A 32-week gestation male infant born to a mother with inadequate antenatal care presents with grunting, nasal flaring, and intercostal retractions within 2 hours of birth. Chest X-ray shows a ground-glass appearance with air bronchograms. What is the most common cause of respiratory distress in this preterm infant?
A. Pneumonia
B. Surfactant deficiency
C. Meconium aspiration syndrome
D. Transient tachypnea of the newborn
Explanation
Most Common Cause of RDS in Preterm Infants
Key Point
Surfactant deficiency (Respiratory Distress Syndrome or Hyaline Membrane Disease) is the most common cause of respiratory distress in preterm infants, particularly those <34 weeks gestation.
Pathophysiology
Surfactant is a lipoprotein complex synthesized by type II pneumocytes. It reduces alveolar surface tension and prevents alveolar collapse during expiration.
Surfactant production begins: ~24 weeks gestation
Adequate levels achieved: ~35 weeks gestation
Deficiency leads to: Atelectasis → increased work of breathing → respiratory failure
Clinical Features of RDS
Table
Feature
Timing
Presentation
Onset
Within 2–4 hours of birth
Immediate respiratory distress
Signs
Grunting, flaring, retractions
Progressive over first 24–48 hours
CXR
Ground-glass appearance
Air bronchograms, white-out in severe cases
Risk factors
Prematurity, maternal diabetes, C-section without labor
Perinatal asphyxia
High-Yield Risk Factors
Mnemonic: CRIB-SURF (risk factors for surfactant deficiency)
Cesarean delivery without labor
Recent maternal diabetes
Intrauterine growth restriction (IUGR)
Brief gestation (<34 weeks)
Second-born twin
Uremia in mother
Rhesus incompatibility
Female infant (paradoxically, males have delayed lung maturity)
Supportive: CPAP or mechanical ventilation, oxygen therapy
Clinical Pearl
The ground-glass appearance on chest X-ray is pathognomonic for RDS and reflects widespread atelectasis with patent airways (air bronchograms visible).
High-YieldNEET PG
Surfactant replacement therapy has dramatically reduced mortality in preterm infants. Early administration (within 1–2 hours of birth) is associated with better outcomes.
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