Blood compatibility and filtration characteristics of a newly developed polyester polymer alloy membrane

BACKGROUND:Many synthetic polymeric membranes have been widely used for blood purification therapies for removing larger solutes and for better blood compatibility.METHODS:Five different filters with polyester polymer alloy (PEPA) membrane (Nikkiso) that included polyvinylpyrrolidone (PVP), that is, standard-pore-size FLX (PEPA with PVP(-)), standard-pore-size FDX (PEPA with PVP(+)), new FDX (PEPA with PVP(++)), larger-pore-size FDY (PEPA with PVP(+)), and new FDY (PEPA with PVP(++)), were evaluated in terms of in vivo blood compatibility and aqueous in vitro sieving coefficient (s.c.) for albumin.RESULTS:FDY showed excellent small changes in C3a concentration during the treatment right after switching from polysulfone membrane, leaving no significant changes in other blood-compatible indices. New FDY, in contrast, showed less biocompatible characteristics in terms of C3a, which may be caused by increased use of PVP. FLX (no PVP) showed the highest s.c. for albumin. With a hydrophilic agent (PVP), the s.c. was greatly reduced in FDX. By enlarging the pore diameter in FDY, the s.c. increased in accordance with the enlargement. Generally speaking, polysulfone filters with PVP(+++) reach the peak s.c. value approximately 10 min after starting the experiment. The s.c. of the PEPA membrane with no or small amount of PVP, which showed excellent blood compatibility, never showed peaks, whereas the peak s.c. values were found in new PEPA with increased amount of PVP that showed higher C3a changes.CONCLUSIONS:The separation characteristics of aqueous albumin may be related to its blood compatibility.