Mass transfer characterization of a new polysulfone membrane.

A new polysulfone capillary membrane has been tested ex vivo for its clearance performance under diffusive, combined diffusive and convective, and pure convective solute mass transfer. As was expected, increasing convective mass transfer produced augmentation only of clearances of high molecular weight solutes, and to a much lesser extent than reported for other membranes. This behavior is explainable by the enormous diffusive clearance capacity of the new membrane, which nearly reaches its theoretical maximal value, as derived from a computer model. Based on the very high hydraulic permeability, which makes this membrane equally suitable for filtrative and diffusive procedures, no membrane solute retention was found up to a molecular weight of 5,000 daltons. Stable hemocompatibility parameters (leukocytes, thrombocyte, and complement measurements) demonstrated absence of activation by this membrane during treatment. It is concluded that since its clearance performance is near the theoretical maximal and it shows superior biocompatibility, the membrane exhibits negligible interaction with the transported solutes independent of the transport mode.