Artificial kidneys; Hemodialysis; Renal replacement therapy
Dialysis is a method of removing toxic substances (impurities or wastes) from the blood when the kidneys are unable to remove these substances.
There are different types of kidney dialysis. This article focuses on hemodialysis.
WHAT IS HEMODIALYSIS?
Hemodialysis works by removing blood from the body and having it flow across a special filter, along with solutions. The filter helps remove toxins. The blood is then returned to the body.
Hemodialysis requires special ways to access the blood in the blood vessels. Access may be needed on a short-term (temporary) or long-term (permanent) basis.
Temporary access involves placing dialysis catheters (hollow tubes) into larger veins, usually in your neck, chest, or leg near the groin. They are most often used in emergency situations for short periods of time. However, catheters called tunneled catheters can be used for weeks or even months.
Permanent access is created by surgically joining an artery to a vein, usually in the arm. This vein becomes thickened over time. To perform the dialysis, blood is removed and returned through the vein. There are two methods to create this access:
An AVF has a lower chance for infections than an AVG and usually lasts longer before it needs to be replaced.
During a hemodialysis session, one or two needles must be inserted into the fistula or graft.
It is important to stick to the diet and medicines the dialysis staff and your kidney specialist (nephrologist) prescribed.
WHERE TO HAVE DIALYSIS
Most often, hemodialysis takes place in a special dialysis center. Patients usually have three treatments per week, during which they must sit in a chair for 3 - 4 hours. Many people feel tired for several hours after the dialysis.
Most dialysis centers have a very busy schedule. Patients who are late may not be able to make up the time.
Because the body continues to make waste products and take on extra fluid between dialysis sessions, you must closely follow a kidney dialysis diet.
Some people can do hemodialysis at home, avoiding having to travel back and forth to a dialysis center. Home dialysis is usually done using one of two schedules:
Home hemodialysis treatments help keep blood pressure lower. Many patients no longer need blood pressure medicines. The longer nightly treatments do a better job of removing waste products. They are done more slowly and are therefore easier on the heart and access site (AVF or AGF).
A dialysis nurse can train patients to do home dialysis. Patients do not have to buy a machine. Supplies can be delivered. Both the patient and any caregivers must learn to:
TAKING CARE OF YOUR GRAFT OR FISTULA
Avoid all pressure on the access site. If the graft or fistula clots, you may need a new one.
Learn how to feel the access site for the "thrill." This indicates that the AV site is still functioning. If the thrill disappears, call your health care provider immediately.
Do not miss or skip any dialysis sessions.
Observe the access site after dialysis, watching for swelling, infection, or bleeding. Call your health care provider immediately if you have a fever or other sign of infection.
The kidneys function as filters for the blood, removing waste products. They also help:
Dialysis replaces some of the functions when the kidneys are no longer working. A buildup of waste products and other imbalances would lead to death if dialysis did not perform these functions.
Dialysis is started after a gradual loss of kidney function in patients with chronic kidney disease. Your doctor and nurse will begin discussing dialysis with you before you need it.
Dialysis also may be used when the kidneys suddenly stop working (also called acute renal failure). On occasion, dialysis can be used to quickly remove drugs or poisons from the body.
The immediate risks include:
Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 133.
Mitch WE. Chronic kidney disease. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 131.
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