In vivo measurements of collapse behavior of human internal jugular vein during head-up tilt tests.

OBJECTIVE: Human internal jugular veins (IJVs) would collapse during posture change from supine to erect, which might influence intracranial hemodynamic. This study aimed to quantitatively describe the gradual collapse behavior of human IJVs during head-up tilt tests from supine to erect.

APPROACH: 10 male and 10 female subjects were enrolled in head-up tilt tests. Ultrasound screening was performed on the right IJV at five equidistant points between its junction with the subclavian vein and the location of the bifurcation of arteria carotis communis(ACC), with body at 0°, +10°, +20°, +30°, 40°, +50°, +60°, +70°, +80°, and +90°. Geometrical models were reconstructed and lumen areas were statistically analyzed based on extracted outlines of venous lumen.

MAIN RESULTS: The right IJV lumen area reduced significantly when tilt angle was increased from 0° to 20°, as the normalized lumen areas reduced to about 0.5 at the lowest point and about 0.2 at the others. The mean normalized lumen areas of the middle point were much smaller, which dropped below 0.1 when tilt angle was larger than 40°.

SIGNIFICANCE: Collapse behavior of human right IJVs was quantitatively described through obtaining variations of lumen outlines and areas at different locations and tilt angles. Reconstructed geometrical models could be used to gain nonlinear pressure-volume relations and inner blood flow characteristics, which would benefit researches on human cerebral venous outflow(CVO).