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Renal Replacement Therapies

What is peritoneal dialysis?

Peritoneal dialysis is a medical treatment that involves using the peritoneal cavity within your body. The peritoneal cavity is the area inside the abdomen. The lining of the abdomen called the peritoneum forms the peritoneal cavity. The peritoneal membrane can be compared to a deflated balloon. The area within the deflated balloon is the cavity.

Dialysis works by using the peritoneal membrane. It acts as a natural filter to remove waste and extra fluid from the blood when your kidneys can no longer function properly. This is done by filling the peritoneal cavity with a special fluid called dialysate. Dialysate is a clear fluid that allows for fluid and electrolyte exchange to occur. Dialysate is composed of different levels of dextrose, or sugar. Most commonly used dialysate fluid is 0.5%, 1.5%, 2.5%, and 4.25%. The percentage of dialysate fluid a patient requires is based on how much fluid needs to be removed. The higher the amount of dextrose, the more fluid is pulled from your body.

When the dialysate fills the cavity, a process called osmosis occurs. Osmosis occurs through the help of sugars and other molecules in the dialysate which helps to pull extra waste and fluid from the blood vessels in the body. The waste and excess water then moves through the peritoneal membrane and into the dialysis fluid in the cavity. The fluid stays in the peritoneal cavity for a specific amount of time to remove further waste and excess fluid from the vessels. This period is called the dwell time. After the dialysate does its job in the peritoneal cavity, the fluid is then drained out of the body and replaced with fresh dialysate, for the whole process to occur again. The process of filling and draining the peritoneal cavity is called the exchange. The exchange takes about 30-40 minutes. This process is repeated four to six times in a 24 hour period. Peritoneal dialysis can be done manually during the day or automatically while you sleep at night.