Newborn With Respiratory Distress

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Case 7 Newborn with respiratory distress - Adam Author: Maxine Author: Maxine Clarke, M.B., B.S., FRCP (C) Queen's University.

Learning Objectives 1. Obtain a neonatal history using appropriate sources: Hospital chart, mother, nursing staff. 2. Complete the physical examination of the newborn, including using the growth chart to assess gestational age. 3. Recognize the symptoms of respiratory distress. 4. Develop a differential diagnosis di agnosis for neonatal respiratory distress. 5. Determine appropriate investigations to evaluate neonatal respiratory distress. 6. Recognize the effects of maternal diabetes on the neonate. 7. Identify and manage neonatal hypoglycemia. 8. Recognize the factors that determine the neonate's readiness for discharge from the hospital. Summary of clinical scenario: scenario : 34-week-gestation premature infant, Adam, delivered via Caesarean section with no meconium and no premature rupture of membrane (PROM) from a diabetic mother with fair glucose control and unknown Group B strep status presents with respiratory distress. Apgar scores at delivery were 8 at 1 minute and 9 at 5 minutes. On physical exam, the newborn is found to be large for gestational age (LGA), tachypneic, with no heart murmur, good perfusion, and equal breath sounds. After considering the differential diagnosis for this patient’s respiratory distress, a chest X-ray was obtained. The X-ray demonstrates “wet”-looking lungs, no consolidation, and no air bronchograms, consistent with transient tachypnea of the newborn. As the infant of a diabetic mother, Adam is also found to be hypoglycemic. Since his tachypnea hampers his ability to breastfeed, Adam is given breast milk and formula through a feeding tube. His respiratory symptoms and hypoglycemia subsequently stabilize within 36 hours.

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Tachypnea Infant of diabetic mother

Key Findings from History

34-week gestation No meconium C-section No PROM

LGA

Key Findings from Physical Exam

Respiratory distress No heart murmur Good perfusion Equal breath sounds

Respiratory distress syndrome Transient tachypnea of the newborn

Differential Diagnosis

Sepsis/pneumonia Pneumothorax Congestive heart failure Hypothermia

Key Findings from Testing

Final Diagnosis

Glucose: 34 mg/dL Chest X-ray: Significant perihilar streaking and fluid in pleural space

Transient tachypnea of the newborn

Case highlights: This case focuses on the evaluation of neonatal respiratory distress. Students work through an appropriate differential diagnosis, see examples of respiratory distress and important components of the neonatal examination, including examination of the hips to detect developmental dysplasia of the hips (DDH). Additionally, students review Apgar scores and assess intrauterine growth and gestational age. Students also explore common problems with LGA infants, transitional issues, and breastfeeding. Multimedia features include: Video of an infant in respiratory distress; video explaining how to perform an infant’s hip exam; and chest X-ray with perihilar streaking and fluid in the pleural space.

Key Teaching Points Knowledge Transition from intrauterine to extrauterine life:

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Intrauterine oxygenation Oxygenated blood from placenta is transported to the fetus by the umbilical vein A portion of the oxygenated blood perfuses the liver Remainder bypasses the liver through the ductus venosus and enters the inferior vena cava: One-third of this vena caval blood crosses through the patent foramen ovale (PFO) to the left atrium and is pumped to the coronary, cerebral, and upper body circulations. The remaining two-thirds combines with venous blood from the upper body in the right atrium, and is directed to the right ventricle and out the pulmonary artery. Vasoconstriction of the pulmonary arterioles produces high pulmonary vascular resistance, allowing only 8–10% of the blood from the right ventricle to flow through the pulmonary vasculature. The remaining 90–92% is shunted through the patent ductus arteriosus (PDA) to the descending aorta. Extrauterine oxygenation: Oxygenation changes dramatically at birth from a passive, placenta-provided source to an active respiration-based process. Successful transition at birth involves: Removal of low-resistance placental circulation by cutting the umbilical cord Initiation of air-breathing At delivery, infant’s first breath results in replacement of fluid in lung with air. Fluid is squeezed out of lungs during uterine contractions with vaginal delivery and absorbed by pulmonary lymphatics Delayed absorption can lead to transient tachypnea of the newborn (TTN). Reduction of the pulmonary arterial resistance Closure of the PFO and PDA Infant of a diabetic mother (IDM): Control of diabetes during pregnancy is an important predictor of fetal outcome, especially with regard to the risk of birth defects: Incidence of major malformations is directly related to the hemoglobin A1c level in the first trimester. Infants born to women with A1c levels >12 have at least a 12-fold increase in major malformations. An IDM is also at risk of being LGA: High levels of maternal serum glucose stimulate the fetal pancreatic beta cells and the development of hyperinsulinemia. Insulin is the primary anabolic hormone for fetal growth.

