Age-related decrease in inferior vena cava diameter measured with echocardiography.

The diameter of the inferior vena cava (IVC) measured with echocardiography is clinically used as a parameter to estimate right atrial pressure, which reflects dehydration or overhydration. Because elderly patients fall easily into dehydration, normal values for IVC diameters in elderly patients may be helpful for geriatric medicine. However, normal values of IVC diameter in relation to age have not been investigated. The purpose of this study was to elucidate age-related changes in IVC diameter using echocardiography. Enrolled in the study were 200 patients (67 ± 15 yrs: range 17-94 yrs) with cardiovascular risk factors but no overt cardiac diseases. IVC diameters throughout the respiratory cycle were measured as maximum and minimum IVC diameters (IVC(max), IVC(min)) using M-mode echocardiography. To assess IVC collapsibility, the respirophasic variation of IVC diameter was calculated as (IVC(max) - IVC(min))/(IVC(max)) ×100. Maximum IVC diameter was decreased with advancing age (r = -0.221, p = 0.002). The respirophasic variation of the IVC diameter was increased with advancing age (r = 0.244, p = 0.001). Stepwise multiple regression analysis showed that age was an independent determinant for both maximum IVC diameter (ß coefficient = -0.249, p < 0.001) and respirophasic variation of the IVC diameter (ß coefficient = 0.268, p < 0.001). Age-related decrease in maximum IVC diameter and increase in the respirophasic IVC collapsibility may indicate the decrease in right atrial pressure in some elderly patients. Therefore, elderly patients with decreased maximum IVC and increased respirophasic IVC collapsibility may need prevention for dehydration.