Risk factors for bronchopulmonary dysplasia in very low birth weight newborns treated with mechanical ventilation in the first week of life

The purpose of this study was to identify the risk factors for bronchopulmonary dysplasia (BPD) in a population of very low birth weight (BW) newborns treated with mechanical ventilation in the first week of life who survived the 28 days. The effects of antenatal steroids, sepsis, patent ductus arteriosus (PDA), fluid management and ventilator support strategies were investigated. This was a prospective study of a cohort of 86 newborns with BW below 1500 g who were born alive between the period of September 2000 to November 2002, treated at the University Hospital of Medical School Campinas, Brazil. The BPD was defined as the oxygen dependence in the 28 days, with consistent radiology findings. A logistic regression analysis was realized to identify the risk factors associated to BPD. Among the very low BW newborns, 45 developed BPD. The univariate analysis showed that besides BW and gestational age (GA), other factors such as FiO(2) >= 0.60 (RR : 2.03; 95% CI: 1.4-2.94), PIP >= 21 cmH(2)O (RR : 1.73; 95% CI: 1.12-2.65), surfactant therapy (RR : 1.68; 95% CI: 1.14-2.48), fluid volume on day 7 > 131 ml/kg/day (RR : 1.81; 95% CI: 1.18-2.78), presence of PDA (RR : 1.95; 95% CI: 1.36-2.8) and pneumothorax (RR : 1.71; 95% CI: 1.18-2.45) were associated to an increase in the risk of BPD. When the variables were analysed concomitantly, using the multivariate logistic regression model, the most important risk factors for the development of BPD were GA <= 30 weeks (RR : 2.76; 95% CI: 1.23-6.19), PIP >= 21 cmH(2)O (RR : 1.92; 95% CI: 1.04-3.54), fluid volume on day 7 > 131 ml/kg/day (RR : 2.09; 95% CI: 1.14-3.85) and presence of PDA (RR : 1.94; 95% CI : 1.03-3.65). The risk for BPD due to the association of these four factors was 96.4%. Finally, it was observed that the most important risk factors for BPD were prematurity, PDA and elevated levels of PIP as well as fluid volume.