CFD Assisted Design of a Wearable Artificial Pump Lung Device

A wearable artificial pump lung (APL) device is being developed to provide ambulatory respiratory support for patients with acute or chronic lung diseases. The design objective of the APL is to create an assembly free, ultracompact, all-in-one system with an optimized blood flow path and minimized device-induced blood damage. This device will combine a magnetically levitated pump/rotor with a uniquely configured hollow fiber membrane (HFM). Computational fluid dynamics (CFD) based multidisciplinary modeling of the device functional performance and biocompatibility was utilized to acquire the precise knowledge of flow field, gas transfer and blood damage characteristics through the whole device. With this knowledge available, the device can be evaluated and optimized to obtain best performance, i.e., maximizing the gas exchange efficiency and minimizing blood damage. The HFM bundle was modeled as porous media with a constant porosity. Flow field was obtained by solving the Navier-Stokes equations, and oxygen transfer process was modeled as a scalar transport. The hemolysis was evaluated based on the shear stress and exposure time distributions which were obtained by post-processing the flow solution. According to the preliminary CFD results, among several designs, the satisfactory one was found regarding flow dynamics, overall biocompatibility and oxygen transfer performances. The average shear stress value was less than 10 Pa, and the outlet oxygen saturation was higher than 95% at standard operating condition. The impeller blade and diffuser angles were compatible to each other resulting in a smooth blood flow in the corresponding region.