Development of a monitoring system for blood flow and metabolism in subarachnoid and epidural tissues using a micro fiberscope

基础研究：研究了激光多普勒法测量局部脑血流（rCBF）与近红外（NIR）法测量组织氧合的结合。在氨基甲酸乙酯麻醉的大鼠中，通过一个小小孔测量脑表面的rCBF，并从另一个半球的颅骨外测量脑组织的氧合情况。由于两次测量的发射光相互干扰，每次测量间隔5-10秒交替进行。当吸入气体中氧气浓度降至5%时，rCBF瞬间升高，氧合血红蛋白（HbO_2）降低，脱氧血红蛋白（Hb）升高。在这种缺氧条件下，心力衰竭引起的严重灌注不足导致脑组织细胞色素aa3减少。因此，rCBF和组织氧合可以通过这种分时技术同时测量。临床研究：1)应用近红外法监测心脏手术中严重灌注不足患者的脑氧合。循环衰竭时，脑内总血红蛋白、HbO_2/Hb比值及细胞色素aa3水平迅速下降。脑循环恢复后，总血红蛋白和HbO_2/Hb比值立即恢复，但细胞色素aa3水平恢复缓慢。2)采用2台近红外光谱仪，研究了星状神经节阻滞（SGB）对脑梗死伴中枢性疼痛患者脑氧合的影响。由总血红蛋白浓度估算的脑血容量在SGB治疗后增加，表明CBF增加，但其在各半球的分布有显著差异。因此，脑梗死患者在接受SGB治疗时应监测脑循环和/或氧合。

Basic research : Combination ofa regional cerebral blood flow (rCBF) measurement by the laser-Doppler method with a tissue oxygenation measurement by the near infra-red (NIR) method was investigated. In the rat anesthetized with urethane, rCBF wa measured on brain surface through a small barr hole, and oxygenation of cerebral tissue was measured from the outside of the skull of another hemisphere. Since emission light of both measurements interfered each other, each mesurement was alternately performed with intervals of 5-10 seconds. When oxygen concentration in inspired gas decreased to 5%, a transient increase in rCBF,a decrease in oxygenated hemoglobin (HbO_2) and an increase in deoxy-hemoglobin (Hb) were coincidentally observed. Severe hypoperfusion by cardiac failure under this hypoxic condition produced a decrease in cytochrom aa3 in brain tissue. Thus, rCBF and tissue oxygenation could be simultaneously measured by this time-sharing technique.Clinical research : 1) Cerebral oxygenation was monitored by the NIR method in patients undergone severe hypoperfusion during heart surgery. When circulation falure occurred, total hemoglobin, HbO_2/Hb ratio and cytochrom aa3 level in the brain were rapidly decreased. Total hemoglobin and HbO_2/Hb ratio were recovered immediately after recovery of cerebral circulation, but recovery of cytochrom aa3 level was retarded. 2) Effects of the stellate ganglion block (SGB) on cerebral oxygenation in patients with cerebral infarction accompanying central pain were investigated by NIR measurements from both hemispheres using two NIR spectrometers. Cerebral blood volume which was estimated from total hemoglobin concentration increased after the SGB treatment, suggesting an increase in CBF,but its distribution to each hemisphere was significantly different. Thus, cerebral circulation and/or oxygenation should be monitored in patients with cerebral infarction when they were treated with the SGB.