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Preoperative fasting guidelines

Marianna Crowley, MD
Section Editor
Natalie F Holt, MD, MPH
Deputy Editor
Nancy A Nussmeier, MD, FAHA


Pulmonary aspiration of gastric or oropharyngeal contents during anesthesia is a rare event, but one with significant morbidity and mortality [1]. Fasting guidelines for patients having anesthesia attempt to reduce the risk of aspiration and the severity of the pulmonary effects should aspiration occur.

Fasting guidelines are based on gastric physiology and expert opinion, as there is limited evidence that these improve outcomes [2]. Because worse outcomes may be associated with aspiration of particulate matter, of acidic contents, and of large volumes of gastric contents, guidelines aim to eliminate particulate matter and decrease the volume and acidity of gastric contents at the time of induction of anesthesia [3].

Preanesthesia fasting guidelines apply to patients having elective surgery and are intended for procedures performed under general anesthesia, regional anesthesia, and monitored anesthesia care. Aspiration may occur during all types of anesthesia in non-fasted patients, because anesthetic and sedative medications reduce or eliminate airway protective reflexes that normally prevent regurgitated gastric contents from entering the lungs [4].

The rationale and recommendations for preoperative fasting are reviewed here. Anesthetic strategies for avoidance of aspiration, the management of patients who have not fasted, and the fasting duration of patients having urgent or emergent procedures are discussed separately. (See "Rapid sequence induction and intubation (RSII) for anesthesia" and "General anesthesia: Induction".)


Recommendations that oral intake of liquids and solids be restricted for varying times prior to anesthesia aim to minimize gastric volume at the time of surgery. Various types of material empty from the stomach at different rates. While experts believe that restricting oral intake will decrease aspiration, gastric volume is a surrogate endpoint used in clinical studies because the incidence of aspiration is low.


