Development of fine fiberscope system for fluorescence observation of epidural and subarachnoid spaces

研制了用于硬膜外和蛛网膜下腔荧光观察的细纤维镜系统，并对该系统在组织氧合监测中的应用进行了研究。用于荧光成像的纤维内窥镜系统由氙灯光源、石英光纤组件（外径：1.0mm）紫外光照射、精密内窥镜、高灵敏度SIT摄像机和视频成像系统组成。紫外光（350nm）照射大鼠脑组织，虽然其自发荧光较弱，但在本系统中仍能观察到明显的自发荧光。在自体荧光的内窥镜图像中，脑组织和表面血管是可区分的。另一个光纤系统用于荧光光谱分析，它由激光发生器、用于紫外光照射和荧光采集的石英光纤组件（外径：1.0mm）和多通道光电二极管阵列光谱仪组成。用波长为363nm的脉冲激光照射大鼠脑组织，测定其自发荧光光谱，观察脑缺血后自发荧光光谱的变化。在脑组织的自发荧光光谱中观察到两个宽带，峰值分别位于400nm和460nm。在低血压下阻断双侧颈总动脉引起的脑缺血过程中，460nm处的荧光峰增加，而400nm处的荧光峰保持不变。脑缺血时自发荧光增强可能与缺氧条件下NAD（P）H增加有关。这些结果表明，用于荧光观察的精细纤维镜系统将适用于硬膜外和蛛网膜下腔组织氧合的临床监测系统。

Fine fiberscope systems for fluorescence observation of epidural and subarachnoid spaces were developed, and applications of the systems for monitoring of tissue oxygenation were investigated. A fiberscope system that was applied to fluorescence imaging is consisted of a Xe-lamp as a light source, a quartz fiber assembly (outer diameter:1.0mm)for irradiation of ultra-violet light, a fine endoscope, highly sensitive SIT camera and a video-imaging system. Although autofluorescence of the rat brain induced by irradiation of ultra-violet light (350nm) was week, it was clearly observed with this system. The brain tissue and the surface vessels were distinguishable in the endoscopic image of autofluorescence. Another fiberscope system is used for fluorescence spectrometry, and it is consisted of a laser-generator, a quartz fiber assembly (outer diameter:1.0mm) for irradiation of ultra-violet light and acquisition of fluorescence and a multichannel optical photodiode-array spectrometer. Autofluorescence spectra evoked by pulsed laser ultra-violet light (wavelength:363nm) were measured from the rat brain, and their changes induced by brain ischemia were observed. Two broad bands with peaks at 400nm and 460nm were observed in the autofluorescence spectra of the brain. The fluorescence with a peak at 460nm increased during brain ischemia induced by occlusion of the bilateral common carotid arteries under hypotension, while the peak at 400nm remained unchanged. The augmantation of autofluorescence during brain ischemia may be due to an increase in NAD(P)H under the hypoxic condition. These results suggest that the fine fiberscope systems for fluorescence observation will be applicable to clinical monitoring system for tissue oxygenation of the epidural and subarachnoid spaces.