OxySim 2 - Fundamental Investigation of Gas Transfer as a Function of Membrane Fiber Geometry and Blood Flow Direction in Oxygenators

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Michael Neidlin © Copyright: CVEAME

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Michael Neidlin

Chief Scientist Modeling & Simulation

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+49 241 80 88616

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  OxySim 2method Copyright: © CVE

Background

Membrane oxygenators are a component of extracorporeal blood circulation taking to partially or completely take over the gas exchange function of the natural lung. In the oxygenator, part of the carbon dioxide is removed from the blood while oxygen is added. The main areas of application are the heart-lung machine and extracorporeal lung support (ECLS). The gas transfer is a diffusive process through microporous fibres with the gas phase on the inside and the blood phase on the outside of the fibres.
The only differences in current oxygenators designs is the distinction between stacked and wound fibre mats resulting in two different blood flow directions. A relationship between gas transfer and parameters such as fibre type, fibre angle and fibre density does not exist and deeper understanding could be necessary for more efficient oxygenator designs in the future.

Aim

Aim of this project is to establish a method for a quantitative prediction of gas transfer in oxygenators by improving the overall understanding for how fibre bundle geometry and blood flow direction affect the gas transfer. More specifically, numerical simulations and in vitro experiments will be used to describe, model and measure the gas transfer for different fibre orientations and use this information to calculate correlation parameters for an investigation of local gas transfer even in complex oxygenator fibre bundle geometries. Based on these findings, the gas transfer in novel hollow fibre membrane oxygenators can be investigated a priori without the need for lab prototype manufacturing.

Methods

To achieve this aim, at first small fully functional fibre segments with different fibre orientations, densities and types will be constructed and the gas transfer for these different configurations will be measured. In the second step, microscopic computational fluid dynamics (CFD) simulations using a multiphase blood model will be used to numerically represent these generic geometries and compute the gas transfer for the various setups. Afterwards, directional correlation parameters will be deduced and implemented into a macroscopic CFD model of an oxygenator following a porous media approach.
At last, this new numerical model will be compared to existing gas exchange measurements to assess its capabilities and limitations.

Funding Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project number 422681948