In peritoneal dialysis the lining of the abdominal cavity (peritoneum) is used to filter toxins from the bloodstream. A soft catheter is implanted in the abdominal cavity which is filled with a fluid (dialysate) which is composed largely of glucose, sodium, calcium and lactate.
The peritoneum serves as a dialysis membrane. Waste materials accumulated in the blood are drawn into the dialysate placed in the abdomen because of the diffusion of molecules from a higher concentration (in the blood) to a lower concentration area (dialysate).
The waste-filled dialysate is then removed from the abdominal cavity via the abdominal catheter after a prescribed period of dwell time (which varies from patient to patient and the method of PD used).
This is known as an exchange. There are several different types of chronic peritoneal dialysis schemes, each prescribed by nephrologists according to the suitability for the patient. Continuous Ambulatory Peritoneal Dialysis (CAPD) - The patient manually inserts the dialysate into the abdomen through the catheter and replaces it with a fresh supply.
The process is performed several times during the day (typically a four to six hour exchange each time) and once while sleeping through the night. Chronic Cyclic Peritoneal Dialysis (CCPD) - A machine, or cycler, performs the dialysate exchanges in CCPD.
It will perform several cycles during the night while the patient sleeps and will leave one exchange in the abdomen before the tubing and cycler are detached in the morning once the patient wakes up. This fluid is removed once the patient hooks up with the machine again at night and the cycles start again as the patient prepares for bed.
Intermittent Peritoneal Dialysis (IPD) - IPD also uses a cycler to perform six or more exchanges at night. However, unlike CCPD, there is no daytime exchange with IPD. IPD is sometimes called NIPD, or nocturnal intermittent peritoneal dialysis.
Patients on CAPD neither require any electricity dependent machine, nor do they have to come to any dialysis centre twice or thrice a week, as is the case in hemodialysis. In other words, they are more independent and free to move.
Moreover in CAPD there is continuous removal of waste products from the body as compared to intermittent process of hemodialysis, so the quality of life is comparatively better.
The infection of the peritoneum (Peritonitis). and high blood sugar levels due to absorption of glucose from the dialysate are the only significant problems related with chronic peritoneal dialysis.