Establishing a Vascular Access for Dialysis
Dialysis and kidney transplantation are two lifesaving methods for treating kidney failure. The most common form of dialysis is hemodialysis. During this process, blood from an artery in the arm flows through a thin plastic tube to a machine called a dialyzer, which acts as an artificial kidney, filtering the blood and then returning it through another tube in a nearby vein in the same arm.
Before one can begin hemodialysis, a route for removing blood from the body (a few ounces at a time) and then returning it must be established by creating a vascular access site. The following are the three kinds of vascular access sites:
- Arteriovenous (AV) Fistula: A fistula is an opening or connection of two parts of the body. An AV fistula connects an artery to a vein, usually in the forearm, to enable more blood to flow in the vein. The vein then grows larger and stronger, enabling easier repeat access to the blood system for hemodialysis. The surgery to create the AV fistula can be performed on an outpatient basis, but it could take several months for it to properly develop. Other highlights of AV fistulas are: infections are rare, fewer complications occur with them and they can last many years, compared to weeks or months with other accesses. Should a patient experience clotting of his or her fistula, it can be swiftly replaced.
- AV Graft: For patients with small veins that will not develop properly into a fistula, vascular access can be achieved through a synthetic tube that connects the artery to a vein. The tube, or graft, functions as an artificial vein that can be accessed frequently for needle placement during hemodialysis. Unlike the AV fistula, the graft may be used as soon as two to three weeks, but because it is more susceptible to clotting and infections, it requires extra care.
- Venous Catheter: If the kidney disease has progressed rapidly, patients may not have the luxury of time to allow for a permanent vascular access to develop for hemodialysis treatments. Hence a venous catheter, or tube with two chambers inserted into the neck, chest or leg, can be utilized as a temporary solution. Because catheters can clog, become infected or cause narrowing of the veins in which they are placed, they are hardly ideal for permanent access. However, a catheter will function for several weeks or months, while a permanent access develops.