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Renal (Kidney) Services

Peritoneal Dialysis

Contact: (0191) 213 7447 Sister Toni Poole

IntroductionShow [+]Hide [-]

What is peritoneal dialysis?

Peritoneal dialysis (PD) is one of the two types of dialysis that may be used to treat people with kidney failure. In PD, the process of dialysis takes place inside the patient's body, using the peritoneum (the natural lining of the abdomen) as the dialysis membrane. PD has been available in the UK since the late 1970s. It has proved to be a highly successful alternative to the “traditional” form of dialysis, known as haemodialysis.

PD is a suitable treatment for most people with end-stage renal failure (ESRF). However, there are a few exceptions. People who have had several major abdominal operations may not be able to have PD. This is because a scarred peritoneum may not be an effective dialysis membrane.

PD requires a lot of commitment from kidney patients and their families. Kidney patients on PD are responsible for exchanging their own dialysis fluid. They perform these exchanges in their own homes. For this reason, PD may be unsuitable for patients who are unable to care for themselves and do not have someone available to help them with their dialysis however; this will be assessed on an individual basis by the PD team.

What does peritoneal dialysis do? Show [+]Hide [-]

PD (like haemodialysis) takes over some of the work that is normally done by the kidneys. It removes the waste products of food and it removes excess water from the body. It can also be used to give people various substances that they are lacking, such as calcium or bicarbonate.

PD and haemodialysis are equivalent techniques in terms of the amount of dialysis they can deliver (about 5% of the function of two normal kidneys). Both relieve the symptoms of kidney failure and both enable patients to go back to work.

How does PD work?

The basic principles of dialysis are the same for PD and haemodialysis. Briefly, both types of dialysis use a special liquid (called the dialysis fluid, dialysis solution or dialysate) and a membrane (called the dialysis membrane) to do some of the work of the kidneys. In PD, the dialysis membrane is the patient’s own peritoneum.

The peritoneum is a natural membrane that lines the inside of the abdominal wall and covers all the abdominal organs (the stomach, bowels, liver etc). The peritoneal membrane resembles a balloon in appearance and texture but has lots of extremely tiny holes in it. These holes allow the peritoneum to be used as a dialysis membrane. As blood flows through the blood vessels in the peritoneum, it flows past the holes. Although the holes are extremely tiny, water and toxins can easily pass through, but blood cells are too large. In this way, the peritoneum in PD works as a “natural filter”, performing the same function as the “artificial filter” used in haemodialysis.

The peritoneum has two layers one lining the inside of the abdominal wall, the other lining the abdominal organs. Between these two layers is a space. This space is called the peritoneal cavity. During PD it is the peritoneal cavity that is used as a reservoir for the dialysis fluid. Normally, the peritoneal cavity contains only about 100 ml of liquid. In fact, it can expand to hold up to five litres of liquid.

How is peritoneal dialysis performed?Show [+]Hide [-]

PD needs to be done every day. It consists of the following three stages:

  • The peritoneal cavity is filled with 1.5 - 3 litres of dialysis fluid from a dialysis bag. (The amount varies, depending on a patient’s individual needs and the type of dialysis fluid used).
  • The dialysis fluid is left to dwell inside the peritoneum to allow dialysis to take place. (The length of time it is left there varies, from between 30 minutes to eight hours, depending on individual requirements and the type of PD).
  • The “used” fluid, containing the water and toxins that the kidneys would normally have passed into the urine, is drained out of the body and discarded, usually down the toilet, then the process begins again. 

More about "access"Show [+]Hide [-]

To receive PD, a kidney patient first needs to have a small operation. During the operation (which is performed using a local or a general anaesthetic), a plastic tube is permanently inserted into the abdomen. This tube is called a PD catheter. It is about 30 cm (12 in) long and as wide as a pencil.

The PD catheter is placed through the lower abdominal wall, into the peritoneal cavity. Half of the catheter lies inside the abdomen, and half lies outside. The catheter comes out on the right or the left side of the abdomen. The PD catheter acts as a permanent pathway into the peritoneal cavity from the outside world. It is the PD patient’s dialysis ‘lifeline’. Patients are usually allowed to go home one or two days after the operation.  The catheter is left undisturbed for seven days or more after the operation. This allows time for the catheter to embed and gives the abdominal  wound  to heal, before using the catheter or dialysis. Occasionally, the catheter may need to be used earlier, should you require urgent dialysis.

Home treatmentShow [+]Hide [-]

PD is performed by patients in their own home, therefore training regarding all aspects of PD will be provided to enable patient’s to perform their own dialysis treatment. This training is usually given to patient’s two weeks or so after their PD catheter operation.  The dialysis training will either take place has an outpatient or at home. Usually training takes anything from 2-7days; this depends upon the individual person. Initially some patient’s find performing their dialysis at home a little daunting, but after a week or so most people feel confident in managing their treatment by themselves with no problems. Always remember support is available from the PD team.  

The way that the dialysis fluid is exchanged depends on the type of PD. There are two main types of PD, which differ only in the way that the dialysis fluid is exchanged. The two different types of PD are:

  • Continuous ambulatory peritoneal dialysis (CAPD
  • Automated peritoneal dialysis (APD).

Continuous ambulatory peritoneal dialysis (CAPD)

‘Continuous’ means ‘all the time’ and ‘ambulatory’ means ‘while you walk around’. In this form of PD, patients walk around with the dialysis fluid in their abdomen. At the end of each period of dialysis, they have to change the dialysis fluid themselves. Usually four times a day and each exchange session takes approximately half an hour.

Automated peritoneal dialysis (APD)

Automated’ means that a machine changes the dialysis fluid for the patient. The patient remains connected to the machine while dialysis is taking place, usually for about eight hours at night. Most patients need to keep dialysis fluid in the peritoneal cavity during the day and some patients also need to perform an additional exchange at teatime. This is to ensure that they receive the most dialysis.

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