Effect of hollow fiber packing density and housing shape on the solute removal performance of CRRT filters for acute blood purification.

Continuous renal replacement therapy (CRRT) has a good therapeutic effect in a variety of diseases, such as acute kidney injury. CRRT filters should feature small membrane surface area, excellent water permeability and solute removal performance for long-term use. Solute removal performance depends on the physicochemical structure of the dialysis membrane as well as on the housing design. On the basis of the same hollow fiber membrane, optimizing the housing design can maximize the performance of the dialysis membrane. In this article, we experimentally demonstrated the influence of hollow fiber packing density (PD) and housing shape (effective hollow fiber length (L) and inner housing diameter (D) ratio (L/D ratio)) on the performance of CRRT filters. In each continuous hemodialysis mode and post-diluted continuous hemodiafiltration mode, we tested nine CRRT filters with the same high-flux membrane but with different PDs (50%, 55%, and 60%) and L/D ratios (2.9, 5.3, and 9.3), and we evaluated the effect of different combinations of the two design factors on solute clearance. Our results showed that unlike with the clearance of small molecular weight solutes, the clearance of medium molecular weight solute was obviously affected by PD and L/D ratio, and the design providing the best removal of medium molecular solutes among the nine experiments was PD = 60% and L/D ratio = 9.3. This article will help address the lack of research on CRRT filter housing design as well as lead to the development of higher performance filters for acute blood purification.