Effects of Beginning a GLP1-Agonist Therapy on Residual Gastric Content and Gastric Emptying

This project explores the elevated risk of pulmonary aspiration during anesthesia in patients undergoing GLP-1 agonist therapy, which prolongs gastric emptying. Despite standard fasting guidelines (6 hours for solids, 2 hours for liquids), some patients still experience aspiration, indicating that GLP-1 therapy may heighten risk. The American Society of Anesthesiologists has advised pausing GLP-1 therapy before surgery, but this recommendation has faced criticism for being too broad. More data on this issue is needed, particularly concerning the effect of tachyphylaxis (reduced drug response over time) on gastric emptying.

The study proposes using gastric ultrasound as a non-invasive tool to evaluate residual gastric content and categorize patients by their aspiration risk. The study will assess the stomach's content and gastric emptying time in patients both before and after starting GLP-1 therapy, comparing results under standard fasting conditions.

The project is a national, single-center, prospective observational study targeting 50 patients, examining factors like patient demographics, GLP-1 therapy details, and gastrointestinal side effects. Data collection will occur through baseline and follow-up sonographic exams before and after therapy initiation. The study aims to improve perioperative management strategies by clarifying the risks associated with GLP-1 therapy

This project investigates the risk of pulmonary aspiration during anesthesia in patients undergoing treatment with GLP-1 agonists, a class of medications that prolong gastric emptying and are commonly used for obesity and diabetes management. Pulmonary aspiration remains a significant cause of morbidity and mortality in anesthesia-related complications, and patients with delayed gastric emptying are at higher risk. Recent reports suggest that patients taking GLP-1 agonists may be at increased risk for aspiration, even when adhering to standard perioperative fasting guidelines (6 hours for solids, 2 hours for liquids).

The American Society of Anesthesiologists (ASA) has issued a warning about the potential risk of aspiration in patients on GLP-1 agonist therapy, recommending pausing the medication before surgery. However, this recommendation has been criticized for being too broad, given the lack of comprehensive data on the exact impact of GLP-1 agonists on gastric emptying and aspiration risk. Since many patients treated with GLP-1 agonists are already at higher risk of aspiration due to comorbidities like obesity and diabetes, understanding how this therapy further affects gastric function is crucial. There are also indications of a "tachyphylaxis" effect, where patients develop tolerance to the drug's impact over time, but its effect on gastric emptying and perioperative aspiration risk is not well understood.

Study Rationale and Objectives

The primary aim of this study is to assess whether patients undergoing GLP-1 agonist therapy have a higher likelihood of a full stomach after the recommended fasting intervals. Additionally, the study aims to evaluate the time taken for gastric emptying in these patients, focusing on the clearance of 500 ml of water.

Study Design

The project is a national, single-center, prospective observational study that will include approximately 50 patients who are starting GLP-1 agonist therapy. Patients will serve as their own control group by undergoing gastric ultrasound before beginning treatment and then again 6-8 weeks after therapy initiation. If therapy is continued, a follow-up ultrasound will occur around 5 months later.

The ultrasound examinations will measure both the gastric content (solid, liquid, or empty) and the cross-sectional area (CSA) of the gastric antrum to estimate gastric volume. These measurements will provide insight into whether patients on GLP-1 agonists have prolonged gastric emptying, contributing to the risk of aspiration during surgery.

Study Population and Procedures

The study population will consist of patients prescribed GLP-1 agonists for obesity, diabetes, or lifestyle reasons. Inclusion criteria include adults beginning a new GLP-1 therapy regimen, while exclusion criteria rule out patients with known gastrointestinal disorders, previous GI surgery, pregnancy, and those at high risk for hypoglycemia due to other medications like sulfonylureas or insulin.

Recruitment will occur through collaboration with the Adipositas und StoffwechselZentrum Hirslanden Zurich, where GLP-1 agonists are regularly prescribed. Patients will be contacted by phone to provide initial study information, and written informed consent will be obtained before the baseline examination. A demographic and medical history will also be collected at the initial visit.

Eligibility Criteria:
Inclusion Criteria:

* Beginning a new treatment with GLP-1 Agonists. Indication and prescription determined by an endocrinologist/obesity specialist
* Signed informed consent

Exclusion Criteria:

* Known pregnancy, known lactation
* Underage (\< 18 years)
* Absence of informed consent (missing or inability to provide)
* Anomalies of the gastrointestinal tract
* Known illnesses of the gastrointestinal tract
* Previous surgery of the gastrointestinal tract
* Elevated risk for hypoglycaemia (Sulfonylurea or Insulin)
* No investigator with completed structural education in gastric sonography is available
* Lack of intention to respect the fasting intervals and predefined standardised meals for the sonographic examination