Study objective: To evaluate three different preoperative oral dosing regimens of ranitidine in ambulatory patients who had significant risk of aspiration pneumonitis (gastric pH < or = 2.5 or volume > or = 25 ml at intubation or extubation).
Design: Double-blind, placebo-controlled, randomized trial.
Setting: St. Francis Hospital of Buffalo, New York.
Patients: Two hundred seventy-one ambulatory patients about to undergo a surgical procedure under general anesthesia, of whom 241 (89%) completed the trial and were considered evaluable.
Interventions: Patients were randomly assigned to receive one of four regimens administered orally before surgery: placebo at bedtime the night before and in the morning on the day of surgery; ranitidine 150 mg at bedtime and in the morning; ranitidine 150 mg at bedtime and placebo in the morning; or ranitidine 300 mg at bedtime and placebo in the morning.
Measurements and main results: Patients who received ranitidine 150 mg twice/day, ranitidine 150 mg at bedtime, or ranitidine 300 mg at bedtime had a significantly (p < 0.05) lower frequency of a gastric pH 2.5 or below at intubation or extubation than those taking placebo twice/day (3%, 45%, and 31%, respectively, vs 86%). In addition, gastric volume at intubation or extubation was 25 ml or above in significantly fewer patients receiving ranitidine 150 mg at bedtime than placebo (37% vs 13%, p < 0.05). Overall, the number of patients with risk factors for aspiration pneumonitis was significantly lower with ranitidine 150 mg twice/day (20%), ranitidine 150 mg at bedtime (48%), and ranitidine 300 mg at bedtime (35%) than placebo (86%) (p < 0.001), and significantly lower with ranitidine 150 mg twice/day than ranitidine 150 mg at bedtime (p < 0.05).
Conclusions: Ranitidine 150 mg twice/day preoperatively reduced to the greatest degree the percentage of patients who developed significant risk factors for aspiration pneumonitis after surgery under general anesthesia.