Objective. The development of bronchopulmonary dysplasia (BPD) often has been attributed to injury from mechanical ventilation and supplemental oxygen. Early lung inflammation in infants with BPD has been thought to be secondary to these factors. The purpose of this study was to evaluate whether preexisting (prenatal) inflammation may be a primary causative factor in the development of BPD.
Methods. Intubated newborns of less than 2000 g birth weight were prospectively enrolled. The presence or absence of chorioamnionitis was documented. Lung inflammation was evaluated on days 1, 2, and 4 of intubation by assaying concentrations of interleukin 1β(IL-1β), thromboxane B2, leukotriene B4, and prostaglandin E2 in tracheal lavages. Infants in whom BPD developed were compared with those in whom it did not using these measures.
Results. Fifty-three infants were enrolled; 41 survived. Thirty-eight had respiratory distress syndrome; 15 were intubated for other diagnoses. Infants prenatally exposed to chorioamnionitis were less likely to present with respiratory distress syndrome; however, chorioamnionitis was significantly associated with both the presence of IL-1β from the first day of intubation and the development of BPD. Tracheal lavage concentrations of IL-1β were higher in infants in whom BPD developed. Thromboxane B2 concentrations were similar on day 1 but were higher on days 2 and 4 in infants in whom BPD developed.
Conclusions. In this study, intubated infants weighing less than 2000 g at birth in whom BPD developed had increased exposure to inflammation prenatally (chorioamnionitis) and evidence of increased lung inflammation from the first postnatal day. We speculate that chorioamnionitis may accelerate lung maturation but that it also causes lung inflammation and subsequent lung injury in intubated infants, fostering the development of BPD.