Alveolar rupture as an independent predictor of bronchopulmonary dysplasia

Abstract

The chest radiographs and charts of 99 surviving neonates treated with positive pressure ventilation for respiratory distress syndrome were reviewed. Forty infants developed alveolar rupture during mechanical ventilation. Of these, 27 (67.5%) developed bronchopulmonary dysplasia (BPD). Only 3 (5.4%) of the remaining 59 infants developed BPD. The relative odds of developing BPD if alveolar rupture occurred increased by a factor of 39 (p < 0.001). Significant associations between BPD and the duration of ventilation with high peak inspiratory pressures (IP) ≥ 40 cm H2O, low peak IP ≤ 39 cm H2O, continuous distending pressure ≥ 5 cm H2O and fractional inspired oxygen concentration (Fio2) ≥ 0.6 were examined. Since these ventilatory parameters had a significant association (p ≤ 0.02) with both BPD and alveolar rupture, an attempt was made to identify the independent contributions of these factors to the development of BPD by a stepwise discriminant analysis. Controlling for the most significant associations, FIO2 ≥ 0.6 and peak IP ≤ 39 cm H2O, subsequent analysis showed no added discriminant power of predicting BPD in the duration of exposure to high peak IP ≥ 40 cm H2O and continuous distending pressure ≥ 5 cm H2O. Alveolar rupture remained overwhelmingly significant (p < 0.001), but it did not account entirely for the development of BPD. Duration of exposure to peak IP ≤ 39 cm H2O and FIO2 ≥ 0.6 remained significant. These results suggest that pulmonary barotrauma as reflected by the occurrence of alveolar rupture during positive pressure ventilation is intimately related with the subsequent development of BPD.