Controlled ultrafiltration (UF) with hemodialysis (HD): analysis of coupling between convective and diffusive mass transfer in a new HD-UF system.

A convertible and versatile dialysis system consisting of a PMMA hollow fiber unit and UFR controller is shown to be useful for evaluating the effect of solute and fluid removal rates on adequacy of dialysis. Post-dilution mode where high UFR is applied to the patient with matching or comparable dilution rate is concluded to be most effective modification for enhancing the clearance for "middle molecules", without sacrificing the removal rates for the small solutes.