In extracorporeal organ support, one or more organ functions are supported via different types of management of the blood outside of the body. Examples of this are intermittent, or continuous renal replacement therapy, and extracorporeal life support (extracorporeal carbon dioxide removal, extracorporeal cardio-pulmonary resuscitation, and extracorporeal membrane oxygenation (ECMO)). The latter are used for temporary lung- and/or heart-failure. About 1.5 million patients require hemodialysis worldwide whereas ECMO has had an essential life-saving role during both the COVID-19 and H1N1 pandemic but could be considered for any kind of refractory respiratory failure when conventional intensive care does not suffice. In both treatments, two or more accesses to the human circulatory system are used; one for blood drainage and another to return oxygenated and/or cleaned blood. The flow velocity in the cannula and the cannulated blood vessels is often significantly higher than physiologically experienced. The high flow rate implies that larger forces (stress) act on the blood cells and the vessel walls that enhance the risk for complications in the form of formation of stenoses and/or thrombi. Both forming of blood clots (thromboembolism) as well as morphological and mechanical changes leading to vessel stenosis are common complications, also influencing treatment efficiency. This project focus on the impact of blood flow on these complications. To connect the onset of thrombus formation or vessel stenosis to the flow dynamics, several different research methodologies, engineering and clinically oriented, need to be applied, synchronized, and carried out in parallel. Clinical data such as medical imaging (computed tomography, CT, and ultrasound, US) are needed to construct laboratory and simulation relevant frameworks. Computational fluid dynamics and fluid mechanical experimental methods are used to assess flow and mixing as well as transport of the different blood components (e.g. blood cells and chemical species). To link the flow to the specific onset of the complications, patient-specific coagulation data is analyzed as well as the response of certain individual human proteins to fluid stresses. This in turn requires a project group consisting of experimental and numerical fluid mechanics expertise as well as clinical specialists in nephrology, intensive care/ECMO, and radiology. The combination of the different tools and close interaction between engineering and medicine will facilitate a considerably better understanding of the underlying pathological processes where the outcome of the research will both enable and facilitate device development and clinical decision-making reducing overall treatment complications.
