Pneumothorax as a function of gestational age: Clinical and experimental studies.

Infants with respiratory distress syndrome are especially prone to pneumothorax and pneumomediastinum as a complication of their disease. In a retrospective clinical analysis of a consecutively delivered population of infants with RDS the data suggested that the less premature infant with RDS was apparently more at risk to develop pulmonary rupture. This clinical observation was confirmed in postmortem studies in premature rabbits. The most immature group of lungs were relatively resistant to pulmonary rupture, owing to high surface forces. Toward term, surface forces were decreased as were lung tissue elastic forces, which predisposed to rupture at lower pressures.