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    Title: 拉伸應力對紅血球溶血的影響
    Other Titles: The Effect of Extensional Stress on Red Blood Cell Hemolysis
    Authors: 盧博堅
    Contributors: 淡江大學水資源及環境工程學系
    Date: 2012-08
    Issue Date: 2015-05-11 16:27:00 (UTC+8)
    Abstract: 人工器官如心室輔助器、人工心瓣、導管等,會在心血管中造成 非生理性的流況,這些流況所產生的血流應力會引發血液的破壞,特 別是紅血球的損傷,稱為溶血。一般以溶血指數(Index of Hemolysis, IH(%))來表示,此溶血指數是切應力(shear stress)大小及暴露時間 (exposure time)的函數。Giersiepen et al.(1990)依據Wurzinger et al.(1986)的實驗導出的溶血指數模式,IH(%)= 0.785 exp 3.62 ⋅105 ⋅τ 2.416 ⋅ t 。 此模式廣被應用在計算流體(CFD)對新設計人工器官的評估上。新型 人工器官經由此模式CFD 所計算的溶血指數和實際原形的實驗值有 相當大的差異。式中的應力是由簡單Couette 黏度儀所產生之剪應 力,而實際流場應包含有剪應力和拉伸應力。單由剪應力無法準確預 估其溶血指數。由於紅血球在剪力場中,會產生如戰車履帶式的轉 動,其破壞的程度可能小於拉伸流場產生的拉伸應力。本研究擬建立 一個零剪應力之拉伸流場,以產生期望的拉伸應力範圍,然後採用新 鮮的猪血的紅血球,進行溶血的測試,以了解拉伸應力對溶血的影響。
    Artificial prostheses such as left ventricular assist devices, artificial heart valves, and tubing can create non-physiologic flow conditions within the cardiovascular system. The stress forces generated in these flow fields can induce blood cell damage, particularly red blood cell damage or hemolysis. The Index of Hemolysis (IH; %) is affected by the magnitude of shear stress and exposure time. Giersiepen et al. (1990), based on experiments by Wurzinger et al. (1986), determined that the Index of Hemolysis can be calculated by IH(%)= 0.785 exp 3.62 ⋅105 ⋅τ 2.416 ⋅ t . This model has been widely used in computational fluid dynamics (CFD) for the evaluation of new artificial prosthesis designs. However, the IH calculated via CFD are often inconsistent with actual measured values from experiments done on prototypes. The stress value in the calculation is based on the shear stress generated from a simple Couette viscometer; however, actual flow field forces include both shear stress and extensional stress. As such, the shear stress alone cannot accurately determine IH. Within a shear flow field, the red blood cells may revolve around in a tank-treading motion, and the magnitude of damage may correlate with the amount of extensional stress. In this study, we attempt to establish a purely extensional flow field without shear stress and perform hemolysis testing with porcine red blood cells in order to better understand the effects of extensional stress on hemolysis.
    Appears in Collections:[水資源及環境工程學系暨研究所] 研究報告

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