[The effects of preoperative drinking and H2 blocker on gastric acid secretion]

We studied the effects of preoperative drinking and H2 blocker on gastric acid secretion in 63 patients (ASA I-II, > 18yrs) scheduled for afternoon surgery. Group A (n = 20), as a control, was not permitted to eat and drink from 9 pm, the day before surgery, and was then given 500 ml of maintainance fluid before anesthesia. Group B (n = 20) fasted from 9 pm the day before surgery, and was allowed to drink clear fluids until 2hs before anesthesia. Group C (n - 23) followed the same guidelines as group B, and was given famotidine (20mg) orally at 9 pm the day before and 2hs before anesthesia. After induction, a Salem sump tube was inserted into the stomach and a gastric fluid aspiration was performed. The fluid volume and pH were measured after collection. Gastric pH was significantly higher (P < 0.001) in group C (6.4 +/- 0.9) than in groups A (3.1 +/- 1.8) and B (2.7 +/- 1.8). Fluid volume was similar in each group (A; 11 +/- 9/B; 12 +/- 9/C; 12 +/- 13ml). The dilution of gastric acid by the ingested fluid was not observed. We conclude that preoperative drinking does not affect gastric contents in elective operative patients. To reduce the risk of developing aspiration pneumonia, we recommend that every patient should receive an oral H2 blocker.