The peritoneum is a space in the abdomen enclosed by a thin lining called the peritoneal membrane. This membrane can be used as a filter to clean the blood and remove excess body water. Accessing the peritoneum for treatment requires a catheter, which is a soft, flexible tube about the size of a straw. The catheter is placed in the lower abdomen during a minor surgical procedure and is usually ready to use about two weeks after surgery. The catheter remains in place the entire time a patient is undergoing peritoneal dialysis.
During peritoneal dialysis, the peritoneum is filled with a PD solution, which remains in the body for a prescribed period of time. This period is called the dwell time. At the end of the dwell time the used solution, which contains excess fluid and impurities pulled from the blood, is drained and replaced with fresh PD solution. This process is called an exchange and is repeated several times in each 24 hour period.
Peritoneal dialysis can be performed in two ways, and both treatment types are normally carried out at home. The choice between them depends on the personal likes and dislikes, lifestyle choices and medical condition of each patient. CAPD, or Continuous Ambulatory Peritoneal Dialysis, is a manual treatment usually perfomed during the day. APD, or Automated Peritoneal Dialysis, is typically performed overnight using a machine called a cycler.