title: Gastric emptying of three liquid oral preoperative metabolic preconditioning regimens measured by magnetic resonance imaging in healthy adult volunteers: a randomised double-blind, crossover study.
abstract: OBJECTIVE
  Preoperative starvation has many undesirable effects but the minimum length of fasting is limited by gastric emptying, which may be dependent on nutrient content, viscosity and osmolarity of the feed. We compared the gastric emptying of two types of preoperative metabolic preconditioning drinks [Oral Nutritional Supplement (ONS) (Fresenius Kabi, Germany) and preOp (Nutricia Clinical Care, UK)] in healthy volunteers.
  
  
  METHODS
  Twenty (10 male, 10 female) healthy adult volunteers were studied on 3 separate occasions in a randomised crossover manner. Volunteers ingested 400 ml preOp, which is a clear carbohydrate drink (CCD) (50 g carbohydrate, 0 g protein), 70 g ONS (50 g carbohydrate and 15 g glutamine) dissolved in water to a total volume of 400 ml (ONS400) and 300 ml (ONS300). Gastric emptying time was measured using magnetic resonance imaging.
  
  
  RESULTS
  Mean (95% CI) T(50) and T(100) gastric emptying times for CCD were significantly lower (p<0.001) compared with ONS400 and ONS300. T(50) was 47 (39-55), 78 (69-87) and 81 (70-92)min for CCD, ONS400 and ONS300 respectively. Correspondingly T(100) was 94 (79-110), 156 (138-173) and 162 (140-184)min. Residual gastric volumes returned to baseline 120 min after CCD and 180 min after ONS400 and ONS300.
  
  
  CONCLUSIONS
  The faster gastric emptying for CCD compared to ONS400 and ONS300 signifies that gastric emptying may be more dependent on nutrient load than volume or viscosity in healthy volunteers. While it is safe to give CCD 2h preoperatively, ONS400 and ONS300 should be given at least 3h preoperatively.
authors.affiliation: Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham, UK. dileep.lobo@nottingham.ac.uk
authors.forename: Dileep N
authors.initials: DN
authors.lastname: Lobo
authors.forename: Paul O
authors.initials: PO
authors.lastname: Hendry
authors.forename: Gabriel
authors.initials: G
authors.lastname: Rodrigues
authors.forename: Luca
authors.initials: L
authors.lastname: Marciani
authors.forename: John J
authors.initials: JJ
authors.lastname: Totman
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Wright
authors.forename: Tom
authors.initials: T
authors.lastname: Preston
authors.forename: Penny
authors.initials: P
authors.lastname: Gowland
authors.forename: Robin C
authors.initials: RC
authors.lastname: Spiller
authors.forename: Kenneth C H
authors.initials: KC
authors.lastname: Fearon
mesh_terms: D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D003681:Dehydration / Q000517:prevention & control; D019587:Dietary Supplements / Q000706:statistics & numerical data; D004311:Double-Blind Method; D005260:Female; D005746:Gastric Emptying; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D012727:Sex Characteristics; D013997:Time Factors; D055815:Young Adult