Noninvasive Ventilation Bundle in Postoperative Respiratory Failure

"Device:BiPAP Vision.~NIV bundle group : Early application of NIV(BiPAP Vision) in 1 h after randomization."

Device:fiberoptic bronchoscopy. NIV bundle group :When patients were inability to spontaneously clear airways from excessive secretions during NIV, fiberoptic bronchoscopy (FBO) was used for suction of secretions.

"Drug:propofol.continuous perfusion of propofol (0.50-2.00 mg/kg/h).~NIV bundle group :When patients showed intolerance or inadequate patient cooperation during the NIV session, they were sedated (Ramsay scale 2-3) by a continuous perfusion of propofol (0.50-2.00 mg/kg/h).~In the conventional treatment group: No intervention."

Conventional treatment group:NIV(BiPAP Vision) was used, when patients failed the supplemental oxygen and met at least two of the following criteria:(1) severe respiratory distress with dyspnoea, respiratory rate\>30breaths/min, and clinical signs suggestive of respiratory-muscle fatigue or increased respiratory effort (use of accessory respiratory muscles or paradoxical abdominal breathing, or intercostal indrawing), (2) respiratory acidosis (arterial pH of 7.35 or less with PaCO2 of 45 mm Hg or more) ;(3) arterial O2 saturation by pulse oximetry less than 90% or PaO2 less than 60 mm Hg at an FiO2\> 0.5 or breathing at least 10 L/min oxygen.