Hemodialysis can be done at home or at a clinic

ON CALL

November 09, 1993|By Dr. Simeon Margolis | Dr. Simeon Margolis,Contributing Writer

Q: I understand that there are two different types of dialysis for patients whose kidneys have stopped working. Could you explain the two procedures and how they differ?

A: The two types of dialysis used for patients with chronic failure of their kidneys are hemodialysis and chronic ambulatory peritoneal dialysis (CAPD). Hemodialysis, the most widely used form, is done at a dialysis center by a staff of professionals -- whereas CAPD is done at home by the patient.

Before beginning hemodialysis, the doctor performs minor surgery on one forearm to create a "shunt" -- a connection between an artery and a large vein -- that allows repeated easy access for a large needle that is needed for the dialysis. Each hemodialysis session takes two to four hours and is usually done three times a week. During dialysis, blood is pumped out of the arterial part of the shunt, passed through a filtering machine (artificial kidney) that removes waste products, and then returned to the vein in the arm.

As waste products accumulate in the blood prior to dialysis, an individual might feel slightly ill. The dialysis itself is not painful, but the person may notice some dizziness for a few hours after the procedure. Although the patient can sleep, read a book or watch television during the dialysis, many find that spending eight to 12 hours each week hooked up to a dialysis machine is a major disruption.

Obstruction of the shunt by a clot is the most common medical complication of hemodialysis. If an obstruction occurs, the doctors must repeat the surgery to form another shunt.

A patient who undergoes CAPD first undergoes thorough training. Then, a tube is surgically placed through the skin into the abdominal cavity. Great care is required to keep the tubing outside the skin free from infection. The patient attaches bags of dialysis fluid to the tubing and hangs the bags on a pole so the fluid flows by gravity into the abdominal cavity. The tubing is sealed and patients continue their other activities.

After four to six hours, the fluid is removed, discarded and replaced.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

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