Year: 2004
Type: dissertation
Abstract: ion was made of the fiber packing (733 fibers/cm2) in the dialyzer to isolate a twelfth part of a single fiber with its surrounding membrane and dialysate compartment (Fig. IV-21). For the implementation in the numerical model, properties of the three domains, i.e. blood, dialysate, and the semipermeable membrane, were derived from literature and experimental investigations . Fig. IV-21: Schematic illustration of a hollow fiber dialyzer on macroscopic (dialyzer) and microscopic (fiber) level. Blood and dialysate inlet (subscript i) and outlet (subscript o) flows and concentrations are indicated as QBi, QBo, QDi, QDo, CBi, CBo, CDi, and CDo. Membrane permeability characteristics were obtained from filtration tests through the membrane . The tests were performed for forward and backfiltration using sterile dialyzers as well as samples in which a protein layer was induced on the membrane simulating a clinical session. The permeabilities of the skin (inner layer) and bulk (outer layer) of the polysulphone membrane were implemented as a series of two resistances. Furthermore, the influence of a protein layer on the overall permeability of the membrane was incorporated as a higher resistive inner layer, based on an overall membrane permeability of 3650nm2/s/Pa. From dialysate samples taken in vivo from the supply and the drain of the dialyzer, dynamic viscosity and density were determined. As both properties were not influenced by dialysis, dialysate flow was assumed as an incompressible, isothermal, laminar Newtonian flow with a constant viscosity (0.687mPa·s) and density (1008kg/m3). dialysate inflow QDi CDi blood outflow QBo CBo Dialyzer QDo CDo Ultrafiltration Quf > 0 Quf < 0 Blood capillary Membrane Dialysate
Author: Sunny Eloot
Language: English
Subfield: Nephrology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2262559159