Peritoneal dialysis is one of the two main forms of dialysis (the other being hemodialysis) and the one most commonly employed at home in self-care or assisted care.

Hemodialysis uses an artificial semi-permeable membrane to remove toxins from the blood by circulating the blood external to the body past a solution called dialysate.

Naturally moving from a fluid of higher to one of lower concentration, waste products and excess minerals seep out of the blood and past the semi-permeable membrane into the dialysate. This form of dialysis is what most people think of, as it employs a “dialysis machine.”

Peritoneal dialysis employs the same principle, but instead of an artificial membrane it makes use of the peritoneal membrane of the body itself. The peritoneum or peritoneal membrane is a semi-permeable or serous membrane that surrounds the abdominal cavity, inside which are the stomach, intestines, and other main organs of digestion.

Blood naturally circulates around and through the peritoneum, so that the body’s own circulation delivers it into contact with the membrane, while the abdominal cavity itself provides a receptacle for dialysate fluid.

In other words, the dialysis is performed inside the body, and the blood is never removed from the body as it is in hemodyalisis. Both forms of dialysis are used to treat contamination of the blood with waste materials and excess minerals due to acute renal failure.

Procedure

A surgical procedure needs to be performed prior to beginning peritoneal dialysis. This procedure inserts a catheter into the abdominal cavity through which dialysate can be inserted and afterwards drained. The dialysate fluid is introduced into the abdominal cavity through the catheter in an amount that varies with the treatment, but can be up to two and a half liters.

The fluid is left in the abdominal cavity for a period of time (typically 4 to 6 hours). This is referred to as a “dwell.” Afterwards, the dialysate is removed from the abdomen and replaced with fresh dialysate fluid.

Typically, anywhere from three to ten dwells are performed each day.

Types

There are two basic types of peritoneal dialysis, continuous ambulatory peritoneal dialysis or CAPD and automated peritoneal dialysis or APD. CAPD is done during the day while the patient is awake. The patient or an assisting caregiver controls the insertion of dialysate, the amount of time the dwell is allowed, and the removal of the spent dialysate manually.

APD, typically done at night while the patient is asleep, automates the entire procedure and requires the use of a machine that inserts and removes the dialysate several times during the night, while monitoring the results.

Comparison Of Peritoneal Dialysis With Hemodialysis

Peritoneal dialysis is less efficient at removing contaminants from the blood than hemodialysis, and for this reason needs to be done more often. There is also a greater potential for complications with peritoneal dialysis, the main complication being the development of peritonitis due to introduction of bacteria into the abdominal cavity through the catheter.

Cleansing of the catheter area prior to a dwell and sterile safety procedures involving dialysate reduces the risk of peritonitis. Another complication that sometimes results is hypertension (high blood pressure) due to absorption of sodium from the dialysate.

The advantage of peritoneal dialysis over hemodialysis is that it can be done at home or while traveling and, except for the initial insertion of the catheter or in the case of complications, does not require a visit to a clinic or hospital.

This method of dialysis allows greater patient mobility, since the patient does not need to be attached to a dialysis machine during the procedure, and the continuous nature of the treatment reduces swings in symptoms.