Postoperative noninvasive ventilation.

General anesthesia and surgery are associated with changes in the shape of the chest that result in atelectasis, a major factor in the development of postoperative respiratory failure. Postoperative noninvasive positive pressure ventilation (NIPPV) has been shown to improve oxygenation and ventilation for high-risk patients. NIPPV has been used as rescue therapy for patients developing acute respiratory distress postoperatively, and appears to be most frequently successful in patients whose problem is atelectasis or obesity. Failure to respond to NIPPV after 20 minutes is usually an indication of intubation, mechanical ventilation, and transfer to the intensive care unit.