1943

Dialysis Machine

Willem Johan Kolff (1911–2009)

In the United States, something like one in ten of the adult population has kidney disease in one form or another. Approximately 400,000 people have kidney failure, requiring dialysis or a transplant. Without dialysis, a person with failed kidneys will die within a few weeks as toxins that would normally be removed by the kidneys build up in the blood.

Physician and inventor Willem Johan Kolff looked at this situation and asked if a machine could perform the same tasks as a kidney. The basic principles of the result of this inquiry—the very first dialysis machine in 1943—are easy to understand.

Dialysis started with two basic elements—a membrane and a liquid. The membrane came in the form of a natural sausage casing, which is simply a long piece of intestine from an animal. Imagine that blood is flowing inside the casing, and pure, sterile water is flowing outside. Certain undesirable chemicals in the blood, like urea, will pass through the membrane and be absorbed in the water. And so will many other useful chemicals

In a dialysis machine, the water is called dialysate and it is carefully mixed with chemicals so that harmful chemicals transfer from the blood to the dialysate while useful ones stay in the blood. By setting concentrations of certain chemicals high in the dialysate, those chemicals stay in the blood.

A typical patient whose kidneys have completely failed will need dialysis three times a week at a treatment center, or more frequently with a home unit. A fairly large flow rate is required for the blood into and out of the machine. To make regular dialysis possible, the patient needs to have surgery of some sort in order to facilitate frequent tapping, usually in a forearm.

Could engineers create an artificial kidney, as they have an artificial heart? Could this engineered kidney create urine that flows naturally to the bladder? There is quite a bit of research in this direction. Devices will probably start outside the body—a so-called “wearable” version. As engineers shrink them even more, we can expect the devices to move inside the body.

SEE ALSO Defibrillator (1899), Laparoscopic Surgery (1910), Artificial Heart (1982), Surgical Robot (1984).

A dialysis machine can be used for home or hospital sessions.