Correlation Between Sonographic Inferior Vena Cava/Aorta Diameter Index and Central Venous Pressure

ABSTRACT

PURPOSE: Body fluid status of patients in an emergency room environment is a very important parameter during clinical evaluation. In this study, we wanted to know the relationship between the diameter of the inferior vena cava and the diameter of the (IVC/Ao index) and central venous pressure (CVP) in hemodynamically unstable patients. METHODS: This study was done prospectively in an emergency medical center of a hospital from January to August, 2009. We compared the diameter of the IVC, the diameter of inferior vena cava/the body surface area index (IVC/BSA index), the IVC/Ao index, and other variables. Before and after hydration of patients with a systolic blood pressure less than 90 mmHg and who had a central venous catheter in place. Then, we calculated the correlation coefficient for DeltaCVP, DeltaIVC/Ao index, and other indexes. RESULTS: Fifty-nine patients were enrolled in the study. The mean IVC diameter before hydration was 14.3+/-2.7 mm; it was 15.6+/-2.7 mm after hydration (p<0.01). The IVC/BSA index before hydration was 8.75+/-1.72 and 9.55+/-1.79 after hydration (p<0.01). The IVC/Ao index before hydration was 1.08+/-0.23; it was 1.16+/-0.25 after hydration (p<0.01). The correlation coefficient for DeltaCVP and DeltaIVC was 0.37 (p<0.01); for DeltaCVP vs. the DeltaIVC/BSA index it was 0.37 (p<0.01); for the DeltaIVC/Ao index it was 0.27 (p=0.04). CONCLUSION: CVP has a higher correlation to IVC diameter and to IVC/BSA index than to the IVC/Ao index. Hence, we should estimate the IVC/Ao index and use that estimate along with other indexes to evaluate body fluid status when dealing with hemodynamically unstable patients.