Respiratory distress syndrome

Q: What is the primary pathophysiological abnormality underlying neonatal respiratory distress syndrome (hyaline membrane disease)?

Neonatal respiratory distress syndrome (hyaline membrane disease) is caused by primary deficiency of pulmonary surfactant in immature lungs. Without surfactant to lower alveolar surface tension, alveoli collapse at end-expiration (atelectasis), reducing functional residual capacity and lung compliance.

Q: What is the approximate incidence of neonatal respiratory distress syndrome in extremely preterm infants born before 28 weeks of gestation compared with those born between 28 and 32 weeks?

The incidence of neonatal respiratory distress syndrome is inversely proportional to gestational age: it affects approximately 60% to 80% of neonates born before 28 weeks of gestation, 15% to 30% of those born between 28 and 32 weeks, and is rare at term unless predisposing risk factors are present.

Q: During fetal lung development, what are the five sequential anatomical stages, and when do type two pneumocytes begin producing surfactant versus achieving adequate levels?

Fetal lung maturation progresses through the embryonic (3–7 weeks, basic lung bud), pseudoglandular (7–17 weeks, no gas exchange), canalicular (17–26 weeks, vascularization begins), saccular (26–36 weeks, primitive alveoli), and alveolar (>36 weeks, mature alveoli) stages. Type two pneumocytes begin producing surfactant around 24 to 28 weeks, reaching adequate levels around 34 weeks.

Q: What is the main phospholipid component of pulmonary surfactant, and how does it prevent alveolar collapse?

Pulmonary surfactant consists primarily of dipalmitoylphosphatidylcholine (lecithin) along with surfactant proteins A, B, C, and D. By reducing surface tension at the air-liquid interface according to Laplace's law, surfactant prevents end-expiratory alveolar collapse (atelectasis), improves lung compliance, and reduces the work of breathing.

Q: Which triad of chest radiograph findings is classic for neonatal respiratory distress syndrome?

On chest radiography, widespread microatelectasis surrounding air-filled larger airways produces the classic triad of neonatal respiratory distress syndrome: a diffuse ground-glass appearance, prominent air bronchograms, and low lung volumes.

Neonatal respiratory distress syndrome, also known as hyaline membrane disease, is an acute respiratory failure in preterm newborns caused by pulmonary...

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Neonatal respiratory distress syndrome, also known as hyaline membrane disease, is an acute respiratory failure in preterm newborns caused by pulmonary surfactant deficiency and structural lung immaturity. High alveolar surface tension leads to progressive alveolar collapse, decreased lung compliance, impaired gas exchange, hypoxemia, and respiratory acidosis within the first hours of life. Understanding fetal lung development stages, antenatal corticosteroid prevention, early continuous positive airway pressure, and exogenous surfactant administration is fundamental for pediatrics and neonatology examinations.

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1.What is the primary pathophysiological abnormality underlying neonatal respiratory distress syndrome (hyaline membrane disease)?

2.What is the approximate incidence of neonatal respiratory distress syndrome in extremely preterm infants born before 28 weeks of gestation compared with those born between 28 and 32 weeks?

3.During fetal lung development, what are the five sequential anatomical stages, and when do type two pneumocytes begin producing surfactant versus achieving adequate levels?

4.What is the main phospholipid component of pulmonary surfactant, and how does it prevent alveolar collapse?

5.Which triad of chest radiograph findings is classic for neonatal respiratory distress syndrome?

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