Omeprazole for prophylaxis of acid aspiration in elective surgery.

The aim of the study was to determine whether a single oral dose of omeprazole 40 mg is effective in increasing the pH of gastric residue above 2.5 at the time of anaesthetic induction in adult patients scheduled for elective gynaecological surgery. The patients were allocated to receive either chlorazepate dipotassium 25 mg alone or omeprazole 40 mg and chlorazepate dipotassium 25 mg on the night before surgery. Gastric volume and pH were measured after induction of anaesthesia. Patients who received omeprazole had a higher mean pH than control patients (p less than 0.001). The pH was less than 3.5 in 50% of patients in the control group, but in only 4.5% of those who received omeprazole (p less than 0.01). Mean (SEM) volume of gastric fluid was 15.2 (2.7) ml in the control group and 9.2 (1.8) ml in the omeprazole group, but the results were not statistically significant. A single dose of 40 mg omeprazole significantly decreased the number of patients at risk of aspiration pneumonitis.