Assessment of blood compatibility of haemodialysis membranes using a miniature flat sheet dialyser

Available pre-clinical techniques of assessing severity of untoward reaction by blood following contact with haemodialysis membranes do not account for the effects of dialysate and flow characteristics in the observed blood changes. A miniature flat sheet dialyser that considered these effects was prepared and tested in both in-vitro and ex-vivo circuits. Changes in platelets and leucocytes in heparinised human blood in-vitro tests did not distinguish regenerated cellulose (Cuprophan 150PM) membrane from a synthetic membrane, a copolymer of acrylonitrile and sodium methyl sulphonate (AN69S). Ex-vivo tests using rats showed more marked leucocyte (41.3%) and platelet (43.1%) depletion by Cuprophan 150PM than AN69S after 90 minutes of dialysis. Leucocyte and platelet loss due to AN69S were 26.9% and 13.4% respectively. In addition, Cuprophan 150PM membranes exhibited high affinity for leucocytes and platelets in both in-vitro and ex-vivo tests compared to AN69S membranes which were primarily covered with erythrocytes. Application of simulated in-use techniques in preclinical evaluation of blood compatibility membranes that are used in extra-corporeal treatment are recommended.