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

IntroductionThe 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.AimThe 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.MethodsGastric 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 III (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 pH < 2.5 (Roberts and Shirley criteria) were considered to be at risk for pulmonary aspiration.ResultsThe 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 I and II (P = .04) and groups II and III (P = .006). Premedicated morbidly obese and lean patients were comparable (P = .46).ConclusionMorbidly 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.