Pulsatile flows to improve function of a long-term oxygenator

尽管技术进步，体外膜氧合（ECMO）电路中氧合器的长期耐用性仍然限制在1 - 2周。对于新的长期应用，如肺桥移植或慢性阻塞性肺病的治疗，延长使用期限是特别必要的。该项目的目的是研究ECMO回路中脉动血流对气体传递效率和血液相容性的影响，从而延长使用时间。因此，我们计划系统地研究ECMO系统中搏动和非搏动血流对氧合器长期性能的影响，以及考虑到凝血和免疫系统激活对血液相容性的影响。以下目标将分几个步骤实现：从理论上讲，脉动流可以防止因诱导二次流而产生的停滞流动区域和提高气体传递效率。为了获得对最佳流型的基本理解，关于平均和最大振幅和周期持续时间，必须首先利用现有的医学和医学技术知识定义和开发不同的流型。2. 最初的体外实验旨在减少正在研究的流动剖面的数量，将通过开发演示器来实现。首先研究了脉动度对气体交换效率的影响。3. 在确定流型的基础上，对演示器和控制进行了优化。随后，进行了一系列体外试验，以系统地检查脉动和非脉动流动对气体交换、流速和血液相容性的影响。除了气体交换和血液创伤外，凝血和免疫系统的参数也用人体血液来测量。最后，对氧合器纤维进行扫描电镜和免疫组织病理学分析。该项目的结果将能够验证脉动性的理论优势，即脉动流是否实际上提高了ECMO系统的效率和长期稳定性。随后，理想流型的表征可用于在体内实验中评估肺支持系统的长期稳定性，并在后续应用中研究其对不同器官系统的影响。最终，在阳性检测结果的情况下，可以实现更有效和更持久的体外肺支持的目标。

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.