Inferior Vena Cava Diameter Measurement Provides Distinct and Complementary Information to Right Atrial Pressure in Acute Decompensated Heart Failure

Abstract

Inferior vena cava (IVC) measurements correlate only modestly with right atrial pressure (RAP). Part of this inaccuracy is due to the high compliance of the venous system, where a large change in blood volume may result in only a small change in pressure. As such, the information provided by the IVC may be different rather than redundant. We analyzed patients in the ESCAPE (Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness) trial who had both pulmonary artery catheter and IVC measurements at baseline (n = 108). There was only a modest correlation between baseline RAP and IVC diameter (r = 0.41; P < 0.001). Hemoconcentration, defined as an increase in hemoglobin levels between admission and discharge, was correlated with decrease in IVC diameter (r = 0.35; P = 0.02) but not with a decrease in RAP (r = 0.01; P = 0.95). When patients had both IVC and RAP measurements that were below the median, survival rates were superior to the rates of those who had only 1 measurement below the median, and when both rates were above the median, patients fared the worst (P = 0.002). IVC and RAP have limited correlation with each another, and changes in intravascular volume appear to correlate better with IVC diameter rather than with RAP. Furthermore, complementary information is provided by pressure and volume assessments in acute decompensated heart failure.