Hydrodynamic and rejection properties of a coil dialyzer

Compliance of coil dialyzers follows a linear dependence on pressure when measured in saline; compliance measurements with non-wetting fluids are inappropriate and underestimate the blood compartment expansion experienced with pressure. The arithmetic mean of inlet and outlet pressures can be used to predict ultrafiltration rate independent of venous outlet pressure, and blood compartment volume varies both with inlet pressure and blood flow. The rejection of carbohydrate marker solutes increases from about 10% for 1,200 Daltons to 100% for 12,000 Dalton species.