Agreement in evaluation of inferior vena cava collapsibility index by medical students using ultrasound compared to emergency physicians

Background: An inferior vena cava (IVC) ultrasound is a useful tool for evaluation of fluid status in emergency patients. However, Thai medical students have never been trained to do IVC ultrasound. Objective: To ascertain whether medical students with minimal training could perform IVC ultrasounds. Materials and Methods: A prospective observational study was conducted among sixth-year medical students who were trained to perform an IVC ultrasound by watching a video clip and doing hands-on practice. The patients, who were older than 18 years and required volume status evaluation, were initially scanned by emergency physicians and then by students. The agreement in IVC measurements between the emergency physicians and the medical students were determined using intraclass correlation coefficient (ICC). Results: Forty medical students performed IVC ultrasounds. A very high inter-observer reliability was observed between IVC collapsibility index (IVC-CI) measured by the students and the physicians (ICC 0.74, 95% CI 0.56 to 0.85). A Bland-Altman plot analysis showed the mean difference in the IVC-CI was 0.89, with a 95% limit of agreement ranging from -33.59% to +31.80%. The sensitivity and specificity of the IVC ultrasounds correlated with the clinical data for evaluation of the hypovolemic status were 95% (95% CI 75.13 to 99.87) and 100% (95% CI 83.16 to 100.00), respectively. Conclusion: After minimal training, the medical students could obtain IVC images; however, their measurement accuracies were poor, as indicated by the wide 95% limit of agreement.