Catheter Vessel Ratio : Now What?

Timothy R Spencer, DipAppSc, BHealth, IC Cert, RN, APN, VA-BCTM

Keegan J Mahoney, BS, RRT, VA-BCTM

Vascular Access Specialist, Global Vascular Access, Scottsdale AZ

Vascular Access Specialist, Banner Gateway/MD Anderson, Gilbert AZ

PRESENTED AT:

WHAT IS THE EVIDENCE?WHAT IS THE EVIDENCE?

Catheter-related thrombosis (CRT) poses a serious, yet challenging situation for clinical providers working withintodays current healthcare environment. The clinical issues generated by this phenomenon are problematic andoften lasting well beyond the initial diagnosis and potential treatment protocols.

Upper extremity-deep vein thrombosis (UE-DVT) refers to the formation of a thrombus within the deep vessels ofthe 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.

An early retrospective venography study (Allen et al, 2000) described high thrombosis rates with 23.3% ofpatients developing thrombosis after the initial PICC placement (overall thrombosis rate 38%), yet did notencompass vessel size as a potential influencing factor, citing age, sex, cannulated vein, catheter size, location,and incidence of thrombosis risks. Whilst there have been more recent considerations regarding catheter to vesselratios (Sharp et al, 2013; Sharp et al, 2015; Sharp et al 2016), there is still limited evidence in its role ofthrombosis reduction strategies in vascular access practices.

Much focus on this phenomenon has targeted the increased use of peripherally inserted central catheters (PICCs)in the last two decades (Elman and Khan, 2006; King et al, 2006; Evans et al, 2010; Cotogni and Pittiruti, 2014;Chopra et al, 2015; Greene et al, 2015; Holder et al, 2017) especially with its increasing demand for non-physician facilitated insertions (Alexandrou et al, 2010, Ramirez et al, 2010; Johnson et al, 2015)

Although there has been a strong focus on larger diameter PICCs and thrombosis risk (Trerotola et al, 2010;Chopra et al, 2012), there has been insufficient information established on what relationship to vessel size isappropriate for a device-specific external diameter. Early references to clinical standards and published guidelinesdid not clearly address appropriateness of vessel size in relation to external catheter diameter.

BASED UPON 3 CORE CONCEPTSBASED UPON 3 CORE CONCEPTS

Virchow's Triad:This pathophysiological explanation describes the precursors around three core relationship development ofvascular thrombosis. The triad consists of the following components: vessel wall damage or endothelial injury,alterations in blood flow (hematological stasis), and hypercoagulability of the blood, deeming it a significanteffector in prevention of vessel- and catheter-related complications.

Vessel Health & Preservation:Directs the clinician through a closer assessment of the patient and uses tools to ensure a thorough vascularassessment and review of the overall patient treatment plan. VHP encompasses current clinical guidelines andevidence-based literature, in doing so, creating a programme that comprehensively addresses the issues ofeducation, assessment, placement, and daily assessment of patient condition to determine device necessity.VHP represents the pinnacle of evidence-based knowledge development as a risk reduction strategy that complieswith many professional organizations;

The Joint Commission (TJC)

Oncology Nurses Society (ONS)

Infusion Nursing Society (INS)

Association for Vascular Access (AVA)

Agency for Healthcare Research and Quality (AHRQ)

Centers for Disease Control (CDC)

Registered Nurses Association of Ontario (RNAO)

Association for Professionals in Infection Control and Epidemiology, (APIC)

The Society for Healthcare Epidemiology of America (SHEA)

Institute for Healthcare Improvement (IHI)

Catheter Vessel Ratio (CVR):To a large extent, it comes down to annular mathematical proportions and is measureable by well-trained clinicians with ultrasound (US). However, this process is often forgotten as part of the vascular assessment process when devices are placed for intravascular therapies. A relatively simple issue, but nonetheless, a very important one which can have significant effect on the functioning of the device, as well as blood flow characteristics within the vessel.

IMPORTANCE OF CVRIMPORTANCE OF CVR

Implications

Catheter-related thrombosis (CRT) has serious implications related to the loss of vascular access, development ofpulmonary embolism (PE), recurrent VTE, infections and post-thrombotic syndrome. The pathogenesis of CRT iscomplex and multifactorial, with risk factors associated with the catheter, the vessel selected for insertion and theunderlying 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 onCRT, by potentially reducing venous stasis and improving flow dynamics around the body of the catheter.

There is now established clinical evidence that shows CRT is related to the catheter size within the intraluminalspace (Trerotola et al, 2010; Chopra et al, 2012; Evans et al, 2013) and the literature regarding these adverseevents emanates from 2 distinct patient populations: those with and without cancer. And as anticipated, venousthromboembolism (VTE) estimates in patients with cancer and critically ill patients consistently exceed those ofpatients without cancer or ICU level of care (Chopra et al, 2012).

