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Use of GLP-1 receptor agonists was linked with increased residual gastric content on preprocedural gastric ultrasonography, even after fasting for the guideline-recommended duration, a cross-sectional study showed.

In 124 patients undergoing an elective procedure requiring anesthesia, the prevalence of increased residual gastric content was 56% for those taking GLP-1 agonists compared with 19% for those without use of these drugs, reported Sudipta Sen, MD, of the University of Texas Health Science Center at Houston, and colleagues in .

After adjusting for confounding, those with GLP-1 agonist use had a 30.5% higher prevalence of increased residual gastric content (adjusted prevalence ratio 2.48, 95% CI 1.23-4.97).

Residual gastric content -- defined as the presence of solids, thick liquids, or more than 1.5 mL/kg of clear liquids on gastric ultrasonography -- is a surrogate for aspiration risk, Sen and team explained. However, aspiration events themselves were not counted in the study.

"Our findings were quite surprising. More than half of the patients on a GLP-1 RA [receptor agonist] had significant gastric contents on gastric ultrasound before an elective procedure, despite adhering to preoperative fasting," Sen said in a statement. "This incidence was significantly higher compared to patients not on a GLP-1 RA, showing a strong link between GLP-1 RA drugs and potential aspiration risk under anesthesia."

"Patients must ensure they disclose their use of this medication to their surgeons and anesthesiologists," she added. "This information is crucial for us to provide appropriate recommendations, such as adjusting drug administration before elective procedures, recommending extended fasting, or rescheduling an elective procedure if necessary."

As the popularity of this drug class has increased over the last few years, concerns about aspiration during surgery have come to light due to how these agents work. GLP-1 agonists are linked with delayed gastric emptying resulting in increased residual gastric content and adverse gastrointestinal events such as nausea, vomiting, and gastroesophageal reflux.

This prompted the American Society of Anesthesiologists to release new guidance in June 2023, warning patients to stop taking them prior to elective surgery. In the guidance, the Task Force on Preoperative Fasting outlined that patients on one of the once-weekly agents should not take their medication a week prior to surgery, and those on a once-daily agent should not take their medication the day of surgery. This guidance applied to both adults and children, and for all patients on one of these agents regardless of the indication.

"The lack of data had previously led societies to rely on expert opinion for guidance," co-author Omonele Nwokolo, MD, also of the University of Texas Health Science Center at Houston, commented. "Our evidence paves the way for informed guidelines and further research to mitigate anesthesia-related risks in this patient population."

For this study, Sen and colleagues prospectively enrolled 124 patients from a large, tertiary, university-affiliated hospital from June 6 through July 12, 2023. Median age was 56, and 60% were women.

Patients with altered gastric anatomy (e.g., from previous gastric surgery), pregnancy, recent trauma (less than 1 month), or an inability to lie in the right lateral decubitus position for gastric ultrasonography were excluded.

Most patients took the last dose of their GLP-1 agonist within 5 days before their procedure. While an exploratory analysis showed a decreasing prevalence of increased residual gastric content with each additional day off the drug, the link between the duration of interruption and the prevalence of increased residual gastric content wasn't significant (adjusted OR 0.86, 95% CI 0.65-1.14). But this may have been due to the small sample size, said Sen's group.

Of the included patients, 63% were on semaglutide (Ozempic, Wegovy), 23% were on dulaglutide (Trulicity), and 14% were on tirzepatide (Mounjaro, Zepbound). The half-lives of the three agents are 7 days, 5 days, and 5 days, respectively. The researchers noted that they didn't include patients on the once-daily GLP-1 agonists exenatide (Byetta, Bydureon), lixisenatide (Adlyxin), and liraglutide (Victoza), since they have shorter half-lives of 1.4 hours, 2.5 hours, and 13.5 hours, respectively.

Future studies are needed to determine more specific safe discontinuation intervals and preprocedural fasting times for these agents prior to elective procedures under anesthesia, Sen's group concluded.

"A simplistic approach of holding the GLP-1 RA for longer intervals (3-5 weeks) may not be tenable, especially when prescribed for glycemic control," they pointed out. "However, this may be a viable strategy for GLP-1 RA use in weight management."

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