Schaller Carlo, Nakase Hiroyuki, Kotani Akihira, Nishioka Toshikazu, Meyer Bernhard, Sakaki Toshisuke
Department of Neurosurgery, University of Bonn, Germany.
Neurol Res. 2002 Mar;24(2):210-4. doi: 10.1179/016164102101199620.
Recent experiments showed an upward shift of the lower limit of autoregulation (AR) following photochemical occlusion of cortical veins in the rat. The goal of the present study was to prove the hypothesis that occlusion of cortical veins will be associated with impairment of the upper limit of autoregulation as well. In n = 28 Wistar rats unilateral frontoparietal cranial windows were drilled for transdural assessment of regional cerebral blood flow (rCBF) by laser Doppler scanning. The animals were allotted to two groups: (1) Group A (n = 5), control group for determination of the upper limit of autoregulation with stepwise induced arterial hypertension by intravenous administration of the alpha adrenergic drug methoxamine under continuous monitoring of mean arterial blood pressure (MABP); (2) Group B (n = 23), in which two cortical veins were photochemically occluded with rose bengal dye and fiberoptic illumination upon baseline CBF measurement. This was followed by repeated rCBF measurements under AR testing. Loss of AR in control Group A with passive increase of rCBF occurred at MABP of 147.5 +/- 2.9 mmHg. In Group B venous occlusion was followed by an initial phase of reduced rCBF, and then by pressure passive increases, thereby indicating loss of AR. Statistically significant changes of rCBF when compared to baseline MABP occurred at MABPbaseline + 10% (112.7 +/- 6.6 mmHg). We conclude that AR is impaired upon cortical venous occlusion with the propensity for hyperperfusion injury at a lower level of MABP when compared with a control group. In the context with earlier findings this may lead to narrowing of the corridor for MABP management following intra-operative occlusion of large cortical veins.
最近的实验表明，大鼠大脑皮质静脉光化学闭塞后，自动调节下限（AR）出现上移。本研究的目的是验证这一假设，即大脑皮质静脉闭塞也会导致自动调节上限受损。在28只Wistar大鼠中，钻单侧额顶颅骨窗，通过激光多普勒扫描经硬脑膜评估局部脑血流量（rCBF）。将动物分为两组：（1）A组（n = 5），为对照组，通过静脉注射α肾上腺素能药物甲氧明逐步诱导动脉高血压，同时持续监测平均动脉血压（MABP），以确定自动调节上限；（2）B组（n = 23），在测量基线CBF后，用孟加拉玫瑰红染料和光纤照明对两条大脑皮质静脉进行光化学闭塞。随后在自动调节测试下重复测量rCBF。A组对照组中，随着rCBF被动增加，自动调节丧失发生在MABP为147.5±2.9 mmHg时。在B组中，静脉闭塞后先是rCBF降低的初始阶段，然后是压力被动增加，从而表明自动调节丧失。与基线MABP相比，rCBF发生统计学显著变化时的MABP为MABP基线+ 10%（112.7±6.6 mmHg）。我们得出结论，大脑皮质静脉闭塞会损害自动调节功能，与对照组相比，在较低MABP水平时更易发生高灌注损伤。结合早期研究结果，这可能导致术中大脑皮质大静脉闭塞后MABP管理的安全范围变窄。
