Gastric Residual Volumes in Infants Fed at 4 and 6 Hours Prior to General Anaesthesia

The safety implications of prolonged fasting in young children prior to general anaesthesia are well described. Current UK guidance recommends a fasting time of 6 hours for formula milk prior to general anaesthesia. European guidance published in 2022 recommended a reduced fast of 4 hours for infants taking formula milk, albeit with a downgraded level 2B of evidence given the paucity of high quality research in this area. Although pulmonary aspiration of gastric contents under anaesthesia in children is a rare event, animal studies suggest that aspiration of particulate matter at volumes greater than 0.8 ml/kg gastric volume are associated with demonstrable lung injury and mortality. Although rate of gastric emptying of formula preparations has been extensively studied in neonatal intensive care settings for preterm babies using ultrasound, few studies have measured gastric volume directly in healthy term infants undergoing anaesthesia.