Aspiration pneumonia remains a serious result associated with general anesthesia. Therefore, we studied the effectiveness of preanesthetic ranitidine in increasing gastric pH to prevent aspiration pneumonia.

Eighty patients scheduled for elective surgery were randomly divided into four groups with twenty patients in each group. Patients in control group were not given preanesthetic ranitidine; patients in group I received 300 mg of ranitidine orally at night before surgery, patients in group II received 150 mg of ranitidine orally both the night before surgery and one hour before surgery respecvtively and patients in group III recieved 150mg of ranitidine orally one hour before surgery.

Compared with control group, the mean gastric pH of preanesthesia and 1 hour after anesthetic induction increased significantly in the group I, II, III (P<0.0001). There was significant increased gastric pH in the group II compared with group I and III.

These results demonstrate that ranitidine markedly increase the gastric pH. So, we recommend that patients receiving general anesthesia would be taken Hz-antagonist such as ranitidine preoperatively.