Gastric emptying after overnight fasting and clear fluid intake: a prospective investigation using serial magnetic resonance imaging in healthy children†

Background Current guidelines recommend preoperative fasting of 2 h for clear fluids, which is often exceeded in routine clinical practice. Existing data on residual gastric volumes in children do not consider fluid intake within <2 h and rely on the aspiration of gastric contents via a gastric tube. This study evaluated the emptying of clear fluids from the stomach using magnetic resonance imaging (MRI). Methods Healthy volunteers aged 6-14 years were asked to fast overnight. MRI scans to assess gastric volumes were obtained before and immediately after drinking 7 ml kg−1 of diluted raspberry syrup and then every 30 min up to 120 min. Volumes were determined by a blinded investigator and indexed gastric fluid/air volumes (GFVw/GAVw) and half-life (t1/2) of GFVw course after clear fluid intake were calculated. Results Sixteen children, median age 9.2 (range 6.4-12.8) years, were investigated. Median (range) GFVw was 0.62 (0.15-0.97) ml kg−1 before and 6.68 (4.77-7.78) ml kg−1 immediately after fluid intake, and 2.92 (0.43-5.04), 1.27 (0.28-3.62), 0.42 (0.07-2.49), and 0.32 (0.04-1.13) ml kg−1 30, 60, 90, and 120 min thereafter. Median GFVw declined exponentially (t1/2=26.1 min). Median individual t1/2 was 23.6 (range 17.9-47.8) min. GAVw showed considerable intra- and inter-individual variation. Conclusions In healthy school children, gastric emptying after ingestion of clear fluid occurs with a median half-life time of