Hollow fiber plasmapheresis process

Claim 1

Improved method for plasmapheresis carried out in a system with a bundle consisting of a plurality of blood wettable porous membrane hollow fibers all of which are in parallel bundle alignment and have a substantially uniform membrane pore diameter and open inlet ends and open outlet ends, each fiber having a lumen diameter (D) no greater than 0.050 cm, the pore diameter being within the range 0.1 to 1.0 μm, comprising: (a) conducting blood in a forward direction into and through the fibers while maintaining a mean positive transmembrane pressure difference across the membranes from inlets to outlets of the hollow fibers; (b) terminating the forward conducting of blood; (c) conducting blood through the hollow fibers in the reverse direction; (d) collecting plasma-depleted blood from the outlets of the hollow fibers; (e) collecting plasma which has passed through the pores of the membranes; and (f) repeating in sequence steps (a), (b) and (c) to collect additional plasma-depleted blood and plasma, the effective length, that is, the portion of each fiber, between the ends, through which plasma passes, of the hollow fibers being such that the L/D ratio is no greater than 16,400 cm -1 D (L and D being in centimeters) and the velocity of the blood in step (a) being such that the shear rate is 200 to 2500 sec -1 , the improved method providing a plasma flux of at least 0.042 mL/min/cm 2 and an outlet plasma-depleted blood hematocrit of at least 65%.