What is Hemodialysis?

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  • Written By: Mary McMahon
  • Edited By: Bronwyn Harris
  • Last Modified Date: 14 February 2020
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Hemodialysis is a medical treatment in which the blood is removed from the body and run through a filter to remove waste products before being returned to the body. This treatment is commonly used to treat people who are experiencing kidney failure, as normally the kidneys perform this function. Depending on the patient and the situation, hemodialysis may be performed on an emergency or long-term basis, and in the case of some long-term patients, it is possible to receive hemodialysis at home.

The hemodialysis process involves several steps. First, a needle is inserted into the patient. Then, his or her blood flows into a dialyzer, a medical device which is also known as an artificial kidney. On the way into the dialyzer, a blood thinner is added to the blood to ensure that it does not clot.

Once blood is inside the dialyzer, it runs through an assortment of tubes which are made from a semipermeable material. The tubes are surrounded by a canister filled with a fluid known as dialysate. The dialysate is specially formulated just for the patient. As the blood passes through the tubes in the artificial kidney, metabolic waste products and other impurities are pulled through the artificial membrane by the dialysate. Waste fluid from the canister is either disposed of or cleaned and recycled, while the cleaned blood is returned to the body through another needle.


In emergency hemodialysis, the goal is to get the patient stable as quickly as possible, and needles are usually inserted into the most convenient sites. For long-term hemodialysis treatment, surgeons may make an artery-vein graft, which increases the volume of dialysis, or they can insert an artificial graft. An access point can also be attached to the site to make it easy to hook the patient up to a hemodialysis machine.

Patients may be prescribed several sessions of hemodialysis a week to compensate for their failing kidneys, either as a long-term treatment approach, or as a holdover until a suitable kidney becomes available for transplant. Hemodialysis can also be used to treat patients who are experiencing kidney failure as a medical complication.

Hemodialysis has a number of side effects which should be discussed with a doctor or medical technician. Because hemodialysis often involves the removal of wastewater, since people with kidney failure urinate less, this can sometimes cause temporary health effects which people should be prepared for, like lowered blood pressure, fatigue, and headaches.


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Post 3

No, because all the blood is returning back to the body. Blood volume is "how much" blood is in one's system.

Post 1

It's amazing to me that hemodialysis is even possible. When the waste products are removed, is anything added to the blood to maintain blood volume?

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