New dialysis membrane for removal of middle molecule uremic toxins.

Because ultrafiltration provides an alternative pass for removal of middle molecules from the bloodstream, high hydraulic permeability is necessary as well as high diffusive permeability. For this reason, polysulfone membrane became a clinically popular material as a dialysis membrane. The author tested one polysulfone dialyzer in vitro (aqueous/bovine plasma) with special interest in its internal filtration, ultrafiltration, and reverse filtration observed in one dialyzer for removing solutes. Results showed that with higher blood and dialysate flow rates, removal of middle molecules was increased as a result of the internal filtration. Module design is crucial for larger fluid exchange with internal filtration. Hemodialysis with internal filtration may be considered as a limited-scale on-line hemodiafiltration with no additional hardware, which may be possible with polysulfone or other high flux membranes when highly purified dialysate fluid is prepared.