Three-Dimensional Inferior Vena Cava for Assessing Central Venous Pressure in Patients with Cardiogenic Shock.

BACKGROUND: The inferior vena cava (IVC) has a complex three-dimensional (3D) shape, but measurements used to estimate central venous pressure (CVP) remain based on two-dimensional (2D) echocardiographic imaging. The aim of this study was to investigate the accuracy of IVC size and collapsibility index obtained by 3D echocardiography for assessing CVP in patients with cardiogenic shock.

METHODS: Eighty consecutive echocardiographic examinations performed in 33 patients (mean age, 72 ± 15 years; mean left ventricular ejection fraction, 19 ± 10%) admitted for cardiogenic shock were prospectively included. Two-dimensional and 3D images of the IVC were acquired simultaneously with invasive measurement of CVP, both at rest and during a sniff test. IVC diameters, 3D IVC area, and IVC collapsibility index (IVCCI) were assessed. The eccentricity index was computed from 3D data as the ratio of maximum to minimum IVC diameter. A cutoff value of 10 mm Hg for CVP defined patients with euvolemic hemodynamic status.

RESULTS: At rest, IVC diameter averaged 23 ± 7 mm by 2D imaging and 25 ± 8 × 19 ± 7 mm by 3D imaging. The IVC had an eccentric shape (eccentricity index = 1.3) that increased when CVP was ≤10 mm Hg and during the sniff test (P < .001). IVC measurements by 2D and 3D imaging 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 a cutoff value of 50% for IVCCI, 11 examinations were misclassified by 2D imaging and only one by 3D imaging. Inter- and intraobserver reproducibility for IVC area was 7 ± 6% and 5 ± 3%, respectively.

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