The relationship of bronchopulmonary dysplasia to the occurrence of alveolar rupture during positive pressure ventilation.

The effect of altered mechanical ventilation on the incidence of alveolar rupture and bronchopulmonary dysplasia (BPD) was reviewed in infants who had neonatal respiratory distress syndrome (RDS) (N = 99). From 1971 to 1974 we attempted to minimize pulmonary oxygen exposure. Accordingly, during the resolution of respiratory distress syndrome, the ventilator pressures were not reduced until the FIO2 had been lowered to 0.4 (n = 61). In 1974 to 1975 earlier reduction of pressure was instituted as the FIO2 was lowered to 0.6 or less (N = 38). Birth weight and gestational age were comparable in the two groups. With earlier reduction of ventilator pressures, there was a significant decrease in the duration of exposure to peak inspiratory pressures greater than or equal to 40 cm H2O (p is less than 0.004) and greater than or equal to 50 cm H2O (p is less than 0.002). The incidence of alveolar rupture during postive pressure ventilation fell from 51 to 24% (p is less than 0.015) and bronchopulmonary dysplasia from 41 to 13% (p is less than 0.003). In addition, there was a decrease in the duration of mechanical ventilation (p is less than 0.02) and exposure to an FIO2 is greater than or equal to 0.6 (p = 0.07). The results confirm the intimate relationship of pulmonary barotrauma, as reflected by the occurrence of alveolar rupture during positive pressure inflation of the lungs, to the subsequent development of bronchopulmonary dysplasia and that prevention of the former is associated with a concomitant fall in incidence of the latter.