Ex vivo preclinical evaluation of membrane plasma separators

Effect of Anticoagulant on Biocompatibility in Membrane Plasmapheresis

The effect of heparin or citrate anticoagulation on blood cellular, complement pathway and coagulation pathway was investigated in a membrane plasma exchange procedure. Two membrane plasma separators constructed of cellulose di-acetate (CA) and polyvinyl chloride (PVC) were evaluated with heparin or citrate alone for anticoagulation in a 26 year old male with myasthenia gravis. Maximum white blood cell counts decrease was 21% at 30 min for the CA with heparin while no decrease was observed for the other schemes. Platelet counts changes were comparable between heparin and citrate, while the PVC groups showed less changes than the CA groups. The CA groups, regardless of the type of anticoagulant used, indicated that complement activation occurred via the classical pathway within the module in addition to the activation via alternative pathway for the CA with heparin. In the PVC groups, complement activation was noted to occur only when heparin was used for anticoagulation. PT and PTT showed slight increases with citrate, while they were remarkably prolonged with heparin. Citrate showed less changes in cellular and humoral factors compared to heparin. CA with heparin was the most activating combination of membrane material and anticoagulant, while the PVC with citrate was the least activating combination.

Surface area effects on efficiency and biocompatibility in experimental membrane plasmapheresis

The effect of different surface areas on cellular, humoral, and hemodynamic changes and on plasma separation performance were investigated. Membrane plasmapheresis, consisting of plasma separation and on-line reinfusion, was carried out on dogs for 3 h with 0.6 and 0.3-m2 polyethylene (PE) and polyvinyl alcohol (PVA) modules. The plasma separation and sieving performance was comparable in both the 0.6 and 0.3-m2 modules. The initial white blood count (WBC) reductions were independent of the surface area difference, but the rebound was greater in the smaller modules. The platelet (PLT) reductions were less with the 0.3-m2 PE module in comparison to those with the larger PE module, but no differences existed between both of the PVA modules. The smaller PVA module showed less complement activation compared to the 0.6-m2 module, whereas both of the PE modules showed comparable changes. Hemodynamic responses, especially the changes in pulmonary vascular resistance, were less with the smaller modules compared to the 0.6-m2 modules. The PE modules themselves showed less blood cellular, humoral, and hemodynamic changes compared to the PVA modules. The smaller modules showed greater rebound of WBC counts, however, PLT reductions, complement activation, and changes in hemodynamic parameters were less in the smaller modules.