Basic physiology of hyperbaric oxygen in brain
Basic physiology of hyperbaric oxygen in brain
复制标题
DOI：
10.1179/016164107x174138
复制
发表时间：
2007-03
影响因子：
1.9
通讯作者：
E. Nemoto;K. Betterman
中科院分区：
文献类型：
--
作者：
E. Nemoto;K. Betterman
摘要氧气是一把众所周知的“双刃剑”，因为它是适度生命的必需品，而过度则有毒，对生命有害。这也是高压氧(HBO)治疗脑缺血-缺氧性损伤(如中风、头部损伤、濒临溺水、窒息、心脏骤停等)时的两难境地，即大脑处于危险之中，缺血区位于明显充血的区域旁边。正常脑组织氧合的自然异质性加剧了不同微血管脑区的问题，这些脑区生活在从0到动脉血氧分压不同水平的氧合水平，这是一个额外的并发症。高压氧的应用，无论是常压还是高压氧，都会导致脑组织从常氧到高氧的氧合，后者可能会加剧所遭受的损伤。在此基础上，可考虑应用多种治疗干预措施，例如，高压氧与自由基清除剂或自由基生成酶抑制剂相结合。尽管在控制氧气输送以治疗脑缺血缺氧损伤方面存在这些困难，但压倒性的临床前证据表明，在损伤期间或损伤后2小时内使用高压氧有效地减轻了脑损伤的严重程度。高压氧临床前和临床疗效之间的主要脱节似乎是应用的时间。临床上，高压氧治疗在侮辱后最早的6小时内进行，但通常在侮辱后12小时或更长时间内进行。院前应用HBO可能是为了清楚地展示临床疗效。
Abstract Oxygen is the proverbial 'double-edged sword' in that it is a necessity for life in moderation and toxic and detrimental to life in excess. This too is the dilemma in hyperbaric oxygen (HBO) treatment in cerebral ischemic–anoxic insults such as stroke, head injury, near drowning, asphyxia, cardiac arrest, etc., i.e. the brain at risk, where regions of ischemia are beside regions of marked hyperemia. The natural heterogeneity of normal brain tissue oxygenation compounds the problem with different microvascular brain regions living at various levels of oxygenation from 0 to arterial PO2 as an added complication. The application of HBO, whether normobaric or hyperbaric, will result in brain tissue oxygenation ranging from normoxic to highly hyperoxic with the latter possibly exacerbating the injury sustained. On this basis, the application of multiple therapeutic interventions may be considered, for example, HBO in combination with free radical scavengers or inhibitors of free radical generating enzymes. Despite these difficulties in moderating oxygen delivery to treat cerebral ischemic–anoxic insults, overwhelming preclinical evidence indicates that HBO administered during or within 2 hours post-insult effectively attenuates the severity of brain damage sustained. The primary disconnection between pre-clinical and clinical efficacy of HBO then appears to be the time of application. Clinically, HBO therapy is applied at the earliest 6 hours post-insult but usually between 12 hours or longer post-insult. Pre-hospital application of HBO may be required for clear-cut demonstration of clinical efficacy.