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High levels in the third trimester result in increased growth of the insulinsensitive organ systems (heart, liver and muscle) and a general increase in fat synthesis and deposition. This combination of increased body fat, muscle mass, and organomegaly produces a macrosomic (LGA) infant. Insulin-insensitive organs, such as the brain and kidneys, are not affected by the elevated insulin levels and have appropriate size for gestational age. Risk factors for neonatal respiratory distress: Infection Prematurity Delivery by Caesarean section (C-section) Maternal diabetes Maternal drug exposure Prematurity PROM (rupture of membranes ! 18 hours prior to delivery) Meconium in amniotic fluid Cyanosis in the newborn: Important to first distinguish cyanosisfrom acrocyanosis (see physical exam below). Etiologies Respiratory : TTN RDS Pneumothorax Diaphragmatic hernia Choanal atresia Pulmonary hypoplasia Cyanotic congenital cardiac defects: Tetralogy of Fallot Transposition of the great arteries Truncus arteriosus Tricuspid atresia Total anomalous pulmonary venous return Pulmonary atresia Central nervous system abnormalities: Hypoxic-ischemic encephalopathy Intraventricular hemorrhage Sepsis/meningitis Other :

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Infectious Respiratory depression secondary to maternal medications Hypothermia Polycythemia/hyperviscosity syndrome Developmental dysplasia of the hip (DDH): Dislocation of the hips is not always detectable at birth. To decrease number of dislocated hips detected later i n infancy, the American Academy of Pediatrics has developed a Clinical Practice Guideline for primary care providers. The main components are recognition of risk factors and regular hip examinations to age 18 months. Clinical features Partial or complete dislocation or instability of the femoral head Risk factors Breech position: 30–50% occur in infants born in breech position Gender: 9:1 female predominance Family history Reference: American Academy of Pediatrics Clinical Practice Guidelines: Pediatrics 2000; 105(4): 896.

Skills Physical exam: Examine neonate immediately after birth to determine general condition of cardiorespiratory, neurologic, and gastrointestinal systems and to detect congenital abnormalities. Apgar score: A method of describing the condition of the newborn immediately after birth. Scores are assigned at 1 and 5 minutes of life, with 0 to 10 total points possible:

Sign

Score=0

Score=1

Score=2

Heart rate

Absent

Below 100

Above 100

Respiratory effort

Absent

Weak, irregular, or gasping

Good, crying

Some flexion of extremities

Well flexed, or active movements of extremities

Muscle tone

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Flaccid

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Reflex irritability

No response

Good cry or Grimace or weak active cry withdrawal

Color

Blue all over, or pale

Body pink, extremities blue

Pink all over

Scoring provides a mechanism to record fetal-to-neonatal transition When properly applied, the Apgar score is a tool for standardized assessment. The Apgar score alone correlates poorly with the future neurological outcome of the term infant because it is affected by gestational age, maternal medications, resuscitation, and cardiorespiratory and neurologic conditions. (Poor neurologic outcome is better associated with documented asphyxia.) Reference: Joint Policy Statement on The Apgar Score of the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. Pediatrics. 2006Volume 117(4):1444-1447. Vital signs Most accurate when obtained when infant is quiet and at rest. If infant is crying, heart rate (HR) and the respiratory rate (RR) may be falsely elevated. In the first hour of life, respiratory and heart rates (RR and HR) are often elevated: HR: 160–180 beats per minute (bpm) RR: 60–80 breaths per minute (bpm) With successful transition, HR will decrease to 120–160 bpm and RR to 40–60 bpm by two hours of life. Signs of neonatal respiratory distress: Tachypnea (>60 breaths/min) Use of accessory muscles for respiration (nasal flaring, intercostals retractions, grunting) Hypoxia, hypercapnia Acrocyanosis Bluish discoloration of hands and feet Commonly seen in the first few hours following birth May recur through early infancy when the baby is cold. After 4–5 hours, cyanosis is usually less marked in hands than feet. If acrocyanosis is not resolved within 8 hours or with warming, may be sign of cyanotic congenital heart disease.

