Blood-membrane interactions can have a large impact on the performance of hemodialysis membranes, particularly for high flux membranes in which the membrane itself provides very low resistance to solute transport. The objective of this study was to examine the effects of exposure to serum on the solute clearance and convective sieving characteristics of high flux polysulfone (Optiflux F250NR), polyethersulfone (ELISIO-25H), and asymmetric cellulose triacetate (SOLACEA-25H) hemodialyzers using both vitamin B and a range of polydisperse dextrans. Zeta potential measurements were used to obtain additional insights into the changes in membrane surface properties. Exposure to serum in a simulated dialysis session caused a significant reduction in both solute clearance and sieving coefficients for the polysulfone/polyethersulfone dialyzers, particularly for the larger molecular weight solutes. In contrast, the transport characteristics of the asymmetric cellulose triacetate dialyzers were almost unchanged after exposure to serum. The zeta potential of the cellulose triacetate membrane became slightly more negative after exposure to serum, consistent with an adsorbed protein layer composed largely of albumin. The net result is that the asymmetric cellulose triacetate dialyzer had dramatically higher clearance of the larger dextrans after exposure to serum, with the clearance and sieving coefficient for a 10 kDa molecular weight dextran being more than an order of magnitude greater than that of the polysulfone/polyethersulfone membranes. These results provide important insights into the expected clinical performance of these high flux dialyzers.

Aims: The objective of this study was to compare the transport characteristics of highly asymmetric cellulose triacetate (ATA™) membranes with that of both symmetric cellulose triacetate and asymmetric polysulfone membranes. Methods: Data were obtained for solute clearance and sieving coefficients of vitamin B₁₂ and a range of polydisperse dextrans using ATA™ SOLACEA-25H and Optiflux F250NR polysulfone dialyzers. Results for these, and the CT190 symmetric cellulose triacetate dialyzer, were analyzed using available membrane transport models. Results: The ATA™ had the largest solute clearance, although the homogeneous CT190 dialyzer had the highest sieving coefficients. These differences were a direct result of the differences in the underlying membrane morphology, with the asymmetric ATA™ membrane providing much higher diffusive transport rates (and thus higher solute clearance). Conclusions: These results demonstrate the importance of membrane morphology on dialyzer transport and provide important insights into the effective clinical performance observed with the highly asymmetric ATA™ dialyzers.

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