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Dialysis is a treatment used when the kidneys do not work well. It removes harmful substances from the blood when the kidneys cannot.

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There are different types of kidney dialysis. This article focuses on hemodialysis.


Hemodialysis removes blood from the body and sends it across a special filter with solutions. The filter helps remove harmful substances. The blood is then returned to the body.

If you have hemodialysis, your health care team will need a way to get to the blood in your blood vessels. This is called access. You may need this for a little while (temporary) or for a long time (permanent).

Temporary access involves putting a hollow tube (called a catheter) into a large vein, usually in your neck, chest, or leg near the groin. This is most often done in emergency situations for short periods of time. However, some 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. There are two ways to do this:

  • An artery and a vein are directly connected to each other. After a few months, they form a connection called a fistula (an arteriovenous fistula, or AVF). This type has a lower risk of infections and lasts longer.
  • A human-made bridge (arteriovenous graft, or AVG) can also be used to connect the artery and vein. An AVG can be used for dialysis within several weeks.
  • When you have dialysis, one or two needles are placed into the access area.


Hemodialysis is most often done in a special dialysis center. Patients usually have three treatments a week. It takes about 3 - 4 hours each time. Many people feel tired for several hours after the dialysis.

Sometimes, dialysis can be done at home. Home dialysis is usually done using one of two schedules:

  • Shorter (2 - 3 hour) treatments done at least 5 - 7 days per week
  • Longer, nightly treatments done 3 - 6 nights per week while you are sleeping

Home hemodialysis treatments help keep blood pressure lower. Many patients no longer need blood pressure medicines. Nightly treatments do a better job of removing waste products. It is done more slowly, so it's easier on the heart and access site.

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:

  • Handle the equipment
  • Place the needle into the access site
  • Monitor the machine and blood pressure during treatment
  • Keep records
  • Clean the machine
  • Order supplies


Avoid all pressure on the access site. If the graft or fistula clots, you may need a new one.

  • Do not allow anyone to take a blood pressure reading on the same arm with the access.
  • Do not wear tight clothing around the access site or on the arm.
  • Avoid placing pressure on the arm with the access while you sleep.
  • Avoid placing pressure on the arm when you are lifting heavy items.
  • Do not allow any blood to be drawn from the arm.
  • Do not use creams or lotions over the access site.

Learn how to feel the access site for the "thrill." This is a sign that the site is still functioning. If the thrill disappears, call your health care provider immediately.

Do not miss or skip any dialysis sessions. Make sure you arrive on time. Many centers have busy schedules. You may not be able to make up the time if you are late.

Watch the access site for swelling, bleeding, or signs of infection. Call your health care provider immediately if you have a fever or other signs of infection.

It is important to follow a strict kidney dialysis diet .

Alternative Names

Artificial kidneys; Hemodialysis; Renal replacement therapy

Why the Procedure Is Performed

The kidneys' main job is to remove toxins from the blood. A buildup of waste products can lead to death.

The kidneys also help:

  • Manage how much water is in the body
  • Maintain the balance of sodium, potassium, phosphorous, and other minerals and vitamins in the body
  • Make sure the blood-acid balance is normal

Dialysis is used to treat 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 ).

Sometimes, hemodialysis can be used to quickly remove drugs or poisons from the body.


Risks of dialysis include:

  • A small bubble of air in the blood that travels to a blood vessel in another part of the body (air embolism)
  • Bleeding from the access site
  • Cramps
  • Electrolyte imbalance
  • Infection
  • Irregular heartbeat
  • Low blood pressure
  • Nausea and vomiting

This list is not all-inclusive.

Outlook (Prognosis)

See: End-stage kidney disease


Tolkoff-Rubin N. Treatment of irreversible renal failure. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 133.

Mitch WE. Chronic kidney disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 131.

Updated: 9/21/2011

David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc; Herbert Y. Lin, MD, PHD, Nephrologist, Massachusetts General Hospital; Associate Professor of Medicine, Harvard Medical School.

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