Surfactant Deficiency in Preemies: Cause of Respiratory Distress Syndrome (RDS)

Pulmonary surfactant is a lipoprotein complex (90% lipids, 10% proteins) secreted by type II alveolar cells. It coats alveoli, lowering surface tension to prevent collapse at end-expiration.

Why Preemies Lack Surfactant

Surfactant production begins ~24 weeks but reaches adequate levels only after 34–36 weeks. Infants born <34 weeks often have insufficient surfactant → alveolar collapse (atelectasis) → ventilation-perfusion mismatch → hypoxemia → Respiratory Distress Syndrome (RDS).

Clinical Presentation

• Tachypnea, grunting, nasal flaring, retractions within minutes-hours of birth
• Chest X-ray: diffuse "ground-glass" reticulogranular pattern, air bronchograms

Management

• Antenatal corticosteroids (betamethasone) at 24–34 weeks accelerate lung maturity.
• Exogenous surfactant (beractant, poractant alfa, calfactant) via endotracheal tube—lifesaving, reduces mortality 40%.
• CPAP/mechanical ventilation for respiratory support.

Outcomes

With modern NICU care, survival >90% for infants >28 weeks. Long-term risk: bronchopulmonary dysplasia (BPD) if prolonged oxygen/ventilation needed.