Abstract
This prospective clinical investigation assessed the effect of placement of a Univent® tube on the anatomy of the internal jugular veins and the success of cannulation of the left internal jugular vein. After obtaining informed consent, 48 adult patients were enrolled. Of these, 42 patients were eligible and were divided into two groups: Univent® tube (group U, n=21) and wire enforced endotracheal tube (group C, n=21). The Univent® tube group were having a left thoracotomy. Using horizontal ultrasound scans just above the thyroid gland, the internal jugular vein was visualized and measured before and after Univent® placement. The number of needle passes necessary to cannulate the left internal jugular vein in the two groups was also compared.
Univent® tubes were associated with lateral displacement of the right carotid artery and internal jugular vein on the convex side of the Univent® tube, with compression of the right internal jugular vein by the artery, resulting in a kidney-shaped cross-section of the vein. On the left (concave side of the tube), the neck was indented, the sheath of the left carotid artery was displaced medially, and the left internal jugular vein distorted to an ellipse. There was a significant increase in the lateral diameter and a decrease in the cross-sectional area of the left internal jugular vein (t-test, P<0.05). The first attempt at cannulation of the left internal jugular vein failed significantly more often in the Univent® group (13/21 vs 5/21 in group C, Chi-square 6.22, P=0.025). Cannulation of the internal jugular vein before placement of the Univent® tube, or placement with ultrasound guidance is suggested.