NONINVASIVE ESTIMATION OF RIGHT ATRIAL PRESSURE FROM THE INSPIRATORY COLLAPSE OF THE INFERIOR VENA-CAVA

To evaluate a simple noninvasive means of estimating right atrial (RA) pressure, the respiratory motion of the inferior vena cava (IVC) was analyzed by 2-dimensional echocardiography in 83 patients. Expiratory and inspiratory IVC diameters and percent collapse (caval index) were measured in subcostal views within 2 cm of the right atrium. Parameters were correlated with RA pressure by flotation catheter within 24 hours of the echocardiogram (38 were simultaneous). Correlations between RA pressure (range 0 to 28 mm Hg), expiratory and inspiratory diameters and caval index were 0.48, 0.71 and 0.75, respectively. Of 48 patients with caval indexes <50%, 41 (89%) had RA pressure ≥10 mm Hg (mean ± standard deviation, 15 ± 6), while 30 of 35 patients (86%) with caval indexes ≥50% had RA pressure <10 mm Hg (mean 6 ± 5). Sensitivity and specificity for discrimination of RA pressure ≥ or <10 mm Hg were maximized at the 50% level of collapse. Thus, IVC respiratory collapse on echocardiography is easily imaged and can be used to estimate RA pressure. A caval index ≥50% indicates RA pressure <10 mm Hg, and caval indexes <50% indicate RA pressure ≥10 mm Hg. © 1990.