acoustic


●


Inspection and Preventive Maintenance System coupling gel is applied. The transducer converts an electrical signal into ultrasonic energy that can be transmitted into tissues. When this ultrasonic energy is reflected back from the tissues, the transducer reconverts it to an electrical signal. The scanner system measures the intensity of the echoes, the time between them, and their direction. This information is then processed and used to generate a display in one of several modes. A scan converter system displays the image on a high-resolution TV monitor. During scanning, the converter assigns discrete shades of gray (gray scale) to the returning echo amplitude levels; the number of shades depends on how many bits of information can be stored for each horizontal and vertical point of image memory. Some scanners offer user-selectable preprocessing and postprocessing features that permit the operator to optimize the image quality by altering the texture and gray-scale emphasis within the image. A data-entry keyboard permits information, such as patient name, date, and type of study, to be entered and displayed along with the scanned image. In some systems, an alphanumeric keyboard interacts with a computer to permit manipulation of the displayed image or system operating parameters. In cardiac and vascular studies, the Doppler effect is used to determine the direction and speed of blood flow. This principle states that sound waves increase in frequency when they echo from objects (in this case, red blood cells) moving toward the transducer and decrease in frequency when they echo from objects moving away from it. This change in frequency, which is related to the velocity of the moving red blood cells, is then measured and used to determine blood flow velocity. Doppler color flow mapping (CFM) simultaneously assesses the direction and relative velocity of blood flow at multiple points along multiple beam paths. The result is an image of the hemodynamics of the heart and great vessels, which is useful for detecting stenoses and valve defects. As conventional 2-D real-time techniques display the heart’s anatomic features in black and white, color superimposed on this image visually depicts the direction and velocity of blood flow. CFM complements and enhances the diagnostic value of conventional 2-D real-time images; it also provides more information about and enables better quantification of the direction and velocity of blood flow abnormalities.

Citations from Health Devices Duplex ultrasound scanners [Evaluation], 1990 Nov; 19:379-422.

2

Test apparatus and supplies Multipurpose ultrasound phantom (see Specifications for a Multipurpose Ultrasound Phantom) Doppler ultrasound phantom (required only for a comprehensive evaluation of ultrasound scanners that have Doppler capabilities; see Specifications for a Doppler Ultrasound Phantom) Blood flow simulator (required if only the basic operation of ultrasound scanners with Doppler is being checked; see Specifications for a Doppler Ultrasound Phantom) ECG simulator (required for cardiology ultrasound systems or general-purpose systems with cardiac options) Leakage current meter or electrical safety analyzer Ground resistance ohmmeter

Specifications for a multipurpose ultrasound phantom A multipurpose phantom is required to comprehensively evaluate the performance of diagnostic ultrasound imaging systems. Some multipurpose phantoms do not contain all of the recommended capabilities. To evaluate both general-purpose and small-parts scanners, it may be necessary to acquire more than one phantom to perform all of the recommended tests. General testing capabilities of the phantom should include: Dead-zone or ring-down Vertical and horizontal measurement calibration Focal zone Sensitivity Axial and lateral resolution Functional resolution Gray scale and displayed dynamic range The phantom should be designed with a combination of monofilament line targets and tissue-mimicking cylindrical targets of varying sizes and contrasts. The monofilament line targets should have a diameter of 0.1 mm to 0.5 mm to optimize the displayed image at frequencies typically used on general-purpose scanners. Monofilament line targets with diameters of approximately 0.5 mm should be present to optimize the displayed image at the high ultrasound frequencies typically used on small-parts scanners.


