Limit of agreement of end expiratory values of caval-aortic index in subcostal and trans-hepatic views

Inferior Vena Cava(IVC) diameter is commonly used for assessment of volume status in the emergency departments and ICU. The ultrasound measurement of the diameter of the IVC indexed to aortic diameter is a reasonable alternative with a reference value of 1.2 ± 0.17 indicating good volume status. Both the IVC and the aorta can be visualized in the trans-hepatic window, and this view is helpful in cases of poor subcostal window due to bowel gas, surgical incision or trauma. However, the measurement of caval-aortic(IVC/Ao) index in trans-hepatic view and its correlation with subcostal view is not known. To assess limits of agreement of end expiratory values of (IVC/Ao) index in subcostal and trans-hepatic view Patients and methods This was a Prospective Observational study carried in our hospital in which 127 patients were analyzed. The internal diameters of the IVC and Aorta were measured in both subcostal and transhepatic views with the patients in semi recumbent position using a cardiac probe of the Sonosite™ (M-Turbo model) ultrasonography (USG) machine. The end-expiratory value of IVC diameter was used to calculate the IVC/Ao index in both views, and limits of agreement of end-expiratory values of IVC/Ao index in both views were analyzed using the Bland-Altman analysis. Patients with clinical signs of active expiration, intra abdominal hypertension and respiratory distress were excluded from study. Results In our study, Bland-Altman analysis(Fig. 1) showed that for Observer 1, 6/127 values and for observer 2, 5/127 values were beyond the upper and lower boundaries of the median, showing good agreement (>95%) between the two techniques. Conclusion The IVC/Ao index obtained from the trans-hepatic view shows good agreement with the IVC/Ao index via the subxiphoid view, and can be used in situations wherein the subcostal view cannot be obtained. References 1) W. Kosiak, D. Swieton, and M. Piskunowicz, “Sonographic inferior vena cava/aorta diameter index, a new approach to the body fluid status assessment in children and young adults in emergency ultrasound-preliminary study,” American Journal of Emergency Medicine, vol. 26, no. 3, pp. 320–325, 2008.2)K. H. Son, M. R. Kim, Y. W. Kim, and Y. S. Yoon, “The utility of the IVC/Aorta diameter index in trauma patients,” Journal of the Korean Society of Emergency Medicine, vol. 21, no. 1, pp. 35–43, 2010.