Rice G Merrill, Snider Dallas, Drollinger Sabrina, Greil Chris, Bogni Frank, Phillips Jeffrey, Raj Anil, Marco Katherine, Linnville Steven
Aerosp Med Hum Perform. 2019 Feb 1;90(2):92-100. doi: 10.3357/AMHP.5228.2019.
Recently, portable dry electroencephalographs (dry-EEGs) have indexed cognitive workload, fatigue, and drowsiness in operational environments. Using this technology this project assessed whether significant changes in brainwave frequency power occurred in response to hypoxic exposures as experienced in military aviation. There were 60 (30 women, 30 men) student Naval Aviators or Flight Officers who were exposed to an intense (acute) high-altitude (25,000 ft) normobaric hypoxic exposure, and 20 min later, more gradual (insidious) normobaric hypoxic exposure up to 20,000 ft while flying a fixed-wing flight simulation and monitored with a dry-EEG system. Using MATLAB, EEG frequencies and power were quantified and analyzed. Cognitive performance was also assessed with a cognitive task validated under hypoxia. Normobaric hypoxia and O₂ saturation (Sp₂) were produced and monitored using the Reduced Oxygen Breathing Device (ROBD2). Significant Sp₂ decreases were recorded at acute 25K and insidious 20K simulated altitudes. Significant power decreases were recorded in all frequencies (alpha, beta, gamma, and theta) and all channels with acute 25K exposures. Gamma, beta, and theta frequency power were significantly decreased with insidious 20K exposures at most of the channels. The frequency power decreases corresponded to significant decreases in cognitive performance and flight performance. Most importantly, frequency power suppressions occurred despite 42% of the volunteers not perceiving they were hypoxic in the acute phase, nor 20% in the insidious phase. Results suggest EEG suppression during acute/insidious hypoxia can index performance decrements. These findings have promising implications in the development of biosensors that mitigate potential in-flight hypoxic physiological episodes.
最近，便携式干式脑电图仪（dry-EEGs）已被用于在作战环境中评估认知负荷、疲劳和嗜睡情况。本项目利用该技术评估了在军事航空中经历的低氧暴露情况下，脑电波频率功率是否发生了显著变化。有60名（30名女性，30名男性）海军飞行学员或飞行军官参与了实验，他们在固定翼飞行模拟器中接受了高强度（急性）高空（25000英尺）常压低氧暴露，20分钟后，又接受了更缓慢（隐匿性）的常压低氧暴露，直至20000英尺，并使用干式脑电图系统进行监测。利用MATLAB对脑电图频率和功率进行了量化和分析。还通过一项在低氧条件下经验证有效的认知任务评估了认知表现。使用低氧呼吸装置（ROBD2）产生并监测常压低氧和血氧饱和度（Sp₂）。在急性25K和隐匿性20K模拟高度下记录到Sp₂显著下降。在急性25K暴露时，所有频率（阿尔法、贝塔、伽马和西塔）和所有通道的功率均显著下降。在隐匿性20K暴露时，大多数通道的伽马、贝塔和西塔频率功率显著下降。频率功率下降与认知表现和飞行表现的显著下降相对应。最重要的是，尽管42%的志愿者在急性期未察觉到自己处于低氧状态，20%的志愿者在隐匿期也未察觉到，但仍出现了频率功率抑制。结果表明，急性/隐匿性低氧期间的脑电图抑制可指示表现下降。这些发现对开发能够减轻飞行中潜在低氧生理发作的生物传感器具有广阔的应用前景。
