GLP1 Fasting Status and Gastric Retention Using Gastric Ultrasound

An Observational Study to Examine Non-inferiority of the Standard ASA Fasting Guidelines Versus 24-hour Clear Liquid Diet for Gastric Volume in Patients Taking GLP-1 Agonists

This study will enroll patients 18 years and older who are taking a GLP-1/GIP medication and 1) are scheduled for elective surgery and meet ASA fasting guidelines (nothing by mouth for at least 8 hours prior), or 2) scheduled elective colonoscopy and have been on a clear liquid diet for at least 24 hours prior. Participants will have a gastric ultrasound prior to surgery to measure any retained gastric contents. The purpose of this study is to determine if people taking GLP-1 receptor agonists and who fast normally are at an equal risk for having retained gastric contents after appropriately fasting for surgery, compared to patients who are on a liquid only diet for 24 hours prior to surgery.

Patients will be classified into one of two groups:

1. Taking a GLP-1/GLP-GIP medication and undergoing an elective colonoscopy and have been on a clear liquid diet for the past 24-hours.

   or

2. Taking a GLP-1/GLP-GIP medication and undergoing am elective surgery and have fasted appropriately according to ASA guidelines.

All participants will undergo a gastric ultrasound in the preoperative area prior to their scheduled procedure. This will be completed to determine the amount of retained gastric contents, if any, after fasting properly prior to the procedure. An anesthesiologist attending who is properly trained on performing gastric ultrasounds and listed as a study team member will be the one performing the scan.

The patient will be placed in supine position. A curvilinear ultrasound probe will be placed on the sagittal plane below the xiphoid process. The probe will then slide along the costal margin to the right until the gastric antrum is identified. At this point, the ultrasound image will be obtained, and appropriate measurements will be taken. The patient will be placed in the right lateral decubitus position (RLD), and the above procedure will be repeated. The measurement of gastric antral cross-sectional area while in the RLD position will be recorded and used to calculate the gastric volume.

If based on the formula: GV (mL) = 27.0+(14.6*CSA)-(1.28*age) the patient is shown to have a gastric volume greater than 1.5mL/kg, or Antral Grade 2, the anesthesiologist assigned to the case will be alerted and will determine whether or not it is safe to continue with the scheduled surgery as the risk for aspiration may be higher based on the gastric ultrasound results.

Qualitative grading of the appearance of the gastric antrum in RLD will be graded as follows:

• Grade 0 antrum appears empty in both positions, and suggests no gastric content is present.
• Grade 1 antrum appears empty in the supine position, but clear fluid is visible in the RLD, consistent with a small volume of gastric fluid.
• Grade 2 antrum is that in which clear fluid is evident in both patient positions, or any solids in any position which is consistent with a higher volume state.

Inclusion Criteria:

• Age 18+

• Have taken a GLP-1 or GLP-GIP agonist medication within the past 30 days

• ASA Physical Classification Status 1-3

• Fall into one of the following groups:

  1. Scheduled elective surgery and meet ASA fasting guidelines (NPO for at least 8 hours prior)
  2. Scheduled elective colonoscopy and have been on a clear liquid diet for at least 24 hours prior

Exclusion Criteria:

• Previous gastric or esophageal surgery
• Abnormal gastric anatomy
• Pregnancy
• Unable to provide written, informed consent
• Non-English speaking