PHYSIOLOGY OF RESPIRATION The process of respiration has three phases: 1. Pulmonary Pulmonary ventilat ventilation ion or the inflow inflow and and outflow outflow of air between between the the atmosphere atmosphere and the alveoli of the lungs. 2. Diffusion Diffusion of of gases gases ( oxygen oxygen and carbon carbon dioxide) dioxide) between between the the alveoli alveoli and pulmonary capillaries. 3. Transport Transport of oxygen oxygen and carbon carbon dioxide dioxide via the blood blood to and from from the tissue tissue cells. cells.
A. PULMONARY VENTILATION - Ventil Ventilati ation on of the the lungs lungs is accom accompli plishe shed d through through the the act act of breath breathing ing.. *Ventilation– refers to the movement of air in and out of the lungs. I. Respiration – refers to the interchange of oxygen and carbon dioxide between the alveoli of the lungs and pulmonary blood. a. Internal – takes place throughout the body; it is the interchange of these same gases between the circulating blood and an d the cells of the body tissue. 1. Inhalation or inspiration – refers refers to the intake of air into the lungs. 2. Exhalation or expiration – refers to breathing out or the movement of gases from the lungs to the atmosphere. *The degree of chest expansion expa nsion during ventilation is minimal with normal breathing but can reach maximum capacities during strenuous activity. *During inspiration, the rib cage is pulled upward by the action of anterior neck muscles and contraction of the external intercostals. *During expiration, the rib cage is pulled downward by the anterior abdominal muscles. II. Pulmonary volumes 1. Tidal Volume – The normal volume of air inspired and expired. Young adults – normal tidal volume is 500 ml in males, 400 ml in females. SUMMARY OF PULMONARY VOLUMES AND CAPACITIES Measurement Respiratory Volumes a. Tidal Volume
Adult male Average Value (mL)
Description
500
Amount of air inhaled or exhaled with each breath under resting resting condition.
b. Inspiratory Reserve volume
3100
c. Expiratory reserve volume
1200
d. Residual volume
1200
Respiratory Capacities 1. Total Lung capacity
6000
2. Vital capacity
4800
3. Inspiratory capacity
3600
4. Functional Residual capacity
2400
Amount of air that can be forcefully inhaled after a normal tidal volume inhalation. Amount of air that can be forcefully exhaled after a normal tidal volume exhalation. Amount of air remaining the lungs after a forced exhalation.
Maximum amount of air contained in lungs after a maximum inspiratory effort: TLC = TV + IRV + ERV + RV Maximum amount of air that can be expired after a maximum inspiratory effort: VC = TV + IRV + ERV (should be 80% TLC) Maximum amount of air that can be inspired after a normal expiration: IC = TV + IRV Volume of air remaining in the lungs after a normal tidal volume expiration FRC = ERV + RV
2. Pulmonary Pressures a.Intrapulmonic pressure – pressures within the lungs b.Intrapleural pressure – pressure outside or around the lungs *During inspiration, the volume of the lungs increases, and thus the intrapulmonic pressure decreases. This decreased allows atmospheric air to enter, since its pressure is greater. On expiration, the volume of the lungs decreases, and the intrapulmonic pressure increases. This allows the air to escape to the atmosphere, where the pressure is lower than that in the lungs. *Intrapleural pressure is always negative, this negative pressure is essential because it creates the suction that holds the visceral pleura and the parietal pleura together as the chest cage expands and contracts. The fluid in the intrapleural space provides more negative pressure, it causes the pleura to adhere together.
Ventilation of the lungs depends on four focus:
1. Adequate atmospheric pressure – it is basic to adequate respiration, concentration of oxygen are lower at high altitudes than at sea level. In some instances, people at very high attitudes need supplementary oxygen. 2. Clear air passages – air passes through the nose, pharynx, larynx, trachea, bronchi and bronchioles to the alveoli. The nose warms, moistens and filters. Air passages are cleared by the mucous membrane lining, which contains cilia. The cough reflex and sneeze reflex are essential cleaning mechanism. It is triggered by irritants that send nerve impulses through the vagus nerve to the medulla. Any foreign matter in the larynx, trachea, or bronchi initiates the cough reflex. The sneeze reflex is to the nasal passages as the cough is to lower respiratory passages. Sneezing is initiated when irritating impulses pass by way of the fifth cranial nerve to the medulla. Sneezing involves a series of reactions similar to the cough reflex. However, the uvula is depressed so that a large volume of air passes rapidly through the nose as well as the mouth, thus helping to clear nasal passages. 3. Lung recoil – The lungs have a continual tendency to collapse away from the chest wall. Two factors are responsible for this recoil tendency: a. Elastic fibers present in the lung tissue. b. Surface tension of the fluid lining the alveoli. *Surfactant – A lipoprotein mixture counterbalancing the surface tension in the alveoli. When surfactant is absent lung expansion is exceed ingly difficult and the lung collapse. 4. Regulation of respiration – Respiratory control basically functions to maintain the correct concentrations. The nervous system of the body adjusts the rate of alveolar ventilations to meet the n eeds of the body, so that Pa02 and PaC02 remain relatively constant.
