Nimodipine improves outcome when given after complete cerebral ischemia in primates

Twenty-seven pigtailed monkeys (Macaca nemestrina) were subjected to 17 min of complete cerebral ischemia followed by 96 h of intensive care treatment. Fourteen of the monkeys were assigned randomly to the treatment group and received nimodipine 10 micrograms . kg-1 5 min postischemia followed by 1 microgram . kg-1 . min-1 for 10 h. Six monkeys (three treated) failed to meet preestablished protocol criteria and were excluded. The remaining treated and untreated monkeys were well matched for age, sex, and other physiologic variables. Neurologic outcome at 96 h postischemia was significantly better in the nimodipine-treated monkeys than in the controls. Eight of the 11 treated animals had an apparent normal level of consciousness; four of these had no detectable neurologic deficits and a fifth had only a slight motor apraxia. Only two of the 10 untreated animals had an apparent normal level of consciousness, and all had major neurologic deficits. Histopathologic examination showed variable ischemic neuronal change and infarction to involve gray matter in distal arterial perfusion zones. Significant white matter changes were not observed. A histopathologic scoring system yielded a significantly better mean score for the treated group than for the untreated group, and there was significant correlation between neurologic function and histopathologic findings. The authors conclude that nimodipine improves the neurologic outcome when given after an episode of complete cerebral ischemia in primates, and they recommend controlled clinical trials in patients resuscitated after cardiac arrest.     

选择性深低温断血流对猴神经功能及神经元超微结构的影响

目的研究选择性深低温断血流对猴神经功能及神经元超微结构的影响。方法建立闭胸式脑局部体外循环,一侧颈内动脉冷灌注,同侧颈内静脉回流,60～80min后恢复脑血流,实验动物自然复苏。手术前后监测各主要脏器的血生化变化、观察神经功能并在预定的时间内处死动物行全脑电镜检查。结果7只猴中2只未能建立实验模型,其余5只均于术后复苏,其中4只长期存活;各主要脏器功能未见显著变化,术后神经功能评分无异常,神经元超微结构无明显异常。结论脑选择性深低温可明显提高脑对缺血缺氧的耐受性,延长血流阻断的时间。     

中深度低温选择性脑灌注在DeBakey-I型夹层动脉瘤术中的应用

目的：为了减少DeBakey-I型夹层动脉瘤患者术后神经系统及其他系统并发症，探讨其灌注方法。方法：20例DeBekey-I型动脉瘤患者均采用中深度低温停循环选择性脑灌注和下半身灌注技术行象鼻手术。结果：全组患者无死亡，1例由于病变压迫髂总动脉而致术后发生第4胸椎以下软瘫，1例术后发生急性肾功能衰竭，其余患者无任何术后并发症，痊愈出院。结论：中深度低温停循环选择性脑灌注和下半身灌注技术可以延长大脑和脊髓的安全保护时限，减少术后并发症，并有效地配合完成手术，提高手术疗效。     

浅低温抑制脑缺血神经元凋亡的机制

浅低温是一近年来研究较多且疗效较为肯定治疗脑缺血的措施,但其确切作用的分子机制尚未阐明。凋亡参与缺血性脑损伤,且加重损伤程度。近年研究发现浅低温可多途径多靶点抑制缺血诱导的神经元凋亡,减少神经元延迟性死亡(PND)而产生脑保护作用。现就浅低温抑制脑缺血神经元凋亡机制的研究作一综述     

Natural hypothermia immediately after transient global cerebral ischemia induced by spontaneous subarachnoid hemorrhage

OBJECT: Spontaneous subarachnoid hemorrhage (SAH) has an aspect of graded transient global cerebral ischemia. The purpose of the present study was the documentation of sequential changes in body temperature immediately after SAH-induced transient global cerebral ischemia in humans. METHODS: Patients admitted within 12 hours after the initial onset of SAH were examined retrospectively (426 patients). Patients with unruptured cerebral aneurysms served as a control group (73 patients). Body temperature measured at the axilla on admission was analyzed. The grade of SAH was established according to the Glasgow Coma Scale (GCS): Grade I, GCS Score 15; Grade II, GCS Score 11 to 14; Grade III, GCS Score 8 to 10; Grade IV, GCS Score 4 to 7; and Grade V, GCS Score 3. The mean body temperature of patients in the control group was 36.49 +/- 0.45 degrees C (mean +/- standard deviation). The mean body temperature of patients in the SAH group who had been admitted within 4 hours of onset for Grades I to V were significantly different (p < 0.001, analysis of variance [ANOVA]): 36.26 +/- 0.7 degrees C, 59 patients; 35.98 +/-0.85 degrees C, 73 patients; 35.52 +/- 0.79 degrees C, 25 patients; 35.9 +/- 1.09 degrees C, 108 patients; and 35.56 +/- 1.14 degrees C, 73 patients, respectively. These values were significantly lower than those in control volunteers, except for patients with Grade I SAH. The reduction in body temperature was unrelated to the location of the cerebral aneurysm and was not the product of circadian rhythm. The temperatures of patients in the SAH group who were admitted beyond 4 hours after onset for each grade were significantly different (p < 0.01, ANOVA): 36.8 +/- 0.91 degrees C, 36 patients; 36.74 +/- 0.68 degrees C, 31 patients; 36.73 +/- 0.38 degrees C, three patients; 37.41 +/- 1.37 degrees C, 17 patients; and 38.9 degrees C, one patient, respectively. These values were significantly higher than those in patients admitted within 4 hours of SAH onset for all grades except Grade V, and significantly higher than control values in patients with Grades I and IV SAH. CONCLUSIONS: These results indicate that body temperature falls and then rises immediately after the SAH-induced transient global cerebral ischemia without cardiac arrest in humans. The reduction in temperature may be a natural cerebral protection mechanism that is activated shortly after ischemic insult.     

