Seo et al used measurements of the inferior vena cava (IVC) to predict central venous pressure (CVP). This is a noninvasive method which can be used in a variety of clinical settings. The authors are from the University of Tsukuba in Japan.
Imaging Method: three-dimensional echocardiography
Location: supine position, subcostal view, 1.0 to 2.0 cm from the junction of the IVC to the right atrium
Measurements assuming elliptical shape:
(1) short diameter (S) of the cross-sectional image of the IVC (inner wall to inner wall)
(2) long diameter (L) of the cross-sectional image of the IVC (inner wall to inner wall)
ratio of S/L
= (short diameter) / (long diameter)
Interpretation:
• minimum ratio: around 0.2
• maximum ratio: 1.0
• The higher the ratio the higher the central venous pressure.
In Figure 4 a line estimate is given:
CVP in mm Hg =
= (23 * (ratio)) - 7.4
In Figure 3 the line appears to be nonlinear and can be approximated by:
CVP in mm Hg =
= (21.66 * ((ratio)^4)) - (0.56 * ((ratio)^2)) +3.001