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Classification of newborn by weight and gestational age: Weight is a good indicator of the intrauterine environment.Plotting weight against gestational age helps identify infants with abnormal growth and allows the anticipation of potential problems associated with each group: LGA (large for gestational age): > 90th percentile Most important pathologic etiology is maternal diabetes mellitus Potential clinical problems: Delivery by C-section, forceps, or vacuum extraction Birth injuries (clavicular fracture, brachial plexus injury, facial nerve palsy) Hypoglycemia AGA (appropriate for gestational age): 10th to 90th percentile SGA (small for gestational age): <10th percentile Also called intrauterine growth restricted (IUGR) An infant with low birth weight may be premature, but low birth weight may also result from many other causes. Potential clinical problems: Temperature instability (hypothermia) Hypoglycemia (due to inadequate glycogen stores) &Polycythemia and hyperviscosity Gestational age assessment: Gestational age and its relationship to birth weight are important in identifying infants with abnormal fetal growth patterns. The first system for evaluating gestational age was developed by Dubowitz in 1970: Detailed scoring system based on infant's external physical characteristics and neurologic findings Requires that infant be alert and active Results often skewed in very immature or sick infants due to low neurologic scores The Ballard assessment, a method developed in 1979 and now more widely used, is a shortened version of the Dubowitz exam: Standardized score based on specific neuromuscular signs and physical characteristics Should be performed on every neonate Most accurate when obtained at 12–24 hours of life Hip exam: Assess every newborn for developmental dysplasia of the hip (DDH): 1. 2. 3. 4.

Remove diaper so does not constrict movement. Do one side at a time. Stabilize pelvis with one hand. Bend infant’s leg and place fingers of hand on greater trochanter, thumb on inside of femur. 5. Perform Barlow maneuver: Movement with leg in adduction

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Push back to feel if femur head is in the joint or dislocating in and out. 6. Perform Ortolani maneuver: Movement with leg in abduction Push out with fingers on greater trochanter to see if clunk is felt (clunk indicates relocation from dislocated position). 7. Repeat on other side.

Differential diagnosis More likely diagnoses 1. Respiratory distress syndrome (RDS): Previously known as "hyaline membrane disease," RDS is caused by a deficiency in lung surfactant. Most common cause of respiratory distress in premature infants. Additional risk factors include: IDM (due to delayed lung maturation) Sibling with history of RDS Male C-section delivery without labor Perinatal asphyxia A chest X-ray can help distinguish between TTN and RDS. 2. Transient tachypnea of the newborn (TTN): Delayed clearance of lung fluid after birth causing early onset mild respiratory distress. This is a benign, self-limited disease related to newborn transition. No evidence that TTN predisposes to long-term pulmonary dysfunction. Generally considered a disorder of term infants, but can occur in premature infants. TTN risk factors: C-section delivery Male Macrosomic IDM A chest X-ray can help distinguish between TTN and RDS. 3. Congestive heart failure (CHF): Important cause of tachypnea. Most often caused by a congenital heart defect. There is an increased risk of heart defect in IDMs, and therefore increased risk of CHF. Usually presents with heart murmur. 4. Sepsis/pneumonia: Early signs of neonatal sepsis are subtle and nonspecific and may include symptoms such as poor feeding, lethargy, or irritability. May alsopresent initially with tachypnea and progress to more severe illness rapidly. Risk factors include: PROM GroupB streptococcal infection transmitted from the mother during labor

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5. Hypoglycemia: May be seen in IDMs due to the chronic hyperinsulinemic state that occurred during gestation. May be more pronounced in premature infants. Tachypnea is a non-specific response to this metabolic derangement. Less likely diagnoses: Congenital diaphragmatic hernia: A congenital malformation resulting from a defect in the development of the diaphragm. Occurs in 1 out of every 2,200 to 5,000 live births Most common type is the Bochdalek hernia (posterolateral hernia), which accounts for majority (> 95%) of cases: Allows passage of abdominal organs into chest cavity and severely impairs lung development. Most defects occur on the left side. Absent breath sounds or presence of bowel sounds on one side of the chest are important diagnostic clues. Pneumothorax: Caused by a collection of gas in the pleural space with resultant collapse of lung tissue. Common risk factors: Mechanical ventilation Underlying lung disease (especially meconium aspiration or severe infant RDS) Absence of breath sounds on one side of the chest in combination with respiratory distress is an important diagnostic clue. Meconium aspiration syndrome: Passage of meconium in utero may indicate fetal stress and hypoxia. Aspiration of meconium may occur in utero with fetal gasping, or at first breath at delivery. Often presents with symptoms of respiratory distress, including tachypnea. Transposition of the great arteries (TGA): Congenital heart defect in which the aorta and pulmonary arteries are transposed, resulting in respiratory distress and severe cyanosis shortly after birth as PDA closes. IDM is a risk factor. Often associated with other congenital heart defects such as a VSD. Murmur may be heard on physical examination. Hypothermia: Should be considered in the differential of a tachypneic newborn. May be associated with neonatal sepsis. Small for gestational age and premature infants are more at risk to become hypothermic because of their small body size and relatively large surface area. Severe coarctation of the aorta: May cause respiratory distress if there is severe left ventricular outflow tract obstruction. Classically, diminished pulses in the lower extremities or asymmetric blood pressure readings suggest the diagnosis. In severely ill neonates, there may be no differences in the pulses because cardiac output is so poor.

