Biomechanical Study of Mechanical Damage of Red Cells in Shear Flows with Reference to Homolysis in Artificial Flow Circuits

这个项目涉及红细胞在剪切过程中损伤的生物力学分析，特别提到了人工血流回路中的溶血。为了阐明红细胞在剪切流动中的力学损伤，我们研究了红细胞在剪切流动中的流动和变形，并检测了作用在细胞膜上的剪切应力。我们在显微镜下直接观察了人体红细胞在剪切流中的运动，以及它们的变形导致细胞膜破裂。由于红细胞的流动和变形在剪切流动中永远不会保持静止，我们设计了新的流动电路，如反向旋转系统和显微镜-频闪系统。通过对细胞图像的强化，得到了形变红细胞的清晰图像。由于红细胞的变形取决于悬浮介质的粘度以及流动的剪切速率，因此我们使用了各种高粘度的流体。观察到红细胞在高剪切作用下发生变形并最终破坏。我们从细胞膜剪切应力诱导的角度考虑红细胞损伤。假设膜为粘弹性壳，对变形后的细胞膜在剪切作用下进行应力分析，发现细胞膜可能受到循环荷载的作用。我们得出结论，红细胞损伤可能主要是由于材料的疲劳循环加载。最后，通过对各种人工流动回路的流动情况进行考察，研究了溶血的可能原因。

This project deals with biomachanical analysis of the damage of red cells induced in shear with a special reference to hemolysis in artificial flow circuits. To elucidate the mechanical damage of the red cell in shear flows, we studied the flow and deformation of red cells in shear flows and examined the shear stress acting on the cell membrane. We directly observed the motion of human red cells in shear flows under microscope, and their deformation leading to the rupture of the membrane. Since the flow and deformation of the red cell never remains stationary in shear flow, we devised new flow circuits, such as counter-rotating system, and a microscope-strobe system. By intensifying the cell image, we obtained the clear image of the deformed red cell. Since the deformation of the red cell depends upon the viscosity of the suspending medium as well as the shear rate of flow, we used various fluids of high viscosity.The red cell was observed to be deformed and finally damaged under high shear. We considered the red cell damage from a stand-point of shear stress induced in the cell membrane. Assuming the membrane as an viscoelastic shell, we made stress analysis of the deformed red cell in shear and found that the cell membrane may be subject to the cyclic loading. We concluded that the red cell damage may be partically due to the material fatigue of the cyclic loading.Finally, by examining the flow condition of various artificial flow circuits, possible causes of hemolysis were studied.