title: The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis.
abstract: OBJECTIVE
  To determine if preoperative gum chewing affects gastric pH and gastric fluid volume.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  Data sources included Cochrane, PubMed, and EMBASE databases from inception to June 2012 and reference lists of known relevant articles without language restriction. Randomized controlled trials in which a treatment group that chewed gum was compared to a control group that fasted were included. Relevant data, including main outcomes of gastric fluid volume and gastric pH, were extracted.
  
  
  RESULTS
  Four studies involving 287 patients were included. The presence of chewing gum was associated with small but statically significant increases in gastric fluid volume (mean difference = 0.21 mL/kg; 95% confidence interval, 0.02-0.39; P = .03) but not in gastric pH (mean difference = 0.11 mL/kg; 95% confidence interval, -0.14 to 0.36; P = .38). Gastric fluid volume and gastric pH remained unchanged in subgroup analysis by either sugar or sugarless gum type.
  
  
  CONCLUSIONS
  Chewing gum in the perioperative period causes small but statically significant increases in gastric fluid volume and no change in gastric pH. The increase in gastric fluid most likely is of no clinical significance in terms of aspiration risk for the patient. Elective surgery should not necessarily be canceled or delayed in healthy patients who accidentally chew gum preoperatively.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD. Electronic address: ouanes@jhmi.edu.
authors.forename: Jean-Pierre P
authors.initials: JP
authors.lastname: Ouanes
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD. Electronic address: bicket@jhmi.edu.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Bicket
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD. Electronic address: brandon@jhmi.edu.
authors.forename: Brandon
authors.initials: B
authors.lastname: Togioka
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD. Electronic address: vgarcia3@jhmi.edu.
authors.forename: Vicente Garcia
authors.initials: VG
authors.lastname: Tomas
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD. Electronic address: cwu3@jhmi.edu.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Wu
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD. Electronic address: jmurphy@jhmi.edu.
authors.forename: Jamie D
authors.initials: JD
authors.lastname: Murphy
mesh_terms: D002638:Chewing Gum; D005745:Gastric Acidity Determination; D005750:Gastric Juice / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D005766:Gastrointestinal Contents; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008409:Mastication / Q000502:physiology*; D057234:Preoperative Period
chemical_list: D002638:Chewing Gum
keywords: Chewing gum; Gastric pH; Gastric volume; Gastrointestinal contents; Meta-analysis; Systematic review