The fluid and solutes in a dialysis process that flow through the dialyser filter system not passing through the membrane that are discarded along with removed toxic substances and metabolic waste products after leaving the dialyser.

Special filter system and essential part of the dialysis machine. A dialyser is used in hemodialysis to remove toxic substances and excess water from the blood.

A semipermeable membrane is a major part of the dialyser filter system. During the dialysis process excess water and metabolic waste products can flow through this membrane into the dialysate and are thus continuously removed from the blood. Another function of the dialyser membrane is to act as a barrier separating the blood from the dialysate.

The preferred dialysis procedure worldwide is hemodialysis using a dialysis machine to remove toxic substances and metabolic wastes from the blood artificially. The dialysis machine and a special filter called dialyser are used to clean the blood. The dialyser has two parts, one for the blood and one for the washing fluid called dialysate. A thin semipermeable dialyser membrane separates these two parts. Blood cells, proteins and other important substances remain in the blood because they are too big to pass through the membrane. The smaller waste products such as urea or creatinine will pass the membrane and could be removed.
The other major form of dialysis is peritoneal dialysis.

The dialysis machine itself can be thought of as an artificial kidney. It filters a patient's blood to remove excess water and waste products. The blood is drawn through a specially created vein in the forearm, which is called an arterio-venous (AV) fistula. Inside, the dialysis machine consists of plastic tubing that carries the removed blood to the dialyser, a bundle of hollow fibers that forms a semipermeable membrane for filtering out impurities. In the dialyser, blood is diffused with a saline solution called dialysate, and the dialysate is in turn diffused with blood. Once the filtration process is complete, the cleansed blood is returned to the patient.

A person who offers blood, tissue or an organ for transplantation. In kidney transplantation, the donor may be someone who has just died or someone who is still alive, usually a relative.