A client with chronic kidney failure is to undergo continuous ambulatory peritoneal dialysis (CAPD). Which statement best describes the therapy?

• A. It provides continuous contact of dialyzer and blood to clear toxins by ultrafiltration.
• B. It exchanges and cleanses blood by correction of electrolytes and excretion of creatinine.
• C. It decreases the need for immobility because it clears toxins in short and intermittent periods.
• D. It uses the peritoneum as a semipermeable membrane to clear toxins by osmosis and diffusion.

Answer: (D)

CAPD clears wastes by using the peritoneum as a semipermeable membrane for diffusion and osmosis. A sterile dialysis solution sits in the abdominal cavity, and wastes such as urea and creatinine move from the blood into the dialysate by diffusion across the peritoneal capillaries. Water is drawn out by osmosis because the dialysate contains glucose, creating an osmotic gradient. This process happens continuously with daily exchanges, providing ongoing toxin and fluid removal without a separate blood-facing dialyzer.