Overview of Hemodialysis

Hemodialysis is a medical treatment given to patients with kidney failure to remove substances from the blood which the failed kidneys are unable to excrete. Hemodialysis is given to patients with temporary or acute kidney failure that lasts for a few days or weeks and to patients with permanent or chronic kidney failure that lasts forever.

During hemodialysis the patient’s blood is circulated through a set of needles, catheters, tubes and a dialysis filter. Patients with chronic kidney failure usually receive 4 hours of hemodialysis three times a week, indefinitely, or until they receive a kidney transplant. Patients with acute or temporary kidney failure usually receive 4 hours of hemodialysis every day for a few days or weeks. To access the patients’ blood, dialysis needles and double lumen dialysis catheters are used.

Hemodialysis with needles requires several devices:

• an arterial needle that withdraws blood from the patient
• an arterial blood line which is a plastic tube that carries the blood from the arterial needle to the dialysis filter
• a dialysis filter which removes toxins, water and other substances from the blood
• a venous blood line which is a plastic tube similar to the arterial blood line that carries blood from the dialysis filter to the venous needle
• a venous needle that returns the cleaned blood to the patient

In patients who suffer from permanent or chronic kidney failure, the arterial needle and the venous needle are inserted into a permanent dialysis vascular access which is a vessel that carries a large volume of blood. The most common permanent vascular accesses are a surgically modified vein called dialysis fistula and a segment of plastic tubing inserted between an artery and a vein called a dialysis graft.

If the patient does not have a permanent vascular access where needles are inserted, a double lumen hemodialysis catheter is used instead of needles. A catheter is a plastic device thick like spaghetti and 1-3 feet long that consists of two thinner plastic tubes attached to each other; one that suctions blood from the patient (like an arterial needle) and another one that returns blood to the patient (like a venous needle).The catheter is inserted into large veins and is commonly used for a short period of time, i.e. few days or weeks.