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  • 學位論文

以壓振法建構一個可估測肱動脈動態順應性的方法

A New Method for Estimation of Dynamic Brachial Artery Compliance Based on Oscillometry

指導教授 : 王士豪 劉省宏
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摘要


一種新的非侵入式評估肱動脈動態順應性(compliance)的技術,其基礎是利用有關於動脈與臂帶模型之壓振式的理論。在充氣的過程中,分別藉由壓力感測器與微量流量計來測量臂帶於充氣時的壓力和體積變化,來建立出臂帶的特性;於洩氣的過程中,利用壓力換能器我們可以得到臂帶內的壓力與臂帶壓振波(OAs),然後利用此兩種參數建立出包絡(envelope)。因此,一旦我們知道了臂帶模型與壓振波的封包,我們就可以計算在不同臂帶壓力下的每次心跳所造成的動脈體積改變量,也就是肱動脈的動態體積—壓力(volume-pressure curve)曲線。然後將此動態體積—壓力曲線,除以脈波壓,肱動脈的動態順應性即可獲得。然而在系統上,我們設計了一個間接校正的系統,用來校正經過系統運算後的動態動脈體積改變量。此外,為了確效系統上所測得之動態動脈順應性,在取得32位病人資料的同時,一並做了以超音波的方式來測量肱動脈的血流速,並計算其肱動脈的順應性,最後將兩者的數據進行比較。而這32位病人均是經由醫師診斷後,需要進一步進行動脈硬化度或動脈阻塞檢查的病患。最後在結果的呈現上,分別針對當臂帶壓等於平均血壓、收縮壓與舒張壓三處時,進行與超音波測到的數據來比較,並得到一正相關的結果,其相關度分別在平均血壓時r=0.707,在收縮壓時r=0.648,在舒張壓時r=0.773。這也表示了此系統採用壓振法所萃取出的壓振波特徵方式來評估動脈動態順應性上頗為有效。

並列摘要


We propose a new method for assessing the dynamic compliance of the brachial artery using an oscillometry-based approach that is mathematically based on artery and air-cuff models. The cuff dynamics during the inflation period were characterized by simultaneously recording the cuff volume and internal pressure with a pressure transducer and an airflow meter, respectively, which yielded the envelope of the oscillation amplitudes (OAs) in the air cuff. This allowed the change in the arterial volume during each heartbeat at different cuff pressures to be calculated, yielding an arterial dynamic volume–pressure curve. The oscillometry-derived dynamic compliance of the brachial artery (Cosci) can be determined from the volume–pressure curve as the dynamic volume divided by the pulse pressure. Furthermore, we developed a direct scheme to calibrate the calculated dynamic change in arterial volume. In addition, the proposed Cosci was validated by comparing it with the compliance of the brachial artery (Cecho) estimated echocardiographically from the brachial arterial blood flow in 32 patients whose lower limbs exhibited numbness or lack of strength. The results showed that Cosci and Cecho were significantly correlated between the cuff pressures levels and the mean arterial pressure, systolic pressure, and diastolic pressure (r = 0.707, 0.648, and 0.770, respectively; p < 0.0001). This suggests that a useful measure of the dynamic arterial compliance can be derived from the pattern of the OA waveform in addition to oscillometry-based blood pressure measurements.

參考文獻


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