Department of Surgical and Medical Science and Translational Medicine, Anesthesia and Intensive Care, Sapienza University, Rome, Italy.
Department of Biomedical Sciences and Public Health, Anesthesia and Intensive Care, Università Politecnica delle Marche Torrette, Ancona, Italy.
Eur J Appl Physiol. 2019 Jan;119(1):247-255. doi: 10.1007/s00421-018-4020-y. Epub 2018 Oct 22.
Underwater divers face several potential neurological hazards when breathing compressed gas mixtures including nitrogen narcosis which can impact diver's safety. Various human studies have clearly demonstrated brain impairment due to nitrogen narcosis in divers at 4 ATA using critical flicker fusion frequency (CFFF) as a cortical performance indicator. However, recently some authors have proposed a probable adaptive phenomenon during repetitive exposure to high nitrogen pressure in rats, where they found a reversal effect on dopamine release.
Sixty experienced divers breathing Air, Trimix or Heliox, were studied during an open water dive to a depth of 6 ATA with a square profile testing CFFF measurement before (T), during the dive upon arriving at the bottom (6 ATA) (T), 20 min of bottom time (T), and at 5 m (1.5 ATA) (T).
CFFF results showed a slight increase in alertness and arousal during the deep dive regardless of the gas mixture breathed. The percent change in CFFF values at T and T differed among the three groups being lower in the air group than in the other groups. All CFFF values returned to basal values 5 min before the final ascent at 5 m (T), but the Trimix measurements were still slightly better than those at T.
Our results highlight that nitrogen and oxygen alone and in combination can produce neuronal excitability or depression in a dose-related response.
当潜水员呼吸包括氮麻醉在内的压缩气体混合物时，会面临多种潜在的神经危害，这可能会影响潜水员的安全。多项人体研究已经清楚地表明，在 4 个大气压时，氮麻醉会对潜水员的大脑造成损害，使用临界闪烁融合频率（CFFF）作为皮质表现指标。然而，最近一些作者在对大鼠进行的重复高氮气压暴露研究中提出了一种可能的适应性现象，他们发现多巴胺释放出现了逆转效应。
60 名经验丰富的潜水员在开放水域潜水到 6 个大气压的深度，潜水时使用空气、三混气或氦氧混合气，潜水前（T）、到达底部时（6 个大气压）（T）、底部停留 20 分钟时（T）和在 5 米（1.5 个大气压）处（T）进行临界闪烁融合频率（CFFF）测量。
无论呼吸何种气体混合物，CFFF 结果均显示在深潜期间警觉性和觉醒度略有增加。CFFF 值在 T 和 T 的变化百分比在三组之间存在差异，空气组的变化百分比低于其他两组。所有 CFFF 值在最后一次上升到 5 米（T）前 5 分钟恢复到基础值，但三混气测量值仍略优于 T 时的测量值。
我们的结果表明，氮和氧单独或组合使用会产生与剂量相关的神经元兴奋或抑制作用。
