Background: Noninvasive positive pressure ventilation (NIPPV) may improve postoperative lung function and reduce postoperative complications in patients undergoing abdominal surgery. The purpose of our study was to determine whether the timing of postoperative NIPPV affects lung function 1 day postoperatively.
Methods: Forty morbidly obese patients with known obstructive sleep apnea undergoing laparoscopic bariatric surgery with standardized anesthesia care were randomly assigned to receive NIPPV immediately after tracheal extubation (immediate group) or supplemental oxygen (standard group). All patients had continuous positive airway pressure initiated 30 minutes after extubation in the postanesthesia care unit (PACU) via identical noninvasive ventilators. Spirometry was performed by a blinded observer in the perioperative holding area 1 hour after admission to the PACU and 1 day postoperatively. The primary outcome was the change in forced vital capacity (FVC) from baseline to 24 hours (FVC baseline-FVC 24 hours).
Results: Forty patients, 20 in each group, were enrolled in the study. Forced expiratory volume in 1 second, FVC, and peak expiratory flow rate were significantly reduced in both groups from perioperative values throughout the study. At 24 hours, the intervention group had lost only 0.7 L FVC, versus 1.3 L for the intervention group (P = 0.0005). An analysis of covariance confirmed this and indicated that the immediate postoperative NIPPV better preserved spirometric function at 1 and 24 hours postoperatively. Specifically, the differences in the primary outcome were statistically significant.
Conclusions: NIPPV given immediately after extubation significantly improves spirometric lung function at 1 hour and 1 day postoperatively, compared with continuous positive airway pressure started in the PACU, in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery.