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

基础研究：将激光多普勒法测量局部脑血流量(RCBF)与近红外(NIR)法测量组织氧合(NIR)相结合。在乌拉坦麻醉的大鼠，通过Barr小孔在脑表面测量rCBF，从另一个半球的头盖骨外部测量脑组织的氧合。由于两次测量的发射光相互干扰，每次测量以5-10秒的间隔交替进行。当吸入气体中氧浓度降至5%时，rCBF出现一过性升高，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低灌流导致脑组织中细胞色素Aa3的减少。因此，这种分时技术可以同时测量rCBF和组织氧合。临床研究：1)采用近红外法监测心脏手术中严重低灌注患者的脑氧合情况。循环衰竭时，脑内总血红蛋白、HbO_2/Hb比值和细胞色素Aa3水平迅速下降。脑循环恢复后，总血红蛋白和HBO_2/Hb比值即可恢复，但细胞色素Aa3水平恢复缓慢。2)采用双侧近红外光谱仪对脑梗塞伴中枢性疼痛患者进行双侧近红外测量，观察星状神经节阻滞(SGB)对脑氧合作用的影响。根据总血红蛋白浓度估算的脑血容量在SGB治疗后增加，这表明脑血流量增加，但其在每个半球的分布明显不同。因此，在脑梗塞患者接受SGB治疗时，应监测他们的脑循环和/或氧合情况。

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.