The influence of intermittent CPAP on hyperoxic lung injury in a preterm rabbit model of bronchopulmonary dysplasia

Introduction: Continuous positive airway pressure (CPAP) and supplemental oxygen are used to treat respiratory failure in preterm infants, however little is known of the functional and structural effects of CPAP on preterm lungs exposed to hyperoxia. Aims and Objectives: This study aims to characterize the effects of intermittent CPAP on lung function and structure in preterm rabbits reared in hyperoxia. We hypothesized the distending pressure of CPAP is biomechanically transduced to have downstream effects on lung function, development and structure in hyperoxia. Methods: Prematurely delivered pups were randomized to normoxia, hyperoxia (FiO2 0.9), hyperoxia plus CPAP (4 hours/day, 5cm H2O). On day 7 of life, pulmonary function tests (pressure-volume, forced oscillation) were performed. Alveolar, vascular and airway morphology was done on pressure fixed lung sections. Results: Hyperoxia significantly altered lung functional and structure. CPAP attenuated the changes of hyperoxia to tissue damping, elastance and the pulmonary artery media and respiratory epithelium. Conclusion: Intermittent CPAP mitigated the functional and structural effects of hyperoxia in preterm rabbits.