Which solute removal mechanism dominates over others in dialyzers for continuous renal replacement therapy?

Selecting dialyzers is more important for blood purification in critical care because other therapeutic options (especially amount of dialysate) are usually limited. Adsorption is a major mechanism of removing toxic substances from patients in these treatments. Several commercial dialyzers designed for acute blood purification therapy were investigated by performing aqueous ultrafiltration experiments to demonstrate the adsorptive importance of membrane materials. Polymethylmethacrylate showed strong adsorptive characteristics to α-chymotripsinogen A (MW 25,000) but showed much less adsorptive characteristics to cytochrome C (MW 12,400). On the contrary, polyacrylonitrile showed relatively lower affinity and polysulfone showed essentially no affinity to these proteins. Time-dependent and concentration-dependent characteristics of clearance for these solutes were also demonstrated in polymethylmethacrylate. Adsorption found in polymethylmethacrylate may be due to the occlusion of protein molecules into pores of the membrane. Choosing membrane materials is, therefore, important not only in removing inflammatory cytokines but also for accounting for the loss of albumin in acute and chronic treatments.