A randomized controlled study was conducted to compare the effectiveness of NIPPV versus NCPAP in the initial treatment of NRDS from the following aspects : reducing CO2 retention , improving oxygenation , reducing second endotracheal intubation and second use of pulmonary surfactant ( PS ) , reducing the duration of invasive respiratory support , reducing the duration of oxygen use , and reducing the incidence of air leak , abdominal distension and ventilator-associated pneumonia .