Pulsatile flows to improve function of a long-term oxygenator

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Despite technical advancements, long-term durability of oxygenators in Extracorporeal Membrane Oxygenation (ECMO) circuits is still limited to 1 - 2 weeks. Prolongation of the period of use is especially necessary regarding novel long-term applications such as bridge-to-lung transplant or treatment of chronic obstructive lung disease. The aim of this project is the investigation of the influence of pulsatile blood flow within an ECMO circuit regarding gas transfer efficiency and hemocompatibility, and thus a prolonged period of use. Therefore, we plan to systematically investigate pulsatile and non-pulsatile flows within ECMO systems regarding the long-term performance of oxygenators and the effects on the hemocompatibility considering the coagulation and the activation of the immune system. Following objectives are to be achieved in several steps: 1. Theoretically, prevention of areas of stagnating flow and an improved gas transfer efficiency due to induced secondary flows can be achieved by pulsatile flows. In order to obtain fundamental understanding of the optimum flow profile, regarding mean and maximum amplitude and cycle duration, different profiles have to be defined and developed first, taking advantage of existing medical and medical-technical knowledge. 2. Initial in-vitro experiments aiming to decrease the number of flow profiles under investigation will be enabled by the development of a demonstrator. The influence of pulsatility on gas exchange efficiency is to be investigated first. 3. On basis of the identified flow profiles, demonstrator and control are optimized. Subsequently, an in-vitro test series is carried out to systematically examine pulsatile and non-pulsatile flow profiles with respect to the effects on gas exchange, flow rates, and hemocompatibility. In addition to gas exchange and blood traumatization, parameters for coagulation and immune system are measured with human blood. Finally, a scanning electron microscope and immunohistopathological analysis of the oxygenator fibers are planned. The results of this project will enable a verification of the theoretical advantages of the pulsatility, i. e. if a pulsatile flow leads in fact to enhanced efficiency and long-term stability of an ECMO system. Subsequently, the characterization of an ideal flow profile can be used to evaluate the long-term stability of a lung support system in in-vivo experiments and to investigate the effects on different organ systems in a follow-up application. Ultimately, in case of positive test results, the goal of a more efficient and a prolonged extracorporeal lung support could be achieved.