A preterm neonate of 28 weeks gestation develops progressive respiratory distress within 2 hours of birth. Chest X-ray shows bilateral ground-glass opacity with air bronchograms and low lung volumes. The PRIMARY pathophysiological defect is:

• A Aspiration of meconium causing airway plugging
• B Increased pulmonary vasculature flow causing pulmonary edema
• C Pneumothorax due to high ventilatory pressures
• D Surfactant deficiency causing alveolar collapse ✓

Explanation

Respiratory distress syndrome (RDS, also called hyaline membrane disease) in preterm neonates is caused by insufficient surfactant production by type II pneumocytes. Surfactant deficiency reduces alveolar surface tension, leading to alveolar collapse at end-expiration (atelectasis), ventilation-perfusion mismatch, hypoxia, and the characteristic ground-glass opacity with air bronchograms on chest X-ray. Treatment is exogenous surfactant instillation (poractant alfa or beractant) plus CPAP or mechanical ventilation.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.