Gastric fluid volume and pH in elective inpatients. Part I: Coffee or orange juice versus overnight fast

Can J Anaesth. 1988 Jan;35(1):12-5. doi: 10.1007/BF03010537.


In order to assess the effect of preoperative oral fluids, with and without ranitidine, on gastric fluid volume and pH, 300 elective surgical inpatients, ASA physical status I or II, were randomly assigned to one of six groups. The three groups that received placebo are discussed in this paper, Part I, and the three that received ranitidine in Part II. Between two and three hours before the scheduled time of surgery patients received either 150 ml coffee (Group 1), or 150 ml orange juice (Group 2), while the control group continued their overnight fast (Group 3). No opiate or belladonna premedication was given. Immediately following induction of anaesthesia the residual gastric fluid was obtained by suction on a nasogastric tube and its volume and pH measured. Residual gastric fluid volumes showed no statistically significant differences among the groups (Group 1: 24.5 +/- 21.6 ml; Group 2: 23.7 +/- 18.4 ml; Group 3: 23.2 +/- 17.3 ml; p greater than 0.1). Values for pH among the groups were also similar (Group 1: 2.18 +/- 1.58; Group 2: 1.95 +/- 1.24; Group 3: 1.95 +/- 1.62; p greater than 0.1).

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Beverages / adverse effects*
  • Citrus
  • Coffee / adverse effects
  • Fasting / adverse effects
  • Gastric Acid*
  • Gastric Juice*
  • Humans
  • Hunger
  • Middle Aged
  • Preoperative Care / methods*
  • Random Allocation
  • Thirst


  • Coffee