Preoperative use of incentive spirometry does not affect postoperative lung function in bariatric surgery

Abstract

Morbidly obese patients undergoing general anesthesia for laparoscopic bariatric surgery are considered at increased risk of a postoperative decrease in lung function. The purpose of this study was to determine whether a systematic use of incentive spirometry (IS) prior to surgery could help patients to preserve their respiratory function better in the postoperative period. Forty-one morbidly obese (body mass index [BMI] > 40 kg/m²) candidates for laparoscopic bariatric surgery were consented in the study. All patients were taught how to use an incentive spirometer but then were randomized blindly into 2 groups. The control group was instructed to use the incentive spirometer for 3 breaths, once per day. The treatment group was requested to use the incentive spirometer for 10 breaths, 5 times per day. Twenty experimental (mean BMI of 48.9 ± 5.67 kg/m²) and 21 control patients (mean BMI of 48.3 ± 6.96 kg/m²) were studied. The initial mean inspiratory capacity (IC) was 2155 ± 650.08 (SD) cc and 2171 ± 762.98 cc in the experimental and control groups, respectively. On the day of surgery, the mean IC was 2275 ± 777.56 cc versus 2254.76 ± 808.84 cc, respectively. On postoperative day 1, both groups experienced a significant drop of their IC, with volumes of 1458 ± 613.87 cc (t test P < 0.001) and 1557.89 ± 814.67 cc (t test P < 0.010), respectively. Our results suggest that preoperative use of the IS does not lead to significant improvements of inspiratory capacity and that it is a not a useful resource to prevent postoperative decrease in lung function.