Dialysis of middle molecules at pulsatile flow.

Pulsatile flow was used in a continuous flow flat-plate dialyzer in order to achieve the more efficient removal of middle molecules. The solutes ranged in the molecular weights from 342 (sucrose) to 1355 (vitamin B-12). The permeability of Cuprophane membrane to sucrose, raffinose and vitamin B-12 were calculated both for pulseless and pulsatile flows. It was found that pulsatile flow is more favorable than steady flow with regard to increase of membrane permeability. However, as the solute molecular weight increases, fluid-phase resistances become relatively less important and the transport rate becomes dominated by the membrane properties.