A COMPARISON OF 3 BRANDS OF POLYSULFONE MEMBRANES

A prospective clinical crossover study comparing the functional perfor mance and biocompatibility of three brands of polysulfone membranes (F resenius Polysulfone(R) (Fresenius Ag, Bad Homburg, Germany), Polyphen (R) (Minntech Corp., Minneapolis, MN), and Biosulfane(R) (WR Grace Inc ., Danvers, MA)) incorporated in ethylene oxide-sterilized dialyzers o f comparable surface area (1.3 to 1.35 m(2)) was undertaken. The clear ance of small molecules by each membrane was comparable, Plasma levels of beta(2) microglobulin fell to 49.9% of pretreatment values by 210 min when using the Fresenius Polysulfone(R) membrane, 60.2% with the P olyphen(R) membrane, and 63.1% with the Biosulfane(R) membrane. The re duction achieved by the Fresenius Polysulfone(R) membrane was superior (P = 0.003). The plasma reductions were associated with the recovery of 195 mg beta(2) microglobulin from the dialysate for the Fresenius P olysulfone(R) membrane and 158 mg for the Polyphen(R) membrane, but no beta(2) microglobulin was recovered from the dialysate with the Biosu lfane(R) membrane. The dialysate collected with the Fresenius Polysulf one(R) membrane also contained a mean of 6853 mg of fetal protein, com pared with 5490 mg with the Polyphen(R) membrane and 8422 mg with the Biosulfane(R) (P = 0.04) membrane. The neutropenia was slight and inde pendent of membrane brand, as were the changes in C3a des arg and SC5b -9 complement components. The reduction in platelet counts was higher for the Biosulfane(R) membrane than for the other brands (P = 0.003). This study indicates that whereas the polymer base of the membrane is the same, its production and subsequent handling during dialyzer produ ction induce changes that attain statistical significance, most notabl y in the way that the membrane removes beta(2) microglobulin and inter acts with proteins. The differences observed are a consequence of the different alloying polymers used during manufacture and, consequently, the membranes cannot be considered equivalent.