In peritoneal dialysis, what is the function of the dialysate dwell time?

• A. It allows diffusion and osmosis to occur between blood and dialysate across the peritoneal membrane.
• B. It cleans the dialysate.
• C. It measures the amount of urea removed.
• D. It controls the dialysate temperature.

Answer: (A)

Dialysate dwell time is the period the dialysis solution stays in the peritoneal cavity to allow exchanges to happen. During this time, diffusion moves waste solutes like urea from the blood into the dialysate, and osmosis pulls excess water across the peritoneal membrane, driven by concentration and osmotic gradients. The peritoneal membrane acts as a semipermeable barrier, so giving enough time for these processes lets wastes and extra fluid move into the dialysate for removal. It isn’t about cleaning the dialysate, measuring how much urea is removed, or controlling the dialysate temperature.