The probability of survival of an infant with pulmonary hypoplasia is dependent on:

• A. Degree to which lung growth is restricted
• B. Availability of ECMO
• C. Availability of high-frequency ventilation
• D. Gestational age at birth

Answer: (A)

The likelihood of survival in pulmonary hypoplasia is driven by how severely the lung growth is restricted. When the lungs are underdeveloped, there is less surface area for gas exchange, fewer alveoli, a smaller and less developed vascular bed, and reduced lung compliance. This makes it hard to achieve adequate oxygenation and ventilation, and it increases the risk of persistent pulmonary hypertension. Those structural limitations set the upper bound of what any support can achieve.

Therefore, the extent of restriction in lung development is the strongest predictor of outcome. Treatments like ECMO or high-frequency ventilation can help support breathing and oxygenation, but they cannot overcome the fundamental deficit of lung tissue. Gestational age at birth matters for overall neonatal respiratory maturity, but it does not determine survival as directly as the degree of pulmonary hypoplasia.