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Literature review current through: Sep 2016. | This topic last updated: Jul 19, 2016.
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  1. Warner MA, Warner ME, Weber JG. Clinical significance of pulmonary aspiration during the perioperative period. Anesthesiology 1993; 78:56.
  2. Schreiner MS. Gastric fluid volume: is it really a risk factor for pulmonary aspiration? Anesth Analg 1998; 87:754.
  3. James CF, Modell JH, Gibbs CP, et al. Pulmonary aspiration--effects of volume and pH in the rat. Anesth Analg 1984; 63:665.
  4. Caplan RA, Posner KL, Ward RJ, Cheney FW. Adverse respiratory events in anesthesia: a closed claims analysis. Anesthesiology 1990; 72:828.
  5. HUNT JN. Some properties of an alimentary osmoreceptor mechanism. J Physiol 1956; 132:267.
  6. Nygren J, Thorell A, Jacobsson H, et al. Preoperative gastric emptying. Effects of anxiety and oral carbohydrate administration. Ann Surg 1995; 222:728.
  7. Sutherland AD, Stock JG, Davies JM. Effects of preoperative fasting on morbidity and gastric contents in patients undergoing day-stay surgery. Br J Anaesth 1986; 58:876.
  8. Agarwal A, Chari P, Singh H. Fluid deprivation before operation. The effect of a small drink. Anaesthesia 1989; 44:632.
  9. Maltby JR, Sutherland AD, Sale JP, Shaffer EA. Preoperative oral fluids: is a five-hour fast justified prior to elective surgery? Anesth Analg 1986; 65:1112.
  10. McGrady EM, Macdonald AG. Effect of the preoperative administration of water on gastric volume and pH. Br J Anaesth 1988; 60:803.
  11. Hutchinson A, Maltby JR, Reid CR. Gastric fluid volume and pH in elective inpatients. Part I: Coffee or orange juice versus overnight fast. Can J Anaesth 1988; 35:12.
  12. Phillips S, Hutchinson S, Davidson T. Preoperative drinking does not affect gastric contents. Br J Anaesth 1993; 70:6.
  13. Awad S, Blackshaw PE, Wright JW, et al. A randomized crossover study of the effects of glutamine and lipid on the gastric emptying time of a preoperative carbohydrate drink. Clin Nutr 2011; 30:165.
  14. Lobo DN, Hendry PO, Rodrigues G, et al. 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. Clin Nutr 2009; 28:636.
  15. Brady M, Kinn S, Stuart P. Preoperative fasting for adults to prevent perioperative complications. Cochrane Database Syst Rev 2003; :CD004423.
  16. Hausel J, Nygren J, Lagerkranser M, et al. A carbohydrate-rich drink reduces preoperative discomfort in elective surgery patients. Anesth Analg 2001; 93:1344.
  17. Houghton LA, Mangnall YF, Read NW. Effect of incorporating fat into a liquid test meal on the relation between intragastric distribution and gastric emptying in human volunteers. Gut 1990; 31:1226.
  18. Edelbroek M, Horowitz M, Maddox A, Bellen J. Gastric emptying and intragastric distribution of oil in the presence of a liquid or a solid meal. J Nucl Med 1992; 33:1283.
  19. Hillyard S, Cowman S, Ramasundaram R, et al. Does adding milk to tea delay gastric emptying? Br J Anaesth 2014; 112:66.
  20. American Society of Anesthesiologists Committee. Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures: an updated report by the American Society of Anesthesiologists Committee on Standards and Practice Parameters. Anesthesiology 2011; 114:495.
  21. Smith I, Kranke P, Murat I, et al. Perioperative fasting in adults and children: guidelines from the European Society of Anaesthesiology. Eur J Anaesthesiol 2011; 28:556.
  22. Søreide E, Eriksson LI, Hirlekar G, et al. Pre-operative fasting guidelines: an update. Acta Anaesthesiol Scand 2005; 49:1041.
  23. Moore JG, Christian PE, Coleman RE. Gastric emptying of varying meal weight and composition in man. Evaluation by dual liquid- and solid-phase isotopic method. Dig Dis Sci 1981; 26:16.
  24. Bennink R, Peeters M, Van den Maegdenbergh V, et al. Comparison of total and compartmental gastric emptying and antral motility between healthy men and women. Eur J Nucl Med 1998; 25:1293.
  25. Datz FL, Christian PE, Moore J. Gender-related differences in gastric emptying. J Nucl Med 1987; 28:1204.
  26. Clegg M, Shafat A. Energy and macronutrient composition of breakfast affect gastric emptying of lunch and subsequent food intake, satiety and satiation. Appetite 2010; 54:517.
  27. Evans MA, Triggs EJ, Cheung M, et al. Gastric emptying rate in the elderly: implications for drug therapy. J Am Geriatr Soc 1981; 29:201.
  28. Søreide E, Hausken T, Søreide JA, Steen PA. Gastric emptying of a light hospital breakfast. A study using real time ultrasonography. Acta Anaesthesiol Scand 1996; 40:549.
  29. Nespoli L, Coppola S, Gianotti L. The role of the enteral route and the composition of feeds in the nutritional support of malnourished surgical patients. Nutrients 2012; 4:1230.
  30. Orozco-Levi M, Torres A, Ferrer M, et al. Semirecumbent position protects from pulmonary aspiration but not completely from gastroesophageal reflux in mechanically ventilated patients. Am J Respir Crit Care Med 1995; 152:1387.
