Background
Gastric point of care ultrasound (POCUS) has been used by clinicians to evaluate gastric contents prior to the induction for intubation in the intensive care unit. This is of particular importance as the presence of gastric contents increases the risk of aspiration during induction, which itself carries increased morbidity and mortality. In upper gastrointestinal bleeds (GIB), sonographic assessment prior to evaluation with esophagogastroduodenoscopy (EGD) may be of significant utility both in risk stratification of anesthesia and the clinical concern for ongoing bleeding.
Research question: Can gastric POCUS be used to reliably measure gastric contents as compared to the gold standard of EGD in upper GIB?
Study design and methods: The primary goal of the study was to compare Esophagogastroduodenoscopy (EGD) stomach content measurement, the gold standard in the diagnosis and potential management of gastrointestinal bleeding, with bedside ultrasound measurement in patients undergoing EGD in all settings. We report the sensitivity, specificity, positive predictive value [PPV] and the negative predictive value [NPV] with their exact 95% confidence intervals (CI). We summarized descriptively the distribution of POCUS measurements, in the cases where the assessment of gastrointestinal content differed between the two methods [specifically detection of contents with ultrasound ie US > 0, but absence of contents on EGD ie EGD=0]. SAS 9.4 (SAS Institute, Inc., Cary, NC) was used for the data analysis.
Results
When comparing POCUS measurements to EGD to detect the presence or absence of stomach contents, the sensitivity of the US measurement was 75.0% (95% CI:19.4-99.4), while the specificity was 76.1% (95% CI:61.2-87.4). The negative predictive value (NPV) was 97.2% (95% CI: 85.5-99.9). The positive predictive value (PPV) was 21.4% (95% CI: 4.7%- 50.1%), based on the 14 observations with US > 0. The Median (IQR) of POCUS for these 11 observations were 97.8 (18.7-260.8).
Interpretation: Gastric ultrasound may be used for gastric content assessment prior to EGD in cases of suspected GIB. Gastric POCUS has a high negative predictive value to exclude the presence of stomach contents. This may have relevance in critical care settings where a high aspiration risk due to suspected stomach contents may lead to need for airway protection via advanced airway and general anesthesia.
