Cardiac Variation of Internal Jugular Vein for the Evaluation of Hemodynamics.

Evaluations of intravascular fluid volume are considered to be one of the most important assessments in emergency and intensive care. Focusing on pulse-induced variation of the internal jugular vein (IJV) area, i.e., cardiac variation, we investigated its correlation with various hemodynamic indices using newly developed software. Software that automatically can track and analyze the IJV during ultrasonography was developed. Eleven healthy patients were subjected to an exercise load to increase their stroke volume (SV) and a dehydration load to decrease their central venous pressure (CVP). The cardiac variation in the area of the IJV, CVP, the SV and the respiratory variation in the inferior vena cava (IVC) were evaluated. The exercise protocol increased the patients' mean SV by 14.5 ± 3.7 mL, and the dehydration protocol caused their mean CVP to fall by 3.75 ± 0.33 cm H2O, which resulted in the collapse index (max IJV area - min IJV area/max IJV area) changing from 0.32 ± 0.04 to 0.44 ± 0.06 and 0.49 ± 0.04, respectively (p < 0.05). The SV exhibited a strong positive correlation with the collapse index (r = 0.59, p = 0.006), and CVP showed a strong positive correlation with the body height-adjusted mean area of the IJV (r = 0.72, p < 0.001). Cardiac variation in the area of the great veins is considered to be induced by venous return to the right atrium under negative pressure. It is possible that intravascular dehydration can be detected and hemodynamic indices, such as CVP and SV, can be estimated by evaluating cardiac variation in the area of the IJV.