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Health Blog :: What is Peritoneal Dialysis and How Does it Work?

April 15, 2016

To replace the kidney function of getting rid of waste products and excess fluids, there are two types of dialysis. One is Hemodialysis which involves blood and the other peritoneal dialysis (or PD) which does not involve any blood. When the kidneys fail, PD is a great option for dialysis. PD involves putting some dialysis fluid inside the belly. There is a natural membrane around the bowels and abdominal wall that does the job of the kidney. It allows filtering of all the toxins and waste products and excess water into the dialysis fluid in the belly. Then the fluid is drained and then dumped in the toilet just like urine.

The first step in preparing for PD is to create an access to the abdominal space. A catheter which is a piece of tubing is usually placed in the lower abdomen to allow filling and draining the abdominal cavity with dialysis fluid. You will go through a class that teaches you how the whole process works and how to keep the catheter clean to prevent infections. The catheter is permanently attached to your abdomen.

What Happens During Peritoneal Dialysis?

The abdominal space is filled with a sterile clean dialysis solution through the catheter into your abdomen. You let the fluid dwell around the membrane in your abdomen for a prescribed period of time. During the dwell time, filtration happens and most of the waste products and extra fluid in your body goes into the dialysis solution. You then drain the dialysis fluid through the same PD catheter into a waste bag. This whole procedure is called a PD exchange. The dialysis solution that is put in contains a sugar that draws waste products and extra fluid through the peritoneal membrane into the abdominal space. Your belly will adjust to the extra fluid that is placed in it but initially it might feel full but not generally uncomfortable.

Your dialysis team will come up with a dialysis prescription, types of fluid and number of exchanges that you will need for your situation. It is very important to perform every exchange and dwell exactly as recommended as skipping a treatment or performing a dwell for shorter or longer than recommended may increase the risk of not getting rid of all the waste products that will accumulate and cause illness or increase the chance of needing hospital care, and can even shorten life.

Two Types of Peritoneal Dialysis

There are different ways to do PD. First you learn to do things manually. This is called continuous ambulatory peritoneal dialysis (CAPD). Then once you learn the manual exchanges you will get a machine to do the exchanges for you. This is called continuous cycling peritoneal dialysis (CCPD). Some patients use a combination of both methods.

Continuous Ambulatory Peritoneal Dialysis

CAPD exchanges are done by hand and can be done almost anywhere that is clean. It does not require a machine. The only equipment you need is a bag full of dialysate fluid, the drainage bag and a mask to prevent the risk of infection. As the word ambulatory suggests, you can walk around with the dialysis solution in the belly. With CAPD, exchanges of dialysis fluid are simple and are usually done every four to six hours during the day. You will do all this by yourself once you have gone through training by a specialized CAPD nurse. This training usually takes one to two weeks.

Continuous Cycling Peritoneal Dialysis

Many people prefer to use a machine to do the exchanges. This is called continuous cycling peritoneal dialysis, CCPD, also known as automated peritoneal dialysis (APD). It is done with your PD catheter connected to a cycler machine. The machine is pre-programmed and automatically controls the timing of exchanges. It drains the dialysis solution in the belly, and fills the abdominal cavity with new warm dialysis solution. The machines are portable and easy to operate and have built-in safety features. You can travel with these machines that come in a suitcase. They can be used wherever there is an electricity supply.

When it comes to dialysis, is PD right for you?

It all depends on your lifestyle and how you want to take charge of your illness. A dialysis doctor and nurse are assigned to you that you can contact all the time. They teach you everything you need to know to do a safe dialysis at the convenience of your home. You will only need to come to the clinic for monthly checkups. You can fit dialysis around your schedule to meet your work, family, and social needs. PD is a gentler form of dialysis and as it is done daily it is less stress on your body because treatment is done more continuously instead of intermittently. PD patients are allowed a more liberal diet and encouraged to eat more protein. If you choose APD you dialyze overnight, making your days free to do other things, work related or leisure. Traveling is easier as well.

What are some of the disadvantages of PD?

To be effective, PD needs to be done every day or every night. Storage space is needed for bags of dialysis fluid. This could be a spare room, a large cupboard, a shed or a garage space. The PD catheter has to be protected from infection and from getting wet. You cannot swim or use a Jacuzzi.

If you choose CAPD you will need to be flexible in your daytime activities so that you have time to do your exchanges which should not take more than 30 minutes.

The choice between CAPD and CCPD or APD is yours and depends on your doctor recommendation based upon your illness, situation, and lifestyle. Of course, nightly CCPD or APD allows significantly more uninterrupted time for work, family, and social activities than CAPD. Please remember to talk with your physician if you have additional questions.

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