B. DIFFUSION OF GASES After the alveoli are ventilated, the second phase of the respiratory process- the diffusion of oxygen from the alveoli and into the pulmonary blood vessels- begins. *Diffusion – Is the movement of gases or other particles from an area of greater pressure or concentration to an area of lower pressure or concentration.
*The alveolar walls are very thin and are surrounded by a closely intertwined network of blood capillaries, these membranes together are often referred to as the respiratory membrane. *When the pressure of oxygen is greater in the alveoli than in the blood, oxygen diffuses into the blood. 40 mm Hg is the normal gradient pressure between the alveoli and the blood. a. Partial pressure of oxygen (Pa02) – Pressure exerted by each individual gas in a mixture according to its concentration in the mixture. *Alveoli – 100 mm Hg *Venous blood – 60 mm Hg b. Partial pressure of carbon dioxide (PaC02) – Carbon dioxide entering the pulmonary capillaries has a partial pressure of about 45 mm Hg. *These partial pressures are frequently used diagnostically to assess deficiencies or excesses of oxygen and carbon dioxide in persons with pulmonary disease. C. TRANSPORT OF OXYGEN AND CARBON DIOXIDE -Oxygen needs to be transported from the lungs to the tissues, and carbon d ioxide must be transported from the tissues back to the lungs. Normally. Most of the oxygen (97%) combines loosely with the hemoglobin ( oxygen carrying red pigment) in the red blood cells and is carried to the tissues as oxyhemoglobin (The compound of oxygen and hemoglobin). The remaining oxygen is dissolved and transported in the fluid of the plasma and cells. Several factors affect the rate of oxygen transport from the lungs to the tissues: 1. Cardiac Output – Amount of blood pumped by the heart. Approx. 5 liters per min. Any pathological condition that decreases cardiac output, diminishes the amount of oxygen delivered to the tissues. 2. Number of Erythrocytes – Red Blood Cells, In men 5 million per cubic milliliter of blood; women 4.5 million per cubic milliliter. Reductions in these normal values can be brought about by anemia of any cause. 3. Exercise – Oxygen transport can be increased up to 20 times normal, due in part to an increased cardiac output and to increase utilization of oxygen by the cells. 4. Hematocrit – Excessive increase in the blood hematocrit increase the blood viscosity, the cardiac output, and therefore reduce oxygen transport. Excessive reductions in the blood hematocrit, such as occur in anemia, also reduce oxygen transport.
FACTORS AFFECTING RESPIRATORY FUNCTION 1. Development – At birth a major respiratory change occurs; the lungs which had been filled with fluid, become filled with air. Infants have a small chest and short airways. The latter predisposes to aspiration of foreign objects that can block the airways. Infants- chest is round. Adult- assumes oval shape. 2. Environment – Altitude, heat, cold and air pollution affect oxygenation. 3. Life- Style – Physical exercise or activity increases the rate and depth of respirations and the heart rate and hence the supply of oxygen in the blood. 4. Health Status – In the healthy person, the cardiovascular and respiratory systems can provide sufficient oxygen to meet the body needs. Disease of the cardiovascular system often affect the delivery of oxygen to the cells of the body. 5. Narcotics – Morphine and Meperidine hydrochloride (Demerol) decrease the rate and depth of respirations by depressing the respiratory center in the medulla.
ALTERATIONS IN RESPIRATORY FUNCTION Respiratory function can be altered by conditions that affect three areas of function: 1. The movement of air into or out of the lungs 2. The diffusion of oxygen and carbon dioxide between the alveoli and the pulmonary capillaries 3. The transport of oxygen and carbon dioxide via the blood to and from the tissue cells Three Major Alterations in respirations: 1. HYPOXIA is a condition of insufficient anywhere in the body, from the inspired gas to the tissues. a. Hypoventilation – inadequate alveolar ventilation due to decreased tidal volume. b. Hypercarbia – accumulation of carbon dioxide in the blood. c. Hypoxemia – refers to reduced oxygen in the blood and is characterized by low partial pressure of oxygen in arterial blood or a low saturation of oxyhemoglobin. d. Cyanosis – Bluish discoloration of the skin, nail beds and mucous membranes, due to reduced oxygen levels of hemoglobin.
