A 28-week preterm neonate develops increasing respiratory distress, grunting, and intercostal retractions within 4 hours of birth. Chest X-ray shows a ground-glass appearance with air bronchograms. Arterial blood gas reveals PaO2 of 45 mmHg on FiO2 of 0.4. What is the primary pathophysiological defect in this condition?
- A Absence of ciliary motility in bronchial epithelium
- B Deficiency of surfactant leading to alveolar collapse ✓
- C Meconium aspiration causing small airway obstruction
- D Pulmonary arteriovenous malformation
Correct answer: B. Deficiency of surfactant leading to alveolar collapse
Explanation
Respiratory distress syndrome (RDS) in preterm neonates is caused by surfactant deficiency; surfactant is produced by type II pneumocytes and is adequate only after approximately 34-35 weeks gestation. Without surfactant, surface tension in alveoli is very high, leading to diffuse microatelectasis. The classic chest X-ray findings are a reticulogranular (ground-glass) pattern with air bronchograms. Treatment includes antenatal corticosteroids, exogenous surfactant instillation, and respiratory support.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.