Improving Patient Safety for Surgical Patients on Semaglutide: A Gastric Ultrasound Initiative

Pulmonary aspiration of gastric contents has long been recognized as a threat to anesthesia patient safety. Most elective surgical patients, however, are considered to be at low risk for this complication provided they abstain from eating solid food for at least 8 hours prior to anesthesia and for clear fluids for at least 2 hours. The recent introduction of GLP-1 agonists (such as Semaglutide), a new class of drugs for the treatment of diabetes and weight loss, has challenged the status quo, and is posing a new threat to perioperative patient safety.There are recent reports of aspiration of large amounts of particulate undigested food in the perioperative period on patients taking Semaglutide despite prolonged fasting of over 12 hours, one of those cases happening at the UHN.This is of great concern given the explosive increase in use of these medications globally.In the month of June 2023, three North American anesthesiology societies (the Canadian Anesthesiologists' Society, the American Society of Anesthesiologists and the Anesthesia Patient Safety Foundation) have raised the alert regarding an increased risk of aspiration under anesthesia while on these drugs.Given the long half-life of up to 7 days, a true reduction of risk would necessitate holding these drugs preoperatively for longer periods than are usually feasible.

Management strategies recommended to date include treating every patient on Semaglutide as if they have a 'full stomach", avoiding general anesthesia if possible and even considering surgical cancellation if the patient presents symptoms such as nausea and vomiting, which are common while on these medications. While these recommendations stand to reason, they are over-arching, targeted to all patients and could result in unnecessary surgical cancellations or invasive procedures (such as nasogastric tube insertion, endotracheal intubation and rapid sequence induction) which have their own set of risks.

This timely study addresses the current knowledge gap and a recently identified threat to perioperative patient safety that has been highlighted by three major anesthesiology societies in the past 2-3 months. Our team at the UHN is uniquely positioned to shed some light into these pressing questions and develop management recommendations that optimize safety while avoiding unnecessary surgical cancellations and targeting invasive procedures for airway management only to those patients that really need them.

Our group has previously developed and validated a simple, non-invasive bedside ultrasound test that can differentiate a safe "empty stomach" from a "full stomach" that may pose an increased risk of aspiration under anesthesia. The investigators have validated this bedside test in the adult, pediatric, obstetric and morbidly obese populations.

Hypothesis: