A Study of the Correlation of Pulse Wave Transit Time and Heart Rate Variability during Anesthesia

在手術房中，麻醉是相當重要且不可缺少的一環，尤其是施打麻醉的劑量更是重要，但過多或過少的麻醉劑量均會帶給病患不好的影響。一般來說，全身性的藥物麻醉會透過阻斷自主神經系統來影響病患心血管狀況，常引發病人的心率改變、心臟收縮力下降、血管彈性改變以及周邊血管擴張等等現象，這種血行動力學的變化會造成受麻醉病人的血壓下降甚至產生休克的風險，尤其是對於本身患有糖尿病或心血管疾病等高危險性病人，更有導致併發症甚至死亡的危險。 心跳變異率（heart rate variability, HRV）在許多文獻中皆有探討到可以用來做為評估自主神經系統活性的工具。由於心跳速率的低頻部分是交感神經與副交感神經所共同作用；高頻部分則由副交感神經所單獨控制。因此，最常見的心跳變異率分析方法即為利用功率頻譜密度（power spectrum density）得到心跳間隔在頻域上的高低頻比值，推估目前心血管系統受到自主神經調控的程度。 本論文的研究內容即是針對手術中之麻醉安全，整合心電圖、光體積描述訊號等非侵入式相關生理資訊，並利用圖形化程式語言LabVIEW8.6軟體為平台開發一套監控程式，分析受測者接受麻醉藥物Bariburates前後心跳變異率以及脈波傳遞時間（PTT）的改變趨勢來推估目前接受麻醉的病人自主神經以及心血管系統變化的情況。最後建立一個評估方法，提供麻醉科醫師在手術時應變的參考，給予病人最適度的麻醉劑量，讓病人可以在手術過後能以最快的時間復原。In an operation room, anesthetics plays an important role and are indispensable. Furthermore, the dosage of anesthetic given is much more important because it may have terrible influences on the patients if it’s not accurate. Generally, general anesthesia affect the patients'' cardiovascular system by cutting off the autonomic nervous system, which causes the patients'' rhythm of the heart and blood vessels'' elasticity to change, weakens the strength of systole, makes the peripheral vascular to extend and so on. These changes of hemodynamic may cause the patients'' blood pressure to drop and will probably result in shock. Moreover, those who suffer from diabetes and cardiovascular disease are even more likely to have complications or die. According to many references, heart rate variability (HRV) is a way to estimate the activity of the autonomic nervous system. Since the sympathetic nervous system and parasympathetic nervous system mutually affect the low-frequency part of the heart rate, while the parasympathetic nervous system alone controls the high- frequency part, the most common way to analyze heart rate variability is to use power spectrum density to get the power ratio (LF/HF) between heartbeats and speculate about how much the cardiovascular system is controlled by the autonomic nervous system. This study aims at the safety of anesthetic in operations, combining relevant, non- intrusive measuring devices : electrocardiograms and photoplethysmographic. The thesis also analyzes the changes of HRV and pulse wave transit time (PTT) during anesthesia by LabVIEW8.6 based application program to estimate the patients’ autonomic nervous system and cardiovascular system. Eventually, the method of assessment to offer doctors a reference during an operation was build so that the patients could recover in the shortest time by giving them the appropriate anesthetic dosage