Pre-operative fasting is one of the longest-held medical dogmas. New Enhanced Recovery After Surgery (ERAS) protocols have challenged these fasting guidelines. But what about patients who receive tube feeding? How do we apply the new pre-op fasting guidelines to them? And is there ever a scenario when intraoperative feeding is appropriate? We combed the research to find out.
Let’s review the ASA fasting guidelines
The American Society of Anesthesiologists (ASA) sets the standards when it comes to pre-op fasting. Their rules are centered around reducing the risk of aspiration, should the patient gag or regurgitate during intubation and induction of anesthesia. The ASA’s most recent set of guidelines, published in 2017, do not have specific recommendations for patients receiving enteral nutrition. However, the guidelines do recommend that patients fast for six hours before surgery after consuming non-human milk or a light meal. The ASA explains this recommendation noting, “nonhuman milk is similar to solids in gastric emptying time.”1 Indeed, enteral nutrition formulas contain a blend of carbs, protein, and fat, mimicking what patients would consume from a meal of solid foods.
Exceptions to every rule
Incidental reports and studies have been published that have trialed intraoperative tube feeding. These patient populations tend to have post-pyloric tubes in place, and they are often trauma or burn patients, who really cannot afford the caloric deficits that result from frequent tube feeding holds. In fact, the Eastern Association for the Surgery of Trauma (EAST) recommended intraoperative nasojejunal feeding as early as 2004.2
Extrapolating this recommendation to general, non-trauma, pre-op patients is difficult. Research published on intraoperative feeding is slim, presumably because of the high risk it presents. If a patient were to aspirate on enteral nutrition formula during intubation, the results could be catastrophic. Despite this, a few studies have emerged that evaluated the safety of intraoperative feeding. The results are surprising.
Feeding during surgery
Two retrospective studies have examined the safety and effectiveness of intraoperative tube feeding for burn patients. Published in 2017, the first study only included patients with a confirmed post-pyloric tube. There were zero incidents of aspiration, and intraoperatively fed patients met a greater percentage of their calorie and protein needs.3VaronAcknowledging the difficulty of successful post-pyloric tube placement, the second study took things a step further. Published in 2019, researchers studied the safety of uninterrupted intraoperative gastric tube feeding. Researchers expanded on the findings from the 2017 study—no aspiration and improved nutrition delivery, but this time, tube feeding was delivered into the stomach.4
How to apply these findings
As time goes on, it seems more and more research is published in favor of aggressive nutrition intervention. However, these results are far from an endorsement of intraoperative feeding for the masses. Let me explain. First, these studies were designed retrospectively. More rigorous studies are needed before implementing widespread intraoperative feeding protocols. Second—and very importantly—the patients in both the 2017 and 2019 studies had secured airways before proceeding into surgery. In other words, these patients already had cuffed endotracheal or tracheostomy tubes. Recall the purpose of the ASA guidelines: to prevent aspiration during intubation. This critical step—intubating the patient—was already completed prior to surgery. And finally, these studies were completed with burn patients. More research focusing on different patient populations is needed before we can apply these findings.
Sara Glanz, MS, RD, LD, CNSC worked as a traveling dietitian for Dietitians On Demand for two years before joining the team as the corporate dietitian. In this role, she has championed the continuing education program to empower dietitians everywhere to achieve their professional goals.
American Society of Anesthesiologists. 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. 2017;126(3):376-393.
Jacobs DG, Jacobs DO, Kudsk KA, Moore FA, Oswanski MF, Poole GV, et al. Practice management guidelines for nutritional support of the trauma patient. J Trauma 2004;57:660–78 discussion 679.
Varon, DE. Freitas G, Goel N, Wall J, Bharadia D, Sisk E, et al. Intraoperative feeding improves calorie and protein delivery in acute burn patients. Journal of Burn Care & Research. 2017;38(5):299-303.
Carmichael H, Joyce S, Smith T, Patton L, Wagner AL, Wiktor AJ. Safety and efficacy of intraoperative gastric feeding during burn surgery. 2019. https://doi.org/10.1016/j.burns.2018.12.009