Continuous systolic pressure measurement based on analysis of photoplethysmogram

血壓的量測主要可以分為連續性的及非連續性的，連續性的血壓量測可以量得每一次心搏的收縮壓與舒張壓，而非連續性的血壓量測主要是利用演算法量得一段時間內的收縮壓及舒張壓，除此之外，需搭配一壓脈帶輔助進行之。由於重症病患的血壓可能會在短時間有急速的變化，因此連續性的血壓值對於需要長期監控的病患一直是重要的生命參數，目前醫院大部分都是以侵入式的插管量測為主，不僅需要專業醫護人員來進行，也可能造成血栓及感染的可能。 本研究主要利用光體積變化描述法(PPG)之波形與收縮壓之間的關聯性，比較目前的各種非侵入式連續推估方法，因目前的非侵入式推估方法仍需要經過校正，因此使用PPG波形輔以壓脈帶來決定收縮壓，並進一步以此當作校正方式，希望能建立一套非侵入式的連續收縮壓量測方法，以降低目前插管所帶來的風險與不便。 以我們目前的實驗結果顯示，利用ECG的R波到PPG波形開始上升點之時間(脈波到達時間)及PPG波形寬度所決定的時間兩種參數對連續收縮壓的推估有較好的結果，而使用PPG判定收縮壓也有和震盪法一致的結果，當我們利用PPG判定收縮壓來校正時，W.Chen的逐跳推估方法似乎可以得到令人滿意的結果，目前兩位病患平均誤差為0.27mmHg，誤差標準差為9.04mm-Hg，未來除了需要更多的病患驗證之外，也要延長推估的時間，更希望進一步求得舒張壓，以獲得完整的非侵入式的連續血壓量測。Due to the measurement result, the method of measuring blood pressure is divided into two: continuous and non-continuous. The continuous blood pressure contains the systolic and diastolic pressure with every heartbeat. For the non-continuous measurement uses algorithm to get the blood pressure during a period of time. It also requires cuff as an auxiliary. Furthermore, the blood pressure of a severe diseased patient may change rapidly in a very short time. For long term monitoring, continuous blood pressure measurement is very crucial for certain patients as one of the important vital signs. This requirement is most commonly met by the placement of an intra arterial catheter. It not only needs the professional staffs to set up, but also brings problems like thrombosis and infection. The aim of our study is to use the relation between photoplethysmogram(PPG) and systolic blood pressure to build a noninvasive method which can obtain the continuous blood pressure variation. In addition to the comparison of the different estimation methods, we also use the combination of PPG and cuff to get systolic pressure measurement as a rectification to the estimation equation. It can reduce the risk and inconvenience of the invasive method. According to the results, the continuous systolic pressure can be estimated well by two parameters: one is duration of the peak of R wave to the beginning of the up-slope of the PPG wave(arrival time); the other is the time of the pulse width of PPG. The outcome of using PPG to determine the systolic pressure is the same as oscillometry. Finally, Chen’s method seems to get a better result when we use the systolic pressure determined by PPG as a rectification. As the measurement result of two patients, the mean difference of 0.27mmHg with a standard deviation of 9.04mmHg. In the future, we will measure more patients to verify our results and extend the time of each measurement. We hope that we can also obtain the diastolic pressure to achieve the completely noninvasive continuous blood pressure measurement.中文摘要……………………………………………………………………………..Ⅰ Abstract………………………………………………………………………………Ⅱ 內容…………………………………………………………………………………..Ⅲ 圖目錄索引…………………………………………………………………………..Ⅴ 表目錄索引…………………………………………………………………………..Ⅶ 第1章 緒論………………………………………………………………………..1 1.1 前言…………………………………………………………………………...2 1.2 目前量測血壓的方式………………………………………………………...3 1.2.1 侵入式……………………………………………………………………3 1.2.2 非侵入式……………………………………………………………… ...4 1.3 研究動機與目標……………………………………………………………..8 1.4 論文架構…………………………………………………………………….10 第2章 實驗原理………………………………………………………………… 11 2.1 PPG原理…………………………………………………………………… 11 2.2 推估連續收縮壓方法……………………………………………………… ..15 2.2.1方法1-DxTek's method.…………………………………………………..15 2.2.2方法2-Chen’s method.…………………………………………………....19 2.2.3方法3-Awad’s method.……………………………………………………22 2.2.4方法4…………………..………………………………………………….24 2.3 以PPG波形決定收縮壓……………………………………………………..26 第3章 實驗方法與材料…………………………………………………………28 3.1 實驗設備…………………………………………………………………….28 3.2 實驗架構…………………………………………………………………….32 3.3 實驗流程…………………………………………………………………….36 3.4 計算推估方程式…………………………………………………………….38 3.4.1 脈波速度推估收縮壓…………………………………………………....38 3.4.2 脈波到達時間逐跳推估收縮壓………………………………………....38 3.4.3 PPG波形寬度推估收縮壓 ……………………………………………...39 3.4.4 其他推估方法…………………………………………………………....39 3.5 實驗方法…………………………………………………………………….40 3.5.1 長時間與短時間的推估比較……………………………………………40 3.5.2 不同推估方法的比較……………………………………………………41 3.5.3 利用PPG判斷收縮壓……………………………………………………41 3.5.4 利用非侵入式進行校正推估收縮壓……………………………………42 3.6 分析方法…………………………………………………………………….43 第4章 結果與討論………………………………………………………………….45 4.1 長時間與短時間的推估比較………………………………………………...45 4.1.1 實驗結果…………………………………………………………………45 4.1.2 結果討論…………………………………………………………………51 4.2 不同推估方法的比較………………………………………………………...53 4.2.1 實驗結果…………………………………………………………………53 4.2.2 結果討論…………………………………………………………………59 4.3 以PPG波形決定收縮壓……………………………………………………..63 4.3.1 實驗結果…………………………………………………………………63 4.3.2 結果討論…………………………………………………………………67 4.4 利用非侵入式進行校正推估收縮壓………………………………………...71 4.4.1 實驗結果…………………………………………………………………71 4.4.2 結果討論…………………………………………………………………75 第5章 結論…………………………………………………………………………79 第6章 未來工作……………………………………………………………………81 第7章 參考文獻……………………………………………………………………8