Hemodialysis

Hemodialysis is one of the methods for the management of kidney failure. It is a process of purifying the blood of a person whose kidneys are not working normally. Dr. Willen J. Kolff, a resourceful Dutch physician invented the first artificial kidney (dialyzer) in a rural hospital during World War II. Hemodialysis can be an outpatient or inpatient therapy. Less frequently hemodialysis is done at home. A nephrologist (kidney specialist) decides the needs and the parameters for a dialysis treatment. These includes frequency (how many treatments per week), length of each treatment, and the blood and dialysis solution flow rates, as well as the size of the dialyzer. the composition of the dialysis solution is also sometimes adjusted in terms of its sodium and potassium and bicarbonate levels.

In hemodialysis, a dialysis machine and a special filter called an artificial kidney, or a dialyzer, are used to clean the blood. To get the blood into the dialyzer, needs an access, or entrance, into the blood vessels.

The access allows blood to travel through soft tubes to the dialysis machine where it is clea
ned as
it passes through a special filter, called a dialyzer. An access is placed by a minor surgery. The access can be done in following ways:

  • A fistula, an access made by joining artery andvein in the arm.

fistula

  • A graft, an access made by using a piece of soft tube to join an artery and vein in the arm.AV graft
  • A catheter, a soft tube that is placed in a large vein, usually in the neck.

Catheter

A fistula is considered as the first choice because it generally lasts longer ans has fewer problems such as infections and clotting. However, some patients may not be able to receive a fistula because their blood vessels are not strong enough. A graft is considered the second choice for an access. Catheters are generally used as a temporary access, but sometimes they are permanent.

The dialyzer, or filter, has two parts, one for the blood and one for a washing fluid called dialysate. A thin membrane separates these two parts. Blood cells, protein and other important things remain in the blood and waste products such as urea, creatinine, potassium and extra fluid pass through the membrane and are washed away.

In hemodialysis, blood is removed from the body and filtered through, and then the filtered blood is returned to the body. The average person has about 10-12 pints of blood; during dialysis only one pint (about two cups) is outside of the body at a time.

Usually, each hemodialysis treatment lasts about four hours and is done three times per week.hemodialyser 400px-Hemodialysis-en.svg