The Effects of Hollow Fiber Membrane Configuration on Hemodynamic Characteristics, Oxygen Transfer Performance and Thrombosis Risk in Oxygenators: A Numerical Research.

BACKGROUND: The effects of hollow fiber membrane (HFM) configuration on hemodynamic characteristics, oxygen transfer performance, and thrombosis risk in oxygenators are not clear, and the present study was accomplished to investigate these effects. METHODS: Three micro-scale 3D HFM array models were established, with the staggered angle between HFM layers (Φ), the spacing between HFMs (d), and the number of HFM layers (n) as variables. Computational fluid dynamics (CFD) was employed as a predictive tool to quantify wall shear stress (WSS), oxygen partial pressure (PO2), and saturation (SO2), activated coagulation factor XII concentration (C[FXIIa]), blood residence time (BRT), and pressure drop (PD) under various flow rates. RESULTS: It was found that larger Φ resulted in higher outlet-averaged PO2/SO2, more concentrated BRT and C[FXIIa] at lower values, and higher PD. Similar trends in oxygen transfer were observed when d was decreased or n was increased. However, those conditions were associated with more extensive high-BRT and high-C[FXIIa] regions, which were interpreted as indicating higher thrombosis risk. CONCLUSIONS: Based on these predictive results, it is suggested that the inter-layer cross angle should be increased within an acceptable PD range, and that the model porosity should be maintained between 0.4 and 0.6. It is also recommended that the number of layers be reduced for a given volume. Furthermore, it was indicated by the simulations that avoiding extremely large or small flow paths is critical, since larger spacings were predicted to markedly reduce oxygen transfer, while smaller spacings were predicted to increase thrombogenic potential. This study can provide guidance for the design optimization of configurations such as the arrangement of HFMs within the oxygenator.