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Copyright © 2014 Dear Consult Guys; We were hanging out in the preadmission testing center the other day when a woman was being given instructions prior to colonoscopy to be done next week under general anesthesia. Her procedure was to be done in the afternoon and she was told not to have anything to eat or drink from midnight the night before. I thought that our policy was incorrect and that she could undergo general anesthesia 4-6 hours after clear liquids. One of the other guys said that general anesthesia is safe when done after only a 2 hour fast following clear liquids. Is our policy incorrect based on the evidence? Dear Consult Guys; We were hanging out in the preadmission testing center the other day when a woman was being given instructions prior to colonoscopy to be done next week under general anesthesia. Her procedure was to be done in the afternoon and she was told not to have anything to eat or drink from midnight the night before. I thought that our policy was incorrect and that she could undergo general anesthesia 4-6 hours after clear liquids. One of the other guys said that general anesthesia is safe when done after only a 2 hour fast following clear liquids. Is our policy incorrect based on the evidence?

Copyright © 2014 Fast from midnight (“NPO after midnight”) Six hour fast Four hour fast Two hour fast NPO (non-nil per os)

Copyright © 2014 Hint for Audience “While it is desirable that there be no solid matter in the stomach when chloroform is administered, it will be found very salutary to give a cup of tea or beef-tea about two hours previously.” Lord Joseph Lister, 1882

Copyright © 2014  1946: Mendelson. High incidence of pulmonary aspiration among OB patients receiving general anesthesia  Animal data: lung injury related to volume of aspirate and decreased pH  Recent data: Pulmonary aspiration rare.  Fasting can lead to dehydration, hypovolemia, hypoglycemia Key Points

Copyright © 2014

Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration (Am Soc of Anesthesiologists, 1999) Pulmonary aspiration is rare Little relation between fasting duration and gastric volume or pH Prolonged fasting may have adverse effects Liquids and solids are eliminated differently from the stomach

Copyright © 2014 Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration (Am Soc of Anesthesiologists, 2010) Minimum preoperative fasting for healthy people  Clear liquids – two hours  Water, fruit juice without pulp, clear tea, black coffee  Light meal (toast + liquid) – six hours  Regular meal (fried or fatty food) – eight hours

Copyright © 2014 Consult Guys Replies Clear liquids safe up to two hours before general anesthesia

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