Gastric Residual Volume Assessment by Gastric Ultrasound in Fasting Obese Patients: A Comparative Study

Gastric ultrasound is an emerging tool for preoperative evaluation of gastric content and volume.

To assess gastric residual volume in normal-weight and obese patients scheduled for elective surgery.

This prospective observational study was conducted on 100 patients assigned to two groups of 50 patients each. The obese group included patients with body mass index (BMI) of 30 - 40 and American Society of Anesthesiologists (ASA) grade II and those with BMI > 40 and ASA III without other comorbidities; the normal-weight group included patients with normal BMI and ASA I. Gastric volume was predicted in each group using sonographic measurement of antral cross-sectional area (CSA) in semi-sitting and right lateral positions (RLP); the two groups were compared to assess the risk of aspiration for each group preoperatively.

Despite intergroup differences in antral CSA, the sonographically predicted gastric volume was < 1.5 mL/kg in both groups in both positions. Both groups were at a low risk for aspiration, and 98% of the patients showed grade 0 or 1 in antrum assessments, corresponding to an empty antrum and minimal fluid only in the RLP, respectively. Only 2% of the patients in both groups showed a distended antrum in both positions.

Despite the differences in CSA between obese and normal-weight participants in both positions (obese > normal-weight), both groups showed a low predicted gastric residual volume < 1.5 mL/kg and were at low risk for aspiration, provided that fasting was initiated at least 8 hours before elective surgery.