Sensitivity of platelet activation in an ECMO pump due to different modelling approaches

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy used in the critically ill to treat heart and/or lung failure. The circuit comprises a membrane lung with heat exchanger, a blood pump, cannulae for drainage and reinfusion of blood from/to the patient, and tubing with connectors. Its use is associated with complications, bleeding, thromboembolism, and hemolysis being primary causes of morbidity and mortality.

Mechanical stresses play a role in platelet activation, assessed as platelet activation state (PAS). CFD can be a valuable tool to investigate effects of circuit component flow structures on thrombogenic properties in different scenarios. However, a proper assessment of the influence of boundary conditions and modelling approach is needed to characterize the sensitivity of the results due to modelling choices employed in the particle tracking. In this work, Lagrangian Particle Tracking (LPT) was used where 100’000 spherical particles, representing platelets, were injected in an ECMO blood pump to record stress history and compute their activation state. The LPT was carried out as a post-processing step on a time-resolved flow field produced using Star-CCM+. Blood was treated as a Newtonian fluid. Considering particle inertia, Newton’s 2nd law was used to compute particle velocity. In this work, drag, lift and pressure gradients were considered. The impact of these forces on platelet trajectories and activation state will be studied for different particle sizes and densities.