Effect of hollow fiber configuration and replacement on the gas exchange performance of artificial membrane lungs

Artificial membrane lungs are composed of hollow fiber membranes. Blood flows with low velocities in the membrane bundle, forming a laminar boundary layer near the membrane surfaces that limits gas transfer. Passive blood mixing within the fiber array is utilized to overcome this limitation. Nevertheless, it is unclear to which extent blood mixing and fiber configuration contribute to the performance of membrane oxygenators.

This study aims to evaluate the effect of fiber configuration and replacement on the gas exchange performance of membrane oxygenators to contribute to a better understanding of the influence of blood mixing to gas transfer and the mechanisms of gas exchange in blood. Furthermore, designs in which hollow fibers of different functions could be combined in highly integrated membrane lungs are provided.

We analyzed the gas transfer performance of membrane oxygenators in a perpendicular configuration with 100%, 75%, or 50% of fibers open, and in a crossed configuration with 100% or 67% of fibers open. 95%–100% of the oxygen transfer of a fully open oxygenator could be maintained in our prototypes with 25% of gas exchange fibers closed in a perpendicular configuration, indicating that several fibers contributed to gas exchange by mixing the blood flow. Closing fibers in a perpendicular configuration resulted in a lower decrease in oxygen transfer. This study contributes to the development of novel membrane oxygenators integrating fibers of different functionalities (e.g. oxygenation and dialysis) maintaining high gas exchange efficiency.