Katsumura H, Kabuto M, Hosotani K, Handa Y, Kobayashi H, Kubota T
Department of Neurosurgery, Fukui Medical School, Japan.
Acta Neurochir (Wien). 1995;135(1-2):62-9. doi: 10.1007/BF02307416.
This study was designed to examine the influence of total body hyperthermia (TBHT) using an extracorporeal circuit with a heat exchanger on the cerebral blood flow (CBF), intracranial pressure (ICP), brain tissue pH, cerebral autoregulation and blood-brain barrier (BBB) permeability in dogs. The rectal temperature of the dow was raised to 41.5 degrees C, maintained at 41.5-42.0 degrees C for 2 hours (HT period) and then reduced to normothermia by cooling. Regional CBF was measured by the hydrogen clearance method before heating, during the HT period and after cooling. ICP and brain tissue pH were monitored during the TBHT treatment. Autoregulation of the CBF during the HT period was assessed by measuring the regional CBF and the ICP in a state of induced hypo- or hypertension. The influence of TBHT on BBB permeability was examined using an immunohistochemical technique. The regional CBF increased from 38.1 +/- 6.5 (mean +/- SD) to 49.1 +/- 9.8 ml/100 g/min and the ICP from 10.3 +/- 4.2 to 16.8 +/- 3.4 mmHg when TBHT was raised. These returned to normal values after cooling. The regional CBF and the ICP changed in parallel with drug-induced changes of mean arterial blood pressure during the HT period. These changes suggest that autoregulation of the CBF is paralysed during the HT period. Brain tissue pH decreased rapidly when the rectal temperature exceeded 41.0 degrees C. The pH was 7.18 +/- 0.05 during the HT period and was relatively stable. The pH returned to a normal value after cooling. Immunopositive stain for albumin was not observed in heated brain tissue except for the normally leaky pineal gland and the choroid plexus, indicating preservation of BBB during TBHT. These results suggest that brain oedema may occur easily due to paralysed cerebral autoregulation when the arterial blood pressure fluctuates excessively, so arterial blood pressure must be controlled strictly during TBHT.
本研究旨在探讨使用带有热交换器的体外循环进行全身热疗（TBHT）对犬脑血流量（CBF）、颅内压（ICP）、脑组织pH值、脑自动调节功能和血脑屏障（BBB）通透性的影响。将犬的直肠温度升至41.5℃，在41.5 - 42.0℃维持2小时（热疗期），然后通过降温恢复至正常体温。在加热前、热疗期和降温后，采用氢清除法测量局部脑血流量。在TBHT治疗期间监测ICP和脑组织pH值。通过在诱导性低血压或高血压状态下测量局部脑血流量和ICP，评估热疗期CBF的自动调节功能。使用免疫组织化学技术检查TBHT对BBB通透性的影响。当进行TBHT时，局部脑血流量从38.1±6.5（平均值±标准差）增加到49.1±9.8 ml/100 g/min，ICP从10.3±4.2 mmHg增加到16.8±3.4 mmHg。降温后这些值恢复到正常水平。在热疗期，局部脑血流量和ICP与药物诱导的平均动脉血压变化呈平行变化。这些变化表明热疗期CBF的自动调节功能麻痹。当直肠温度超过41.0℃时，脑组织pH值迅速下降。热疗期pH值为7.18±0.05，相对稳定。降温后pH值恢复到正常水平。除了正常渗漏的松果体和脉络丛外，在加热的脑组织中未观察到白蛋白免疫阳性染色，表明TBHT期间BBB保持完整。这些结果表明，当动脉血压过度波动时，由于脑自动调节功能麻痹，可能容易发生脑水肿，因此在TBHT期间必须严格控制动脉血压。
