Vascular Access

Introduction:

More than 90% of dialysis patients in the United States rely on chronic hemodialysis (HD) for renal replacement therapy¹. A standard hemodialysis treatment includes the continuous processing (removing of waste products and free water) of approximately 200-500 cc of blood per minute over a 2-6 hour period and is performed on a 3 times per week basis. This treatment requires safe and readily available access to the circulatory system to provide sufficient blood flow for HD to be performed.

The primary goal of chronic HD vascular access is to provide repeated access to the circulation with minimal complications². A well-functioning vascular access is essential for patients survival. It serves as their lifeline because the quality of a patient’s dialysis and more importantly, the quality of their life depends strongly on its performance. The ideal vascular access should have the following characteristics:

Safe
- Well tolerated
- Few complications
Reliable
- Provide repeated access to circulation
- Provide continuous blood flow of 400 cc/min
- Long lasting
Simple
- Easy to place
- Easy to use
Acceptable to patient
- Painless
- Cosmetically acceptable³

A well functioning surgically created arteriovenous fistula (AVF) comes closest to meeting these ideal characteristics. AVF are the most reliable and have the fewest number of complications of any currently available HD access. For this reason, the AVF is considered the access of choice and has become the world standard.

In addition to the AVF, two other forms of chronic HD vascular access are in use:

Prosthetic bridge graft. This is an artificial conduit that is surgically placed under the skin and connects an artery and vein. Prosthetic bridge grafts or AV grafts (AVG) are most commonly placed in the arms or thighs. Currently, AVG are made from the following materials:
- Polytetrafluethylene (PTFE)
- Bovine vein
- Human cryopreserved vein
- Polyurethane
- Other
Central venous catheter. This is a plastic tube (usually silicone or polyurethane composites²) that is placed through the skin into a large vein (usually the jugular, femoral or subclavian).
- Temporary
- Tunneled cuffed catheter
AV shunts—These are surgically placed external cannulae composed of a U-shaped Silastic tube with Teflon tips (example Quinton-Scribner or Thomas shunt^1,4 ) that connect an artery and vein. Although rarely used today, they were the original “permanent” vascular access for HD.

Creation and maintenance of a functional AVF will remain one of the greatest challenges in the dialysis field⁵. Despite the fact that multiple studies have demonstrated the AVF’s overall superiority of clinical outcomes (much lower rates of thrombosis, infection, septicemia)⁶, there is a wide global variation in vascular access utilization. This variance has been attributed in varying degrees to patient characteristics, surgical practice patterns, delivery systems, available technologies, and practitioner and patient bias. The international renal community is working together to meet these challenges with dedicated and sustained efforts to improve vascular access technology, clinical practice and healthcare policy.

References:

Maya ID and Allon M. Core curriculum in nephrology vascular access: Core curriculum 2008. Am J Kidney Dis 51:702-708, 2008
Oliver MJ. Chronic hemodialysis vascular access: Types and placement. Retrieved from www.uptodate.com on January 14, 2008
Sands JJ. Vascular access 2007. Minerva Urol Nefrol 59:237-249, 2007
Coronel F, Herrero JA, Mateos P, Illescas ML, Torrente J, del Valle MJ. Long-term experience with the Thomas shunt, the forgotten permanent vascular access for haemodialysis. Nephrol Dial Transplant 16:1845-1849, 2001
Ethier J, Mendelssohn DC, Elder SJ, Hasegawa T, Akizawa T, Akiba T, Canaud BJ, Pisoni RL. Vascular access use and outcomes: An international perspective from the dialysis outcomes and practice patterns study. Nephrol Dial Transplant 23:3219-3226, 2008
Astor BC, Eustace JA, Powe NR, Klag MJ, Sadler JH, Fink NE, Coresh J. Timing of nephrologist referreal and arteriovenous access use: the CHOICE Study. Am J Kidney Dis 38:494-501, 2001

P/N 101031-01 2/2009