Nephrology (Renal Medicine)

Kidney dialysis: haemodialysis

Introduction to Kidney dialysis: haemodialysis

Dialysis is a procedure where a machine removes waste materials and excess water from your blood when your kidneys are not functioning properly.

Written by Doctify Team 27/04/2020

What is Haemodialysis?

Dialysis is a procedure where a machine removes waste materials and excess water from your blood when your kidneys are not functioning properly. When your kidneys are working normally, they remove toxins, waste products and excess water from the blood and excrete it as urine. When the kidneys are damaged, such as in kidney disease or kidney failure, these harmful products build up in the blood, causing unpleasant symptoms and if left untreated can be fatal.

Sometimes dialysis may only be needed temporarily, and can be stopped when your kidneys are working normally again. However, often dialysis is required for a longer period of time as the kidneys are too damaged to work properly again. In this case, you will most likely need a kidney transplant and must continue with dialysis until donor is found.

How is Haemodialysis performed?

There are two main types of dialysis- haemodialysis and peritoneal dialysis.

Haemodialysis is the most common type of dialysis. During the procedure two small needles attached to tubes are placed in your arm. Blood passes out of one tube into an external machine, which acts like a kidney, and filters out harmful waste products from your blood. The blood then returns down the other tube and back into your body. As all the blood in your body needs to pass through this machine, the procedure can take quite a while, about 4 hours. Usually you will need haemodialysis carried out 3 times a week. Haemodialysis isn’t painful, but some people can feel nauseous, dizzy or get muscle cramps, this is due to the changing composition of your blood.

How to prepare for Haemodialysis?

Before haemodialysis can begin, you will usually need to have a special type of blood vessel made in your arm, called an arteriovenous fistula (AV). This new blood vessel is made by attaching a vein and an artery together; this makes a stronger blood vessel for the tubes of the dialysis machine to attach to. This procedure is usually done 4 to 8 weeks before you are due to start dialysis, so it has time to properly heal.

It may be beneficial to talk to any family or friends who are going through dialysis to further understand what the procedure entails.

What happens after Haemodialysis?

If you are having dialysis in a hospital, after the procedure the needles are removed, a plaster is put over your AV fistula and you can go home. If you are undergoing haemodialysis you usually have to limit the amount of fluid you drink, as the dialysis machine is not able to cope with too much fluid. You may also have to be careful with your diet as many minerals such as sodium and potassium that are normally filtered out by the kidneys may build up in your bloodstream. You are usually referred to a dietician who can help design a suitable diet.

As with any medical procedure there are associated risks and side effects. The most common side effect is fatigue, muscle cramps, itchy skin and weight gain. There is a risk of infection, either in the abdomen (peritonitis) or of the blood (sepsis), so you should go to your doctor is you feel dizzy or have a temperature.

Find out more about other relative procedures:

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