title: Gastric emptying after overnight fasting and clear fluid intake: a prospective investigation using serial magnetic resonance imaging in healthy children.
abstract: 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 (GFV(w)/GAV(w)) and half-life (t(1/2)) of GFV(w) course after clear fluid intake were calculated.
  
  
  RESULTS
  Sixteen children, median age 9.2 (range 6.4-12.8) years, were investigated. Median (range) GFV(w) 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 GFV(w) declined exponentially (t(1/2)=26.1 min). Median individual t(1/2) was 23.6 (range 17.9-47.8) min. GAV(w) 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 <30 min but with considerable inter-individual variation.
authors.affiliation: Department of Anaesthesia, University Children’s Hospital, Steinwiesstrasse 75, CH 8032 Zurich, Switzerland. achim.schmitz@kispi.uzh.ch
authors.forename: A
authors.initials: A
authors.lastname: Schmitz
authors.forename: C J
authors.initials: CJ
authors.lastname: Kellenberger
authors.forename: R
authors.initials: R
authors.lastname: Liamlahi
authors.forename: M
authors.initials: M
authors.lastname: Studhalter
authors.forename: M
authors.initials: M
authors.lastname: Weiss
mesh_terms: D000293:Adolescent; D002648:Child; D004326:Drinking; D005215:Fasting / Q000502:physiology*; D005260:Female; D005746:Gastric Emptying; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011446:Prospective Studies