Volume-dependent echocardiographic parameters are not useful for estimating baseline blood volume but are useful for detecting acute changes in vascular filling state.

To assess the hypothesis that echocardiographic variables vary as a function of baseline blood volume and change in response to changes in vascular filling state, we evaluated the relationship between the atrial and ventricular dimensions and left ventricular function, as measured by combined Doppler and M-mode echocardiography on the one hand, and blood volume as measured by a standard radioactive isotope technique on the other. Furthermore, we determined the effect of an increment in vascular filling state induced by plasma volume expansion. Test subjects were ten male and six female volunteers. Blood volume/kg was the only factor not different between male and female subjects and therefore suitable for our study. None of the echocardiographic variables correlated with blood volume/kg. Volume loading increased stroke volume, left atrial diameter, right atrial area, left ventricular end-diastolic dimension, mean velocity of circumferential fiber shortening and left ventricular ejection time. It is concluded that echocardiographic variables are unsuitable for estimating blood volume. Serial measurements of atrial dimensions and left ventricular dimensions are useful for detecting rapid changes in vascular filling state.