Purpose: Postoperative respiratory insufficiency in cardiac surgery has become a common problem, and prolonged tracheal intubation may be complicated by ventilator-associated pneumonia and ventilator dependence, leading to deterioration of the condition. The application of noninvasive ventilation for the treatment of acute respiratory failure and acute cardiogenic pulmonary edema caused by chronic obstructive pulmonary disorders has been reported more successfully, but there are fewer reports on the treatment of postoperative respiratory insufficiency in cardiac surgery. The purpose of this paper is to make a preliminary analysis of the causes of postoperative hypoxemia in cardiac surgery and to summarize the effectiveness, safety, and postoperative recovery of some patients treated with noninvasive ventilation in our department. Methods: 429 cases of cardiac surgery from December 2005 to December 2009 were divided into a study group (group N, n=28) and a control group (group C, n=401) according to the presence or absence of respiratory insufficiency. The former included 21 patients with coronary artery bypass grafting and 7 patients with valve replacement; etiologically, 46% (13) had cardiogenic pulmonary edema, 21% (6) had pulmonary atelectasis, 21% (6) had acute lung injury due to extracorporeal circulation, and 11% (3) had pulmonary infection. The patients in group N were treated with noninvasive positive pressure ventilation, and the changes of respiratory counts, arterial blood gases, heart rate, pulmonary artery pressure, oxygenation index and alveolar-arterial oxygen partial pressure difference were recorded at 7 time points before, 16h, 8h and 8h, 16h, 24h and 48h after treatment, respectively. Results Smoking patients 75.0% in group N and 47.5% in group C; oxygenation index 320.5±49.7 in group N and 385.2±76.0 in group C; age 63.6±8.6 years in group N and 58.0±10.4 years in group C; ejection fraction <40% in group N 17.9% and 11.5% in group C; the above indexes were statistically different between the two groups. mean NPPV in group N treatment time was 40.8±15.4 h. The number of breaths (32.3±9.5 vs. 23.6±11.4), heart rate (104.±29.7 vs. 95.5±20.4), pulmonary artery pressure (27.7±14.0 vs. 22.6±10.2), alveolar-arterial oxygen partial pressure difference (30.5±9.38 10.8±5.3) before and after NPPV treatment and oxygenation index (174.2±24.5 vs. 242.9±32.5) compared to pre-treatment, with statistically significant differences (P<0.05). Noninvasive ventilation was effective in the treatment of cardiogenic pulmonary edema, pulmonary atelectasis and acute lung damage. There were 3 patients with respiratory insufficiency due to pulmonary infection, 2 of whom were re-intubated, 1 died, and 1 was re-ventilated with non-invasive ventilation after 72 h of invasive ventilation and improved after 7 d. The total effective rate was 92.8%. From the postoperative results, there were statistically significant differences in the length of stay in the monitoring room (40.9±24 h in group N and 26.0±13.4 h in group C), length of hospital stay (40.9±24 h in group N and 26.0±13.4 h in group C) and reintubation rate (7.1% in group N and 0.75% in group C) compared with the two groups. It was suggested that the patients in group N were relatively sicker. CONCLUSION: Noninvasive ventilation therapy can improve pulmonary function, reduce reintubation and improve prognosis in patients with difficult extubation after cardiac surgery, and provide a new idea for the treatment of respiratory insufficiency after cardiac surgery.