Effects of Atropine, Glycopyrrolate, and Cimetidine on Gastric Secretions in Morbidly Obese Patients

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Abstract
Gastric volume and pH were studied immediately after induction of anesthesia and endotracheal intubation in 40 morbidly obese patients undergoing gastric bypass procedures. Of 14 patients receiving intramuscular atropine (0.6 mg) preoperatively, 67% had gastric pH values < 2.5; 33% of these patients had both a gastric pH 20 ml. When the drug administered was intramuscular glycopyrrolate (0.3 mg), 62% of the patients had gastric pH values 20 ml. Differences between the two drugs were not significant. Thirteen patients received cimetidine orally at midnight preoperatively and again 2 to 4 hours before the induction of anesthesia. Patients in this group had gastric pH values that were significantly higher than those observed in patients given anticholinergic drugs. Only 15% had gastric pH values 20 ml, this was not statistically different from the observations made in patients receiving atropine or glycopyrrolate. Despite this, it is concluded that cimetidine administered before the induction of anesthesia in morbidly obese patients may reduce the high risk of aspiration pneumonitis in such patients.