Ultrasound Scanners For dead-zone or ring-down evaluation, at least 6 monofilament line targets should be present at depths ranging from 2 mm to 10 mm. For vertical distance measurement calibration, the monofilament line targets should have an interval spacing of 1 cm at a depth of 1 cm to a total depth of at least 18 cm. To evaluate small-parts scanners, an interval spacing of 0.5 cm is recommended. For horizontal distance measurement calibration, the monofilament line targets should have an interval spacing of 1 or 2 cm. To evaluate small-parts scanners, an interval spacing of 0.5 cm is recommended. Targets should be available at more than one depth for accurate determination of horizontal distance measurement calibration. For axial and lateral resolution evaluation, multiple monofilament line targets are required with interval spacings of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm or less. To evaluate small-parts scanners, the smaller interval space should be 0.5 mm or less. Targets should be available at more than one depth to properly evaluate lateral resolution. The phantom should contain multiple anechoic (nonechogenic) cylindrical target structures of varying sizes from 2 mm to at least 6 mm. Anechoic target structures with a 1 mm diameter are recommended when evaluating ultrasound scanners that are routinely used for small parts. The phantom should contain multiple gray-scale (echogenic) cylindrical targets, calibrated in decibels (dB), to evaluate the displayed dynamic range and gray-scale processing performance. The phantom should be constructed of a tissue-mimicking material with a recommended attenuation coefficient of 0.5 dB/cm/MHz or 0.7 dB/cm/MHz. The velocity calibration of the tissue-mimicking material should be 1,540 meters per second. The dimensions of the scanning surface should be sufficiently large to permit evaluation of the longest flat linear-array transducer. The phantom should be contained in a protective housing. A built-in scanning well is recommended to permit the use of water or a low-viscosity gel as the coupling agent. A deep scanning well, either built-in or removable, is recommended for proper evaluation of some endoscanning transducers.

Specifications for a Doppler ultrasound phantom A calibrated Doppler flow phantom is required for a comprehensive evaluation of ultrasound scanners that incorporate continuous-wave, pulsed-wave, or colorflow Doppler capabilities. Some Doppler phantoms are designed specifically for evaluating either peripheral vascular or cardiac systems. General testing capabilities of the phantom should include: Flow velocity Location of flow Directional discrimination The phantom can be either the tissue-mimicking type with one or more fluid-flow channels (containing a nondegradeable blood-mimicking solution with calibrated reflecting targets) or the type that incorporates a moving string target within a fluid-filled container. The string phantom provides greater accuracy for flow velocity calibration. For peripheral vascular system evaluation, the target(s) within the phantom should move parallel to the phantom’s scanning surface (perpendicular to the transducer’s beam path). For cardiac system evaluation, the target(s) within the phantom should move at an angle of approximately 45° to the phantom’s scanning surface. Although not optimum, phantoms designed specifically for cardiac system evaluation can be used to evaluate peripheral vascular systems. The phantom should provide user-variable velocity of the moving target(s). To check only basic Doppler operation, it is not necessary to use the calibrated Doppler phantoms described above. A less-costly blood-flow simulator may be purchased, or one may be constructed using a fluid pump and flexible tubing submerged within a fluid-filled container. In lieu of the nondegradeable blood-mimicking solution with calibrated reflecting targets, any echogenic fluid, such as a detergent-water solution, may be used.

Procedure Before beginning an inspection, carefully read this procedure and the manufacturer’s instruction and service manuals; be sure that you understand how to operate the equipment and the significance of each control and indicator. Also determine whether any special inspection or preventive maintenance


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Inspection and Preventive Maintenance System procedures or frequencies are recommended by the manufacturer. This procedure should be documented with the ultrasound scanners inspection form no. 474.

1.8

Cables. Inspect any cables (e.g., transducer, electrode, remote control) and their strain reliefs for general condition. Carefully examine cables to detect breaks in the insulation and to ensure that they are gripped securely in the connectors at each end to prevent rotation or other strain. Verify that there are no intermittent faults by flexing electrical cables near each end and looking for erratic operation or by using an ohmmeter.

1.9

Fittings/Connectors. Examine all electrical cable connectors for general condition. Electrical contact pins or surfaces should be straight, clean, and bright. Verify that leads and electrodes are firmly gripped in their appropriate connectors. If keyed connectors are used, make sure that no pins are missing and that the keying is correct.



1.2

Mount/Fasteners. If the device is mounted on a stand or cart, examine the condition of the mount. If it rests on a shelf, check the security of this attachment.

1.3

Casters/Brakes. If the device moves on casters, check their condition. Verify that they turn and swivel, as appropriate, and look for accumulations of lint and thread around the casters. Check the operation of brakes and swivel locks, if the unit is so equipped. Conductivity checks, where appropriate, are usually done more efficiently as part of a check of all equipment and furniture in an area.

