Final answer:
Continuous Ambulatory Peritoneal Dialysis (CAPD) is a gravity exchange process where the patient manually performs dialysis fluid exchanges throughout the day using the natural filtering abilities of the peritoneal lining to remove waste and excess water from the blood.
Step-by-step explanation:
Continuous Ambulatory Peritoneal Dialysis (CAPD) is a method of renal replacement therapy that involves the manual exchange of dialysate in the peritoneal cavity. The process utilizes the lining of the abdominal cavity as a natural semipermeable membrane to filter waste products and excess fluid from the blood into a dialysate solution that is then drained. This is performed multiple times a day.
In CAPD, a gravity exchange process is employed. A bag of sterile dialysis fluid is connected to a catheter in the patient’s abdomen. The bag is raised above the level of the catheter to allow the dialysis fluid to flow into the abdominal cavity, taking advantage of gravity. This fluid is left in the abdomen for several hours to absorb waste products and excess water from the bloodstream. After the prescribed dwell time, the now waste-filled fluid is drained out by lowering the bag below the level of the abdomen, again using gravity. The process is repeated with a fresh bag of dialysis fluid, and this exchange is typically done 3-5 times a day.
CAPD allows patients with renal failure the ability to perform dialysis exchanges throughout the day while they continue with their regular activities, which is why it is referred to as 'ambulatory'. This process is distinct from automated peritoneal dialysis, which uses a machine to perform exchanges, typically while the patient sleeps.