- 學位論文
組織血流血量量測系統的研製
Design a measurement system of tissue blood perfusion and plethysmograph
摘要
以肉眼判斷燒燙傷程度的困難點在於無法直接判斷皮膚燒燙傷的深度，而量測微循環血流也因不同個體和解剖位置有極大差異，無法以血流量的大小來判定燒燙傷程度，因此，需經由加熱以觀察其變化程度來判斷燒燙傷深度。 臨床上使用雷射都卜勒測量加熱前後血流速的改變，在判斷燒傷深度已有不錯的結果。但是目前為止，由於判斷方法和使用雷射血流計性能不一，仍未有一個客觀統一的判斷程序。一般市面上所使用的雷射都卜勒血流計檢測光源大都為紅光或近紅外光雷射，其量測的範圍為較深層的皮膚組織。由於燒傷程度最難判別的是二度深層及三度燒傷間的模糊地帶，其深度範圍大約為深真皮及皮下組織的交界處，深度僅約為1mm，因此，本研究使用綠光雷射作為檢測光源，並且為了縮短光源與檢測位置的距離以限制測量的深度，所以採用光纖來做光的傳導與檢測，此研究並且架構一測量血流及血量變化的系統，將光學機構、光電檢測線路、電源、與電腦整合成一套完整系統，並且設計出一套能夠同時即時量測血流血量在加熱前後變化的人機介面，用來量測皮膚組織在加熱至42℃前後的都卜勒頻譜變化以作為血流平均頻率變化的指標，同時也量測血管收縮舒張時血量改變所造成的光吸收度變化(亦即光體積描繪圖)以做為血量訊號功率變化的指標。依照這些指標來判斷皮膚組織中的微血管是否仍能正常擴張，以決定皮膚燒燙傷程度。 在加熱前後血流平均頻率的變化量大約為102％～127％，而血量的訊號功率變化量則約為200％～1220％，都能夠反映出人體皮膚組織在加熱前後的明顯變化，而多數受測樣本血量變化情形較血流變化大，由於不同體質的人其數據變化也會有所差異，因此，仍須增加量測的樣本數以為判斷的依據，並且結合醫院資源建立一套判斷燒燙傷程度的標準規範。
並列摘要
It is difficult to quantify burn wound based on its appearance because the eye can not tell the burn depth. Since tissue blood perfusion is affected by many factors, it is also difficult to judge the burn depth by just measuring the perfusion rate. Therefore, the change of tissue perfusion after heating is used a more reasonable index of burn depth. Although laser Doppler velocimeter (LDV) have been used in clinic to measure blood perfusion of tissue, most of them may not be appropriate for quantifying the burn depth. Generally, it is the most difficult to judge between the second and third degree of burn wound, which has the burn depth of about 1 mm. Because most laser Doppler instruments use red or near-infrared diode laser as the light source, they tempt to measure the blood perfusion of the deep tissue rather than the upper skin. In this study a green diode laser was used as the light source to reduce the probing depth. To further restrict the measurement volume, optical fibers were used to guide the source light and the modulated reflection. A measurement system including the optical system, amplifier circuit, signal processing unit, and operating interface was constructed for monitoring the change of mean Doppler frequency drift and the change of photoplethymograph signal power before and after heating the skin tissue to 42℃. These factors are used to tell whether the capillary system in the burnt skin is still alive or not. The test on normal subjects show that the mean Doppler frequency drift increased in the range from 102% to 127% while the blood pulse signal power increased from 200% to 1220%. The change in blood volume with heating is more sensitive than change in blood flow. Further study on more subjects will be helpful in establishing a criterion for judging the burn depth.