Waste products pass from the blood vessels through the peritoneal membrane and into the dialysate. People can perform CAPD themselves by connecting a flexible plastic bag filled with dialysate to a piece of tubing attached to the catheter. Next, the bag is raised to shoulder height. Gravity makes the dialysate flow down into the abdominal cavity. After the bag is empty, it can be disconnected.
Some people leave the bag there, but roll it up and place it under their clothing.
When the dialysate is in the abdomen, wastes and excess water pass from the tiny blood vessels in the peritoneal membrane into the dialysate. The person can move around freely and perform most daily activities. Afterward, the bag is again connected to the catheter and lowered below the abdomen. Gravity now makes the dialysate containing waste products drain out. Once the bag is full, it is discarded.