Kidney dialysis becomes necessary when someone's kidneys stop working, usually because of disease. This state is known as kidney failure and is fatal if left untreated.
In haemodialysis, blood is taken from the body to be cleaned in a filter called a dialyser, or artificial kidney. A dialyser has blood flowing along one side of a semi-permeable membrane made of cellulose or a similar product, with the dialysate flowing along the other side. The dialysate contains minerals normally present in the blood. Because the blood of someone with kidney failure contains some minerals at very high levels, these leave the blood and flow into the dialysate through the membrane by diffusion. Excess fluid and substances in the blood pass throughand are taken away in the dialysate until blood contains the correct balance of minerals once more.
As only a very small amount of blood is in the dialyser at any given time, blood needs to circulate from patient to dialyser to patient for about 4 hours. Treatment is usually 3 times per week.
In haemodialysis, blood is taken from the body to be cleaned in a filter called a dialyser, or artificial kidney. A dialyser has blood flowing along one side of a semi-permeable membrane made of cellulose or a similar product, with the dialysate flowing along the other side. The dialysate contains minerals normally present in the blood. Because the blood of someone with kidney failure contains some minerals at very high levels, these leave the blood and flow into the dialysate through the membrane by diffusion. Excess fluid and substances in the blood pass throughand are taken away in the dialysate until blood contains the correct balance of minerals once more.
As only a very small amount of blood is in the dialyser at any given time, blood needs to circulate from patient to dialyser to patient for about 4 hours. Treatment is usually 3 times per week.