High-risk residual gastric content in fasted patients undergoing gastrointestinal endoscopy: a prospective cohort study of prevalence and predictors

In this prospective cohort study, we examined the residual gastric contents of 255 fasted patients undergoing gastrointestinal endoscopy. The volume and pH of residual gastric contents collected by suction under direct visualisation during gastroscopy were accurately quantified. All patients completed the minimum two-hour fast for clear fluids and 97.2% of patients completed the minimum six-hour fast for solids. High-risk residual gastric content, defined as volume >25 ml and pH <2.5, was present in 12.2% (95% CI 8.7% to 16.7%) of patients. We used multiple logistic regression analysis to identify demographic and clinical factors associated with high-risk residual gastric content. The odds of having high-risk residual gastric content were reduced with increase in age (adjusted odds ratio 0.77, 95% CI 0.61 to 0.96, P=0.0230), and use of a proton pump inhibitor or histamine type 2 receptor antagonist (adjusted odds ratio 0.24, 95% CI 0.10 to 0.55, P=0.0013), and were increased in male patients (adjusted odds ratio 2.36, 95% CI 1.06 to 5.28, P=0.0348). Notably, residual gastric content was classified as high-risk in 20.4% of patients who did not take a proton pump inhibitor or histamine type 2 receptor antagonist versus only 5.6% of those who did. Our findings suggest that, despite currently recommended fasting, males presenting for endoscopy are more likely to have high-risk gastric content than females, and that the incidence appears to be reduced with increasing age, and by the use of proton pump inhibitors or histamine type 2 receptor antagonists, we were unable to confirm or exclude an effect of body mass index, peptic pathology, diabetes or other clinical or demographic factors in our study population.