Fraction of Inspired Oxygen as a Predictor of CPAP Failure in Preterm Infants with Respiratory Distress Syndrome: A Prospective Multicenter Study

Abstract

Introduction: There are limited data available regarding the fraction of inspired oxygen (FiO₂) predictive of the failure of continuous positive airway pressure (CPAP) in preterm infants with respiratory distress syndrome (RDS). Therefore, we investigated factors predictive of CPAP failure in the first 72 h of life, with special attention to the prognostic role of FiO₂. Methods: This multicenter, prospective study enrolled infants <30 weeks gestation in whom CPAP was initiated within the first 15 min after birth. In the univariate and multivariate logistic regression models, demographic, perinatal, and respiratory parameters were analyzed. The FiO₂ threshold was determined with ROC curve analysis. Results: Of 389 recruited newborns, CPAP failure occurred in 108 infants (27.8%). In the univariate model, each gestational week reduced the odds of CPAP failure by 19%, and each 100 g of birth weight reduced the odds by 16% (both p < 0.05). The risk was increased by 4.2 and 7.5% for each 0.01 increase in FiO₂in the first and second hours of life, respectively. In the final multivariate model, birth weight and FiO₂ in the second hour of life were the predictive measures. The prognostic threshold was FiO₂ = 0.29 in the second hour of life (AUC 0.7; p < 0.0001), with a sensitivity of 73% and a specificity of 57%. CPAP failure implied a more than 20-fold higher risk of death and pneumothorax and a 2- to 5-fold higher risk of typical complications of prematurity, including bronchopulmonary dysplasia and severe intraventricular hemorrhage. Conclusion: FiO₂ in the second hour of life is a significantpredictor of CPAP failure. The threshold of 0.29 best discriminates the CPAP outcome. Nonresponders to CPAP have a remarkably higher incidence of complications and a higher mortality rate.