A healthy 40-year-old man is scheduled for an elective abdominal hernia repair. He asks about drinking restrictions and chewing gum before surgery. ASA recently released a modular update to its 2017 practice guidelines for preoperative fasting. According to these updated guidelines, which of the following recommendations is BEST for this patient?
- □ (A) He is encouraged to drink carbohydrate-containing clear liquids until two hours before his procedure.
- □ (B) He is encouraged to drink protein-containing clear liquids until one hour before his procedure.
- □ (C) His surgery should be delayed if he is chewing gum on arrival.
Recently, ASA released a modular update to its 2017 practice guidelines for preoperative fasting. As with all ASA guidelines, these recommendations may be modified or adopted to fit the clinical needs and constraints of a local institution’s preexisting policies, or disregarded.
The current ASA Task Force on Preoperative Fasting not only reviewed the 2017 guidelines but also focused on four new elements: ingestion of carbohydrate-containing clear liquids, ingestion of protein-containing clear liquids, chewing gum, and duration of pediatric fasting (Table 1). The task force used high, moderate, low, and very low grades to define the strength of evidence compiled (Table 2). They also assigned a grade of strong or weak to their strength of recommendations. The task force assessed whether patients felt hunger or thirst and the occurrence of aspiration or regurgitation for each type of liquid consumed by patients.
Table 1: Recommendations from ASA Task Force on Preoperative Fasting. Used with permission, from Joshi GP, Abdelmalak BB, Weigel WA, et al. 2023 American Society of Anesthesiologists practice guidelines for preoperative fasting: carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration. A modular update of the 2017 American Society of Anesthesiologists practice guidelines for preoperative fasting (Anesthesiology 2023;138:132-51).
The types of carbohydrate-containing clear liquids were not specified in this article, but examples include energy drinks, soft drinks, and electrolyte-balanced drinks. The task force stated these drinks can contain simple or complex carbohydrates. Maltodextrin in water was given as an example of a complex carbohydrate. The task force also stated that healthy adult patients drinking carbohydrate-containing clear liquids two hours before elective surgery experienced less hunger or thirst than those who fasted or drank noncaloric clear liquids. Therefore, the task force recommended that healthy adults drink up to 400 mL of carbohydrate-containing clear liquids until two hours before elective procedures requiring general anesthesia, regional anesthesia, or procedural sedation. The strength of this recommendation was strong, and the strength of evidence was moderate (Tables 3 and 4). Of note, the benefits of any liquid, noncaloric or caloric, were very clearly superior to nothing by mouth. It is for this reason that the task force specifically worded their recommendation saying to ingest liquid up to two hours before surgery, which varies from previous wording not to ingest liquid less than two hours before surgery.
The task force did not recommend protein-containing clear liquids two hours before an elective procedure in healthy adults because of insufficient evidence. No benefit was found over carbohydrate-containing clear liquids. The strength of evidence was very low. The task force commented that patients who drank protein-containing clear liquids two hours before a procedure experienced less hunger or thirst than those who fasted or ingested clear liquids without carbohydrates.
Chewing gum before elective surgery was found to have a very low strength of evidence. Therefore, the task force did not make any recommendations except to suggest that a procedure should not be delayed in a healthy adult after confirming removal of chewing gum. Evidence was inconsistent regarding hunger or thirst in patients chewing gum compared to those fasting. Also, no clinically relevant increase in gastric volume or pH was observed, and aspiration was not reported.
The last area the task force evaluated was one-hour versus two-hour clear-liquid fasting in healthy pediatric patients before elective procedures. They did not find sufficient evidence regarding favorable or adverse outcomes to recommend changing the current guidelines from two hours to one hour of clear-liquid fasting. The task force suggested that the ingestion of clear liquids two hours before an elective procedure should be encouraged so as to minimize dehydration, hunger, and thirst.
In summary, for healthy adults having an elective procedure, the ASA Task Force on Preoperative Fasting reaffirmed the 2017 recommendations for ingestion of clear liquids two hours before a procedure and added carbohydrate-containing clear liquids to the recommendations. Compared to noncaloric clear liquids, these carbohydrate-containing clear liquids have been shown to reduce hunger or thirst. Since evidence was insufficient, the task force stated without recommendation that neither protein-containing liquids nor chewing gum appeared to benefit or harm healthy adult patients. However, they suggested not to delay an elective procedure in healthy patients chewing gum on arrival.