Gastric sonography in the severely obese surgical patient: a feasibility study.

BACKGROUND: Gastric ultrasonography allows qualitative and quantitative assessment of gastric contents and volume in nonobese subjects. In this study, we sought to determine the feasibility of gastric ultrasound in severely obese patients (body mass index [BMI] ≥35 kg/m). We defined feasibility as the ability to identify a full cross section of the gastric antrum in at least 80% of subjects when imaged in the right lateral decubitus position.

METHODS: This was a prospective cohort study on fasted surgical patients with BMI >35 kg/m. The primary outcome measure was the feasibility of gastric sonography. Secondary outcomes included the distribution of antral grade following an existing 3-point grading system. In addition, the antral cross-sectional area (CSA) and gastric volumes in this cohort were compared with historical data from a published study in nonobese individuals. Time to image capture, antral wall thickness, and depth of the antrum are also reported.

RESULTS: Sixty patients (BMI range 35.1-68.7) were studied. The antrum was identified in 95% of subjects in the right lateral decubitus (95% CI, 0.86-0.99) and 90% of subjects in the supine position. Definition of antral grade (0-2) was possible in 88.3% (95% CI, 0.77-0.95) of cases. As expected, antral grade correlated with antral CSA and gastric volumes (P < 0.0001). When compared with historical data, our results suggest that severely obese patients have a larger baseline CSA and gastric volume than nonobese patients (P < 0.001) but a similar gastric volume per unit of weight (P = 0.141).

CONCLUSIONS: Gastric ultrasound assessment is feasible in fasted severely obese subjects. Our data also suggest that obese individuals present larger antral size and gastric volume than their nonobese counterparts.