ObjectiveTo explore the reason of failure in noninvasive positive pressure ventilation (NPPV) for treatment of postoperative hypoxemia, in order to better guide use of NPPV after cardiac surgery. MethodsWe retrospectively analyzed the clinical data of 64 patients after heart surgery with undergoing NPPV treatment due to hypoxemia in our hospital between January 2012 and December 2013 year.There were 49 males and 15 females at age of 28 to 87 years. There were 17 patients with NPPV failure. The related factors for failure of NPPV were analyzed. ResultsFactors associated with failure of NPPV included smoking history, preoperative pulmonary function abnormalities, blood transfusion amount > 1 000 ml, simplified acute physiology score Ⅱ(SAPS Ⅱ) before NPPV > 35 points, oxygenation index (PaO2/FiO2) < 100 mm Hg before NPPV, PaO2/FiO2 < 150 mm Hg after NPPV treatment for 1 h, mechanical ventilation time > 72 h at the first time, and pneumonia (P < 0.05). The SAPS Ⅱ > 35 points before NPPV and pneumonia were the independent risk factors for NPPV treatment failure for postoperative hypoxemia. ConclusionPostoperative NPPV for heart disease should be according to the cause of low oxygen and severity. For patients with SAPS less than 35 points before NPPV or patients with pneumonia, NPPV should not be used. In the process of NPPV, if clinical effect is not satisfied, it should be converted to invasive ventilation immediately.