Hemodialysis is a process that uses a machine to cleanse your blood because your kidneys are no longer able to do the job. Each treatment usually takes 4 to 5 hours and is done three times a week. Some people may need more frequent or shorter treatments. Hemodialysis is usually done in a hospital or clinic setting, but may be done at home after proper training.

Many people receiving hemodialysis are waiting for a kidney transplant. However, some people have issues that put a transplant out of the question, and they will remain on dialysis for the rest of their lives.

How is hemodialysis done?

Because repeated access to your bloodstream is required for hemodialysis, an artificial connection between an artery and a vein (arteriovenous fistula) is made, using a small surgical procedure. The preferred method is an arteriovenous fistula in the forearm. This results in expansion or enlargement of the vein so it can easily be punctured with a large needle each time dialysis is undertaken. An alternative is an implanted plastic arteriovenous graft that is usually placed in the forearm.

If a fistula or graft cannot be done, then a central line may be inserted. For a central line, a tube is inserted into a large vein, usually in the neck or under the collarbone, with the other end of the tube coming out of the skin.

Blood flowing through a tube from your vein is pumped through the dialysis machine, called a dialyzer (see Figure 1).


Figure 1


There are various types of dialyzers. The dialyzer passes the blood on the other side of a membrane from the dialysis fluid. This allows substances that would normally be removed by the kidney to cross from your blood into the dialysis fluid. The amount of water and salt removed from the blood can be adjusted by changing the pressure on the blood as it passes through the dialyzer. The tiny holes in the membrane are too small for blood cells to pass through. The dialysis fluid becomes waste and the "cleaned" blood is returned to the body.

In between treatments your kidneys are still not working well enough, so you will need to follow a special diet. Most importantly, you will need to control your intake of salt, water, and potassium, or complications can occur before your next dialysis treatment. Your doctor or dietitian will tell you what changes you will need to make to your diet.

What are the complications of hemodialysis?

If you are receiving hemodialysis, your body may not be able to regulate certain substances in your blood and significant fluctuations can occur that sometimes cause symptoms. Let your health care team know about any symptoms you experience such as nausea, dizziness, or muscle cramps. Your health care team will be able to help reduce the symptoms.

Most people on hemodialysis are able to continue working and live relatively normal lives, except for the inconvenience of the regular treatment. Complications of long-term hemodialysis include difficulties with access (fistula of shunt), anemia - now generally managed by administering erythropoietin injections - and, less commonly, as in untreated renal failure, problems with bones, nerves, and other organs.

If you are receiving hemodialysis or peritoneal dialysis, you will usually require medication for phosphate control, as phosphate is not efficiently removed by dialysis. Medications for blood pressure and erythropoietin to prevent severe anemia are also required.

Written and reviewed by the MediResource Clinical Team