The purpose of using counter-current flow in dialysis is to

The purpose of using counter-current flow in dialysis is to

• A. Reduce pressure in the dialyzer
• B. Increase patient comfort
• C. Reduce dialysate usage
• D. Increase the rate of waste removal

Answer: (D)

The main idea is that diffusion relies on a concentration gradient, and counter-current flow keeps that gradient strong along the entire length of the dialyzer. Blood entering the dialyzer carries a high concentration of waste products, while dialysate enters with a low concentration. As they flow in opposite directions, fresh dialysate continually contacts blood with high waste levels, and the exiting dialysate carries away increasingly more waste. This setup prevents the gradient from collapsing along the membrane, so wastes diffuse into the dialysate more efficiently. The outcome is a higher overall rate of waste removal, which is exactly what counter-current flow is designed to achieve.

The main idea is that diffusion relies on a concentration gradient, and counter-current flow keeps that gradient strong along the entire length of the dialyzer. Blood entering the dialyzer carries a high concentration of waste products, while dialysate enters with a low concentration. As they flow in opposite directions, fresh dialysate continually contacts blood with high waste levels, and the exiting dialysate carries away increasingly more waste. This setup prevents the gradient from collapsing along the membrane, so wastes diffuse into the dialysate more efficiently. The outcome is a higher overall rate of waste removal, which is exactly what counter-current flow is designed to achieve.