Intra-operative change of gastric pH during laparotomic cholecystectomy under general anaesthesia: A prospective case-control study

BACKGROUND: Gastric decompression by suctioning often shows greenish/greenish-yellow-coloured gastric aspirates following cholecystectomy under general anaesthesia (GA). Possible intraoperative regurgitation of duodenal contents into stomach because of surgical manipulation may be the reason for such alteration in colour of the gastric secretions. AIM: We conducted this study to determine whether there were any pH changes of gastric secretions during laparotomic cholecystectomy operation to confirm our hypothesis of regurgitation of duodenal contents into the stomach. SETTINGS AND DESIGNS: Prospective observational controlled study in the Department of Anaesthesiology and Critical Care in a tertiary care university teaching hospital. METHODS: Fifty adult ASA I and II patients scheduled for open cholecystectomy operation under GA were included in the study group and another 50 non-abdominal surgical patients without any gall bladder disease were taken as controls. Three to five milliliters of gastric secretions were aspirated just after intubation and also before reversal of residual neuromuscular blockade for analysis of pH. STATISTICAL ANALYSIS: Analysis of variance test and Chi-square test with Fisher's exact correction were used for statistical analysis. Differences were significant when the P value was <0.05. RESULTS: Post-operative values of pH in the study group were significantly higher than their pre-operative values (2.40±1.10 vs. 4.04±1.6, P≤0.001). Forty-nine patients (98%) in the study group had altered coloured post-operative gastric aspirations, while no patient in the control group had such changes (P<0.001). CONCLUSIONS: A significant change in gastric pH takes place during laparotomic cholecystectomy due to reflux of duodenal content into the stomach.