Saturday, May 4, 2024
5/4/2024
Project Summary Blood contacting medical devices, including rotary blood pumps, cause shear-induced blood damage that may lead to adverse effects in patients. However, there is currently not a uniformly accepted engineering model for predicting the blood damage caused by complex flow fields within ventricular assist devices (VADs) and other blood contacting medical devices. Our research group has designed and fabricated a novel device that can expose whole blood to controlled fluid shear flows that are representative of those experienced in these pumps. The device is able to accurately control the shear rate and exposure time experienced by blood and minimize the effects of other uncharacterized stresses, such as mechanical or fluid lubricated bearings. We plan to use this novel device to study red cell damage (hemolysis) and platelet activation in this shear flow. Although the effects of shear flow have been studied, we believe that our novel device will generate data that is a quantum step forward. Our one-of-a-kind device creates a shear relevant to those experienced in modern VADs without including incidental exposure to heat and shear in the mechanical bearings of other shearing devices. Our recent publication suggests that a paradigm shift (shear rate vs. shear stress) may be necessary to generate a truly predictive model of shear damage that would be useful in designing future devices. If funded, we will complete the study of shear rate instead of shear stress as a predictor for hemolysis (Aim 1), expand measurements to shear activation of platelets (Aim 2), and explore the variation in damage between species (Aim 3), which is critical because pre- clinical in vitro testing of medical devices typically uses non-human blood. Although there have been significant advances in the ability of computer programs to predict the velocity and shear flows through medical devices, the ability to then subsequently predict the damage resulting from this flow is, frankly, poor. The results of this project will be a significant step towards a quantitative predictive model that relates properties of the fluid flow field to damage. Additionally, we will share the results in the form of easy to access quantitative models that relate hemolysis and platelet activation to shear stress and shear strain. We will also create and share a tool to relate damage observed in non-human species to human blood. Although our focus is on supraphysiologic flows caused by ventricular assist devices, the findings are relevant to other blood contacting medical devices as well, such as prosthetic valves, dialysis, oxygenators, and cannulae.
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