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A new study finds GLP-1 drugs may increase risk of surgical complications. PixelCatchers/Getty Images
  • Obesity and diabetes drugs like Ozempic and Mounjaro could lead to complications from anesthesia during surgery, according to a new study.
  • The research found that patients who took these drugs were more likely to have food and liquids in their stomach than those who did not.
  • Gastric content is a known risk factor for pulmonary aspiration risk.

A popular class of obesity and diabetes drugs known as glucagon-like peptide-1 receptor agonists (GLP-1 RAs) could lead to complications from surgery, suggests a new study.

Research published this week in the journal JAMA Surgery found that patients prescribed GLP-1 RAs were more likely to have residual gastric content — solids and liquids in the stomach — during surgical procedures, a major risk factor for aspiration while under anesthesia.

Pulmonary aspiration is when food, stomach contents, or other foreign substances enter into the lungs and airway. While not always serious, it can lead to severe complications including infection, aspiration pneumonia, and death.

GLP-1 RAs, which include name brand drugs like Ozempic (semaglutide) and Zepbound (tirzepatide), work by simulating a hormone secreted in the gut that slows digestion, increases insulin, and promotes feelings of satiety in the brain. One of the known effects of the drugs is delayed gastric emptying, or slowing the rate at which food passes through the stomach.

Prior to surgery, patients are told to fast in order to minimize the amount of stomach content. However, due to the slowing effects of GLP-1 RAs on digestion, the normal recommendations may not be sufficient. So, surgeons and anesthesiologists are seeking more data and clearer guidelines for patients using these drugs.

“The idea is that patients who are appropriately fasted prior to an elective surgery should have an empty stomach, because we are putting them on anesthesia and we are giving them paralytics. The hope is that they don’t regurgitate contents from their stomach into their lungs,” Dr. Sudipta Sen, an associate professor of anesthesiology at UTHealth Houston, and first author of the study, told Healthline.

“But this particular class of patients who were on this drug had a lot of residual gastric content,” she said.

Sen led a small study of 124 patients who were scheduled for an elective, non-emergency, surgery. Half of the patients were prescribed a GLP-1 RA, while the other half (the control group) were not taking the drug. The average age of participants was 56 years old and predominantly (60%) female.

Using a technique known as gastric ultrasound, the researchers were able to evaluate the stomach content of the patients prior to anesthesia. Residual gastric content was defined as three different types of content in the stomach: solids, thick liquids, or more than 1.5ml/kg of clear liquids.

More than half (56%) of patients using GLP-1 RAs had increased amounts of gastric content compared with just 19% of the control group. After further statistical analysis, the study indicates that GLP-1 RAs are associated with a 30% increased likelihood of residual gastric content than the control.

“This study definitely addresses a timely issue, because these drugs are being used so much more now. For the surgeons, we don’t know what to do with these…drugs,” Dr. Cindy Kin, an associate professor of surgery at Stanford Medicine, told Healthline.”It’s introducing some new questions.”

According to a 2009 study from the American Society of Anesthesiologists, aspiration of gastric contents contributes to up to 9% of all anesthesia-related deaths.

Pulmonary aspiration can lead to aspiration pneumonia, a serious infection of the lungs that can lead to respiratory failure and death. This type of pneumonia can result in up to 70% mortality rate depending on the type of volume and type of aspirate, according to one study.

A study from 2023 estimates the likelihood of aspiration events from anesthesia between 2-7 per 20,000 cases.

While there is a connection between residual gastric content and aspiration risk, the new study doesn’t demonstrate a clear link between GLP-1 RAs and pulmonary aspiration, a serious potential complication.

“Data linking a full stomach and aspiration risk has not been studied, but it is just a predictor that these patients are at a higher risk of their stomach contents getting into their lungs,” said Sen.

Dr. Mark Schutta, a professor of Diabetes and the Medical Director of the Penn Rodebaugh Diabetes Center at Penn Medicine, told Healthline that the study is of limited value without looking at the number of aspiration events, which the study didn’t investigate, rather than just stomach content.

“This is a small study. This is 124 patients, right? I don’t think that you can really draw any firm conclusions. The real issue to me and the outcome that we need to know about is the actual incidents of aspiration. That’s what we’re concerned about,” he said.

“Maybe there is this residual gastric content that’s greater in people on this drug than those that are not, but the question is, is it clinically significant or not?” Schutta added.

The main question the study raises is how surgeons and anesthesiologists should prepare patients who take GLP-1 RAs, to get ready for surgery.

However, the answer to that question isn’t clear yet.

Currently, the American Society of Anesthesiologists recommends patients taking weekly doses of these drugs to stop taking them one week before surgery.

It’s not yet clear how fasting guidelines, otherwise known as NPO status, should be modified for patients taking GLP-1 RAs. Future studies will be needed to know how or if these guidelines need to be updated.

For now, however, anyone taking a GLP-1 RA who is planning on getting surgery should ensure that their doctor is aware of their medication history.

“It’s a new drug that we don’t know a ton about in terms of the perioperative risks. So anyone on this drug should, you know, make sure that they tell their surgeon, ‘Hey, I’m on this GLP-1. Is there anything special I need to do?’” said Kin.

“This is just preliminary evidence and we’re going to need more data and a different type of study to really guide us and guide the anesthesiologist,” said Schutta.

People taking GLP-1 RAs, obesity and diabetes drugs like Ozempic and Mounjaro, should be aware of potential complications from surgery.

GLP-1 RAs slow down digestion, which can lead to the presence of residual gastric content (stomach content) during surgery, which is a risk factor for pulmonary aspiration.

Pulmonary aspiration can lead to aspiration pneumonia, an infection of the lungs that can cause respiratory failure and death.