Introduction

Central venous access is a cornerstone of medical resuscitation in a variety of scenarios. Three primary sites of central cannulation exist, and all three have perceived advantages and disadvantages. Of the three routes, a number of studies have shown benefit to subclavian as opposed to Internal Jugular (IJ) or femoral insertion, although this route has fallen out of favor due to the relative difficulty of using ultrasound to visualize the vessel itself and the perceived increased risk of mechanical complications. Primarily, concern for pneumothorax and arterial puncture are heightened as a result of the necessitated “blind” approach. Recently, a few studies have been published showing that it is viable to visualize these vessels using ultrasound, but that topic can be broached in a future post.

The Paper

The 3Sites Trial was a multicenter, non-blinded, randomized control trial that took place at nine hospitals in France from 2011 to 2014. The paper looked to identify the relative risk of a number of common complications including central line associated bloodstream infections, or CLABSIs, symptomatic thrombosis, and mechanical complications of the line placement itself among the three common insertion sites.

The author’s primary outcome was a composite outcome of CLABSIs and symptomatic DVTs as a result of catheterization. The secondary outcome was the rate of grade 3 or higher mechanical complications as a result of catheter insertion (with pneumothorax defined as grade 3 as opposed to the normal grade 2).

Results

The trial was completed and published in 2015, and showed a statistically significant decrease in the primary outcome with the placement of subclavian central lines, as opposed to both IJ and femoral lines (hazard ratios 2.1 and 3.5, respectively). There was no statistical difference between IJ and femoral lines. The chart below shows the rate differences between the three line insertion sites, with the two colored blocks demonstrating the primary composite outcome.

Rates of the secondary outcome, mechanical complications, were highest in subclavian lines. The choice to include only symptomatic DVT and CLABSI in the primary outcome, and leave mechanical complications as its own secondary outcome is interesting. Most likely, the trial designer was attempting to look at only complications that were not strictly dependent on provider skill, but all proceduralists were required to have completed at least 50 lines, or to be supervised by someone who had completed that many, so they all were considered proficient at the procedure. If one included this type of complication in the primary composite outcome, all three line variations would likely have not had significant difference.

Analysis

According to the data from this study, subclavian lines are associated with a decreased number of non-preventable central line complications as opposed to IJ or femoral lines. Recent practice has moved away from the placement of subclavian lines due to provider preference for ultrasound guidance, but it may be appropriate to increase proficiency in this type of line, as mastery of the technique would likely lead to a decrease in mechanical complications of the procedure and an overall improvement in patient outcomes. Although technically difficult, it is also possible to use ultrasound to guide these lines with sufficient practice, further decreasing mechanical risks.

Another takeaway from this large randomized trial is that there is no significant difference in the composite outcome between IJ and femoral lines (hazard ratio, 1.3). In fact, if including mechanical complications, femoral lines had a lower overall percentage of adverse events than IJ insertions. This runs counter to the long-held belief that IJ is preferable to femoral insertion due to the increased risk of infection in femoral lines. More research is needed, but this does fit within a recent trend suggesting that femoral lines, when placed properly, carry no increased infection risk compared to jugular cannulation.

Written by: Nicholas Wolff, MD

Reviewed by: Stevley Koshy, MD

References:

1. Parienti, J. J., Mongardon, N., & Megarbane, B. (2016). Intravascular complications of central venous catheterization by insertion site. Journal of Vascular Surgery, 63(3), 846. https://doi.org/10.1016/j.jvs.2016.01.007
2. https://upload.wikimedia.org/wikipedia/commons/a/ac/A_technique_for_the_fixation_of_central_venous_catheters.png