This page explains what Haemodialysis is. Much of this text is taken from NHS Choices.
There are two main types of dialysis: haemodialysis and peritoneal dialysis.
Haemodialysis involves diverting blood into an external machine, where it's filtered before being returned to the body
Peritoneal dialysis involves pumping dialysis fluid into the space inside your abdomen (tummy) to draw out waste products from the blood passing through vessels lining the inside of the abdomen.
Preparing for treatment
Haemodialysis can be performed with either a catheter line or fistula. You can discuss which method is best for you with your renal doctor.
Before haemodialysis can start, you'll usually need to have a special blood vessel created in your arm, called an arteriovenous fistula
(AV fistula). This blood vessel is created by connecting an artery to
a vein. Joining a vein and an artery together makes the blood vessel larger and stronger. This makes it easier to transfer your blood into
the dialysis machine and back again.
The operation to create the AV fistula is usually carried out around four to eight weeks before haemodialysis begins. This allows the tissue and skin surrounding the fistula to heal. If your blood vessels are too narrow to create an AV fistula, an alternative procedure known as an AV graft may be recommended. A piece of synthetic tubing (graft) is used to connect the artery to the vein. As a short-term measure, or in an emergency, you may be given a neck line. This is where a small tube is inserted into a vein in your neck.
The haemodialysis process
Most people need three sessions of haemodialysis a week, with each session lasting around four hours. This can be done in hospital, or at home if you've been trained to do it yourself.
Two thin needles will be inserted into your AV fistula or graft and
taped into place. One needle will slowly remove blood and transfer
it to a machine called a dialyser or dialysis machine.
The dialysis machine is made up of a series of membranes
that act as filters and a special liquid called dialysate.
The membranes filter waste products from your blood, which are passed into the dialysate fluid. The used dialysate fluid is pumped out of the dialyser and the filtered blood is passed back into your body through the second needle.
During your dialysis sessions, you will sit or lie on a couch, recliner
or bed. You will be able to read, listen to music, use your mobile phone or sleep.
Haemodialysis isn't painful, but some people feel a bit sick and dizzy, and may have muscle cramps during the procedure. This is caused by the rapid changes in blood fluid levels that occur during the treatment.
After the dialysis session, the needles are removed and a plaster is applied to prevent bleeding. If you were treated in hospital, you can usually go home shortly afterwards.
Fluid and diet restrictions
If you're having haemodialysis, the amount of fluid you can drink will be severely restricted. This is because the dialysis machine won't be able to remove two to three days' worth of excess fluid from your blood in four hours if you drink too much. This can lead to serious problems where excess fluid builds up in your blood, tissues and lungs.
The amount of fluid you're allowed to drink will depend on your size and weight. Most people are only allowed to drink 1,000-1,500ml (two to three pints) of fluid a day.
You'll also need to be careful what you eat while having haemodialysis because minerals such as sodium (salt), potassium and phosphorus that would normally be filtered out by your kidneys can build up to dangerous levels quickly between treatment sessions.
You'll be referred to a dietitian so a suitable diet plan can be drawn up for you. Diet plans differ from person to person, but it's likely you'll be asked to avoid eating foods high in potassium and phosphorus and to cut down the amount of salt you eat.