Catheter to vessel ratio (CVR) may be defined as the
“indwelling space or area consumed or occupied by an intravascular device inserted and positioned within a venous or arterial blood vessel.”
The CVR is an extremely important assessment factor for all vascular access specialists and like-minded clinicians placing intravascular devices.
Catheter-related thrombosis (CRT) poses a serious, yet challenging situation for clinical providers working within todays current healthcare environment. The clinical issues generated by this phenomenon are problematic and often lasting well beyond the initial diagnosis and potential treatment protocols. With short and long-term issues for both patients and clinicians, such as catheter dysfunction, infection, and superior vena cava (SVC) syndrome, accompanied by the considerable costs of ongoing treatment and care, several clinical conundrums, particularly when there are varying thoughts and evidence on how-to-treat within this topic, exist. Vascular access (VA) devices continue to be the most frequently performed invasive procedure in any given healthcare institution today, and the potential for CRT increases with many contributing factors, not to mention the comorbidities that impact thrombosis risk on a pathophysiological level.
Magnitude of the problem.
Upper extremity-deep vein thrombosis (UE-DVT) refers to the formation of a thrombus within the deep vessels of the upper arm and chest: primarily the subclavian, axillary and brachiocephalic veins, but also the basilic, brachial, and the more increasingly, superficial cephalic veins, in the arm. It has been described as either idiopathic (primary) due to anatomical variants or as secondary, more associated with tumor disease, intravenous catheters, and pacemaker leads .
Much focus on this phenomenon has targeted the increased use of peripherally inserted central catheters (PICCs) in the last two decades [2-8] especially with its increasing demand for non-physician facilitated insertions [9-11]. Around this time, a prospective study looking at triple lumen PICCs highlighted a symptomatic thrombosis risk of 20% that was considered unacceptably high by the study oversight committee. The study was terminated due to patient risk. Venous thrombosis (symptomatic or asymptomatic) was detected in 26 of 45 patients (58%) when examined with ultrasound (US) .
Catheter-related thrombosis has serious implications related to the loss of vascular access, development of pulmonary embolism (PE), recurrent VTE, infections and post-thrombotic syndrome. The pathogenesis of CRT is complex and multifactorial, with risk factors associated with the catheter, the vessel selected for insertion and the underlying patient co-morbidities and their treatments. The monitoring of the catheter to vessel ratio (CVR), whereby vessel and catheter size are measured for relationship appropriateness, may have potential influence on CRT, by potentially reducing venous stasis through improving flow dynamics around the body of the catheter.
Timothy R. Spencer, Keegan J. Mahoney (2017). Reducing catheter-related thrombosis using a risk reduction tool centered on catheter to vessel ratio. Journal of Thrombosis and Thrombolysis, 44(4): 427-434 https://doi.org/10.1007/s11239-017-1569-y
I have put up a PDF version for download of our award winning poster from the Association for Vascular Access 31st Scientific Meeting held in Phoenix, AZ, USA.
Click the link posted below to open and save a copy of our poster that can be used to help make the best decision for appropriateness of catheter diameter and vessel size to help prevent catheter-related thrombosis.
Here are some images from the Association for Vascular Access 31st Scientific Meeting ePoster Theatre session where we presented our research.
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Ramirez C, Malloch K, Agee C. Evaluation of respiratory care practitioner central venous catheter insertion program. The Journal of the Association for Vascular Access. 2010 Jan 1;15(4):207-11.
Johnson D, Snyder T, Strader D, Zamora A. Positive Influence of a Dedicated Vascular Access Team in an Acute Care Hospital. Journal of the Association for Vascular Access. 2017 Mar 31;22(1):35-7.
Trerotola SO, Stavropoulos SW, Mondschein JI, Patel AA, Fishman N, Fuchs B, Kolansky DM, Kasner S, Pryor J, Chittams J. Triple-lumen peripherally inserted central catheter in patients in the critical care unit: prospective evaluation. Radiology. 2010 Jul;256(1):312-20.