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 Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration

Anesthesiology. 2017;126(3):376-393. 

In This Article

Guidelines

Preoperative Assessment

A preoperative assessment includes a review of medical records, a physical examination, and a patient survey or interview. No controlled trials were found that address the impact of conducting a review of medical records, physical examination, or survey/interview on the frequency or severity of perioperative pulmonary aspiration of gastric contents. Observational studies indicate that some predisposing patient conditions (e.g., age, sex, ASA physical status, emergency surgery) may be associated with the risk of perioperative aspiration (Category B2-H evidence). [1–5] Observational studies addressing other predisposing conditions (e.g., obesity, diabetes, esophageal reflux, smoking history) report inconsistent findings regarding risk of aspiration (Category B1-E evidence).[6–11]

The consultants and ASA members strongly agree that a review of pertinent medical records, a physical examination, and patient survey or interview should be performed as part of the preoperative evaluation. They also strongly agree that patients should be informed of fasting requirements and the reasons for them sufficiently in advance of their procedures. In addition, both the consultants and ASA members strongly agree that verification of their compliance with the fasting requirements should be assessed at the time of the procedure.

Recommendations for Preoperative Assessment

  • Perform a review of pertinent medical records, a physical examination, and patient survey or interview as part of the preoperative evaluation.

    • The history, examination, and interview should include assessment of ASA physical status, age, sex, type of surgery, and potential for difficult airway management as well as consideration of gastroesophageal reflux disease,†† dysphagia symptoms, other gastrointestinal motility and metabolic disorders (e.g., diabetes mellitus) that may increase the risk of regurgitation and pulmonary aspiration.

  • Inform patients of fasting requirements and the reasons for them sufficiently in advance of their procedures.

  • Verify patient compliance with fasting requirements at the time of their procedure.

  • When these fasting guidelines are not followed, compare the risks and benefits of proceeding, with consideration given to the amount and type of liquids or solids ingested.

Preoperative Fasting of Clear Liquids. Meta-analysis of RCTs comparing fasting times of 2 to 4 h versus more than 4 h report equivocal findings for gastric volume and gastric pH values in adult patients given clear liquids 2 to 4 h before a procedure (Category A1-E evidence).[12–21] RCTs reported less thirst and hunger for fasting times of 2 to 4 h versus more than 4 h (Category A2-B evidence).[12,13,19,22–24] Similarly, RCTs comparing nutritional or carbohydrate drinks at 2 to 4 h versus more than 4 h of fasting report equivocal findings for gastric volume, gastric pH, blood glucose values, hunger, and thirst (Category A2-E evidence).[15,21,24–32] A meta-analysis of RCTs reports a lower risk of aspiration (i.e., gastric volume < 25 mL and pH > 2.5) when clear liquids are given 2 to 4 h before a procedure (Category A1-B evidence).[12,13,16,17,19,20]

Meta-analysis of RCTs report higher gastric pH values (Category A1-B evidence) and equivocal findings regarding differences in gastric volume (Category A1-E evidence) for children given clear liquids 2 to 4 h versus fasting for more than 4 h before a procedure.[33–42] Ingested volumes of clear liquids in the above studies range from 100 ml to unrestricted amounts for adults, and 2 ml/kg to unrestricted amounts for children. One randomized controlled trial comparing 2 h fasting with fasting from midnight reported equivocal findings for blood glucose and insulin values (Category A3-E evidence).[43]

Both the consultants and ASA members strongly agree that for otherwise healthy infants (< 2 yr of age), children (2 to 16 yr of age) and adults, fasting from the intake of clear liquids for 2 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained.

Recommendations for Clear Liquids

  • Clear liquids‡‡ may be ingested for up to 2 h before procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia.

  • These liquids should not include alcohol.

Preoperative Fasting of Breast Milk. The literature is insufficient to evaluate the effect of timing of the ingestion of breast milk and the perioperative incidence of pulmonary aspiration, gastric volume, pH, or emesis/reflux. Nonrandomized comparative studies assessing the impact of ingesting breast milk before a procedure are equivocal for gastric volume or pH when compared with the ingestion or clear liquids or infant formula (Category B1-E evidence).[44–46]

The consultants agree and the ASA members strongly agree that for otherwise healthy neonates (< 44 gestational weeks) and infants, fasting from the intake of breast milk for 4 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained.

Recommendations for Breast Milk

  • Breast milk may be ingested for up to 4 h before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia.

Preoperative Fasting of Infant Formula. The literature is insufficient to evaluate the effect of timing of the ingestion of infant formula on the perioperative incidence of pulmonary aspiration, gastric volume, pH or emesis/reflux.

Both the consultants and ASA members agree that for neonates and infants, fasting from the intake of infant formula for 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained. The consultants agree and the ASA members strongly agree that for children, fasting from the intake of infant formula for 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained.

Recommendations for Infant Formula

  • Infant formula may be ingested for up to 6 h before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia.

