Review Question - QID 216481

This premature infant who was born to a mother with type 2 diabetes mellitus and presents with grunting, retractions, hypoxemia, and a "ground-glass" appearance on chest radiograph most likely has neonatal respiratory distress syndrome. This disease is caused by a deficiency of surfactant production from type 2 pneumocytes.

Neonatal respiratory distress syndrome (also known as hyaline membrane disease) is caused by a deficiency of surfactant production in immature fetal lungs. Surfactant is normally produced by type 2 pneumocytes; however, these cells mature relatively late during fetal development, so surfactant production is insufficient before 34 weeks of development. The reduced level of surfactant results in low lung compliance and subsequent atelectasis, intrapulmonary shunting, and acute lung injury. The pathophysiology of this disease should be differentiated from transient tachypnea of the newborn, which is caused by temporarily retained lung fluid.

Zhong et al. discuss the pathophysiology and treatment of neonatal respiratory distress syndrome. They find that administration of pulmonary surfactant leads to a significantly decreased incidence of bronchopulmonary dysplasia.

Figure/Illustration A shows a chest radiograph of a newborn with diffuse opacities of both lungs (yellow circles). This "ground-glass" appearance is classically seen in patients with neonatal respiratory distress syndrome.

Incorrect Answers:
Answer 1: Bacterial infection caused by group B streptococci can result in pneumonia during the neonatal period. These patients will present with fever, tachycardia, and decompensation of respiratory function. A radiograph will reveal focal consolidation.

Answer 2: Type 1 pneumocytes are thin epithelial cells that line the alveolar basement membrane. These cells may also be relatively immature in premature infants; however, the primary pathophysiology in this patient is caused by deficient surfactant production by type 2 pneumocytes.

Answer 4: Retention of lung fluid is responsible for transient tachypnea of the newborn (TTN), which can be distinguished from neonatal respiratory distress syndrome by chest radiograph. Findings consistent with TTN include hyperinflation, prominent perihilar vascular markings, edema of interlobar septae, and fluid in the fissures.

Answer 5: Viral infection with respiratory syncytial virus can cause severe respiratory distress in premature newborn infants. These patients may have a similar appearance on radiography, but this disease will present after birth with acute decompensation of respiratory function. Infants will typically present with coughing and wheezing progressing to difficulty breathing. Symptoms generally last 7-21 days. Bronchiolitis is a lower respiratory tract infection characterized by inflammation and obstruction of the small airways in the lungs, and RSV accounts for 70% of bronchiolitis cases.

Bullet Summary:
Neonatal respiratory distress syndrome is caused by a deficiency of surfactant production from type 2 pneumocytes in premature infants.