A MATHEMATICAL-MODEL FOR SHEAR-INDUCED HEMOLYSIS

The time-varying history of stress exposure within a rotary blood pump makes it difficult to arrive at a quantifiable design criterion for p redicting cell traumatization. Constant stress experiments have reveal ed that there is a threshold stress level above which damage to blood cells occurs depending upon the time of exposure. The shear stress his tory experienced by cells within a rotary blood pump, however, is high ly unsteady. In order to better predict cell trauma under these realis tic conditions, a mathematical damage model based on a concept of ''da mage accumulation'' has been developed. This model is evaluated within the context of red cell trauma. Experimental results support the hypo thesis that the rate of damage accumulation increases nonlinearly with the stress level as well as the age of the cell.