How to define the CVR

Nifong and McDevitt (2011) state the presence of a catheter within the lumen of a vein will “decrease blood flowand potentially create venous stasis, and that the size of the catheter versus the vein has significant impact,particularly with peripherally inserted central catheters (PICCs)”. The understanding that catheter size maypotentially influence venous stasis within the vessel and exacerbate venous thrombosis had not been scientificallyexplored before, and although is now gaining more attention, there is still no clear process to facilitate properclinical standards about vessel and catheter sizes.

We have defined the Catheter to Vessel Ratio (CVR) as the “indwelling space or area consumed or occupied by an intravascular device inserted and

positioned within a venous or arterial blood vessel.”

CVR TOOL RACVR TOOL RATIONALETIONALE

Although a broad literature search was performed, no identifiable evidence was returned regarding the “rule of thumb” often inherently followed by many practicing vascular access clinicians when inserting intravascular devices, or that the ‘default’ 33% catheter vessel ratio was referenced as a standard of clinical practice.

A review of the INS Standards of Practice (SOP) from both 2006 and 2011 did not specify a recommended vessel size or measurement to set an upper limit of diameter for a vascular device to be placed.

The 2016 INS SOP however did include more recent evidence to say that a catheter vessel ratio of <45% was a satisfactory risk prevention strategy. The publication by Sharp et al, (2015) showed that there was statistical significance with catheter vessel ratios >45%, with a 13-fold increase in CRT risk.

We compared the traditional ‘rule of thumb’ (or 33%), and the recent 45% rule of catheter to vessel ratios. However, these general rules are based on a two-dimensional measurement, not focusing on the area the catheter takes up within the vessel, which is a three dimensional perspective.

rcath - radius of catheter

rvess - radius of vessel

ecc - distance between catheter and vessel center

We have designed a preliminary tool using a mathematical-based formula to determine consumed area by apotential intravascular device. This will help clinicians with decision making in the appropriateness of a catheterto vessel ratio of 45% or less.

INTRODUCTION OF THE TOOLINTRODUCTION OF THE TOOL

The Catheter Vessel Ratio Tool

Understanding the tool.

The example below demonstrates a 5 French catheter showing the relationship of vessel size and area consumedby the catheter.

RED ZONE - 45% or greater - high risk zone

YELLOW ZONE - 34-44% - cautionary zone

GREEN ZONE - 33% or less - safe zone

Using this conversion process the authors could determine the areas where catheter and vessel sizes were withinthe 3 zones.

How to use the tool.

Here is an working example of how to determine the CVR for a measured vessel (4.2mm) and a 5Fr catheter.

1. Assess the vessel with US to obtain vessel size

2. Refer to the tool and find the closest size along the top row

3. Slide your finger down to find the corresponding catheter size you wish to insert

4. What color do you see at the intersection?

Behind the scenes mathematics..

DISCLOSURES

Timothy R Spencer

Vascular Access Specialist

Global Vascular Access, Scottsdale, AZ

KOL/Faculty – Ultrasound Guided Central & Arterial Access: Advancing Vascular Access - Teleflex

Consultant/Speakers Bureau - Ethicon/BioPatch

Keegan J Mahoney

Vascular Access Specialist

Banner Gateway/MD Anderson Cancer Medical Center, Gilbert, AZ

Faculty – Ultrasound Guided Central & Arterial Access: Advancing Vascular Access - Teleflex

ABSTRACT

Background: Throughout the practice of vascular access, catheter to vessel ratio has been used byclinicians to help select the most appropriate device for the insertion vessel. In 2016, the INS Standards ofPractice set a recommendation that the catheter to vessel ratio can increase from 33% and now take up to45% or less of the vessel diameter.

Purpose: To standardize the process of vessel assessment, incorporating catheter to vessel ratio, vesselhealth and preservation, and Virchow’s triad, empowering an evidence-based approach to deviceplacement.

Project: Definitions will be provided to help the clinician have the basic understanding of the concepts ofcatheter to vessel ratio, vessel health and preservation and Virchow’s triad. This will conceptualize andillustrate the differences of the two-dimensional diameter measurement taken from an ultrasound duringassessment, and the three-dimensional area involved in the catheter to vessel ratio. Graphicalrepresentations of calculations will be shown to portray the historical change catheter to vessel ratio hasundergone from the “rule of thumb,” to the 1/3 to 2/3, and moving to the present 45% rule.

Results: Through calculations based on the area of the 33% and 45% rule, a simple tool will be presentedto help guide the bedside clinician to make informed decisions when placing peripherally-based vasculardevices.

Implications: Increasing the understanding and utilization of catheter to vessel ratio will lead to a safer,more consistent, approach to device placement. The future of evidence-based data relies on the clinician tocapture accurate vessel measurements and device-related outcomes, based around catheter to vessel ratios.This will lead to a more dependable data pool, propelling the field of vascular access forward, improvingpatient outcomes.

REFERENCESAllen, A. W., Megargell, J. L., Brown, D. B., Lynch, F. C., Singh, H., Singh, Y., & Waybill, P. N. (2000). Venous thrombosis associated with the placement of peripherally inserted central catheters. Journal of Vascular and Interventional Radiology, 11(10), 1309-1314.

