Correlation of caval index, inferior vena cava diameter, and central venous pressure in shock patients in the emergency room

Objectives: This study aims to determine the correlation of the caval index, inferior vena cava (IVC) diameter, and central venous pressure (CVP) in patients with shock in the emergency room. Materials and methods: This is a prospective double-blind observational study conducted in the emergency room of a tertiary care center. All patients who presented with shock and had a central venous catheter insertion performed were enrolled. The caval index was calculated as a relative decrease in the IVC diameter during the normal respiratory cycle. The correlation of CVP and the caval index were calculated by Pearson's product-moment correlation coefficient. Results: Among the 30 patients enrolled, the median age was 59.90 +/- 21.81 years and 17 (56.7%) patients were men. The summary statistics that were generated for the participants' characteristics were divided into CVP,10 cm H2O, 10-15 cm H2O, and >15 cm H2O. The correlation of the CVP measurement with the ultrasound IVC caval index was r=-0.721 (P=0.000) by -two-dimensional mode ultrasound and r=-0.647 (P=0.001) by M-mode. The correlations of CVP with the end-expiratory IVC diameter were r=0.551 (P=0.002) by two-dimensional mode ultrasound and r=0.492 (P=0.008) by M-mode. The sensitivity and specificity of the caval index were calculated to predict the CVP. The results showed that the cut-off points of the caval index were 30, 20, and 10 at CVP levels,10 cm H2O, 10-15 cm H2O, and >15 cm H2O, respectively. Conclusion: The caval index calculated from the IVC diameter measured by bedside ultrasound in the emergency room has a good correlation with CVP.