Effect of sterilization on solute transport performances of super high-flux dialyzers

The effect of sterilization was quantitatively evaluated for modern super high-flux dialyzers in terms of solute transport performances for autoclave sterilization (AC), gamma ray sterilization (G-ray), combination of these two and no sterilization (NS) as reference. A commercial polysulfone dialyzer (Kawasumi Laboratory Co., Tokyo, Japan) was chosen for investigation with six different sterilization processes, i.e., sterilization with AC one time and two times, that with G-ray using either no additives or an additive, that with AC one time followed by G-ray using no additive and that with NS. In vitro dialysis and ultrafiltration experiments were performed with aqueous test solution as pseudo blood, varying Q(B) , Q(D) , and Q(F) . Creatinine (MW113), vitamin B(12) (MW1355), and α-chymotrypsin (MW25000) were chosen as test solutes for dialysis experiments. Clearances (C(L) ) calculated from dialysis experiments and the sieving coefficient for albumin (MW66000) from ultrafiltration experiments were compared among six models. A dialyzer with NS showed much lower clearances for all three solutes than those with sterile. Therefore, the sterilization increases the solute transfer performances. Although no significant changes in clearances for creatinine and vitamin B(12) were found among five sterile models, much higher clearances for α-chymotrypsin were found in AC sterile models. Then, the effect of sterilization may become greater with the increase of molecular weight of solutes. According to the results of the sieving coefficient for albumin, AC may have enlarged the pore size of the membrane that could increase clearances for large solutes without changing those for relatively small solutes. The sterilization increases the solute clearance even in so-called super high-flux dialyzers and the effect of sterilization may be greater in larger solutes.