Time-dependent Recovery of Gastric Emptying After Cessation of Glucagon-like Peptide-1 Receptor Agonists: a Prospective Observational Gastric Ultrasound Study

Study design and setting: This is a prospective observational cohort study conducted at a tertiary academic hospital to evaluate gastric emptying recovery after cessation of GLP-1 receptor agonists. Adult patients (≥18 years) receiving GLP-1 RAs and scheduled for elective surgery under general anesthesia will be enrolled consecutively to minimize selection bias. Prespecified exclusions include prior gastric or esophageal surgery, known gastroparesis, severe gastroesophageal reflux disease, emergency surgery, pregnancy, and inability to provide informed consent.

Exposure (no intervention assignment): The study does not assign or modify GLP-1 RA therapy. Time since the last GLP-1 RA dose will be recorded in days using patient report and medical records and analyzed both as a continuous variable and as prespecified categories (≤3 days, 4-7 days, ≥8 days). Information on GLP-1 RA formulation (weekly vs daily) and dose equivalence may be collected for sensitivity analyses. Potential confounders such as fasting duration and type of surgery will be recorded.

Gastric ultrasound procedures: Point-of-care gastric ultrasound will be performed immediately before induction of anesthesia using a standardized protocol by trained consultant anesthesiologists. The gastric antrum will be assessed in the supine and right lateral decubitus positions. Qualitative assessment of gastric content will be documented, and quantitative measurements of antral cross-sectional area will be used to estimate gastric volume.

Outcomes: The primary outcome is estimated gastric volume normalized to body weight (mL/kg). Secondary outcomes include the presence of a high-risk stomach, as defined by prespecified gastric volume criteria and qualitative ultrasound findings. Additional exploratory analyses will evaluate whether body mass index modifies the association between cessation interval and gastric volume and whether patient-reported gastrointestinal symptoms correlate with ultrasound findings.

Analysis overview: Associations between time since the last GLP-1 RA dose and gastric ultrasound outcomes will be assessed using prespecified regression models adjusted for relevant covariates (e.g., age, sex, BMI, diabetes status, fasting duration, and symptom measures). The interaction between BMI and cessation interval will be evaluated to characterize potential effect modification.