Patients with chronic renal failure have an accumulation of extracellular fluid and waste
products (uremic toxins) which are normally excreted by the kidney. There are diff erent renal
replacement therapies, which can partially correct these abnormalities. Peritoneal dialysis (PD)
is one of these modalities. Since the introduction of continuous ambulatory peritoneal dialysis
(CAPD) in 1976, the use of PD has increased steadily and is now used worldwide. On January
1st 2009, 6292 patients were on dialysis in The Netherlands, of which 18.1 % (n=1139) were on
PD (source:RENINE www.renine.nl).
In PD the peritoneal membrane is used as a dialyzer membrane. By gravity a sterile dialysis
solution is instilled in the peritoneal cavity via an intra-abdominal catheter. Through a combination
of diff usion and convection waste products and fl uid are transported between the
peritoneal capillaries and the dialysis fluid. After a few hours an equilibration is reached, and
the effl uent is drained. In the regular CAPD scheme, this cycle is performed 4 times a day for 4
hours with a long night dwell.
Dialysis solutions contain varying concentrations of glucose in order to provide an osmotic
gradient necessary for the transport and removal of excess body water. The glucose is absorbed
by the peritoneal capillaries, which leads to a decrease of the osmotic gradient. In the early
nineties icodextrin was introduced as a new dialysis fl uid. This is a glucose polymer derived
from starches, which is absorbed slowly by the capillaries. Therefore it is very eff ective for
ultrafi ltration, particularly in long dwells. Although, the side eff ects of icodextrin appear to be
limited, sterile peritonitis due to icodextrin has been reported.
Normal peritoneum comprises diff erent components; a thin layer of mesothelial cells and a
submesothelial layer with vessels and fi broblasts. The inner abdominal wall is lined with a parietal
membrane, where as a visceral membrane covers the intestines. Continuous exposure to
dialysis solutions and other exogenous factors results in changes of the peritoneal membrane.
In long term PD there is mesothelial denudation, the submesothelial layer becomes thicker and
new vessels develop.
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