On the Significance of Exposure Time in Computational Blood Damage Estimation

Abstract

The reliability of common stress-based power law models for hemolysis estimations in blood pumps is still not satisfying. Stress-based models are based on an instantaneous shear stress measure. Therefore, such models implicitly assume that red blood cells deform immediately due to the action of forces. In contrast, a strain-based model considers the entire deformation history of the cells. By applying a viscoelastic tensor equation for the stress computation, the effect of exposure time is represented as a biophysical phenomenon. Comparisons of stress-based and strain-based hemolysis models in a centrifugal blood pump show very significant differences. Stress peaks with short exposure time contribute to the overall hemolysis in the stress-based model, whereas regions with increased shear and long exposure time are responsible for damage in the strain-based model.