Sharp, R., Gordon, A., Mikocka-Walus, A., Childs, J., Grech, C., Cummings, M., & Esterman, A. (2013). Vein measurement by peripherally inserted central catheter nurses using ultrasound: a reliability study. Journal of the Association for Vascular Access, 18(4), 234-238.

Sharp, R., Cummings, M., Fielder, A., Mikocka-Walus, A., Grech, C., & Esterman, A. (2015). The catheter to vein ratio and rates of symptomatic venous thromboembolism in patients with a peripherally inserted central catheter (PICC): a prospective cohort study. International Journal of Nursing Studies, 52(3), 677-685.

Sharp, R., Grech, C., Fielder, A., Mikocka-Walus, A., & Esterman, A. (2016). Vein Diameter for Peripherally Inserted Catheter Insertion: A Scoping Review. Journal of the Association for Vascular Access, 21(3), 166-175.

Elman, E. E., & Kahn, S. R. (2006). The post-thrombotic syndrome after upper extremity deep venous thrombosis in adults: a systematic review. Thrombosis Research, 117(6), 609-614.

King, M. M., Rasnake, M. S., Rodriguez, R. G., Riley, N. J., & Stamm, J. A. (2006). Peripherally inserted central venous catheter-associated thrombosis: retrospective analysis of clinical risk factors in adult patients. Southern Medical Journal, 99(10), 1073-1078.

Evans RS, Sharp JH, Linford LH, et al. (2010) Risk of symptomatic deep venous thrombosis associated with peripherally inserted central catheters. Chest. 138(4):803-810.

Cotogni, P., & Pittiruti, M. (2014). Focus on peripherally inserted central catheters in critically ill patients. World Journal of Critical Care Medicine, 3(4), 80.

Chopra, V., Fallouh, N., McGuirk, H., Salata, B., Healy, C., Kabaeva, Z., Smith, S., Meddings, J. and Flanders, S.A., (2015). Patterns, risk factors and treatment associated with PICC-DVT in hospitalized adults: A nested case–control study. Thrombosis Research, 135(5), 829-834.

Greene, M. T., Flanders, S. A., Woller, S. C., Bernstein, S. J., & Chopra, V. (2015). The association between PICC use and venous thromboembolism in upper and lower extremities. The American Journal of Medicine, 128(9), 986-993.

Holder, M. R., Stutzman, S. E., & Olson, D. M. (2017). Impact of Ultrasound on Short Peripheral Intravenous Catheter Placement on Vein Thrombosis Risk. Journal of Infusion Nursing, 40(3), 176-182.

Alexandrou, E., Spencer, T. R., Frost, S. A., Parr, M. J., Davidson, P. M., & Hillman, K. M. (2010). A review of the nursing role in central venous cannulation: implications for practice policy and research. J Clin Nurs 2010; 19:1485–1494

Ramirez, C., Malloch, K., & Agee, C. (2010). Evaluation of respiratory care practitioner central venous catheter insertion program. Journal of the Association for Vascular Access, 15(4), 207-211.

Johnson, D., Snyder, T., Strader, D., & Zamora, A. (2017). Positive Influence of a Dedicated Vascular Access Team in an Acute Care Hospital. Journal of the Association for Vascular Access, 22(1), 35-37.

Trerotola, S.O., Stavropoulos, S.W., Mondschein, J.I., Patel, A.A., Fishman, N., Fuchs, B., Kolansky, D.M., Kasner, S., Pryor, J. and Chittams, J. (2010). Triple-lumen peripherally inserted central catheter in patients in the critical care unit: prospective evaluation. Radiology, 256(1), 312-320.

Chopra, V., Anand, S., Krein, S. L., Chenoweth, C., & Saint, S. (2012). Bloodstream infection, venous thrombosis, and peripherally inserted central catheters: reappraising the evidence. The American Journal of Medicine, 125(8), 733-741.

Evans, R. S., Sharp, J. H., Linford, L. H., Lloyd, J. F., Woller, S. C., Stevens, S. M., ... & Weaver, L. K. (2013). Reduction of peripherally inserted central catheter-associated DVT. Chest, 143(3), 627-633.

Nifong, T. P., & McDevitt, T. J. (2011). The effect of catheter to vein ratio on blood flow rates in a simulated model of peripherally inserted central venous catheters. Chest, 140(1), 48-53.

Gorski, L. A. (2007) Infusion nursing standards of practice. Journal of Infusion Nursing, 30(3), S1-92.

Gorski, L. A., Eddins, J., Hadaway, L., Hagle, M. E., Orr, M., Richardson, D., Williams, P. A. (2011) Infusion nursing standards of practice. Journal of Infusion Nursing, 34(1S), S1-S110

Gorski, L. A., Hadaway, L., Hagle, M. E., McGoldrick, M., Orr, M., Doellman, D. (2016) Infusion nursing standards of practice. Journal of Infusion Nursing, 39(1S), S1-S159