Gastric Ultrasound Assessment for Patients Taking GLP1 Agonists

Glucagon-like peptide 1 (GLP-1) agonists have existed since 2005, however the newer once-weekly injectable medications particularly semaglutide, and tirzepatide have exploded in popularity due to their weight loss potential.

Anesthesiologists nationally have seen an increase in perioperative complications amongst patients taking these medications due to delayed gastric emptying increasing the risk of aspiration in the perioperative period. At HSS the majority of our anesthetics are done under sedation and therefore would not protect the patient from aspiration in the event of vomiting.

Protecting patients from aspiration secondary to vomiting during induction or maintenance of anesthesia has always been an important goal to make anesthesia safer leading to the development of NPO guidelines which are intended to protect against the presence of gastric content during anesthetic care. However there is growing concern that patients taking GLP-1 agonists may not be adequately protected using the current nothing by mouth or "NPO" guidelines. Up to this day there is no literature on how much gastric emptying is delayed during the use of GLP1 following the standard NPO guidelines.

Recently Gastric Ultrasound (GUS) has been introduced as a bedside tool for assessing a patients stomach contents and for the risk of aspiration. Gastric ultrasound can identify an empty stomach, a stomach filled with clear liquids, thick liquids or solid food content. If a stomach has clear liquid the volume can be calculated accurately. Generally a stomach with solid or thick liquid content or with clear liquid measuring more than 1.5 ml/kg body weight is considered a full stomach. As GUS is noninvasive and well tolerated, it offers the perfect solution to assessing patient risk in the preoperative period.

Inclusion criteria

• GLP 1 patient group: any patient on GLP1 agonists that are dosed once per week (semaglutide, dulaglutide, tirzepatide), for all indications.
• Control group (No GLP 1 patients): any patient not on GLP1 agonists that are dosed once per week, for all indications.

Exclusion criteria

• patient refusal to participate
• patients with gastric bypass or any other gastric surgery
• large hiatal hernia
• patients with large ascites
• patients on peritoneal dialysis
• emergency surgery
• pre-existing diagnosis of gastroparesis