Dynamic assessment of gastric emptying patterns after endoscopic bowel preparation using ultrasonography: A...

Optimal fasting time after polyethylene glycol (PEG) bowel preparation for sedated endoscopy is unclear, creating a conflict between minimizing aspiration risk and ensuring high-quality bowel preparation. This study aimed to use gastric ultrasonography (GUG) to dynamically assess gastric emptying patterns and determine a safe and effective fasting interval.

In this prospective, single-center observational study, 150 ASA I-II patients scheduled for elective endoscopy underwent standardized GUG assessments. A trained anesthesiologist measured the antral cross-sectional area (CSA) at 0, 1, 2, 3, and 4 h after completion of the oral PEG solution. The primary safety endpoint was "Target Attainment," defined as an antral CSA < 340 mm², indicating a low risk of aspiration. The cumulative probability of attainment was analyzed using the Kaplan-Meier method, and predictors of attainment at 2 h were identified via multivariate logistic regression.

The cumulative probability of achieving the safety endpoint was 68.7% at 2 h, 90.0% at 3 h, and 100% by 4 h. Multivariate analysis identified diabetes as a significant predictor for delayed gastric emptying at 2 h. Conversely, a higher BMI (overweight category) was associated with faster emptying compared to the normal-weight group. A predictive model combining BMI and diabetes status demonstrated fair discriminatory power for target attainment at 2 h (AUC = 0.713).

Gastric emptying after PEG-based bowel preparation is relatively rapid, with a substantial portion of patients reaching a low-risk gastric state within two hours. This supports the feasibility of a two-hour fasting window, which may enhance patient comfort and procedural efficiency, these findings mainly apply to relatively healthy populations (ASA class I-II, BMI < 30 kg/m²). However, as diabetes is a predictor of delayed emptying, bedside GUG is an invaluable tool for individualized risk assessment to ensure safety, particularly for high-risk patients (ChiCTR.org.cn: ChiCTR2400092657).