What is Peritoneal Dialysis

Peritoneal dialysis has been a practical treatment since the 1980s, and is now a common treatment for kidney failure patients. It is a very practical type of of home kidney dialysis.

Peritoneal dialysis takes advantage of the peritoneal membrane surrounding the intestine being a natural semi-permeable membrane. Dialysis fluid is introduced to the abdominal cavity, where waste products transfer through the peritoneal membrane into the fluid, thus doing the work normally done by the kidneys. On draining the abdomen, the waste is removed.

There are two main versions. the first is continuous ambulatory peritoneal dialysis (CAPD), which doesn't require a machine. The patient is able to walk around with the dialysis solution in their abdomen. The second form, continuous cycler-assisted peritoneal dialysis (CCPD), requires the use of a machine called a cycler to fill and drain the abdomen, usually while the patient sleeps. CCPD is also sometimes called automated peritoneal dialysis (APD).

A catheter in the abdomen Peritoneal Y-piece, ready to connect Relaxing during peritoneal dialysis

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A catheter (tube) is inserted surgically in the stomach wall, often near the navel. With CAPD, a two bag system is used via a Y piece inserted into the catheter, and clamping one side of the Y allows fluid to enter the abdomen from the full bag (held at some high point above the patient). The fluid is left in the abdomen for between 4 and 6 hours (called the dwell time).

Waste products are transferred through the peritoneal membrane into the dialysis fluid. The clamp on the fresh fluid bag side of the Y piece is then closed, and the one on the other side is opened. This allows the fluid to drain from the abdomen to the second bag which has been placed below the patient, usually on the floor, and thus the waste products are removed from the body. When carrying out a fluid exchange like this, the first step is to drain away the fluid from the last exchange to the bag on the floor, then refill with fresh dialysis fluid from the new bag. This takes around 30-40 minutes to complete. It is repeated several times during the day.

With CCPD, the patient connects to the machine when they go to bed, and the process occurs automatically overnight, with the solution being refreshed several times.

There are various advantages and disadvantages to this method of dialysis. The main advantage of CAPD is that it can be carried out by the kidney patient at home - no scheduled hospital or clinic visits are required. It can then be carried out at times convenient to the patient. The patient does all the work by themselves. It makes it easier to travel, as only bags of fresh fluid need be carried around, rather than arranging to use a local clinic when on holiday.

But there are a few disadvantages as well. The kidney patient must work to a high standard of cleanliness while carrying out the procedure to avoid the risk of infection. This requires a bit of self-discipline to continually maintain, and the patient has to undergo initial training on the procedures to be used. With direct access to the abdomen, there is a risk of infection, and unfortunately renal failure patients usually have a weakened immune system, which makes them more susceptible to infection than is usual.