Cisapride does not alter gastric volume or pH in patients undergoing ambulatory surgery

Purpose: To evaluate the efficacy of 20 mg cisapride po in reducing residual gastric volume and pH in adult ambulatory surgical patients. Methods: Using a prospective randomised double-blind controlled design, we administered either 20 mg cisapride po or placebo preoperatively to 64 ASA 1- 2 ambulatory surgical patients. Following induction of anesthesia we measured volume and pH of residual gastric contents, using blind aspiration through an orogastric tube. Parametric data were analysed using unpaired, one tail Students' t test. Non-parametric data were analysed using Fishers Exact test and Chi square analysis. Statistical significance was accepted at the probability level of < 0.05. Results: Residual gastric volumes were similar in the two groups (19.5 ±23.8, 23.9 ± 24.4 ml), in the cisapride and placebo groups respectively, P = 0.24). Data shown are mean (± SD). The proportions of patients with a residual gastric volume exceeding 0.4 ml · kg-1 were similar in the two groups (4 of 28, and 8 of 23 patients in the cisapride and placebo groups respectively, P = 0.09). The pH of the residual gastric contents were similar in the cisapride and placebo groups (1.6 ± 0.5, 1.4 ± 0.5, respectively, P = 0.26). The proportions of patients with pH 2.5 was also similar in the cisapride and placebo groups (21 of 25, and 20 of 21 patients respectively, P = 0.2). Conclusions: Preoperative administration of 20 mg cisapride po to patients scheduled for outpatient surgery does not alter either the volume or the pH of gastric contents. Its use in this setting is of no apparent clinical benefit.