Minimodule dialyser for quantitative ex vivo evaluation of membrane haemocompatibility in humans: comparison of acrylonitrile copolymer, cuprophan and polysulphone hollow fibres.

Abstract Minimodule hollow fibre dialysers, representing clinical dialysis modules on a scale of 1 25 , enable quantitative evaluation of the haemocompatibility of hollow fibre membranes in an ex vivo flow system in humans. On line heparinization, adjusted for donor sensitivity, is maintained at a minimal level (~0.14 units/ml). Blood samples collected at the minimodule exit over 30 min are analysed for heparin (anti-Xa activity), activated partial thromboplastin time, fibrinopeptide A, platelet count and β-thromboglobulin, complement fragment C3a, leucocyte count and polymorphonuclear neutrophil elastase. Initial experiments were performed using well-characterized reference materials: acrylonitrile copolymer (AN 69 HP), polysulphone and cuprophan (CUP®). Activation of coagulation and platelets was low for AN 69 HF®, intermediate for CUP® and greatest for polysulphone, while complement activation was negligible in the presence of AN 69 HP®, moderate for polysulphone and most important for CUP®. Future applications will be directed towards haemocompatibility screening of prototype membranes with the aim of developing clinical dialysers with improved biocompatibility.