Responses to atropine, glycopyrrolate, and riopan of gastric fluid pH and volume in adult patients

Abstract

From a study in 250 surgical patients it is concluded that atropine or glycopyrrolate in usual adult doses for preanesthetic medication did not increase gastric fluid pH to above 2.5 or reduce volume to below 20 ml at the time of anesthetic induction. In contrast, an antacid, Riopan, given shortly before anesthetic induction reliably elevated the gastric fluid pH to far above 2.5. This desirable effect must be weighted against the possible hazards of increased gastric fluid volume in patients pretreated with an antacid. Routine antacid therapy may be reasonable to consider in view of the fact that 16 - 17 percent of fasted patients awaiting elective operations were found to be at risk should aspiration have occurred (i.e., gastric fluid pH below 2.5 and volume of more than 20 ml). Certainly, anatacids would seem indicated when a cuffed endotracheal tube is not placed or difficult and prolonged anesthetic induction or tracheal intubation is anticipated.