Patients with kidney failure may need to undergo dialysis (cleaning of the blood) in order to survive.
Hemodialysis is a mechanical method of dialysis, which uses a machine to filter wastes from the blood. There are 3 different types of accesses for hemodialysis, each with its own advantages and disadvantages:
- Arteriovenous (AV) fistula (native tissue)
- AV graft (synthetic material)
- Central venous dialysis catheter
AV fistula is when a vein is surgically connected to an artery, allowing a large amount of blood flow through the vein. As a result, the vein will increase in size and will allow rapid removal and cleaning of blood and return of blood back to the individual.
The AV fistula is considered the best long-term vascular access for hemodialysis, because it provides adequate blood flow and has a lower complication rate than other types of accesses. Most fistulas can take 6 weeks to 3 months to mature (be ready to use for dialysis). Some can take longer.
Creating an AV fistula requires a quality vein. An experienced physician can create an AV fistula in about 80 percent of patients.
If an AV fistula cannot be created, another option would be an AV graft. An AV graft is a synthetic tube usually implanted under the skin to connect an artery to a vein. The graft usually can be used in 2 to 3 weeks. Compared to fistulas, the grafts have a higher rate of infection and thrombosis. Grafts have a patency (staying open) rate of 50 to 70 percent per year.
Venous dialysis catheter
If the patient needs to be started on hemodialysis urgently and does not have time to have a permanent vascular access constructed, a venous catheter can be used as a temporary access.
A catheter is a tube inserted into a vein in the neck or groin. Catheters are not ideal for permanent access. They have a very high rate of infection and thrombosis, and they can cause narrowing of the veins. Ninety percent of patients should have the catheter replaced by a fistula or graft within 3 months to avoid serious complications.