Department of Anesthesiology, The Mount Sinai School of Medicine, New York, NY 10029, USA.
J Neurosurg Anesthesiol. 2011 Apr;23(2):124-30. doi: 10.1097/ANA.0b013e3181fa75ca.
Hypothermia is known to provide neuroprotection from focal ischemia. However, lethal cardiovascular complications resulting from total body cooling have greatly restricted hypothermia as a therapy for stroke. This study determined whether selective cerebral cooling induced after reversible cerebral artery occlusion would decrease the infarct volume.
Under general anesthesia, 8 baboons were subjected to 1-hour simultaneous occlusion of the left internal carotid artery and anterior cerebral arteries by transorbital surgical approach. Four animals were treated with selective cerebral hypothermia to 25°C, initiated 2.5 hours after placement of cerebral artery clips. Selective cerebral hypothermia was achieved, after heparinization, by continuous withdrawal of femoral arterial blood into an extracorporeal closed-circuit pump system, cooling by water bath and perfusion into the right internal carotid artery. Pump flow was adjusted to maintain right internal carotid artery pressure near systemic blood pressure. Cerebral cortical temperature was maintained below 27°C for 12 hours, whereas systemic temperature was preserved near normal by convective air mattresses and warm water blankets. Four control animals were maintained at 36°C. Blood pressure, pH, and blood gases were maintained at normal values for both groups. Forty-eight to 72 hours after cerebral artery occlusion, magnetic resonance imaging brain scans were obtained and infarct volume measured.
Normothermic baboons had infarction of 35.4±4.4% (mean±SD) of the left cerebral hemisphere compared with 0.5±1% for baboons treated with cerebral hypothermia (P<0.01). In brain-cooled animals, esophageal temperature was maintained greater than 34°C, despite cerebral temperature less than 27°C.
Selective brain cooling initiated 2.5 hours after onset of focal ischemia resulted in marked reduction in infarct volume, without cardiovascular derangement.
众所周知，低温可提供针对局部缺血的神经保护。然而，全身降温引起的致命心血管并发症极大地限制了低温作为中风治疗的应用。本研究旨在确定在可逆性大脑中动脉闭塞后诱导选择性脑冷却是否会减少梗塞体积。
在全身麻醉下，8 只狒狒通过眶内手术方法同时阻塞左颈内动脉和大脑前动脉 1 小时。4 只动物接受选择性脑低温治疗，在放置大脑中动脉夹后 2.5 小时将体温降至 25°C。在肝素化后，通过从股动脉连续抽出血液进入体外闭路泵系统、水浴冷却和向右侧颈内动脉灌注来实现选择性脑低温。通过调整泵流量来维持右侧颈内动脉压力接近全身血压。脑皮质温度维持在 27°C 以下 12 小时，而全身温度通过对流空气床垫和温水毯保持接近正常。4 只对照动物保持在 36°C。两组动物的血压、pH 值和血气均维持在正常范围。在大脑中动脉闭塞后 48 至 72 小时，进行磁共振成像脑扫描并测量梗塞体积。
正常体温的狒狒左侧大脑半球的梗塞面积为 35.4±4.4%（平均值±标准差），而接受脑低温治疗的狒狒的梗塞面积为 0.5±1%（P<0.01）。在大脑冷却的动物中，尽管大脑温度低于 27°C，但食管温度仍保持在 34°C 以上。
在局灶性缺血发作后 2.5 小时开始的选择性脑冷却导致梗塞体积显著减少，而无心血管紊乱。
