探討剪應率、血容比與管徑對層流之血液凝固特性的影響

The Effects of Shear Rate, Hematocrit, and Tubing Size on the Properties of Coagulating Blood under Laminar Flow

張哲文(Che-Wen Chang)

指導教授 ： 王士豪

中原大學/工學院/醫學工程研究所/碩士(2007年)

https://doi.org/10.6840/cycu200700624

摘要

近年許多使用超音波技術偵測血液凝固的研究，多數探討靜態血液的凝固性質，而正常人體的血流皆為動態，故本研究嘗試使用都卜勒超音波量測動態血液之凝固性質，探討不同流管直徑、血液流速與血容比對血液凝固的影響。
本研究首項工作為建構一套可攜式的數位脈衝都卜勒超音波系統來應用於血液凝固的偵測。系統以微處理器為核心控制之單元，由數位訊號處理器即時計算與顯示都卜勒訊號，提供電腦端訊號擷取、分析與即時顯示的連結介面。經不同血容比血液與流速的驗證結果，顯示本自製數位脈衝都卜勒超音波系統的功能及準確性，適合用於血液相關特性的偵測。血液凝固於不同流管直徑的探討是使用直徑3 與7 mm的流管，調整血液之流速，使血流的剪應率皆相同；血液凝固於不同剪應率的探討則是在單ㄧ流管下設計兩種剪應率，分別為145 s-1、310 s-1。結果顯示在相同剪應率下，大流管之血流較小流管平均早224秒發生凝血。血流在相同流管直徑下，兩種不同的剪應率的實驗結果，顯示凝血的起始時間隨剪應率的增加而平均提前165秒。血容比對於流動血液凝固影響的實驗結果顯示，血容比由20%增加到80%時，凝血的起始時間平均提前225秒。而流速變化與散射訊號變化的時間差距並不因血容比上升而改變(p>0.1)。

關鍵字

數位脈衝都卜勒超音波系統 ； 血液凝固 ； 剪應率

並列摘要

Many recent studies on the application of ultrasonic technologies for detecting blood coagulation were carried out from the blood under static conditions. This opposes the dynamic condition for blood flows in normal human. Hence, the coagulating properties of dynamic blood were measured using Doppler ultrasound in this work. Specifically, the effects of different diameters of the flow conduit and hematocrits on the blood coagulation were explored.
A portable digital pulsed Doppler ultrasound system (DPDUS)was developed to detect the blood coagulation. The system is equipped with a micro-processor as a core control unit. The Doppler signals were real-time computed and displayed via a digital signal processor which also provides interfaces capable of signal acquisition, analysis, real-time display with the computer. The capability and accuracy of the developed DPDUS, which is appropriate for the detection of blood properties, was verified with velocity measurements from the blood of various hematocrits. The blood coagulation dependent on different diameters of the flow conduit was explored using the tubing of 3 and 7 mm diameter. The unity shear rate (145 s-1 and 310 s-1) of blood flow was adjusted corresponding to those of different velocities of blood flow circulating in different conduits. Results demonstrated that the time for the initiation of blood coagulation tended to start in the blood flow of large conduit earlier than that of small conduit under blood flows of the same shear rate. For those blood flows circulating in the conduit of same diameter, the time for the initiation of blood coagulation tended to decrease with the increase of shear rate and blood hematocrit. The time difference between variations flow velocity and backscattering signals is not apparent associated with the increase of blood hematocrit.

並列關鍵字

digital pulsed Doppler ultrasound system ； blood coagulation ； shear rate

參考文獻

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