*Adequate oxygenation is essential for cerebral functioning. The cerebral cortex can tolerate hypoxia for only 3 to 5 mins. Before permanent damage occur. The face of acutely hypoxic person usually appears anxious, tired and drawn. The person usually assumes a sitting position, often leaning forward slightly to permit greater expansion of the thoracic cavity.
2. ALTERED BREATHING PATTERN – Breathing patterns refer to the rate, volume, rhythm and relative ease or effort of respiration. a. Eupnea – Normal respiration, quiet, rhythmic, and effortless. b. Tachypnea – Rapid rate, seen with fever, metabolic acidosis and pain and with hypercapnia(elevated blood CO2) Anoxemia ( decreased oxygen in the blood). c. Bradypnea – Is an abnormally slow respiratory rate, which may be seen in clients who have taken drugs such as morphine sulfate or who have increased intracranial pressure. d. Dyspnea – Diificult or labored breathing. e. Orthopnea – inability to breathe except in an upright sitting or standing position. *Hyperventilation – Is an excessive amount of air in the lungs. It is often called alveolar hyperventilation, because the amount of air in the alveoli exceeds the body’s metabolic requirement. One particular type of hyperventilation that accompanies metabolic acidosis is Kussmaul’s Breathing, by which the body attempts to compensate by blowing off the carbon dioxide through deep and rapid breathing. *Hypoventilation – Inadequate alveolar ventilation, that is, ventilation that does not meet the body’s requirements. As a result, carbon dioxide is retained in the bloodstream. Abnormal Respiratory Rhythms: 1. Cheyne-Stokes breathing – Marked rhythmic waxing and waning of respirations from very deep to shallow breathing and temporary apnea(cessation of breathing) 2. Apneustic breathing – Prolong grasping inspiration followed by a very short, usually insufficient, expiration. 3. Biot’s breathing – Shallow breaths interrupted by apnea; may be seen in healthy people and in clients with central nervous disorder.
3. OBSTRUCTED AIRWAYS – A complete or partially obstructed airway can occur anywhere along the upper or lower respiratory passageways. Can arise because of foreign object, such as food; because the tongue falls back into the oropharynx when a person ins unconscious; or when secretions collect in the passageway. Maintaining an open (patent) airways is a frequent nursing intervention, one that requires immediate action.
*Partial Obstruction – Is indicated by a low pitched snoring sound during inhalation. *Complete Obstruction – Indicated by extreme inspiratory effort that produces no chest movement.
F. ASSESSMENT
1. ASSESSMENT INTERVIEW 1. Current health problems – Have you noticed any changes in your breathing pattern ( shortness of breath, difficulty in breathing, need to be in upright position to breathe, or rapid shallow breathing)? Which of your activities might cause the above symptoms to occur? 2. History of respiratory disease – Have you had colds, allergies, croup, asthma, tuberculosis, bronchitis, pneumonia or emphysema? ; How frequently hav e these occurred? How long did they last? And how were they treated? 3. Current or Past cardiovascular Problems – Do you have a history of cardfiac or blood circulation problems (eg. Anemia, hypertension, heart disease)? 4. Lifestyle – Do you smoke? If so how much? If not, did you smoke previously, and when did you stop? Does any of your family member smoke? 5. Presence of Cough – How often and how much do you cough? Is it productive, that is, accompanied by sputum, or non-productive, that is dry? Does the cough occur during certain activity or at certain times of the day? 6. Description of sputum – When is the sputum produced? What is the amount, color, thickness, odor? Is it ever tinged with blood? 7. Presence of Chest pain – Do you experience any pain with breathing or activity? Where is the pain located? Describe the pain. How does it feel? Does it occur when you breathe in and out? How long does it last, and how does it affect your breathing? What activities precede your pain? What do you do to relieve the pain? 8. Presence of Risk Factors – Do you have a family history of lung cancer, cardiovascular disease ( including strokes, or tuberculosis? 9. Medication history – Have you taken or do you take any over the counter or prescription medication for heart, blood pressure ore breathing (eg. Bronchodilator, inhalant, narcotic)? Which one? And what are the dosages, times taken and results, including side effects? 2. NURSING HISTORY A comprehensive nursing history relevant to oxygenation status should include data about current and past respiratory and cardiovascular problems. 3. PHYSICAL EXAMINATION In assessing a client’s oxygenation status the nurse uses all four physical examination techniques: Inspection, Palpation, Percussion, Auscultation. The nurse observes the rate, depth, rhythm and quality of respirations, noting the position the client assumes for breathing. Variations in the shape of the thorax may indicate adaptation to chronic respiratory conditions.
