Effect of blood contact on the transport properties of hemodialysis membranes: a two-layer membrane model.

The effects of blood-membrane interactions on hydraulic permeability, sieving coefficients, and diffusive permeabilities of Cuprophan and AN69 polyacrylonitrile hemodialysis membranes were studied using polydisperse dextrans (MW 5,000-20,000). Blood contact had no effect on the transport characteristics of the Cuprophan, but it caused a significant reduction in all of the transport parameters for the AN69 membrane due to the formation of a layer of adsorbed plasma proteins on the upper surface of the membrane. The transport characteristics of the membrane after exposure to blood are described using a two-layer membrane model, with this model able to accurately account for the different effects of blood contact on the sieving coefficients and diffusive permeabilities as well as the observed asymmetry in solute transport through the blood-contacted membrane. These results have important implications for solute transport during clinical hemodialysis.