细胞因子对猴脑选择性超深低温断血流复苏缺血性脑保护的影响机制

目的观察猴脑选择性超深低温断血流复苏实验前后血清中细胞因子的动态变化，了解脑缺血后选择性超深低温复苏对缺血性脑保护的炎性机制。方法健康恒河猴4只，先阻断双侧颈总动脉血流10分钟，然后建立闭胸式脑局部体外循环，行一侧颈内动脉冷灌注，同侧颈内静脉回流。60分钟后恢复脑血流，自然复苏。应用ELISA法统一测定实验前后猴血清中IL-2、IL-10、TNF-α、IFN-γ的浓度。结果4只恒河猴术后安全复苏并长期存活，术后头颅MRI检查正常，术后神经功能评分无异常。4种细胞因子在灌注结束后较术前均明显增高（P〈0．05），24小时后恢复至术前水平，72小时测得值与术前无显著差异（P〉0．05）。Spearman相关系数统计显示不同时间点促炎因子IL-2、TNF-α、IFN-γ与抑炎因子IL-10之间呈明显的正相关。结论猴脑选择性超深低温断血流复苏可引起抗炎细胞因子与促炎细胞因子一过性增高，其中抑炎因子IL-10的明显表达和促炎因子之间互相抑制，互相作用，促使细胞因子网络维持动态平衡，从而减轻机体炎性反应同时抑制了脑缺血后机体炎性反应所引起的脑组织损伤，发挥脑保护作用。     

低温在心肺复苏后脑保护的研究进展

背景 心肺复苏后大脑功能不全是心脏骤停复苏后高死亡率的主要原因,大量文献证明低温具有确切的脑保护作用,低温疗法能显著提高复苏后患者的脑功能.目的 探讨现有低温疗法的利弊,为相关临床研究提供新的思路.内容 文章对低温脑保护的发展历史、低温脑保护的机制以及降温方法进行了系统综述.趋势 低温疗法具有广阔的应用前景,头部选择性降温将是研究的热点.     

Cerebral protection for aortic arch surgery: mild hypothermia with selective cerebral perfusion

Historically, reconstruction of the aortic arch has been exclusively performed during deep hypothermic circulatory arrest. Antegrade cerebral perfusion (ACP) has been popularized, offering a more physiologic method of perfusion and extending the safe limits for arch repair. Initially, deep hypothermia has been used as an adjunct to ACP almost universally. More recently, the absolute necessity for deep hypothermia during aortic surgery once ACP with flow rates and pressures within the physiologic range is provided has been questioned from our institution, as well as others. To our best knowledge we have been one of the pioneering centers to start such an aggressive temperature management in aortic arch surgery back in 2000. To date 426 patients underwent aortic arch replacement in our unit employing the standardized surgical protocol described herein.     

Circulation in profound hypothermia

Circulation was maintained in dogs at 5°C using a noninvasive pulsatile pumping system (MVA) and studied using ^99mTechnetium-labeled microspheres. Cardiac output, blood pressure, and stroke volume decreased as temperature fell and peripheral resistance increased.Seven of eight dogs were successfully resuscitated after rewarming but cardiac output and blood pressure remained low and peripheral resistance remained high.The distribution of cardiac output increased to the heart (×3) and brain (×2) and decreased or remained the same in other organs at 5°C.Blood flow in the heart and brain remained high at 5°C, despite a low cardiac output. After rewarming, blood flow was normal in the heart but remained low in the brain, kidney, and gastrointestinal tract. Circulation in profound induced hypothermia may be similar to circulation in deep hibernation.