Effect of preanesthetic intramuscular ranitidine on gastric acidity and volume in children

Study Objective: To evaluate the effects of preanesthetic administration of intramuscular (IM) ranitidine on pH and volume of gastric contents in children. Design: Three randomized treatment groups. Setting: Central operating rooms at a university hospital. Patients: Forty children age 1 to 10 years undergoing a variety of elective surgical procedures requiring general anesthesia with endotracheal intubation. Interventions: IM ranitidine 1 mg/kg (n = 15) or 2 mglkg (n = 15) was administered 2 hours prior to induction of anesthesia. Ten patients without ranitidine served as the control group. An orogastric tube was inserted into each patient. Measurements and Main Results: Gastric fluid pH and volume were measured every hour in the three groups. Plasma ranitidine concentrations were measured in ten patients of the ranitidine-treated groups. The mean volume of gastric fluid at induction of anesthesia was significantly lower in the ranitidine-treated patients (2.4 ml for ranitidine 1 mg/kg, 3.2 ml for ranitidine 2 mglkg) than in the controls (8.6 ml, p < 0.05). The mean pH values at induction of anesthesia were significantly higher in the ranitidine-treated patients (4.6 for 1 mg/kg, 6.7 for 2 mg/kg) than in the controls (2.1; p < 0.05). Dose-dependent plasma ranitidine concentrations were obtained. Conclusions: Preanesthetic IM ranitidine 1 to 2 mglkg resulted in a higher pH and lower volume of gastric fluid at the time of induction and in a higher pH during 3 hours of anesthesia. This therapy may be a useful adjunct to premeditation for children who have a greater than normal risk of pulmonary aspiration during anesthesia.