| 摘要: | 隨著高血壓患者的年齡層逐漸年輕化，患病的人口比例亦逐年漸長，若能隨時隨地對動脈血管壓力（Arterial blood pressure）的生理資訊做監控，相信預防醫學這個理念能夠更落實、成效更為顯著。
光體積描記圖（Photoplethysmography, PPG）裝置具有容易架設、非侵入人體、價格低廉以及操作便利等優點，另外呈現出人體末梢手指血管血液量的變化情形中含有多種生理訊號；因此本論文以PPG的光電技術為基礎、動脈血流動力學為理論依據，提出一項新的生理指標參數ΔRI (Delta Reflection Index, ΔRI)：以PPG訊號波形的重搏波（Dicrotic Notch）為臨界指標，計算其左右兩峰值之間的時間差，並以白努力定律（Bernoulli′s principle）為計算基礎準則，估算出受測者的動脈血管舒張壓（Systolic blood pressure）及收縮壓（Diastolic blood pressure）。
目前文獻常見的動脈血管壓力評估演算法有：PPG振幅比值法 (PPG Intensity Ratio, PIR) 、心房收縮舒張時間比值法 (t1 & t2)以及脈波傳導速率法 (Pulse Wave Velocity, PWV)這三種；前兩者方法因為使用單一PPG裝置，有著非侵入以及操作簡便的優點，但因為皆使用標準值為基準值，若受測者偏離健康狀況太多，就會導致誤差值提升；而PWV法，即使是不同狀態的受測者仍能保持低誤差的優點，但因為須同時使用PPG以及心電描記圖（Electrocardiography, ECG）兩項裝置，以至於失去便利性這個優點。
於受測者不限制其生理狀態時所量測而得的結果如下：ΔRI（收縮壓5.18%和舒張壓8.32%），能保持PIR、t1 & t2兩種演算法（平均誤差值：收縮壓9.89%和舒張壓15.13%）擁有設備簡便的優點，同時也能達到與PWV誤差值（收縮壓5.98%和舒張壓8.68%）相當的優勢。;As the hypertensive rate increase, hypertensive tends to strike patients at young age. Preventive medicine can obviously take hold if arterial blood pressure can be monitored anytime and anywhere.
Photoplethysmography can tell variation of blood volume on fingertip and lots of physiological information. Apart from that, the device contains several benefits including easy setup, non-invasive measurement and low price. Therefore, this dissertation, which is based on PPG photoelectric technology and arterial hemodynamics presents a new physiological parameters ΔRI (Delta Reflection Index). Applying dicrotic notch as a critical indicator, and Bernoulli′s principle as calculation criteria can determine ΔRI. Further, following the above-mentioned rules an estimate systolic blood pressure and diastolic blood pressure.
PPG Intensity Ratio, t1 & t2 ratio and Pulse Wave Velocity are three common algorithms to calculate arterial blood pressure in current literatures. With using single PPG device, PIR and t1 & t2 have the advantages of non-invasive measurement and convenient to operate. However, health condition of the experimental subjects deviate from reference because of following standard blood pressure or standard atrial contraction and diastolic time as a reference value. Pulse Wave Velocity gives small percentage of error and stability in the different state of the trial, but it needs to have access to both PPG and electrocardiography, which cause inconvenient operation
As the results obtained general physiological state, it shows that not only can ΔRI(Error value about SBP: 5.18% and BBP: 8.32%) keep the advantages of PIR and t1 & t2 ratio (Average error value about SBP:9.89% and DBP:15.13%), it also has the similar error to PWV(Error value about SBP: 5.98% and BBP: 8.68%). |
