Respiratory distress syndrome
Also called hyaline membrane disease and infant respiratory distress syndrome, respiratory distress syndrome is the most common cause of neonatal mortality.
Respiratory distress syndrome affects 10% of premature infants while rarely affecting infants born at full term. It’s more common in neonates of diabetic mothers and in neonates born with acidosis, such as those delivered under stressful conditions—for example, by cesarean section or suddenly after antepartum hemorrhage.
Aggressive management using mechanical ventilation improves prognosis.
Although the airways and alveoli of a neonate’s respiratory system are present by the 27th week of gestation, the intercostal muscles are weak and the alveoli and capillary blood supply are immature. In respiratory distress syndrome, the premature neonate develops widespread alveolar collapse because of lack of surfactant, a lipoprotein present in alveoli and respiratory bronchioles.
Surfactant normally lowers surface tension and aids in maintaining alveolar patency, preventing collapse, particularly at end expiration. But a deficiency results in widespread atelectasis, which leads to inadequate alveolar ventilation with shunting of blood through collapsed areas of lung, causing hypoxia and acidosis.
Signs and symptoms
Although a neonate with respiratory distress syndrome may breathe normally at first, he usually develops rapid, shallow respirations within minutes or hours of birth, with intercostal, subcostal, or sternal retractions; nasal flaring; and audible expiratory grunting. This grunting is a natural compensatory mechanism designed to produce positive end-expiratory pressure (PEEP) and prevent further alveolar collapse.