Infusion-free hemodiafiltration: simultaneous hemofiltration and dialysis with no need for infusion fluid.

A new simultaneous hemofiltration and dialysis system was developed which has no need of infusion fluid. The system employs two hemodiafilters in a direct series. An ultrafiltration rate and dialysate flow rate control system was employed to control the dialysate flow at the inlet and outlet, and the difference in volume was arranged to be the amount of water removed from the body. When the blood circuit was narrowed between the two hemodiafilters, the ultrafiltration was performed at the first hemodiafilter; at the second one, the dialysate moved to the blood side as a dilution fluid. To remove pyrogens and bacteria, tap water was subjected to activated charcoal, ion exchange and reverse osmosis treatment, followed by preparation of the dialysate. In clinical evaluation, this system showed marked improvement in clearance of middle and large molecules.