Preoperative Fasting of Solids and Nonhuman Milk. An RCT comparing a light breakfast consumed less than 4 h before a procedure with overnight fasting reports equivocal findings for gastric volume and pH levels for adults (Category A3-E evidence).[47] A second RCT reports equivocal findings when a light breakfast is allowed at 4 h compared with 6 h before a cesarean section (Category A3-E evidence), although a significant reduction in maternal and neonatal blood glucose levels was reported when fasting was extended beyond 6 h (Category A3-H evidence).[48] Nonrandomized comparative studies for children given nonhuman milk 4 h or less before a procedure versus children fasted for more than 4 h report equivocal findings for gastric volume and pH (Category B1-E evidence).[49–51] One nonrandomized study indicated that fasting for more than 8 h may be associated with significantly lower blood glucose levels (Category B1-H evidence).[51] The literature is insufficient to evaluate the effect of the timing of ingestion of solids and nonhuman milk and the perioperative incidence of pulmonary aspiration or emesis/reflux. Although the literature is insufficient to evaluate the influence of preoperatively adding milk or milk products to clear liquids (e.g., tea or coffee) on either pulmonary aspiration, gastric volume, pH, or gastric emptying, some studies with healthy volunteer subjects have reported equivocal findings for gastric volume and gastric emptying when these products are added to clear liquids.[52–54]

The consultants agree and the ASA members strongly agree that fasting from the intake of a light meal (e.g., toast and a clear liquid) of 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained. Both the consultants and ASA members strongly agree that fasting from the intake of a meal that includes fried or fatty foods for 8 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained.

Both the consultants and ASA members agree that for infants, fasting from the intake of nonhuman milk for 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained. The consultants agree and the ASA members strongly agree that for children and adults, fasting from the intake of nonhuman milk for 6 or more hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia should be maintained.

Recommendations for Solids and Nonhuman Milk

  • A light meal or nonhuman milk may be ingested for up to 6 h before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia.§§

    • Additional fasting time (e.g., 8 or more hours) may be needed in cases of patient intake of fried foods, fatty foods, or meat.

  • Consider both the amount and type of foods ingested when determining an appropriate fasting period.

  • Since nonhuman milk is similar to solids in gastric emptying time, consider the amount ingested when determining an appropriate fasting period.

Preoperative Gastrointestinal Stimulants. Meta-analysis of placebo-controlled RCTs indicate that metoclopramide is effective in reducing gastric volume and pH during the perioperative period (Category A1-B evidence).[55–60] The literature is insufficient to evaluate the effect of metoclopramide on the perioperative incidence of pulmonary aspiration.***

Both the consultants and ASA members disagree that gastrointestinal stimulants should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia in patients with no apparent increased risk for pulmonary aspiration.

Recommendations for Gastrointestinal Stimulants

  • Gastrointestinal stimulants may be preoperatively administered to patients at increased risk of pulmonary aspiration.

  • Do not routinely administer preoperative gastrointestinal stimulants for the purpose of reducing the risk of pulmonary aspiration in patients with no apparent increased risk for pulmonary aspiration.

Preoperative Pharmacologic Blockade of Gastric Acid Secretion . Histamine-2 Receptor Antagonists: Meta-analysis of blinded placebo-controlled RCTs indicate that orally-administered ranitidine is effective in reducing gastric volume and acidity; the frequency of gastric volume > 25 mL; the frequency of gastric pH levels < 2.5; and the risk of aspiration (i.e., gastric volume > 25 mL and pH < 2.5) during the perioperative period (Category A1-B evidence). [56,61–70] Placebo-controlled RCTs of intravenous ranitidine report similar results for gastric pH (Category A2-B evidence) and equivocal findings for gastric volume (Category A2-E evidence).[66,71–74]

Meta-analysis of placebo-controlled RCTs indicate that orally-administered cimetidine is effective in reducing gastric volume and acidity; the frequency of gastric volume > 25 mL; the frequency of gastric pH levels < 2.5; and the risk of aspiration (i.e., gastric volume > 25 mL and pH < 2.5) during the perioperative period (Category A1-B evidence).[58,59,66,75–87] Placebo-controlled RCTs of intravenous cimetidine report similar results for gastric pH (Category A2-B evidence), but equivocal findings for gastric volume (Category A2-E evidence).[60,66,71,78,88]

Placebo-controlled RCTs indicate that orally-administered famotidine is effective in reducing gastric volume and acidity during the perioperative period (Category A2-B evidence).[64,89–91] One placebo-controlled RCT reports similar findings for intramuscular famotidine (Category A3-B evidence).[92] The literature is insufficient to evaluate the effect of administering histamine-2 receptor antagonists on perioperative pulmonary aspiration or emesis/reflux.

Proton Pump Inhibitors: Meta-analysis of placebo-controlled RCTs indicate that omeprazole is effective in reducing gastric volume and acidity (Category A1-B evidence).[63,67,93–95] RCTs report similar findings for lansoprazole (Category A2-B evidence),[67,68,96,97] pantoprazole (Category A2-B evidence),[63,73,98] and rabeprazole (Category A3-B evidence).[68] The literature is insufficient to evaluate the effect of administering proton pump inhibitors on perioperative pulmonary aspiration or emesis/reflux.

