Last updated: 11/24/2009

Many advances in the treatment of kidney failure have been seen since the first attempts at dialysis treatments were made in the 1920s. At one time dialysis was only thought of as a way to keep people alive until kidney function could be restored....

Often the treatment for kidney failure had to be discontinued within several days because patients' veins could not endure the trauma of frequent withdrawing and replacing blood. The first breakthrough came in 1960 with the introduction of an implantable Teflon tube, called a shunt, that was the first effective vascular access device. Since then, the development of the AV fistula has marked another important advance, allowing effective treatment for longer periods of time. The goal of researchers and medical institutions is to continue to improve treatment and improve the length and quality of life for people with chronic kidney failure.

The kidneys are two organs in the mid-abdomen, one on each side of the middle back. Their function is to clean the blood of wastes and regulate fluid and chemical balance in the body. Dialysis performs these functions in place of the failing kidneys. Dialysis cannot restore the kidneys, but it can prolong life, often for years, by preventing the build-up of waste products in the body. Acute kidney failure can happen in many conditions and diseases that place an extra burden on the renal system, such as in advanced kidney and liver diseases; in rapidly progressing terminal illnesses, such as cancer and certain severe anemias; after severe allergic reactions or reactions to drugs or medications; in diseases that involve the vascular system, such as heart and lung diseases or the formation of blood clots (embolism); and often following heart bypass surgery. Diabetes and vascular diseases, especially those with hypertension (high blood pressure), are the two most common underlying diseases contributing to chronic kidney failure.

Hemodialysis

Dialysis is performed as critical life support when someone suffers acute or chronic kidney failure. It is a mechanical way to cleanse the blood and balance body fluids and chemicals when the kidneys are not able to perform these essential functions. Because kidney function can be reversible in some cases, dialysis can provide temporary support until renal function is restored. Dialysis may also be used in irreversible or chronic kidney shutdown when transplantation is the medical goal and the patient is waiting for donated kidneys. Some critically ill patients, with life-threatening illnesses, such as cancer or severe heart disease, are not candidates for transplantation and dialysis may be the only option for treating what is called end-stage renal disease (ESRD).

There are two types of dialysis, hemodialysis and peritoneal dialysis. In hemodialysis, the blood circulates through a machine outside the body and is filtered as it circulates. In peritoneal dialysis, the blood is filtered through a membrane that has been placed in the abdomen. Blood remains in the body and waste material is filtered into an exchange fluid through an opening in the abdomen called a port. Only hemodialysis requires an AV fistula or other vascular access.

Hemodialysis circulates blood through a dialysis machine that contains a filter membrane. The blood is slowly pumped out of the body and into the machine for filtering. After being filtered, the blood is returned to the body through the same vascular access. About one cup of blood is outside the body at any given moment during the continuous circulation process.

Hemodialysis is usually done three times a week, taking between three and five hours each time. Healthcare professionals perform the procedure either at independent dialysis centers or in hospitals or medical centers. Dialysis patients must go to the hemodialysis center where they will sit to receive the treatment. Although they cannot walk around, they can watch television, read, or talk to other patients. The dialysis center offers patient education, including videos and brochures that describe treatment options and self-care. Patients can also be given advice and information about paying for this ongoing treatment through nationally sponsored programs that are available especially for dialysis patients. Often the dialysis center offers emotional support as well, letting people meet and talk with other people who have kidney problems. Some people prefer to perform their own dialysis by having a home dialysis machine. This requires that the dialysis patient and another person, usually a family member, take a three- to six-week training program to learn how to do the treatment.

Vascular access

An access or entry to the vascular system is needed to perform the blood-cleansing role of the kidneys through hemodialysis. There are three types of vascular access: arteriovenous fistula, grafts, and catheters.

ARTERIOVENOUS FISTULA. An AV fistula has proven to be the best kind of vascular access for people whose veins are large enough, not only because it lasts longer but it is also less likely than other types of access to form clots or become infected. If the veins are not large enough, or there is no time to wait for a fistula to develop, a graft or a catheter must be used.

GRAFT. Grafts are often the access of choice when a hemodialysis patient has small veins that will not likely develop properly into a fistula. This type of access uses a synthetic tube implanted under the skin of the arm that can be used repeatedly for needle placement. Unlike a fistula, which requires time to develop, a graft can be used as soon as two to three weeks after placement. Grafts are known to have more problems than fistulas, such as clots and infection, and will likely need replacement sooner.

CATHETER. A catheter may be used to provide temporary vascular access. When kidney disease has progressed quickly, there may not be time to prepare permanent vascular access before dialysis treatments are started. The catheter is a tube that is inserted into a vein in the neck, chest, or in the leg near the groin. Two chambers in the tube allow blood to flow in and out. Once the catheter is in place, needle insertion is not necessary. Catheters are effective for dialysis for several weeks or months while surgery is performed and an AV fistula develops. They are not selected for permanent access because they can clog, become infected, or can cause the veins to narrow. Long-term catheter access must be used in patients for whom fistula or graft surgery has not been successful. If more than three weeks' use is expected, catheters can be made to tunnel under the skin, which increases comfort and reduces complications