Once a patient's kidneys are no longer functioning, long-term dialysis becomes necessary. To prevent infections in the bloodstream and narrowing of veins, permanent hemodialysis access is favored over short-term tunneled catheter use. Permanent access to the patient’s vascular system is obtained either through an arteriovenous fistula or graft.
The arteriovenous (AV) fistula connects the vein directly to the artery under the skin. A large vein is used, often from the forearm at the wrist or from the arm near the elbow.
The AV graft is a synthetic graft that connects the artery to the vein. The graft is made of the same material used in Teflon coatings and is usually a tube 6 mm in diameter.
If the patient’s veins are of poor quality, meaning they are too narrow or thin, a graft is the preferred access option. The graft is also the favored option in patients with a history of smoking or diabetes.
When a fistula is placed, it will need a minimum of 8 to 12 weeks to become large and strong enough for dialysis use. If dialysis is required before the fistula is mature enough for dialysis, a tunneled catheter will be placed for short-term use.
Once placed, a graft can be used in as little as 2 weeks.
The fistula is more durable than the graft option. According to the U.C. San Diego Vascular Surgery Department, half of all grafts will clot off within the first year.
Age and Gender
Researchers at John Hopkins School of Public Health have discovered that men younger than 72 have fewer complications with placements of fistulas than with graft placements. In contrast, women under 72 years of age have shown fewer complications with graft placements.
Most of the risks associated with permanent dialysis access are lower with a fistula than with a graft. Some of these risks include clotting, infection and reduced blood flow to the hand.