Studies Complete blood count (CBC) with differential:

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Usefulto rule out neutropenia, leukopenia, abnormal immature-to-totalneutrophil ratio, and thrombocytopenia as signs of sepsis maybe underlying respiratory distress Blood and CSF cultures: Critical in the diagnosis and management of neonatal sepsis. Arterial blood gas (ABG): ABG helpful in determining the oxygenation (PaO2), ventilation (PaCO2),and acid-base status (pH and HCO3) of the infant. If infant is cyanotic, knowing pCO2 helps elucidate the cause. If respiratory distress is mild, the infant pink in color, and the infant is not otherwise at risk, blood gas determination is not essential. Pulse oximetry: Detects oxygen saturation of the blood. Oxygen challenge test (hyperoxia test): Can help differentiate between cardiac and pulmonary etiology in cyanotic infants Oxygen will increase the PaO2 of i nfant whose cyanosis is caused by a respiratory condition, but not significantly increase PaO2 if cyanosis is caused by a cardiac lesion. Chest X-ray: Integral part of initial assessment of the newborn with respiratory distress Size and shape of heart may yield some clues to the diagnosis Appearance of lungs may suggest pneumonia, meconium aspiration, RDS, etc. Normal inspiratory films should have eight or more intercostal spaces of lung fields on both sides. Findings typical of TTN include: Significant perihilar streaking due to interstitial fluid and engorged lymphatics Coarse, fluffy densities that represent fluid-filled alveoli Fluid in the pleural space and fissures Findings typical of RDS include: Air bronchograms Diffuse reticulogranular appearance of lung fields ("ground-glass appearance") Findings in infant with diaphragmatic hernia include: Air-filled loops of bowel in left side of chest Displacement ofheart and mediastinum to contralateral side Echocardiogram:

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Gold standard in diagnosis of congenital cardiac lesions and persistent pulmonary hypertension of the newborn Indicated when there is persistent cyanosis and no indication of lung disease, or when there are other signs suggesting a heart defect, such as a murmur, abnormal electrocardiogram (ECG), or chest X-ray showing abnormal cardiac contour Glucometer test: The glucometer test is a screening test only, and must not be used to confirm hypoglycemia. Confirm glucometer reading with serum or plasma glucose level. If low, start treatment immediately; do not delay until laboratory results are available.

Management Transient tachypnea of the newborn (TTN): Monitor to ensure signs of respiratory distress—including tachypnea —resolve. If respiratory symptoms do not improve, suspect pneumonia. Order a repeat chest X-ray and start antibiotics. Feeding and respiratory distress: Recommendations vary, depending on physician’s experience or the policy of the neonatal unit. No evidence from controlled studies that feeding a tachypneic infant by mouth is contraindicated (although many physicians are reluctant to try this because they feel that oral feedings place the infant under greater stress) Some infants may need nasogastric feeding or IV fluids if respiratory distress worsens with feeding Infants with respiratory rates of > 80 per minute will have difficulty with both oral and nasogastric feedings and often require intravenous fluid support. Use of a nasogastric feeding tube avoids use of a bottle (after feeding from a bottle, some babies may get frustrated when they breastfeed because the milk does not flow as fast from the breast as from a bottle). Hypoglycemia: Glucose is the primary substrate for brain metabolism in the neonate, and even asymptomatic hypoglycemia may have negative consequences for long-term neurodevelopment: Goal: Maintain glucose levels between 41–50 mg/dL. Threshold values for initial intervention: Asymptomatic infants and infants at risk for hypoglycemia: < 35 mg/dL Symptomatic infants: < 45 mg/dL

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Milk feeding (formula or breast) raises glucose levels, maintains stable levels, and avoids rebound hypoglycemia that is associated with glucose water. Monitor glucose levels until levels are stable (> 40 mg/dL). If the blood glucose is not > 40 mg/dL with the first enteral feeding, initiate IV dextrose infusions. Frequency of monitoring depends on severity of the hypoglycemia; may range from every 30 minutes to every 3 hours prior to feeds. Prematurity: Before discharge, establish breastfeeding and self-maintenance of body temperature. Confirm: Physical examination without major defects Minimal or no jaundice No blood group incompatibility Breastfeeding well every two to four hours Six or more wet diapers daily Transition from meconium to seedy, soft, tan-yellow stools Weight loss < 10% Car seat available Good support for mother at home Back-to-sleep program reviewed Prescription for Vitamin D completed (for exclusively breastfeeding infants, recommended 200 IU of vitamin D daily) Follow-up visit arranged identified primary care physician Risks of co-bedding (with parent or other children) reviewed: Infant may be brought into bed for nursing or comforting but should be returned to their own bassinet or crib when parent is ready to return to sleep Infant should not be brought into bed when parent is excessively tired or using medications or substances that could impair his or her alertness. Back to Top Copyright © 2011 iInTIME. All Rights Reserved.

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Newborn With Respiratory Distress

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