Direct removal of heparin from whole blood using affinity adsorption hollow fiber membranes

Heparin is routinely used in procedures requiring extracorporeal blood circulation. After surgery it must be removed or neutralized rapidly, generally with protamine. However, protamine dosage is imprecise and the procedure is complicated by adverse reactions. A novel affinity adsorption hollow fiber membrane module is proposed that removes heparin directly from whole blood.; The module is similar to traditional plasma filters. Here, fibers are potted on the inlet side only, with the fiber ends open to the shell and no side port in the shell. As blood moves through the fiber lumens, plasma is filtered through the walls into the shell. DEAE (di-ethyl-aminoethyl) groups attached in the fiber wall adsorb heparin dissolved in the plasma. At the end of the device whole blood and shell side plasma recombine and exit. The module operates in the transitional region of filtration in which the filtration is a function of transmembrane pressure and shear rate.; A numerical model solving the governing conservation equation for fluid and cell motion was developed to simulate the flow in the device. The numerical model accounts for concentration polarization and shear induced diffusion of red blood cells. The results from the numerical model agree well with data presented in the literature.; Filtrate flow experiments determined the fractional plasma yield, which is inversely proportional to the heparin removal time. An increase in fiber length at constant pressure drop across the module increases the fractional plasma yield. However, length increases ≥14 cm for PES TF10 fibers (300 μm inner diameter) and >8 cm for PES TF7 fibers (200 μm inner diameter) are no longer beneficial. An increase in pressure drop from 40 to 100 mmHg reduces the fractional plasma yield for all fiber types, but changes in hematocrit between 15 and 45 percent have only minor effects.; The dynamic heparin capacity of the DEAE modified PA fiber is 7640 IU/ml membrane volume and sufficient to operate the module far away from saturation. The heparin adsorption module removes heparin rapidly (90% within 13 minutes) avoiding protamine induced adverse reactions.