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APD – CAPD - PERITONEAL DIALYSIS

Why are APD and CAPD performed?

In patients with severe kidney failure, waste products accumulate, making them feel ill. Dialysis is needed in such patients to remove the waste products from the blood.

Preparations needed for APD and CAPD

A small soft plastic tube called a catheter needs to be placed in the abdomen. This can be done either with a local or a general anaesthetic. The catheter is not uncomfortable, and once the small wound has healed, is quite secure. The catheter can be used at once if dialysis is needed urgently. Usually the catheter is not used until 2 weeks later. This allows the cut in the skin to be well healed. This good healing ensures that there will be no leakage of dialysate from the abdomen back through the skin. You will be asked to stay in hospital for 1 to 2 weeks to learn how to do the bag changes. Once confident with the technique, you can return home. After a short while, the bag changes are easily fitted into the daily routine.

What happens during APD and CAPD

Peritoneal dialysis is a method of cleaning the blood without the blood leaving the body. Clean fluid (dialysate) is run through a tube into the abdominal cavity. A thin membrane called the peritoneum lines the inside of the abdomen. The peritoneum has tiny holes (or pores) through which the waste products can pass from the bloodstream into the dialysate. When the dialysate is drained out again through the tube, the waste products are removed from the body at the same time. There are two types of peritoneal dialysis – CAPD (Continuous Ambulatory Peritoneal Dialysis) and APD (Automated Peritoneal Dialysis).

CAPD is done manually, while a machine is used for APD. In both types, dialysate fluid comes in plastic bags which are stored in the patient’s home. The fluid is drained into the abdomen, and after staying there for a period of time, it is drained out into an empty bag. In CAPD, four bags are used during a 24-hour period – three during the day and one at night. It takes 5 to 10 minutes for the fluid to run in, and 20 to 30 minutes for the fluid to drain out. The bag changes can be done at home or at work. There is complete freedom to carry out daily living routines between bag changes.

APD takes place at night. The patient is attached to a machine that cycles fluid in and out of the abdomen while the patient is asleep, usually over an 8 to 9 hour period. Often, fluid is left in the abdomen during the day. This type of dialysis allows freedom from exchanges during the day. The machines used are about the size of a video-recorder, and can sit on top of a bedside table. APD is mostly used for patients who for some reason would find it difficult to do bag changes during the day.

Possible Complications with APD and CAPD

Catheter or exit-site infection can occur at any time. It is best prevented by daily cleaning of the exit site. Mild infections can be treated by antibiotics. If the infection is more severe with pus forming, the catheter needs to be removed. It is then usual to use haemodialysis with an artificial kidney for 2 to 4 weeks until the infection is cleared. A new catheter can then be inserted. Leakage of fluid may occur when the catheter is first used. The dialysate fluid comes out through the skin or tracks down under the skin to cause swelling of the abdominal wall (and the scrotum in men). This means that the catheter is not fully healed into the skin. The catheter is then given a rest for another 2 weeks. If dialysis is needed meanwhile, haemodialysis can be used.

Poor drainage of fluid occurs if the catheter end is pointing upwards in the abdomen instead of downwards into the pelvis. Usually this means that the catheter needs to be replaced. Poor drainage also occurs if the patient is constipated. After laxative or an enema, fluid drainage will improve. Peritonitis (infection of the peritoneum) is the major drawback of peritoneal dialysis (PD). The signs and symptoms are cloudy drainage fluid, a temperature, pain and sickness. Drainage fluid always needs to be watched carefully. If it becomes cloudy it is important to go to the hospital as soon as possible. Peritonitis is treated by giving antibiotics either by mouth, or directly into the dialysate bags before running the fluid into the abdomen. If the infection is severe and does not improve, the catheter may need to be removed. Haemodialysis is then used. After a few weeks, it may be possible to insert a new catheter. Repeated attacks of peritonitis damage the peritoneum, making the dialysis less efficient. You would then have to be transferred to haemodialysis. It is best to avoid peritonitis by having a good sterile technique during bag changes. Various devices have been designed over the last few years to prevent infection occurring at bag changes. The average incidence of peritonitis is now only one episode every 2 years.

If APD and CAPD are not performed

PD is life-saving. If a patient on CAPD cuts down on the number of bag changes done each day, then waste products will accumulate and sickness will result. If PD is no longer possible for any of the reasons mentioned above, then haemodialysis can be used instead.

Advantages/disadvantages of Peritoneal Dialysis

The main advantage of PD is that it can be done at home. It is easy to travel. The bags can be delivered directly tp many parts of the world. The machine for APD comes in a case on wheels, and so is easily transported too. Patients on PD are therefore very independent, and need only visit hospital every one to three months for a check-up. Since the dialysis is continuous, there are fewer dietary and food restrictions than on haemodialysis. Some people however, do not like doing the bag changes, and feel that they can never get away from this commitment. The major drawback of PD is peritonitis. PD cannot be used in someone who has had many abdominal operations. In this situation, the peritoneum tends to be scarred, and will not function correctly.

Effects on Family of APD and CAPD

Although you can do PD on your own, it is helpful if other family members also know the routine needed for changes. This is particularly important if you are elderly, blind or unwell for other reasons.