Effects of oral rehydration therapy on gastric volume and pH in patients with preanesthetic H2 antagonist

Kishiko Nakai, Hidetomo Niwa, Masatou Kitayama, Yutaka Satoh, Kazuyoshi Hirota

Recent preanesthetic fasting practice allows patients to take clear fluids up to 2 h before surgery without taking any antacid for the prophylaxis of aspiration pneumonia; this practice is defined as oral rehydration therapy (ORT). It has been reported that with ORT the gastric volume may be significantly lower than that with a standard fasting regimen, although in a standard fasting regimen without preanesthetic antacid, gastric pH and volume values could be critical for causing aspiration pneumonia. In this study we compared gastric fluid status in patients with ORT and those with a standard fasting regimen; patients in both groups received a preanesthetic H(2) antagonist. One hundred and four patients were randomly assigned to either the ORT or standard fasting group, and all were given roxatidine 75 mg 2 h before surgery. After the induction of anesthesia, the gastric contents were collected via a gastric tube to measure gastric volume and pH. Neither gastric volume nor pH differed between the groups (ORT 9.6 ± 8.2 ml and 5.6 ± 1.7, respectively, vs. standard fasting 8.5 ± 6.8 ml and 5.5 ± 1.7, respectively). These data suggest that ORT may not reduce gastric volume in patients receiving a preanesthetic H(2) antagonist.