The Effects of Preanesthetic Low Dose Famotidine on Gastric pH and Volume in Children / 대한마취과학회지

BACKGROUND: Children undergoing general anesthesia are at increased risk of aspiration pneumonia. Cimetidine and ranitidine, specific histamine (H2-receptor) antagonists, markedly reduce the acidity and volume of gastric content when given 2 3h preoperatively. A newer compound, famotidine, is a more specific antagonist that has no inhibitory effect on the drug metabolizing microsomal enzyme systems of the liver (cytochrome P-450), in contrast to cimetidine. An additional clinical advantage is a possible longer duration of action. The aim of this study is to evaluate the lowest effective dose of famotidine on gastric pH and volume in children. METHODS: Fifty-five children, aged 2 to 14 years (ASA physical status I-II) were divided into four groups (Group I:placebo, normal saline 10 ml, Group II:famotidine 0.1 mg/kg, Group III:famotidine 0.15 mg/kg, Group IV:famotidine 0.2 mg/kg.). Doses were administered intravenously 2 or 3 hours before the operation. Following induction with oxygen, enflurane and pentothal sodium, anesthesia was maintained with N2O/O2 and enflurane. A nasogastric tube was passed into the stomach and the gastric contents were aspirated in a uniform manner. Gastric volume was recorded and pH values were measured with pH meter. The incidence of high risk for aspiration pneumonia, defined as gastric pH 0.4 ml/kg of gastric juice, was measured in all groups. RESULTS: In the placebo group, 10 of 13 children (77%) had a pH 0.4 ml/kg. Group II (famotidine 0.1 mg/kg) was not found to produce a significant increase in the gastric pH. Groups III and IV (famotidine 0.15 mg/kg and 0.2 mg/kg) were found to produce a significant increase in the gastric pH. The gastric juice volume was reduced in all famotidine groups, but was not statistically significant compared with the placebo group. The incidences of high risk for aspirationpneumonitis decreased in all famotidine groups. CONCLUSIONS: The results suggest that the preoperative intravenous administration of famotidine 0.15 mg/kg is enough to decrease both gastric juice acidity and volume in this high-risk group.

The Effect of Famotidine on Lowering Gastric Acidity in Gastric Carcinoma Patients / 대한마취과학회지

BACKGROUND: To identify the gastric pH of gastric carcinoma patients after more than 8 hours of fasting and ascertain the antisecretory effects of H2-receptor antagonists, the gastric volume and pH of 41 gastric carcinoma patients was checked immediately after the induction of inhalational general anesthesia (endotracheal intubation). METHODS: The patients were divided randomly into two groups: the control received IV normal saline as a placebo and the famotidine group received IV famotidine as a premedicant 1 to 2 hours before the induction of anesthesia. Immediately after the induction of anesthesia, the gastric contents were aspirated blindly with a 60 ml syringe. Fisher's exact test was used to compare the percentage of patients 'at risk' between the two groups in relation to their pH and volumes. RESULTS: The percentage of patients 'at risk' (volume > 0.4 ml/kg and pH < 2.5) of acid aspiration pneumonitis in the control and famotidine groups was 8.7% and 5.6%, respectively, which was 30 77% lower than for patients with no premedication, as observed in other studies. In the present study, the difference in percentage of patients 'at risk' between the two groups was not statistically significant. CONCLUSIONS: The gastric carcinoma patients exhibited a higher gastric pH when fasting and a lower risk of acid aspiration pneumonitis relative to their gastric contents. The effect of famotidine on lowering gastric acidity and volume in gastric carcinoma patients was rather weak. Accordingly, the routine use of H2-receptor antagonists to decrease gastric secretion in gastric carcinoma patients should be reevaluated.