What is Peritoneal Dialysis?

By Dr John Wright - 2008-01-12 - Viewed 673 times. Find more articles like this in our Disability Articles category.

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When a patient has serious kidney problems there are sometimes only two options available - a kidney transplant or dialysis.

There are two main types of dialysis that can be used - hemodialysis, where the patient is connected to a kidney machine for several hours at a clinic or hospital, and peritoneal dialysis, which we are discussing in this article.

In the case of peritoneal dialysis, the patient's own body is used as a substitute for the kidneys, those essential organs for purifying the blood. The peritoneal membrane, which surrounds the intestines, is a natural semi-permeable membrane and this enables waste products and toxins in the blood to diffuse through it. If dialysis fluid is introduced into the abdominal cavity and left there for a while, the blood will slowly but surely be purified. Then all that remains is for the fluid to be drained away and disposed of. This is obviously a lot cheaper than having to use an expensive kidney machine and visit a clinic or hospital for a prolonged period of time, with trained medics in attendance.

There are actually two versions of peritoneal dialysis. The first method that we'll discuss is continuous ambulatory peritoneal dialysis (also known as CAPD). With this technique the patient can actually walk around with the dialysis fluid inside their abdomen, which obviously gives them a lot more freedom and enables them to work or visit friends, and even to take holidays without careful planning, something that is not really possible with hemodialysis.

The second variation is called continuous cycler-assisted peritoneal dialysis (also known as CCPD). This is a sort of half-way house between the traditional kidney machine and continuous ambulatory peritoneal dialysis. Here the patient is connected to a machine (the cycler) and fluid is introduced into their abdominal cavity and drained away while they sleep. The machine fills and then drains the fluid from the abdomen automatically. While not quite as convenient as CAPD, it is more convenient than having to attend a clinic at set times.

In both types of peritoneal dialysis, a catheter is inserted into the patient's stomach wall in a minor surgical procedure (don't worry, it doesn't hurt), which takes place some time before the patient begins their course of treatment. The catheter is often inserted near the belly button (navel).

With continuous ambulatory peritoneal dialysis the patient uses a two-bag system and a Y piece connected to the catheter, and then uses clamps to close or open access to each bag. Fluid is drained into the abdomen from the fresh bag, and left there for several hours, often four to six. During this period the patient is free to walk around (hence the name of the treatment, ambulatory means walking). Then the patient connects to the empty drain bag and adjusts the clamps to left the now dirty dialysis fluid drain away. The process actually starts by draining away the last refill which has been carried in teh body for some time, and then the fresh solution is introduced to replace it. This draining and refilling process takes about 30 - 40 minutes, during which time the patient has to sit still. This is repeated several times throughout the day.

With continuous cycler-assisted peritoneal dialysis, the patient waits until it is time for bed, connects to the machine and the process begins. The patient then just goes to sleep and the cycler fills and drains the abdominal cavity several times during the night.

The big advantage of continuous ambulatory peritoneal dialysis is that there is no need to schedule visits to the clinic or hospital, and the patient is not restricted to finding alternative clinics and booking in if they wish a holiday of some sort. They just have to take their fresh bags and supplies with them on any holiday. In both cases, the patient does the work themselves. Peritoneal dialysis also has the advantage that problems with fluid retention and mineral balance are easier to control than with the traditional kidney machine, which is used only a couple of times a week.

But this does mean that the patient has to be strictly rigorous and maintain a high standard of cleanliness if they wish to avoid catching some other infection. They also have to take some training in what to do, to avoid any problems that would require a medic to attend. And not everyone can take as disciplined an approach as is required. Especially children.

The author, Dr Wright, is a former scientist whose father was refused dialysis due to his age. The author maintains an informational website, Kidney Dialysis Information Centre, to help educate others about dialysis.

Dr John Wright is a former research scientist and university lecturer, specialising in nuclear magnetic spectroscopy. He now spends his time as a web developer and IT consultant, specialising in information web sites, database driven sites and SEO.

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