Observe the respiratory rate while the infant is undisturbed. At several hours after birth, the rate may vary from 20 to 80 breaths per minute, with an average of 30 to 40. Because of the wide variation, respirations should be counted for 1 to 2 minutes.
Inspect the respiratory pattern. The breathing pattern of newborns is almost entirely diaphragmatic. Irregular, shallow respirations are common in newborns. Periodic breathing is characterized by periods of apnea lasting 5 to 15 seconds and is not associated with bradycar-dia. True apnea has a duration of more than 20 seconds and is associated with bradycardia. The latter is more commonly found in premature infants with pulmonary disease. Infants with true apnea are thought to be at higher risk for sudden infant death syndrome (SIDS). The presence of an expiratory grunt, retractions of the chest, or flaring of the nostrils is indicative of respiratory distress.
Inspect for deformities. The most important chest deformity in newborns is asymmetry owing to unequal chest expansion on one side. Other deformities seen in adults, such as pectus excavatum and pectus carinatum, are rarely seen in newborns.
Auscultate the chest with either the bell or the small diaphragm of the stethoscope. Bronchovesicular breath sounds should be easily heard throughout the lung fields and are higher in pitch than those in adults. Absence of breath sounds on one side may be indicative of pneumothorax or a diaphragmatic hernia. Pneumothorax is relatively common in newborns as a result of the large transpulmonary pressures involved in inflating the lungs for the first time.
If respiratory distress is present, percuss the chest by using either one finger to tap the chest or using the method discussed for adults (see Chapter 13, The Chest). Normally, the thorax of a newborn is hyperresonant throughout. Dullness may indicate an effusion or consolidation.
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