We undertook a prospective laboratory study to examine the effect of head position on the relative positions of the carotid artery and the internal jugular vein (IJV). Volunteers (n = 12) from departmental staff, 18-60 yr of age, who had never undergone cannulation of the IJV underwent imaging of their IJV and carotid artery. With the subject in a 15 degrees Trendelenburg position, two-dimensional ultrasound images of the IJV and the carotid artery were obtained on the left and right sides of the neck at 2 and 4 cm from the clavicle along the lateral border of the sternal head of the sternocleidomastoid muscle at 0 degrees, 40 degrees, and 80 degrees of head rotation from the midline. The percent overlap of the carotid artery and IJV increased significantly at 40 degrees and 80 degrees head rotation to both the right and left (P < 0.05). Data from 2 and 4 cm above the clavicle did not differ and were pooled. The percent overlap was larger on the left than the right only with 80 degrees of head rotation (P < 0.05). The increased overlap of carotid artery and IJV with head rotation > 40 degrees increases the risk of inadvertent puncture of the carotid artery associated with the common occurrence of transfixion of the IJV before it is identified during needle withdrawal. The IJV frequently collapses with needle insertion. This may result in puncture of the posterior wall of the vessel, and thus of the carotid artery when the two vessels overlap. To decrease this risk, the head should be kept in as neutral a position as possible, that is < 40 degrees rotation, during IJV cannulation.
Perforation of the vena cava or atrium is a serious complication of monitoring with a central venous catheter. We designed an in vitro model with a pulsating simulated membrane to evaluate a number of variables that could affect relative perforating potential of different types of central venous catheters. To determine the perforating potential of central venous catheters, we studied the effects of (1) the angle of incidence (n = 6) between catheter and simulated membrane; (2) catheter material (polyurethane and polyethylene); (3) make (manufacturer and model) (n = 6), with 3 catheters of each make tested; (4) design (n = 3 each: silicone rubber, open-ended, blunt-ended, and polyurethane pigtail); and (5) number of lumens (single, double, or triple). Each trial was repeated five times with each catheter that was tested. Perforation was significantly more likely when the angle of incidence between catheter and pulsating simulated membrane was greater than 40 degrees than when it was 40 degrees (P less than 0.05). Perforation was less likely with single-lumen than comparable French-sized double- and triple-lumen catheters; among single-lumen catheters, perforation required many more pulsations with a polyurethane than a polyethylene catheter (P less than 0.001). Perforation potential differed significantly among 6 makes of 7-French triple-lumen catheters (P less than 0.05). Compared with other materials or designs, silicone rubber or a pigtail tip decreased the perforation potential of catheters (P less than 0.001). These data offer additional objective information to consider when choosing and positioning central venous catheters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.