An Introduction to peritoneal dialysis

Illustration showing the Peritoneum
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With this method, instead of being cleaned by an artificial membrane outside the body, the blood is cleaned inside the body, through the Peritoneum. This is the thin membrane that surrounds the outside of the organs in the abdomen.

The peritoneum allows waste products to pass through it and is very rich in small blood vessels. By running a dialysis fluid into the peritoneal cavity, through a tube called a Tenckhoff Catheter - and then out again - waste can be filtered from the blood. The catheter is inserted with a small operation usually under a general anaesthetic and left to heal for approximately 2 weeks before it is used.

There are two types of peritoneal dialysis:

CAPD - which stands for Continuous Ambulatory Peritoneal Dialysis - happens throughout the day, at home or at work, while the person goes about his or her daily life. Between 1.5 and 3 litres of fluid is run in four times a day, exchanging for the fluid from the previous exchange. This takes about 30-40 minutes.

APD - Automated Peritoneal Dialysis - in which the dialysate solution is changed by a machine, at night, while you are asleep. The machine will exchange 8-12 litres over 8-10 hours and then leave 1-2 litres to dwell during the day.

You will be trained by the PD nurses - the techniques need to be done correctly and in a clean manner - but are designed to be done at home perhaps with the help of a partner. Although you are at home, you will be contacted frequently by the nurses and will come to the out-patient clinic every few weeks.

What is the Peritoneal Dialysis Fluid?

  • Peritoneal dialysis fluid is a sugar (glucose) solution containing other salts. Bags come in 3 strengths (1.36%, 2.27% and 3.86% or light, medium and heavy) - the "heavier" the bag (ie.3.86%), more water will be removed from the body.
  • If you have a lot of fluid in the body, you would use heavy bags to remove fluid. If you are dehydrated, you would use some light bags so that the dialysis does not remove fluid.
  • The sugar solution can be a problem for diabetic patients and changes in therapy may be needed.

How good is peritoneal dialysis?

  • Peritoneal dialysis can provide good, efficient dialysis but needs to be monitored carefully and checks made that enough toxins are being removed. It needs to be performed daily with breaks only because of unusual circumstances.
  • The nurses and doctors will measure how effectively the dialysis is being performed and change the volume and strength of the fluids.
  • If good dialysis cannot be achieved it is important to think about a change - from CAPD to APD or from PD to haemodialysis.

What are the problems with peritoneal dialysis?

  • There can be problems with the catheter not working or with fluid leaks in the groin or around the catheter when dialysis starts. These problems can be managed easily.
  • Infections are the major risk - either in the exit site or most importantly in the tummy itself, peritonitis. This shows as tummy pain, a fever and a cloudy fluid bag. It is important to ring the kidney unit immediately if a cloudy bag develops. Peritonitis is treated with antibiotics added to the bags and may need admission to hospital for a few days. Rarely, the infection may be so bad that the catheter has to be removed.
  • In the long term, there can be a thickening of the peritoneal membrane so that it does not work efficiently. The dialysis fluid may need to be changed or switched to haemodialysis.

Having a Tenckhoff catheter

The Tenckhoff Catheter provides permanent long-term access to the peritoneal cavity. It is a thin, non-irritating, flexible tube. One end of this tube rests in the peritoneal cavity, while the other extends from the body by about 4 inches, so that it can be attached to the dialysis fluid. This end is sealed off when fluid is not being run in or out of the abdomen.

The catheter can be put in place either under sedation, with a local anaesthetic (patients describe it as an uncomfortable procedure rather than painful). Or it can be done as a minor surgical operation under general anaesthetic. Once in place, however, it will not be used for 2 weeks, to allow healing.

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See also: Treating kidney failure through Dialysis