[Omeprazole in the prophylaxis of Mendelson syndrome in elective surgery]

To study the efficacy of different doses of omeprazole and the influence of premedication in the prophylaxis of the acid aspiration syndrome.

A double blind prospective study was carried out ASA I-III on 103 patients (mean age 51.08 yr) undergoing either general, gynecological or orthopedic surgery, allocated into 4 groups. Group NP: 24 non premedicated patients; group P: 29 patients premedicated with 1 mg of lorazepam the previous night and 50 mg of meperidine 1 hour before surgery and haloperidol or dipotassic chlorazepate according to age; group 020: 25 patients premedicated with the same drugs and doses as in group P plus 20 mg or oral omeprazole the night prior to surgery; group 040: 25 patients premedicated as in group P 40 mg of oral omeprazol the night prior to surgery. Following induction of anesthesia a nasogastric tube was placed and gastric juice withdrawn to determine the pH; were excluded patients with an aspiration volume of less than 8 ml.

No significant differences were found in regard to pH among the non premedicated and premedicated groups, however a change between the latter two groups having received omeprazole was observed. The results of the pH were significantly higher in the group treated with 40 mg of omeprazole (mean 4.87 +/- SD 2.35) with respect to the group treated with 20 mg of omeprazole (mean 3.78 SD +/- 2.35). In the group treated with 40 mg of omeprazole, the incidence of pH < 1.5 was 4% vs 24% of cases in the group treated with 20 mg of omeprazole.

Premedication with 40 mg of oral omeprazol the night prior to surgery increases pH up to safe values for the prophylaxis of the acid aspiration syndrome.