Effect of hollow fiber diameter and membrane surface area of polymethyl methacrylate membrane on filter lifetime

Abstract

Background When polymethyl methacrylate (PMMA) membranes are used in continuous renal replacement therapy, especially in patients with high cytokine levels, inflammatory cytokines and other substances are removed by the adsorption effect. However, such filters are prone to clogging, and the filter lifetime can be short. This study investigated the effects of hollow fiber inner diameter and membrane area on filter lifetime and protein removal performance using an in vitro continuous hemofiltration (CHF) experimental model with porcine blood. Methods Three types of filters with different hollow fiber inner diameters and membrane areas were used: CH-1.0N (membrane material, PMMA; membrane area, 1.0 m2; hollow fiber inner diameter, 200 µm), CH-1.0W (prototype: PMMA; 1.0 m2; 240 µm), and CH-1.8W (PMMA; 1.8 m2; 240 µm). During the experiment, pressure changes, filter lifetime measured from pressure and protein removal performance were measured using an in vitro CHF experimental model with porcine blood. Results The filter lifetime of CH-1.8W was significantly longer than those of CH-1.0N and CH-1.0W. The total protein adsorption was significantly higher for the CH-1.0W and CH-1.8W filters than for the CH-1.0N filter. Conclusions A larger membrane area from 1.0 to 1.8 m2 contributed to a longer filter lifetime, while an increase in the hollow fiber inner diameter from 200 to 240 µm did not. On the other hand, the protein removal performance, especially the adsorption performance, was higher for membranes with a larger hollow fiber inner diameter from 200 to 240 µm.