氢-氧联合治疗对心肺复苏后大鼠脑缺血再灌注损伤的保护作用及其机制研究

Cerebral ischemia reperfusion injury is the leading cause of in-hospital death of patients who were successfully resuscitated after cardiac arrest. Apoptosis mediated by increasing free radical, calcium overload and leukocytosis is a fundamental component element of cerebral ischemia reperfusion injury. Recently, we found that, during cardiopulmonary resuscitation and at the early postresuscitation phase, small amounts of inhaled hydrogen mixed with high concentrations of oxygen could significantly reduce serum level of apoptosis promoting factor and improve cardiac function and neurological outcome in rats. However, whether the concentration ratio of hydrogen and oxygen would affect the neuroprotective effects of hydrogen-oxygen combined therapy on post-resuscitation cerebral ischemia reperfusion injury. Excessive oxygen delivery can be harmful by exacerbating oxygen free radical formation and subsequent reperfusion brain injury that increase the risk of in-hospital mortality of successfully resuscitated patients. In the proposed project, in order to find the best concentration ratio, we will study on the influence of concentration ratio on neuroprotective effects of hydrogen-oxygen combined therapy for post-resuscitation cerebral ischemia reperfusion injury in rats, and aim to study the mechanisms of hydrogen-oxygen combined therapy on post-resuscitation cerebral ischemia reperfusion injury; to quantify EEG indexes that are related to severity of brain injury and prognosis of neurological outcome; to develop a mathematical model and decision algorithm for the prognosis evaluation of neurological outcome and optimization of post resuscitation hydrogen-oxygen combined therapy; and to provide a feasible solution to improve the success rate of cerebral resuscitation.

脑缺血再灌注损伤是导致心肺复苏成功后患者死亡的首要原因。自由基生成增多介导的神经元凋亡是脑缺血再灌注损伤的主要环节。我们前期发现，心肺复苏期间和复苏后早期，氢气配合高浓度氧气治疗能显著降低复苏后大鼠血清中神经元凋亡相关因子水平，提高大鼠神经功能及存活率。然而，氧浓度在氢-氧联合治疗中对脑缺血再灌注损伤保护作用的影响尚不明确。尽管氧疗是及早逆转心脏骤停后缺血缺氧对脑组织损害的关键，但摄入过多氧气会增加氧自由基的生产，进一步加重脑损伤，增加患者院内死亡风险。因此，本项目拟通过动物实验研究不同氧浓度的氢-氧联合治疗对复苏后大鼠脑缺血再灌注损伤保护作用的影响，结合脑损伤的病理/生化检测结果以及神经元凋亡相关因子的表达情况，进一步探讨氢-氧联合治疗的抗神经元凋亡保护机制，提取与脑康复效果及神经功能预后相关的脑电量化指标，建立可用于指导氢-氧联合治疗的决策算法，为提高脑复苏的成功率提供可行的解决方案。

脑缺血再灌注损伤是导致心肺复苏成功后患者死亡的首要原因。在心肺复苏期间和复苏后早期给予患者最大浓度（纯氧）的氧疗，一方面能迅速逆转脑组织缺血缺氧损伤，另一方面也会增加氧自由基介导的神经元凋亡，加重脑缺血再灌注脑损伤。氢气配合高浓度氧气治疗能显著降低复苏后大鼠血浆中神经元凋亡相关因子水平，提高大鼠神经功能及存活率。然而，氧浓度在氢-氧联合治疗对脑缺血再灌注损伤保护作用中的影响尚不明确，致使缺乏可用于临床实践的最佳氢-氧联合治疗气体浓度比的数据支持。本项目的主要研究内容即：研究不同氧浓度混合2%氢气的氢-氧联合治疗对室颤心脏骤停大鼠的神经元保护作用的影响；研究氢-氧联合治疗对神经元凋亡相关因子的影响；研究不同浓度氧气混合氢气的氢-氧联合治疗对室颤心脏骤停大鼠复苏后EEG特征的影响，提取与脑损伤程度的相关的EEG特征指标，建立脑复苏预后的动态数学模型和优化氢-氧联合治疗的决策算法。.我们按照预定研究计划进行了项目研究。研究结果表明：（1）无论是常温还是亚低温治疗下，中/高氧浓度（50%和98%）混合2%氢气的氢-氧联合治疗能显著提高大鼠复苏后96小时生存率。（2）常温下，2%氢气联合高氧浓度（98%）的气体治疗能提高脑组织SOD值，同时也造成了氧化指标8-OHDG的升高。（3）常温下，不同氧浓度（21%，50%和98%）混合2%氢气，对复苏后6小时组织凋亡相关蛋白BCL-2和BAX组间差异无统计学意义。（4）无论是常温还是亚低温下，中/高氧浓度（50%和98%）混合2%氢气的氢-氧联合治疗能显著缩短连续脑电出现的时间，表明中/高氧浓度（50%和98%）混合2%氢气确实有助于脑复苏。.研究结果的科学意义：（1）无论是在常温或者低温条件下，中/高氧浓度的氢-氧联合治疗能显著改善复苏后的生存率。（2）氢气的脑保护和脑复苏效果可能不是通过BCL-2/BAX相关凋亡通路来发挥抗凋亡作用。（3）氢-氧联合治疗能改善复苏后脑电恢复，提示基于脑电信号特征分析开展氢-氧联合治疗决策算法是可行的。