Both the consultants and ASA members disagree that histamine-2 receptor antagonists should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia in patients with no apparent increased risk for pulmonary aspiration. ASA members disagree and the consultants strongly disagree that proton pump inhibitors should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia in patients with no apparent increased risk for pulmonary aspiration

Recommendations for Pharmacologic Blockade of Gastric Acid Secretion

  • Medications that block gastric acid secretion may be preoperatively administered to patients at increased risk of pulmonary aspiration.

  • Do not routinely administer preoperative medications that block gastric acid secretion for the purpose of reducing the risk of pulmonary aspiration in patients with no apparent increased risk for pulmonary aspiration.

Preoperative Antacids. Placebo-controlled RCTs indicate that preoperative antacids (e.g., sodium citrate or magnesium trisilicate) increase gastric pH during the perioperative period [57,79,99–101] (Category A2-B evidence), with inconsistent (i.e., equivocal) findings regarding gastric volume (Category A2-E evidence).[57,79,99–101] The literature is insufficient to examine the effect of administering preoperative antacids on aspiration or emesis/reflux.

The consultants and ASA members both disagree that preoperative antacids should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia in patients with no apparent increased risk for pulmonary aspiration. The consultants and ASA members both strongly agree that, when antacids are indicated for selected patients, only nonparticulate antacids should be used.

Recommendations for Antacids

  • Antacids may be preoperatively administered to patients at increased risk of pulmonary aspiration.

    • Only administer nonparticulate antacids.

  • Do not routinely administer preoperative antacids for the purpose of reducing the risk of pulmonary aspiration in patients with no apparent increased risk for pulmonary aspiration.

Preoperative Antiemetics. The literature is insufficient to evaluate the effect of preoperative antiemetics on the perioperative incidence of pulmonary aspiration, gastric volume, or pH.†††

The consultants and ASA members both disagree that preoperative antiemetics should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia in patients with no apparent increased risk for pulmonary aspiration.

Recommendations for Antiemetics‡‡‡

  • Antiemetics may be preoperatively administered to patients at increased risk of postoperative nausea and vomiting.

  • The routine preoperative administration of antiemetics to reduce the risk of nausea and vomiting is not recommended for patients with no apparent increased risk for pulmonary aspiration.

Preoperative Anticholinergics. Placebo-controlled RCTs are equivocal regarding the efficacy of glycopyrrolate to reduce gastric volume or acidity (Category A2-E evidence),[83,102] and two nonrandomized placebo-controlled comparative studies report equivocal findings the efficacy of atropine on gastric volume and acidity (Category B1-E evidence).[103,104]

The ASA members disagree and the consultants strongly disagree that preoperative anticholinergics should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia to decrease the risk of pulmonary aspiration.

Recommendations for Anticholinergics

  • The administration of preoperative anticholinergics to reduce the risk of pulmonary aspiration is not recommended.

Preoperative Multiple Agents. RCTs report equivocal findings for gastric volume and acidity when histamine-2 receptor antagonists (i.e., cimetidine, ranitidine) are combined with gastrointestinal stimulants (i.e., metoclopramide) compared with either drug alone (Category A2-E evidence).[56,58–60,105–107] RCTs comparing histamine-2 receptor antagonists or metoclopramide with sodium citrate report equivocal findings for gastric volume and acidity (Category A2-E evidence).[57,106]

The ASA members disagree and the consultants strongly disagree that preoperative multiple agents should be routinely administered before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia in patients with no apparent risk for pulmonary aspiration.

Recommendations for Multiple Agents

  • The routine administration of preoperative multiple agents is not recommended for patients with no apparent increased risk for pulmonary aspiration.

††The term "gastroesophageal reflux disease" refers to positional reflux and its consequent symptomology, rather than food intolerances (e.g., "tomatoes do not agree with me").
‡‡Examples of clear liquids include, but are not limited to, water, and fruit juices without pulp, carbonated beverages, carbohydrate-rich nutritional drinks, clear tea, and black coffee.
§§The Task Force notes that intake of fried or fatty foods or meat may prolong gastric emptying time.
***Evidentiary information and recommendations regarding the administration of preoperative gastrointestinal stimulants and postoperative nausea and vomiting findings may be found in: Practice guidelines for postanesthetic care: An updated report by the American Society of Anesthesiologists Task Force on Postanesthetic Care. ANESTHESIOLOGY 2013; 118:291–307.
†††Evidentiary information and recommendations regarding the administration of preoperative antiemetics and postoperative nausea and vomiting may be found in: Practice guidelines for postanesthetic care: An updated report by the American Society of Anesthesiologists Task Force on Postanesthetic Care. ANESTHESIOLOGY 2013; 118:291–307.
‡‡‡These guidelines do not address the use of antiemetics during the extended postoperative period after upper airway protective reflexes are no longer impaired.

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