COMPUTATIONAL FLUID-DYNAMIC OPTIMIZATION OF THE DISTRIBUTOR/COLLECTOR FOR THE PUMPING OXYGENATOR

Abstract

An innovative extracorporeal circulation (ECC) device, the Pumping Oxygenator (PO), functionally integrating pulsatile blood pumping and membrane oxygenation, was previously proposed by our group. ECC is normally performed with non-pulsatile flow, large priming volume circuits and extended blood contact with foreign surfaces. The PO design gathers the benefits of physiologic hemodynamics with integration and compactness. In this work, computational fluid dynamics (CFD) were used to optimize the PO's blood distributor/collector. 3D models were developed of the hydraulic connection of the venous/arterial line's proximal end with the rectangular inflow/outflow face of the central PO unit. CFD simulations wefe used to compromise among minimizing priming volume (Vp), shear stress (τ), and flow unevenness in the parallel membrane modules (measured by the standard deviation of flow rate, SDFR). The central unit was modeled as an anisotropic porous medium. Steady flow was used, to keep simulation time low. First, the best mutual orientation of the circular and rectangular sections was selected for the distributor, by comparing 7 configurations with identical Vp and using SDFR as a score index. The side configuration (conduit at 90° vs. the rectangle's short edge) was best (SDFR reduced by 26%). Then, through a 3D parametric model, 13 different side geometries were compared, by weighing the contributions of Vp, ± and SDFR. The optimized distributor geometry was then proved to be suitable for the collector's function as well, with no need for different manufacturing processes.