不同认知任务诱发高性能战斗机飞行员脑疲劳时脑平均血流速度变化特征

目的 为飞行员脑功能鉴定及防护提供试验方法和依据.方法采用经颅多普勒超声连续观察45名飞行员(平均年龄27.5±2.6岁)在完成5 h连续心算和连续操作任务期间的脑平均血流速度(Win),同步分析大脑前动脉(ACA)、中动脉(MCA)、后动脉(PCA)的Vm、神经行为能力指数(NAI),并对脑疲劳诱发的嗜睡倾向进行斯坦福嗜睡量表(SSS)评定.结果在完成连续心算任务的第2 h,大脑ACA的Vm增快,第4 h以后减慢,MCA、PCA的Vm无显著变化.完成连续操作任务的第4 h以后,PCA的Vm先于MCA的Vm减慢,ACA、MCA和PCA的Vm直至第5 h才明显减慢.反映连续操作能力的NAI指数在第2 h上升,第4 h以后下降.反映心算能力下降的错误反应率和反映脑功能状态的SSS评分在第4 h以后显著上升,表明脑功能出现显著抑制.结论 不同认知活动对大脑Vm的影响存在差异.5 h连续心算任务没有诱发Vm的显著变化,但5 h连续操作任务诱发MCA的Vm大幅度降低,有可能是晕厥前症状或立位耐力降低的诱发因素之一.

Changes of mean cerebral blood velocity during cerebral fatigue Induced by different cognitive tasks in high performance fighter pilots

Objective To provide the methods and evidences for monitoring and protection of pilot's cerebral function(CF). Methods Forty-five male pilots(average age were 27.5±2.6 years,ranging from 25 to 32 years)served as subjects.Mean blood velocity(Vm)in anterior cerebral artery(ACA),middle cerebral artery(MCA)and posterior cerebral artery(PCA)was tested by transcranial Doppler ultrasongraphy during 5 h mental arithmetic tasks and consecutive performance tasks.Neurobehavioral ability index(NAI)and scores of Stanford sleepiness scale(SSS)were analyzed individually. Results When performing mental arithmetic tasks.Vm in ACA increased at the second hour and decreased after the fourth hour,there were no significant changes in MCA and PCA.When performing consecutive performance tasks,Vm in PCA declined earlier than that in MCA after the fourth hour.Vm in ACA,MCA and PCA did not decrease significantly until the fifth hour.The rising trend of NAI Was found after the second hour,while falling trend after the fourth hour.After the fourth hour,the false responding rate of mentaI arithmetic tasks and SSS scores increased significantly which showed depression of CF. Conclusion The effect of cognitive tasks on Vm was different.5 h mental arithmetic tasks didn't have significant effect on Vm in MCA.Significant decrease of Vm in MCA when performing consecutive performance tasks for 5 h may be a factor inducing presyncope or poor orthostatic tolerance.