A Randomised Trial of Ultrasonographic Assessment of Gastric Emptying Following Water Ingestion in Healthy Volunteers

Background: Current guidance on pre-operative fasting for clear fluids to reduce aspiration risk may result in unnecessary dehydration and more liberal fluid regimes are being advocated. Methods: This randomised single blinded crossover study used an established ultrasound protocol to measure the gastric volume of 15 healthy volunteers following the 2011 European Society of Anaesthesia (ESA) ‘Perioperative Fasting in Adults and Children’ guidelines (nil-by-mouth two hours before induction of anaesthesia) and the 2005 Scandinavian guidelines (150 mL water with medication up to 1 hour before induction of anaesthesia). Results: We observed that gastric volumes increased following ingestion of water in all individuals compared to their fasted states. Water left the stomach within 30 minutes following ingestion in ten individuals, and within an hour in three individuals (gastric volume < 1.5 ml kg − 1 ). A reduction in thirst was observed in the group allowed to drink water, whereas hunger and anxiety scores were unaffected.