How Does Dialysis Work?


Quick Answer

Dialysis is a medical procedure that artificially performs the function of the kidneys for patients suffering from renal failure. The National Kidney Foundation explains that dialysis usually becomes necessary when kidney function drops to around 10 or 15 percent of normal levels. The procedure entails removal of the patient's blood, cleaning it in a machine called a dialyzer and returning it to the patient's body.

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Full Answer

During dialysis, blood is removed from the patient's body through a shunt and drawn into the dialyzer. Inside the machine, the blood enters one of two chambers. The second chamber contains a quantity of cleaning agent called dialysate, notes the National Kidney Foundation. The two chambers are separated by a very thin membrane that is semipermeable to the chemicals in the blood. Small molecules, such as urea and potassium, pass through this membrane via pressure osmosis, while the larger constituents of blood, such as blood cells, remain in the bloodstream and are returned to the patient with the processed blood.

According to the National Kidney Foundation, dialysis may be done in the hospital, which is common for new patients admitted for complications arising from renal failure; at a specialized dialysis center; or in the patient's home. Sessions usually take around four hours and are repeated approximately three times a week.

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