Evaluation of central venous pressure (CVP) by inferior vena cava (IVC) measurements is crucial in the management of patients with cardiogenic shock to optimize drugs therapy. IVC has a complex 3-dimensional (3D) shape but measurements used to estimate CVP remain based on 2-dimensional (2D) echocardiographic imaging.

The aim of this study was to investigate the accuracy of CVP estimation by IVC size and collapsibility index obtained using 3D-echocardiography compared with 2D in patients with cardiogenic shock.

Eighty consecutive echocardiographic examinations performed in 33 patients (72±15 years, left ventricular ejection fraction=19±10%) admitted for cardiogenic shock were prospectively included. Two and three-dimensional images of the IVC, performed at baseline and when CVP was≤10mmHg, were acquired simultaneous with invasive measurement of CVP, both at rest and during sniff test. 2D and 3D IVC diameters, 3D IVC area and collapsibility index (IVCCI) were assessed. The eccentricity index (EI) was computed from 3D data as the ratio of maximum over minimum IVC diameter. The cut-off value of 10mmHg of CVP defined patient with euvolemia hemodynamic status.

At rest, the IVC diameter averaged 23±7mm by 2D and 25±8×19±7mm by 3D. IVC had an eccentric shape (EI=1.3) that increased when CVP was ≤10mmHg and during sniff test (P<0.001). IVC measurements by 2D and 3D were correlated with CVP. The best correlation was obtained with IVCCI derived from 2D diameters (R=-0.69) and 3D areas (R=−0.82). Using the cutoff value of 50% for IVCCI, a discrepancy between invasive CVP measurements and IVCCI has been observed for 11 examinations (13%) by 2D but only one was misclassified by 3D. Inter and intra-observer reproducibility for IVC area was 7±6% and 5±3%, respectively (Fig. 1).

In patients with cardiogenic shock, IVCCI from area by 3D echocardiography is reproducible and accurate to evaluate CVP.