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.