  31. Kollef MH, Von Harz B, Prentice D, et al. Patient transport from intensive care increases the risk of developing ventilator-associated pneumonia. Chest 1997; 112:765.
  32. Jiyong J, Tiancha H, Huiqin W, Jingfen J. Effect of gastric versus post-pyloric feeding on the incidence of pneumonia in critically ill patients: observations from traditional and Bayesian random-effects meta-analysis. Clin Nutr 2013; 32:8.
  33. Dubin SA, Jense HG, McCranie JM, Zubar V. Sugarless gum chewing before surgery does not increase gastric fluid volume or acidity. Can J Anaesth 1994; 41:603.
  34. Søreide E, Holst-Larsen H, Veel T, Steen PA. The effects of chewing gum on gastric content prior to induction of general anesthesia. Anesth Analg 1995; 80:985.
  35. Ouanes JP, Bicket MC, Togioka B, et al. The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis. J Clin Anesth 2015; 27:146.
  36. Merchant R, Chartrand D, Dain S, et al. Guidelines to the Practice of Anesthesia--Revised Edition 2014. Can J Anaesth 2014; 61:46.
  37. Association of Anaesthetists of Great Britain and Ireland. AAGBI safety guideline. Pre-operative assessment and patient preparation. The role of the anaesthetist. January 2010. London. http://www.aagbi.org/sites/default/files/preop2010.pdf (Accessed on June 27, 2011).
  38. Verbankdmitteilung DGAI. Praoperaives Nuchternheitsdebot bei Elektiven Eingriffen. Anesthesiol Intensivmed 2004; 12:722.
  39. Dennhardt N, Beck C, Huber D, et al. Impact of preoperative fasting times on blood glucose concentration, ketone bodies and acid-base balance in children younger than 36 months: A prospective observational study. Eur J Anaesthesiol 2015; 32:857.
  40. Dennhardt N, Beck C, Huber D, et al. Optimized preoperative fasting times decrease ketone body concentration and stabilize mean arterial blood pressure during induction of anesthesia in children younger than 36 months: a prospective observational cohort study. Paediatr Anaesth 2016; 26:838.
  41. Splinter WM, Stewart JA, Muir JG. The effect of preoperative apple juice on gastric contents, thirst, and hunger in children. Can J Anaesth 1989; 36:55.
  42. Splinter WM, Schaefer JD. Unlimited clear fluid ingestion two hours before surgery in children does not affect volume or pH of stomach contents. Anaesth Intensive Care 1990; 18:522.
  43. Splinter WM, Stewart JA, Muir JG. Large volumes of apple juice preoperatively do not affect gastric pH and volume in children. Can J Anaesth 1990; 37:36.
  44. Brady M, Kinn S, Ness V, et al. Preoperative fasting for preventing perioperative complications in children. Cochrane Database Syst Rev 2009; :CD005285.
  45. Song IK, Kim HJ, Lee JH, et al. Ultrasound assessment of gastric volume in children after drinking carbohydrate-containing fluids. Br J Anaesth 2016; 116:513.
  46. Litman RS, Wu CL, Quinlivan JK. Gastric volume and pH in infants fed clear liquids and breast milk prior to surgery. Anesth Analg 1994; 79:482.
  47. Cavell B. Gastric emptying in preterm infants. Acta Paediatr Scand 1979; 68:725.
  48. Cavell B. Gastric emptying in infants fed human milk or infant formula. Acta Paediatr Scand 1981; 70:639.
  49. O'Hare B, Lerman J, Endo J, Cutz E. Acute lung injury after instillation of human breast milk or infant formula into rabbits' lungs. Anesthesiology 1996; 84:1386.
  50. Chin C, Lerman J, Endo J. Acute lung injury after tracheal instillation of acidified soya-based or Enfalac formula or human breast milk in rabbits. Can J Anaesth 1999; 46:282.
  51. Wright RA, Krinsky S, Fleeman C, et al. Gastric emptying and obesity. Gastroenterology 1983; 84:747.
  52. Glasbrenner B, Pieramico O, Brecht-Krauss D, et al. Gastric emptying of solids and liquids in obesity. Clin Investig 1993; 71:542.
  53. Cardoso-Júnior A, Coelho LG, Savassi-Rocha PR, et al. Gastric emptying of solids and semi-solids in morbidly obese and non-obese subjects: an assessment using the 13C-octanoic acid and 13C-acetic acid breath tests. Obes Surg 2007; 17:236.
  54. Jackson SJ, Leahy FE, McGowan AA, et al. Delayed gastric emptying in the obese: an assessment using the non-invasive (13)C-octanoic acid breath test. Diabetes Obes Metab 2004; 6:264.
  55. Zahorska-Markiewicz B, Jonderko K, Lelek A, Skrzypek D. Gastric emptying in obesity. Hum Nutr Clin Nutr 1986; 40:309.
  56. Macfie AG, Magides AD, Richmond MN, Reilly CS. Gastric emptying in pregnancy. Br J Anaesth 1991; 67:54.
  57. Wong CA, Loffredi M, Ganchiff JN, et al. Gastric emptying of water in term pregnancy. Anesthesiology 2002; 96:1395.
  58. Wong CA, McCarthy RJ, Fitzgerald PC, et al. Gastric emptying of water in obese pregnant women at term. Anesth Analg 2007; 105:751.
  59. Scrutton MJ, Metcalfe GA, Lowy C, et al. Eating in labour. A randomised controlled trial assessing the risks and benefits. Anaesthesia 1999; 54:329.
  60. Feldman M, Smith HJ, Simon TR. Gastric emptying of solid radiopaque markers: studies in healthy subjects and diabetic patients. Gastroenterology 1984; 87:895.