抄録
Hemolysis is a major factor for developing successful blood pumps. A major cause of hemolysis is the mechanical stress acting on the corpuscles passing through the pump. The empirical formula, which expresses the relationship of the shear stress, exposure time, and hemoglobin release serves as a basic model for the estimation of blood damage. We have conducted computational fluid dynamics (CFD)-based assessment for the hemolysis within the blood pump using one of the above mathematical models. Assuming that the red blood cells pass along the streamlines, a blood damage index was calculated based on the changes in shear stress with time along the streamlines starting from entrance of the pump. The feasibility of this method has been confirmed by making comparisons with experimental results. The indices of hemolysis of different pumps should be compared under the same flow rate and pressure head conditions. In the CFD-based estimation of hemolysis, the preliminary analyses for deriving the rotational speed conditions giving a flow rate of 5 L/min and a pressure head of 100 mmHg should be conducted. In this study, the pump performance derived from CFD analysis coincided well with the experimental results. From the results of the CFD analysis, the existence of reverse flows was found in the inflow cannula and passages between the guide vanes. The reverse flows resulted in the reduction of pump performance and hemo-compatibility due to the increase of the red blood cells passing the impeller area repeatedly. In conclusion, pump design can be improved by CFD analysis of the rotary pump and CFD-based estimation of hemolysis.