G. DIAGNOSTIC PROCEDURES 1. PULSE OXIMETRY – Is a non-invasive device that measures a client’s arterial blood oxygen saturation ( Sa02 or 02 sat) by means of a sensor attached to the client’s finger. The pulse oximeter can detect hypoxemia before clinical signs and symptoms, such as dusky skin color and dusky nailbeds color develop. It has two parts: a. Two light emitting diodes (LEDs) – one red the other infra-red, that transmits light throught he nails, tissue, venous blood, and arterial blood. b. A photodetector – placed directly opposite the LEDs- the photodectector receives red and infrared light, by a process called spectrophotometry. The photodetector measures the amount of red and infrared light absorbed by oxygenated and deoxygenated hemoglobin in the arterial blood. 2. SPECIMEN SPUTUM – Is the mucous secretion from the lungs, bronchi, and trachea. It is important to differentiate it from saliva, the clear liquid secreted by the salivary glands in the mouth, sometimes referred to as spit. Clients need to cough to bring sputum up from the lungs, bronchi and trachea into the mouth in order to expectorate it into the collecting container. a. Culture and sensitivity – Identify specific micro-organism and its drug sensitivity. b. Cytology – identify the origin, structure, function, and pathology of cells. Specimen for pathology require serial collection of three early morning specimens and are tested to identify cancer in the lung and its specific cell type. c. For Acid Fast Bacilli (AFB) – which also requires serial collection, often for 3 consecutive days, to identify the presence of tuberculosis, some agencies use a specific glass container when the presence of AFB is suspected. *To assess the effectiveness of therapy – The specimen are collected in the morning, upon awakening, the client can cough up the secretions that have accumulated during the night. When a client cannot cough, the nurse must sometimes use pharyngeal suctioning to obtain a specimen. To collect a sputum specimen, the nurse follows these steps: 1. Offer mouth care so that the specimen will not be contaminated with microorganisms form the mouth. 2. Ask the client to breathe deeply and then cough up 1 to 2 tablespoons or 15 to 30 ml of sputum. 3. Wear gloves to avoid direct contact with the sputum, particularly if hemoptysis (blood in the sputum) is present. 4. Ask the client to expectorate (spit out) the sputum into the specimen container. Make sure the sputum does not contact the outside of the container. 5. Following sputum collection, offer mouthwash to remove any unpleasant taste.
6. Document amount of sputum collected, color, odor, consistency (thick, tenacious, watery) and presence of hemoptysis. 3. THROAT CULTURE – sample is collected from the mucosa of the oropharynx and tonsillar regions using a culture swab. The sample is then cultured and examined for the presence of disease-producing microorganisms. To obtain a throat culture specimen, the nurse inserts the swab into the oropharynx an d runs the swab along the tonsils and areas on the pharynx that are reddened or contain exudates. 4. BLOOD SPECIMEN – Specimens of venous blood are taken for a complete blood count (CBC) which includes hemoglobin and hematocrit measurements; erythrocyte (RBC) count. Leukocyte (WBC) count, and a differential red cell and white cell count. a. Hematocrit – Is the packed cell volume, it denotes the percentage of a given volume of whole blood occupied by erythrocytes. Therefore, a hematocrit level of 25% indicates that erythrocytes make up 25% of the total volume of whole blood. b. Erythrocytes count – shows the number of red blood cells in 1uL or 1 mm of whole blood. c. White blood cells count – determines the number of circulating leukocytes ( white blood cells) in 1 uL of whole blood. Above- normal WBC indicates presence of pathogens in the body. Dereased WBC indicates presence of viruses or toxic chemicals in the body. d. Differential Leukocyte and erythrocyte counts – enumerate the different kinds of white and red blood cells in the blood specimen. A number of white blood cells are identified and classified according to their morphology( form and structure). 4. PULMONARY FUNCTION TEST- Determine the ability of the lungs to efficiently exchange oxygen and carbon dioxide. Basic ventilation studies are performed with a spirometer and recording device as the client breathes through a mouthpiece into a connecting tube. Usually performed in a pulmonary function laboratory. 5. VISUALIZATION PROCEDURES – Chest x-ray examination, bronchoscopy, and lungs cans are used to visualize structures of the respiratory system.
