Development of a novel polyimide hollow fiber for an intravascular oxygenator

The authors have synthesized a novel fluorinated polyimide to develop a membrane material for oxygenators and fabricated polyimide hollow fibers for use in an intravascular oxygenator. A dry/wet phase inversion process has been applied to a spinning process to prepare an asymmetric polyimide hollow fiber. The outer surface of the hollow fiber consists of an ultrathin, dense skin layer, with a calculated apparent thickness of approximately 60 nm. The fiber diameter was 800 microns with a wall thickness of 130 microns. The asymmetric hollow fiber has two advantages because (a) the hollow fiber does not produce plasma leakage due to the dense skin layer of the surface and (b) O2 and CO2 transfer rates through the hollow fiber are enhanced due to the ultrathin skin layer and are significantly larger than those of presently available membrane oxygenators. The blood compatibility of the polyimide hollow fiber without heparinization has been evaluated in vitro. Deformation and aggregation of platelets adherent to the fibers were not observed, and the polyimide suppressed platelet activation. The polyimide significantly reduced the production of anaphylatoxin and also suppressed complement activation.