1.4

AC Plug/Receptacles. Examine the AC power plug for damage. Attempt to wiggle the blades to check that they are secure. Shake the plug and listen for rattles that could indicate loose screws. If any damage is suspected, open the plug and inspect it. If the device has electrical receptacles for accessories, verify the presence of line power, and insert an AC plug into each and check that it is held firmly. If accessories are plugged and unplugged often, consider a full inspection of the receptacles.

1.10 Transducers. Check the surface areas of ultrasound transducers for deterioration, cracks, or dents in the membrane. Check the acoustic fluid of mechanically steered transducers; refill with the recommended fluid if air bubbles are present and indicate this in section 3 of the inspection form. 1.11 Filters. Check the condition of all air vents and filters. Clean or replace filters, if appropriate, and indicate this in section 3 of the inspection form. 1.12 Controls/Switches. Before changing any controls, check their positions. If any settings appear inordinate (e.g., a gain control at maximum), consider the possibility of inappropriate clinical use or of incipient device failure. Record the setting of those controls that should be returned to their original positions following the inspection. Examine all controls and switches for physical condition, secure mounting, and correct motion. Check that control knobs have not slipped on their shafts. Where a control should operate against fixed-limit stops, check for proper alignment, as well as positive stopping. During the course of the inspection, be sure to check that each control and switch performs its proper function.

1.5


1.6

Strain Reliefs. Examine the strain reliefs at both ends of the line cord. Be sure that they hold the cord securely. If the line cord is detachable (by the user), affix the cord to the unit so that it cannot be removed by the operator. (See Health Devices 1993 May-Jun; 22:301.)

1.13 Fans. Check the physical condition and proper operation of the system’s cooling fan(s), if present. Clean and lubricate the fan(s) if required, and note this in Items 3.1 and 3.2 of the inspection form.


1.14 Indicators/Displays. During the course of the inspection, confirm the operation of all lamps, indicators, meters, gauges, and visual displays on the unit. Be sure that all segments of a digital display function. Observe an image on the CRT

1.7

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Ultrasound Scanners display, and check its quality (e.g., distortion, focus, 60 Hz noise). Record the reading of an hour meter, if present.

All portions of a simulated ECG waveform should be clearly visible, including the P wave and QRS complex. 60 Hz noise should not be present.

1.15 User Calibration. Verify that any calibration functions are operating. (Where a quantitative check is required, it will be included in Section 2, Quantitative Tests.)

The accuracy of intervals between the timing marks displayed by the scanner should be consistent with the timing of the ECG simulator.

1.16 Audible Signals. Operate the device to activate any audible signals. Confirm appropriate volume, as well as the operation of a volume control, if so equipped.

1.20 Accessories. Confirm the presence and condition of accessories (e.g., electrodes and coupling gel). Verify that expiration dates have not been exceeded.



1.18 System Performance. Use the multipurpose ultrasound phantom to evaluate the overall performance of the scanner. Use the test object’s multiple gray-scale (echogenic) targets to evaluate the displayed dynamic range and gray-scale processing performance. Use the multiple anechoic (nonechogenic) cylindrical targets to observe the absence of echogenicity. The anechoic target should be clearly resolved. Higher-frequency transducers should produce the clearest images of the smaller anechoic targets. Using normal gain and output power settings, check for sensitivity/penetration relative to the frequency of the transducer being used. (See the table below.)

2.1

If the device has an accessory receptacle, check its grounding to the main power cord. 2.2

Typical sensitivity/penetration of a multipurpose phantom Transducer Frequency 1.9 MHz 2.3 MHz 3.0 MHz 3.5 MHz 5.0 MHz 7.5 MHz 10.0 MHz

Penetration 20 cm 18 cm 16 cm 15 cm 8 cm 5 cm 3 cm

Leakage Current. Measure chassis leakage current to ground with the grounding conductor of plug-connected equipment temporarily opened. Operate the device in all normal modes, including on, standby, and off, and record the maximum leakage current. (Many leakage current meters cannot be used because of the high-current demands (e.g., greater than 10 amps) of the larger, more complex ultrasound scanners.) Measure chassis leakage current to ground with all accessories normally powered from the same line cord connected and turned on and off. This includes other equipment that is plugged into the primary device’s accessory receptacles, as well as equipment plugged into a multiple outlet strip (“Waber strip”) so that all are grounded through a single line or extension cord.

