Quantitative Measurement of Blood Flow in the Internal Jugular Veins in Different Body Positions in Healthy Subjects

Background. Of as yet, flow in the internal jugular veins has not been quantitatively studied in lateral decubitus position. Optimal venous outflow during sleep has been hypothesized to be potentially protective against neurodegeneration. Methods. Using ultrasonography, we measured the cross-sectional areas and flow volumes in middle parts of the internal jugular veins in group of 25 healthy individuals. These measurements were performed in the supine, upright and lateral decubitus positions. Results. In lateral decubitus positions we revealed collapse of the internal jugular vein located higher, and dilatation of the opposite vein; yet there was also a high heterogeneity of the cross-sectional area changes and in many participants this pattern was not observed. Regarding flow volumes, there was a shift of flow from one vein to the opposite one, depending on which side the person was lying, but in comparison with the supine position the total outflow through both internal jugular veins was not significantly different. Conclusions. In terms of venous outflow, the lateral decubitus position does not differ significantly from the supine one. Working hypothesis of potentially protective effect of this body position during sleep against neurodegeneration, through improved venous outflow, has not been proven, at least in healthy persons.