A mechanistic model of plasma filtration.

A model describing the sieving and transmembrane pressure behavior of plasma filtration is developed and numerically simulated. The model assumes a mechanistic criteria for particle passage through a membrane with cylindrical pores. The initial pore diameter distribution and porosity are assumed to be known. Model inputs include the particle diameter distribution, concentration and total flow rate of the permeate plasma solution. Outputs of the model include transmembrane pressure, the time-averaged sieving coefficients, and size distributions of the deposited particles and accumulated filtrate particles. Optimal filtration is characterized by high, stable sieving coefficients for desired particles, high retention of larger particles and relatively small increases in transmembrane pressure. These characteristics are realized for membranes with mean pore diameters equal to or slightly larger than mean permeate particle diameters. Simulations demonstrate that the incorporation of membrane properties into models of plasma filtration is both significant and readily possible.