模拟高海拔缺氧和潜水对人体脑电图和主观评价的影响

Effects of simulated high altitude hypoxia and diving on human EEG and subjective evaluations

目的 应用脑电图中的α波衰减系数（alpha attenuation coefficient,AAC）、事件相关电位（event-related potential,ERP）和主观评价的方法,研究模拟高海拔缺氧和潜水对人脑功能的影响.方法 4名潜水员在高、低压舱内分别暴露于模拟海拔3 000、4 000、5200m,各停留2d,在此期间进行30 m和50 m摸拟氦氧潜水60 min.在脑电图上进行AAC、听觉ERP测试和分析,用视觉模拟评分法（visualanalogue scale,VAS）测试受试潜水员的疲劳和嗜睡感,并作为主观评价的指标.结果 在高海拔暴露时,AAC随海拔高度的升高逐渐减小,与海平面相比差异有统计学意义（P＜0.05）,各海拔高度之间的差异也有统计学意义（P＜0.05）.P300潜伏期有随海拔高度升高逐渐延长的趋势,在5 200 m时的差异有统计学意义（P＜0.05）;振幅有随海拔高度升高而逐渐下降的趋势,由于实验环境的限制,受试对象较少,并且个体差异较大,其平均值呈减少趋势,但差异无统计学意义（P＞0.05）.受试者主观评价结果表明,随着海拔高度的升高,缺氧程度的加重,人体的疲劳感和嗜睡感增加,表现为高海拔缺氧时人的脑功能、觉醒水平和认知功能下降.在高海拔处进行模拟潜水并进行高压、高氧暴露时AAC增大,主观感觉好转.结论 高海拔潜水时脑电图和主观感觉都有向正常水平转化的趋势.

Objective To investigate the effects of simulated high altitude diving and hypoxia on human cerebral function by using alpha attenuation coefficient （AAC） of EEG,event-related potential P300 （ERP P300） and subjective evaluations.Methods Four divers as research subjects were exposed respectively to the altitudes of 3 000,4 000 and 5 200 meters in the hypobaric and hyperbaric chamber for 2 days,during which 30 m and 50 m simulated helium-oxygen mixture gas dives were made for a duration of 60 minutes.Detection and analysis of AAC and auditory-evoked event-related potentials were performed by using recorded EEG.Feelings of fatigue and drowsiness of the divers were detected with visual analogue scale （VAS） and were used as the criteria for subjective evaluation.Results At high altitude exposure,AAC decreased with the elevation of sea levels,and statistical differences could be noted,when it was compared with the data measured at the sea level （P 〈 0.05）.Statistical significance could also be seen,when comparisons were made between different altitudes（P 〈0.05）.P300 latency seemed to be prolonged with the elevation of sea level,with the difference at 5 200 m being statistically significant（P 〈 0.05）.However,amplitude seemed to decrease with the elevation of sea levels.Due to limitations of experimental conditions,few research subjects and individual differences between the subjects,the average values tended to decrease,but without statistical significance.Analysis of subjective evaluation indicated that symptoms of hypoxia seemed to be worsened with the elevation of sea levels,and feelings of fatigue and drowsiness increased,which was manifested with the decreased cerebral function,awareness and cognition of the divers.In simulated high altitude diving,AAC tended to increase and subjective evaluation seemed to be better during hyperbaric and hyperoxia exposures.Conclusions When compared with hypoxic conditions,no difference could be noted in AAC during the dives,but there was significant increase in AAC during high altitude hypoxic exposure,indicating that EEG and subjective evaluation tended to return to the baseline level.