由于氦气的分子量小、呼吸阻力小、无任何麻醉作用，因此，氦氧混合气长期用于大深度潜水作业，在临床上很早就用于急慢性阻塞性呼吸困难。由于氦气属于惰性气体，在生物体内几乎绝对不可能与其他物质发生化学反应，因此一直认为氦气无任何生物学效应。不过最近几年发现呼吸氦气具有心脏和脑保护效应，这一效应的发现，让人们不得不重新审视氦气的生物学效应。虽然氦气不可能与其他物质发生化学反应，但不等于氦气不会产生生物学效应。潜水医学研究早就发现，高压可以导致神经兴奋，就是所谓的高压神经综合征，就是在研究氦氧混合气潜水过程中发现的。而且氦气由于具有更大的热比容，呼吸氦气容易导致体热散失，增加热量散失必然可以造成生物学效应。另外，呼吸氦气时，体内氮可以发生脱饱和，也许大家认为氮是没有生物学效应的，这也是一个误解。

因此从道理上看，呼吸氦气产生生物学效应是有可能的。最近的研究发现，预先呼吸氦气可以保护心脏和脑缺血。本研究是在过去研究基础上，探讨是否延迟呼吸氦气仍具有脑保护效应。当然结果发现，这种保护效应只能在缺血即刻，这对临床治疗来说是个不幸的消息，因为这样导致其应用价值大大折扣，因为只能在发生疾病后马上呼吸才有价值，很少有临床患者具有这样的可能。不过，这一研究并不能否定这一可能，因为呼吸的时间和方式仍有可以改进的。例如可以呼吸时间延长，呼吸可以采用间歇方式，另外，也许延迟时间更长一些可能会有效果，不过这一研究会延迟这些研究的开展。因为大家都会为表面现象所迷惑。或者盲目相信试验结果。

摘要就不翻译了，有兴趣的童鞋自己研究吧。

The effect of heliox treatment in a rat model of focal transient cerebral ischemia Neuroscience Letters
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Yi Pan^{a, ,} , Haibo Zhang^a, Aninda B. Acharya^a, Salvador Cruz-Flores^a and W. Michael Panneton^b

^a Department of Neurology & Psychiatry, Saint Louis University, 1438 S. Grand Boulevard, Saint Louis, MO 63104, USA

^b Department of Pharmacological and Physiological Science, Saint Louis University, Saint Louis, MO 63104, USA

Received 22 February 2011; 

revised 31 March 2011; 

accepted 19 April 2011. 

Available online 27 April 2011.

Abstract

Manipulation of inhaled gases during ischemia/reperfusion is a potential novel therapy for acute stroke. We previously found that treatment with a mixture of 70%/30% helium/oxygen (heliox) or 100% oxygen protects the brain against acute focal ischemia–reperfusion injury. This study evaluates the potential neuro-protective effects of delayed heliox treatment and its dose response effects in a rat transient focal cerebral ischemia model. Adult male rats were subjected to 2-h middle cerebral artery occlusion and then assigned to 1 of 4 inhaled gas exposure groups: I: 70%/30% nitrogen/oxygen (control); II: 70%/30% helium/oxygen administered immediately after occlusion; III: 70%/30% helium/oxygen administered after a 30–60 min delay; or, IV: 40%/30%/30% nitrogen/helium/oxygen administered immediately after occlusion. Outcome measurements included infarct size and neurological deficit score. Mean infarct sizes from groups I to IV were 228, 35, 109, and 124 mm³ respectively (p = 0.012). Only group II had significantly smaller infarct size compared to the control group (p = 0.008). In addition, only Group II had a significantly lower neurological deficit score at 24 h post ischemia when compared to the control group (p < 0.001). Since heliox reduced infarct size and improved neurological deficit scores if initiated immediately after onset of ischemia, it may be a useful adjuvant to other stroke therapies.

Highlights

► Helium/oxygen protects the brain against acute focal ischemia stroke. ► 70%/30% helium/oxygen decreased infarct size and improved neurological outcome. ► Delayed treatment for 30–60 min resulted in a trend towards beneficial effects. ► 40%/30%/30% nitrogen/helium/oxygen was less effective than 70%/30% helium/oxygen.

Keywords: Helium; Heliox; Acute stroke; Transient focal ischemia; Rat model

Article Outline

Conflicts of interest

Acknowledgements

References