What is peritoneal dialysis? Peritoneal dialysis is a type of dialysis in which a patients peritoneum is used as the dialysis membrane. The peritoneum is a membrane that covers our intestines inside our abdomen. It is a naturally occurring membrane. In hemodialysis, an artificial membrane is used. In peritoneal dialysis, we take advantage of the semipermeable qualities of a naturally occurring membrane. In peritoneal dialysis, a permanent flexible plastic tube is inserted into the abdomen by a physician. This tube is called the peritoneal dialysis catheter. After the tissues around the tube have healed, the tube is used toinstill dialysate into the abdomen. The dialysate fluid is allowed to remain in the abdomen for several hours. During this time, poisons and toxins leave the blood vessels of the intestine, pass through the peritoneal membrane, and collect in the dialysate fluid. The dialysate is then drained by gravity through the peritoneal dialysis catheter and collected in a bag. The dialysate fluid containing poisons and toxins can then be discarded into a sink drain or toilet. Another bag of dialysate, usually containing 2 liters of fluid is then infused into the abdomen. Each dialysis drainage and infusion is called an exchange because the fluid is removed and replaced. Patients usually perform four exchanges every day. The peritoneal dialysis exchanges are initially done by the peritoneal dialysis nurse. The patient on peritoneal dialysis is then trained over a period of weeks to safely perform the dialysis. The exchanges can be done at home, at work, or in any clean, quiet place because no special machine is required. This form of peritoneal dialysis is called continuous ambulatory peritoneal dialysis, or CAPD. The continuous means that the dialysis will continue throughout the day. Ambulatory refers to the dialysis being done outside of a hospital or medical facility. CAPD is the most popular form of peritoneal dialysis.