BIO17: Simulating Thrombus Formation In A Blood Oxygenator Considering Fibrin Formation, Platelet Activity, And Contact Activation

A numerical simulation of thrombus formation was performed in a blood oxygenator hollow fiber bundle microchannel. The numerical results were compared with in-vitro data. A model of factor XII contact activation, platelet activation, and fibrin formation was used to simulate thrombus formation. The simulating approach is based on the model of Wu et al.1, which solves the Navier-Stokes equations for flow dynamics and convection-diffusion-reaction equations for blood constituent concentrations. The geometry has a path length of 2 cm with fiber rods of 380 µm diameters and 40% packing density (see fig. 1A.) The simulation was conducted for an average fiber bundle velocity of 16 cm/min, which is similar to the velocity in commercial oxygenators. Blood constituent concentrations and properties were assumed to be those of healthy human participants. The model was implemented and solved in OpenFOAM. The numerical results after 10 min were compared to experimental studies that lasted 15 min. Despite the time course difference, interesting similarities were observed. After 10 min of simulation, clot formed preferentially downstream towards the narrowing outlet (see fig. 1B.) Minor platelet aggregation was observed, and the main constituent of the thrombus was fibrin (see fig. 1C and 1D.) Both observations are in line with the experimental results from Lai2 as it is shown figure 1E where the thrombus is shown in red downstream the oxygenator. The model captured the fibrin trail observed experimentally behind the fiber bundles (see Fig. 1C and F). Our results suggest that when simulating thrombosis in blood oxygenators, fibrin formation must be included, which could be explained by the large surface area to volume ratio and low velocities in the oxygenator. References 1.Lai, A. (2019). Carnegie Mellon University. 2.Wu, et al. (2017). Scientific Reports. Figure 1. A) Blood oxygenator geometry. B) Thrombus volume fraction field at middle plane. C) Fibrin concentration field behind fiber bundles. D) Middle plane fibrin concentration field. E) Experimental thrombus probability maps. F) Experimental thrombus composition. Red arrows indicate the flow direction.