The kidneys excrete the waste products of the body. In renal (kidney) failure, the body is unable to rid itself of all the waste. Dialysis is a mechanical way to clean the blood of wastes and to regulate the body's fluids and chemicals.
Why is it done?
Kidney failure leads to an accumulation of waste products in the blood known as uraemia. Untreated kidney failure may lead to death. Dialysis is used in kidney failure and may be lifesaving. Dialysis is started when the working of kidneys is reduced to less than 10% capacity. Some people need dialysis temporarily, while others may need it life-long.
How is dialysis done?
Dialysis can be done by two methods - haemodialysis and peritoneal dialysis.
Haemodialysis is the most commonly used method of dialysis. The blood is filtered through a dialysis machine that removes the body wastes and extra fluid. A plastic tube or catheter is inserted into a large vein in the neck or upper chest. Alternatively, a permanent connection or shunt is installed between an artery and a vein, usually in the forearm. The dialysis machine is attached to the catheter or shunt. Regular haemodialysis is done about thrice weekly, usually in special dialysis clinics by trained staff. The dialysis procedure is painless and takes 2 to 3 hours per session.
Peritoneal dialysis uses the lining of the abdominal cavity as a filter to clean the blood. Once a day, a special fluid is put in the abdomen through an opening or port made surgically. The lining of the abdominal cavity allows fluid, wastes, and electrolytes to pass from the blood to the fluid in the cavity. The fluid is left inside for about 2 hours and then drained out through the port. The body wastes are removed along with the fluid. Peritoneal dialysis can be done at home with special training. The latter is called CAPD (Continuous Ambulatory Peritoneal Dialysis).
What are the alternatives?
Dialysis is the initial treatment in kidney failure. In acute kidney failure, dialysis is done until the cause of the kidney problem is corrected. In chronic kidney failure, nutritional therapy is also needed along with dialysis. People with renal failure can survive for years on dialysis. A kidney transplant is the definitive treatment in selected patients. A kidney from a related or unrelated donor or a brain-dead person is used to provide a permanent cure to the kidney problem.