Hemodialysis removes toxic wastes and excess fluid from the blood of a patient with renal failure. In hemodialysis, blood is removed from the body through a surgically created access site, pumped through a filtration unit to remove toxins, and then returned to the body. The extracorporeal dialyzer works through a combination of osmosis, diffusion, and filtration. (See How hemodialysis works.) Hemodialysis removes by-products of protein metabolism—notably urea and uric acid—as well as creatinine and excess water, thereby helping to restore or maintain acid-base and electrolyte balance and prevent complications associated with uremia.

Hemodialysis can be performed in an emergency in acute renal failure or as long-term therapy in end-stage renal disease. In chronic renal failure, the frequency and duration of treatments depend on the patient’s condition. Hemodialysis can also be performed to treat acute poisoning or drug overdose.

Continuous renal replacement therapy may be used in patients for whom hemodialysis is contraindicated, as in the
acutely ill patient with unstable blood pressure. The method is similar to hemodialysis; however, it removes toxins and fluid at a slower rate, making it more suitable for the hemodynamically unstable patient.

Specially trained nurses usually perform hemodialysis in a dialysis center. However, home dialysis, which is more convenient and allows greater flexibility and comfort, is an option for some patients.