We previously reported that H2-antagonist medication given for longer than 4 wk may produce complete tolerance to preanesthetic H2 antagonist therapy. In this study, we evaluated the efficacy of preanesthetic proton pump inhibitor (PPI; oral rabeprazol) use in patients receiving regular H2-antagonist (oral famotidine) therapy for more than 4 wk. Forty-eight patients with assumed complete tolerance to H2 antagonists undergoing elective surgery were recruited and randomly assigned to receive either a preanesthetic PPI (rabeprazol 20 mg; n = 24) or H2-antagonist (H2 group; roxatidine 75 mg; n = 24) at 9:00 pm on the day before surgery and 2 h before the induction of anesthesia. Volume of gastric contents and pH values were measured after the induction of anesthesia. Gastric pH value in the PPI group (5.38 +/- 2.42) was significantly higher than in the H2 group (3.27 +/- 1.98; P < 0.01). Gastric volume in the PPI group (8.6 +/- 1.5 mL) was significantly smaller than in the H2 group (15.4 +/- 2.8 mL; P < 0.05; cf. PPI). Fourteen patients in the H2 group were at risk of acid aspiration pneumonia (gastric pH <2.5 or volume >25 mL), whereas only four patients in the PPI group (P < 0.05) were at risk. These data suggest that in patients receiving H2-antagonist therapy for longer than 4 wk, prophylaxis for acid aspiration pneumonia should include preanesthetic PPI medication.
Implications: We previously reported that more than 4 wk of administration of H2-antagonists may produce a full tolerance to preanesthetic H2-antagonists. The present study suggests that a proton pump inhibitor may be effective for prophylaxis of acid aspiration pneumonia in patients showing the full tolerance to H2 antagonists.