Evaluation of dialyzers used in shortened dialysis

The clearance of urea and beta 2-microglobulin are important considerations along with biocompatibility in selecting membranes for use in shortened dialysis. During 3 hr of dialysis we have measured the in vivo urea clearances, pre- and post-beta 2-M levels, plasma clearance and simultaneous dialysance of beta 2-M. Leucopenia was compared after 15 min of dialysis on a cellulose acetate (CA) dialyzer and a polyacrylonitrile dialyzer (PAN). Clearance of urea was similar in both dialyzers. In contrast to CA, PAN removed beta 2-M and exhibited minimal leucopenia. The dialysance of beta 2-M was significantly less than the simultaneous blood side clearance. The disparity between blood clearance and dialysance by PAN membranes suggests removal of beta 2-M by adsorption and diffusion. We conclude that in comparison with CA dialyzers, PAN membranes remove beta 2-M, have equivalent urea clearances, and are more biocompatible.