Determining residual gastric volume in healthy children using ultrasound
Canadian Journal of Anaesthesia
Submitted September 2023 by Dr Marlene Johnson
Summary This Canadian study was a prospective, observational study of 33 healthy volunteers aged between 2-14. It examined residual gastric volume using ultrasound, after patients were given 250mL of clear fluid. A baseline ultrasound was performed prior to clear fluids, and then at 30, 60, 90 and 120 minutes after fluid consumption. The primary outcome was the time to achieve a gastric volume of less than 1.5mL/kg.
Results were as follows: Baseline 0.51 mL/kg (95%CI 0.46-0.57) 30 min 1.55 mL/kg (95%CI 1.36-1.75) 60 min 1.17 mL/kg (95%CI 1.01-1.33) 90 min 0.76 mL/kg (95%CI 0.67-0.85) 120 min 0.58 mL/kg (95%CI 0.52-0.65)
Individual results were not reported in the paper.
Take Home Message This study adds further support to liberal (1 hour) clear fluid guidelines for healthy, elective paediatric patients. By 60 minutes, patients had gastric volumes of less than 1.5mL/kg. The authors argue that previous papers have shown 1.5mL/kg confers “negligible risk for significant aspiration”. By 120 minutes, gastric volumes returned to normal.
Limitations to this study include small sample size, a fixed volume of clear fluid for all participants (rather than weight based), and no discussion on the sensitivity or specificity of the formula used to estimate gastric volume. Of note, there were two “outlier” participants with higher than expected volumes at 60 and 90 minutes, highlighting the variable nature of gastric emptying.
