Ultrasound Assessment of Gastric Volume

Alex Macario, MD, MBA


March 14, 2013

Validation of a Mathematical Model for Ultrasound Assessment of Gastric Volume by Gastroscopic Examination

Perlas A, Mitsakakis N, Liu L, et al
Anesth Analg. 2013;116:357-363

Study Summary

The goal of this study was to better understand how to accurately measure the volume of gastric contents using ultrasound. This information would be useful in the case of patients arriving for urgent surgery (such as after a motor vehicle accident), when pulmonary aspiration of gastric contents would be a serious perioperative complication. If it were possible to reliably identify patients with full stomachs, then specific measures such as nasogastric decompression and emptying of the stomach could be undertaken.

Perlas and colleagues enrolled 108 patients undergoing elective upper gastrointestinal endoscopy (but not having surgery) after 8 hours of fasting. After a baseline ultrasound examination of their stomachs, patients were randomly assigned to ingest 1 of 6 predetermined volumes of apple juice (0 mL, 50 mL, 100 mL, 200 mL, 300 mL, or 400 mL). The ultrasound examination was repeated within a few minutes to obtain the cross-sectional area of the antrum because the larger the antrum, the greater the volume of gastric contents. To conclude the study protocol, the gastroenterologist then placed an endoscope and suctioned under direct vision. This gastric fluid was measured to the nearest milliliter.

The overall result of the study was that a previously reported model tends to overestimate gastric volume, particularly at low volume states. A new, better mathematical model was developed to predict gastric fluid volume on the basis of measurements of the cross-sectional area of the antrum. This formula is: gastric volume = 27.0 + (14.6) x (cross-sectional area of antrum in right lateral decubitus position) – 1.28 x age, which shows a correlation of r2= 0.731.


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