Comparative evaluation of gastric pH and volume in morbidly obese and lean patients undergoing elective surgery and effect of aspiration prophylaxis

Introduction: The anesthetic management of patients with morbid obesity is challenging. There is no consensus on the routine use of aspiration prophylaxis in morbidly obese patients undergoing elective surgery. Aim: The aim of this study is to assess the risk of pulmonary aspiration and effect of premedication with ranitidine and metoclopramide on gastric pH and volume in morbidly obese and lean patients. Methods: Gastric volume and pH were measured in 3 groups of 20 patients each: group I (lean, no aspiration prophylaxis), group II (morbidly obese, no aspiration prophylaxis), and group Ill (morbidly obese; tablet ranitidine, 150 mg; and tablet metoclopramide, 10 mg administered the night before and 2 hours before surgery). Patients with critical gastric volume >25 mL and critical <2.5 (Roberts and Shirley criteria) were considered to be at risk for pulmonary aspiration. Results: The percentage of patients with gastric volume >25 mL and pH <2.5 was 5%, 30%, and 0% in groups I, II, and III, respectively. Statistically significant difference existed between groups and 11 (P = .04) and groups II and III (P = .006). Premedicated morbidly obese and lean patients were comparable (P = .46). Conclusion: Morbidly obese patients undergoing elective surgery are at a higher risk for regurgitation and pulmonary aspiration when compared with lean patients. Preoperative aspiration prophylaxis decreases gastric volume and increases gastric pH and thus should be routinely prescribed. (C) 2015 Elsevier Inc. All rights reserved.