The reason? A greater potential risk of aspiration under anesthesia, according to the University of Texas Health (UTHealth) Houston study published in the Journal of the American Medical Association Surgery.
“Our findings were quite surprising. More than half of the patients on a GLP-1 RA had significant gastric contents on gastric ultrasound before an elective procedure, despite adhering to preoperative fasting,” said first author Sudipta Sen, MD, of McGovern Medical School. “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.”
The cross-sectional study involved 124 patients who fasted for the guideline-recommended duration. It found that the prevalence of increased residual gastric content (RGC) on gastric ultrasonography was 56% in GLP-1 RA users compared with 19% in nonusers, a significant difference after confounder adjustment.
“Glucagon-like peptide-1 receptor agonist (GLP-1 RA) use is rapidly increasing in the U.S., driven by its expanded approval for weight management in addition to hyperglycemia management in patients with type 2 diabetes,” according to the study team, which noted that the perioperative safety of the medications, especially with aspiration risk under anesthesia, has been uncertain.
The goal of the study was to assess the association between GLP-1 RA use and prevalence of increased RGC—a major risk factor for aspiration under anesthesia—using gastric ultrasonography.
The patients in the cross-sectional study were prospectively enrolled from a large, tertiary, university-affiliated hospital from June 6, 2023, through July 12, 2023. The participants followed preprocedural fasting guidelines before an elective procedure under anesthesia. Excluded were any patients with altered gastric anatomy (e.g., from previous gastric surgery), pregnancy, recent trauma in the last month, or an inability to lie in the right lateral decubitus position for gastric ultrasonography.
The results apply to once-weekly GLP-1 RA, with the primary outcome defined as the presence of increased RGC. That meant the presence of solids, thick liquids, or more than 1.5 mL/kg of clear liquids on gastric ultrasonography.
The prevalence of increased RGC was 56% among the exposure group compared with 19% (12 of 62) in patients who were not taking a GLP-1 RA drug (control group). Of the 124 participants, who had a median age of 56 years (interquartile range, 46-65 years), most (60%) were female.
“After adjustment for confounding, GLP-1 RA use was associated with a 30.5% (95% CI, 9.9%-51.2%) higher prevalence of increased RGC (adjusted prevalence ratio, 2.48; 95% CI, 1.23-4.97),” the researchers wrote. “There was no association between the duration of GLP-1 RA interruption and the prevalence of increased RGC (adjusted odds ratio, 0.86; 95% CI, 0.65-1.14).”
They suggested that preprocedural fasting called for in current guidelines might be “inadequate in this group of patients at increased risk of aspiration under anesthesia.”
The authors advised that anecdotal reports attribute an increased risk of pulmonary aspiration in patients undergoing anesthesia to GLP-1 RA use. “Use of GLP-1 RAs has been associated with slowed gastric emptying, leading to increased residual gastric content (RGC) in patients presenting for elective procedures despite following recommended preoperative fasting guidelines,” they added. “Increased RGC is one of the main factors associated with aspiration risk under anesthesia. Recent consensus-based guidance from the American Society of Anesthesiologists (ASA) offers expert-opinion recommendations to address the aspiration risk associated with GLP-1 RA based on sparse evidence, noting the urgent need for more evidence.”
At UTHealth Houston, the study was prompted by internal quality reviews after anecdotal cases of aspiration under anesthesia were reported by staff for patients taking GLP-1 RAs for weight loss, despite adequate fasting before the procedure.
“Patients must ensure they disclose their use of this medication to their surgeons and anesthesiologists,” Dr. Sen said. “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.”
In June 2023, the American Society of Anesthesiologists released new guidance for screening GLP-1 RA use before surgery and informing patients of the risk of adverse outcomes. Recommendations included the consideration of pausing GLP-1 RAs prior to elective surgery.
“Our study fills a significant gap in the current understanding and management of patients on GLP-1 RAs undergoing surgery,” said senior author Moonee Nwokolo, MD. “The lack of data had previously led societies to rely on expert opinion for guidance. Our evidence paves the way for informed guidelines and further research to mitigate anesthesia-related risks in this patient population.”
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