Clinical meaning
Bronchopulmonary dysplasia (BPD) results from arrested lung development in premature infants exposed to supplemental oxygen and mechanical ventilation during the critical period of alveolarization (24-36 weeks gestation). Oxygen-derived free radicals and barotrauma/volutrauma damage the immature alveolar epithelium and inhibit secondary septation, resulting in fewer, larger alveoli with decreased surface area for gas exchange. Pulmonary vascular remodeling causes thickened vessel walls, reduced vascular bed density, and pulmonary hypertension. Chronic inflammation with fibrosis further impairs lung compliance and gas exchange.
Exam relevance
Risk factors: - Prematurity (< 28 weeks gestation, highest risk) - Very low birth weight (< 1500 g) - Prolonged mechanical ventilation - High FiO2 exposure - Chorioamnionitis or postnatal sepsis - Patent ductus arteriosus requiring treatment - Intrauterine growth restriction - Male sex
Diagnostics: - Chest X-ray showing diffuse haziness, hyperinflation, or cystic changes - Continued oxygen requirement at 36 weeks corrected gestational age (diagnostic criterion) - Echocardiography to assess for pulmonary hypertension - Serial pulmonary function testing (in older children) - ABG or capillary blood gas showing chronic respiratory acidosis - Growth chart monitoring for failure to thrive