Patent ID: 7056458
Filing Date: 2006-06-06
Classification: A61L,B01D

Abstract:
1. A method for reducing the thrombogenic character of an exchanger for treating blood or plasma by extracorporeal circulation, comprising two compartments separated by a semipermeable membrane having a surface oriented towards a first compartment intended for the circulation of blood or plasma, the method comprising: (a) preparing a semipermeable membrane, in the form of a flat membrane or a bundle of hollow fibres, from a solution of polyacrylonitrile carrying anionic or anionizable groups; (b) assembling the various components of the exchanger, in particular fitting the semipermeable membrane or a bundle of hollow fibres in a case; (c) preparing a solution containing at least one cationic polymer carrying cationic groups that form ionic bonds with the anionic or anionizable groups of the polyacrylonitrile, the cationic polymer further comprising only polymer chains whose size is sufficient for the chains not to pass through the semipermeable membrane, and bringing this solution into contact with the surface of the semipermeable membrane intended to be placed in contact with the blood or plasma, stage (c) being carried out before or after stage (b); (d) in the event that stage (c) is carried out after stage (b), purging the exchanger of the solution containing the cationic polymer; (e) preparing a solution containing, in the dissolved state, at least one anticoagulant agent carrying anionic groups that form ionic bonds with the cationic groups of said cationic polymer, and bringing this solution into contact with the surface of the semipermeable membrane intended to be placed in contact with the blood, stage (e) being implemented after stage (c) but before or after stage (b); (f) in the event that stage (e) is carried out after stage (b), purging the exchanger of the solution containing the anticoagulant agent; and (g) sterilizing the exchanger once the semipermeable membrane based on polyacrylonitrile carrying anionic or anionizable groups is coated with the cationic polymer and the anticoagulant agent.