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Tuesday, March 11, 2014
Dialysis is a process by which waste products are removed from the blood and excess fluid is removed from the body. There are two types of dialysis: continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis.
Continuous ambulatory peritoneal dialysis (CAPD) involves instilling 2 to 3 liters (quarts) of fluid at a time into the person's abdominal (or "peritoneal") cavity through a flexible plastic catheter that is implanted in the abdominal wall. The fluid is allowed to remain in the abdominal cavity for a period of hours, gradually absorbing waste products and toxins from the body; it is then drained out and replaced with fresh fluid.
This procedure of fluid exchange is performed by the patient, and is done 4-5 times a day, 7 days a week. The procedure involves careful use of sterile technique and constant monitoring of blood pressure, fluid volumes, and weights. A variation on this procedure is dialysis with a cycler, in which the patient performs one or two fluid exchanges daily, as described above, and then hooks up to an automatic cycler, which performs several more exchanges during the night as the patient sleeps.
Like hemodialysis, CAPD requires preparatory surgery. A flexible catheter must be surgically implanted in the abdominal wall and then requires several weeks to scar firmly in place.
Flexibility in Schedule - Although CAPD requires a great deal of work on the part of the patient, patients who have the manual dexterity and ability to learn the procedure and the ability to be compulsive about record keeping and sterile technique find that this type of dialysis gives them more flexibility of schedule and greater freedom to work, go to school, and be active in general.
Flexibility in Diet - CAPD also allows a more liberal diet than hemodialysis, because fluid and potentially harmful substances (such as potassium, salt, and protein) are continuously removed by dialysis as they are eaten, and thus do not accumulate in harmful or dangerous amounts.
The main complication of this type of dialysis is infection, of which there is a risk every time an exchange is performed and every time the abdominal catheter is uncapped in order to add fluid to the abdominal cavity or to drain fluid from it. The symptoms of abdominal cavity infection, or "peritonitis," are abdominal pain, fever, and cloudy fluid draining from the abdomen.
This type of infection, which can be quite serious, is treated with antibiotics given either IV or in the dialysis fluid that is instilled into the abdomen. In order to avoid peritonitis, it is extremely important for the patient to carefully follow sterile technique every time they do a fluid exchange, which requires wearing sterile gloves and a mask, as well as using sterile disposable equipment, tubing, and dialysis fluid. Repeated episodes of peritonitis can cause scarring in the abdominal cavity, sometimes so severe that peritoneal dialysis can no longer efficiently be performed.
Many research studies are underway to help us learn about peritoneal dialysis. Would you like to find out more about being part of this exciting research? Please visit the following links:
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Last Reviewed: Sep 03, 2013
Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University