Which statement best describes the pathophysiology of RDS in premature infants?

• A. Surfactant deficiency causing alveolar collapse.
• B. Delayed clearance of fetal lung fluid.
• C. Viral infection of the lungs.
• D. Pneumonia.

Answer: (A)

Surfactant deficiency in premature infants leads to high surface tension in the alveoli, so they tend to collapse at the end of expiration. This collapse lowers lung volume and markedly reduces lung compliance, causing widespread atelectasis, V/Q mismatch, and severe hypoxemia—classic features of respiratory distress syndrome in preemies. Surfactant normally reduces surface tension and helps keep alveoli open; when it’s lacking, the lungs become stiff and difficult to inflate, requiring respiratory support and often exogenous surfactant therapy. The chest X-ray typically shows a diffuse granular or “ground-glass” pattern with air bronchograms, reflecting widespread atelectasis and edema.

While delayed clearance of fetal lung fluid can cause respiratory distress in newborns, and infections like viral pneumonia can cause breathing problems, these are not the primary pathophysiologic mechanism for RDS in premature infants.