Use a blood-flow simulator to check the basic operation of the Doppler system, if installed. 1.19 ECG. Using an ECG simulator, verify normal operation of ultrasound scanners configured for echocardiography, according to the following criteria: The baseline should have constant thickness; it should be horizontal and not drift vertically. On systems equipped with a position control, check the range of movement.



Transducer Identification and Scanner Settings for Tests with the Multipurpose Ultrasound Phantom. Before performing tests 2.4 to 2.8/2.9, record transducer identification and


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Inspection and Preventive Maintenance System instrument settings as noted in the table below for each transducer on the back of the ultrasound scanners inspection form no. 474. Set the controls for optimum penetration and image quality for each transducer to be tested. A picture or printout should be made to document the image obtained with each transducer. Most equipment parameters will be displayed on these hard-copy recordings. See Figure 1 for reference scanner images.

2.8

Horizontal Distance. Place the transducer over a horizontal distance calibration line target group. Use the scanner’s digital calipers and/or marker grids to determine the accuracy of linear measurements perpendicular to the sound path. On images produced by flat sequenced linear-array transducers, check at 20 mm and 60 mm measured distances, using any left to right location. On images produced by sector transducers, check at 20 mm and 60 mm measured distances, but at multiple left to right positions. If the transducer has adjustable transmit focus, perform measurements within the focal zone, if possible.

2.9

Doppler Calibration. If a calibrated Doppler ultrasound phantom is available, verify the accuracy of flow velocity, directional discrimination, and, if applicable, pulsed-Doppler gate positioning. Measurement parameters and display quality should not vary between inspections with the same transducer configuration, scanner settings, and technique.

Transducer Identification Type/Configuration Serial No. Frequency

MHz

Scanner Settings Power Gain Dynamic Range Preprocessing Postprocessing Persistence Transmit Focus Other:

2.4

2.5

2.6

dB dB dB

cm

Dead Zone. Place the transducer over the dead zone line target group. Determine the minimum distance (in mm) at which the scanner can resolve individual structures. Axial Resolution. Place the transducer over one of the axial resolution line target groups. Determine the minimum reflector separation (in mm) along the axis of the transducer beam required to produce separate reflections. Lateral Resolution. Place the transducer over each lateral resolution line target group. Determine the minimum reflector separation (in mm) perpendicular to the sound path needed to produce discrete reflections. Because lateral resolution can vary with depth, multiple transducer locations should be used. Record the lateral resolution for each depth checked. If the transducer has adjustable transmit focus, verify its operation and perform each lateral resolution measurement in the respective focal zone, if possible.


Clean the scanner exterior, as well as the interior if needed. Use only manufacturer-approved solutions on the scanning surfaces of transducers. Clean the exterior and the interior of image recording devices, including multi-image cameras, video page printers, and videocassette recorders.

3.2

Lubricate moving parts, including wheels, casters, and drawer slides.

3.3

Refill mechanically steered transducers with the recommended acoustic fluid if air bubbles are present.

3.4

Clean air vents and or filters, if required.


2.7

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Vertical Distance. Place the transducer over a vertical distance calibration line target group. Use the scanner’s digital calipers and/or marker grids to determine the accuracy of linear measurements along the axis of the transducer beam at 20 mm and 100 mm measured distances.

Record baseline image values determined in items 2.4 to 2.8/2.9 for comparison with values determined in subsequent inspections.

Before returning to use Ensure that all controls are set properly. Controls should be in their normal pre-use positions.


Ultrasound Scanners Scanning Surface

Figure 1. Multipurpose Phantom line target groups and corresponding scanner images (For Items 2.4 to 2.8) A. Dead Zone: Nine line targets, positioned 2 mm thru 10 mm from the scanning surface. B. Axial Resolution: Six line targets, positioned with 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm separations. C. Lateral Resolution: Six line targets, positioned with 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm separations. D. Vertical Distance: Eleven line targets, positioned with 10 mm separations. E. Horizontal Distance: Seven line targets, positioned with 10 mm separations.

Image with all line target groups displayed.

Image showing 4 mm dead zone, 1 mm axial resolution, and 3 mm lateral resolution. See Items 2.4, 2.5, and 2.6.

Image showing normal vertical-distance calibration. See Item 2.7.

Image showing normal horizontal-distance calibration. See Item 2.8.


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Inspection and Preventive Maintenance Procedures

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