Comparison of ultrasonographic measurement of gastric antral volume and pH with or without pharmacological acid aspiration prophylaxis in low-risk surgical patients – A randomized clinical trial

Abstract

The role of preoperative pharmacological prophylaxis in preventing aspiration pneumonitis under general anesthesia (GA) in patients at low risk of aspiration pneumonitis is still under debate. We addressed the need for routine pharmacological aspiration prophylaxis in at-risk population by assessing the change in gastric volume using ultrasound with and without pharmacological acid aspiration prophylaxis. A single-center, randomized double-blinded trial, with 200 adult patients scheduled for elective surgical procedures under GA, were randomized into a prophylaxis group, in which the patients received oral famotidine and metoclopramide, and a no prophylaxis group, in which the patients did not receive any prophylaxis. Gastric volume derived from preinduction measurement of gastric antral volume by ultrasound, postinduction gastric pH, and incidences of aspiration pneumonitis were compared. Bland–Altman plot was used to determine the level of agreement between measured gastric volume and ultrasonography based on calculated gastric volume. The gastric antral cross-sectional area (CSA) and volume in the no prophylaxis group (3.12 cm2 and 20.11 ml, respectively) were comparable to the prophylaxis group (2.56 cm2 and 19.67 ml, respectively) (P-values 0.97 and 0.63, respectively). Although there was a statistically significant decrease in gastric pH in the no prophylaxis group (P-value 0.01), it was not clinically significant to increase the risk of aspiration pneumonitis based on Roberts and Shirley criteria (P-value 0.39). In an adequately fasted low-risk population, the amount of residual gastric volume was similar and below the aspiration threshold, regardless of the aspiration prophylaxis status.