Dialysis is a process of removing waste products and excess fluid which build up in the body when the kidneys are not functioning adequately. Dialysis uses a membrane as a filter and a solution called dialysate to regulate the balance of fluid, salts and minerals carried in the bloodstream. The membrane may be man made as in haemodialysis or natural as in peritoneal dialysis.
How does haemodialysis work?
Blood is taken from the body to be cleaned in a filter known as a dialyser (artificial kidney). A dialyser works on the principle of blood flowing along one side of semi-permeable membrane made of cellulose or a similar product, with the dialysate flowing along the another side. The dialysate contains a regulated amount of minerals normally present in the blood, but in renal failure they are present in excess. The membrane has tiny holes of different sizes so that the excess fluid and substances in the blood pass through at different rates, small molecules quickly and larger ones more slowly, to be taken away in the dialysate until a correct balance in the blood achieved.
As only a very small amount of blood can circulate from patient to dialyser at any given time, blood needs to circulate from patient to dialyser and back to patient for about 4 hours. Treatment is usually 3 times per week.
Blood is carried from the patient to the dialyser and returned through dialysis lines (plastic tubes) which are connected to the patient .
The joining of vein and artery just under the skin, usually on the forearm makes the vein swell to allow needles to be inserted and removed after each treatment. Between treatments only a small scar and swelling are visible.
Central Venous catheter
A soft plastic tube inserted into the internal jugular vein in the neck. This can be used as a temporary access for dialysis until fistula is ready, and is capped off and left in the place when not in use.
Living with Kidney Failure
Becoming a dialysis patient is a turning point in your life. Modern medicine makes it possible for you to live long and continue with many day-to-day activities.
As patients, we know that the path will not always be easy. Dialysis is now part of your life and that of your family. Do not let it dominate-the aim is to enable you to enjoy a good quality of life.