Gastric emptying for liquids of different compositions in children

Background. Pre-operative fasting balances safety against patient discomfort. We compared the gastric emptying profiles of a novel clear, high protein drink against a traditional clear and a non-clear fluid. Methods. We conducted a prospective cross-sectional study with 48 healthy volunteers, eight to 14 yr of age, fasted overnight and without risk factors for abnormal gastrointestinal motility. Subjects were randomized in equal ratio to ingest 296 ml of apple juice, 2% milk or Ensure Clear. The gastric antrum was seen by ultrasound in the right lateral decubitus position at baseline, after ingestion, then every 30 min thereafter until return to baseline or six h. Gastric antral cross-sectional area was measured independently by two anaesthetists, and compared between drinks. Results. Gastric emptying differed between apple juice, 2% milk and Ensure Clear by analysis of co-variance (P<0.0001), and was faster in males than females (P<0.01). The terminal phase however was similar using interval-censored time to gastric emptying in a survival model (P=0.17) or by comparing proportions with empty stomach vs not empty at 90 min (P=1.0), 120 min (P=0.32), 150 min (P=0.11), 180 min (P=0.76) or 210 min (P=1.0). Conclusions. Despite early differences, clearance from the stomach of apple juice, 2% milk or Ensure Clear is similar at the terminal phase, which is the period of greatest relevance to preoperative fasting recommendations. The stomach is essentially clear by 3-3.5 h for all three drinks studied. The differentiation between liquids in current guidelines is not supported by this study.