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PNAS:在全身麻醉期间探测意识的失去和恢复

科研人员发现了具有高度结构的脑电图(EEG)特征,可能用于准确追踪进入和脱离由异丙酚诱导的无意识状态的转变过程。

Patrick L. Purdon及其同事记录了10位健康人的高密度脑电图(EEG),同时给它们注射浓度增加或减少的异丙酚;根据这些人对每隔4秒发出的词语和咔嗒声做出响应的能力评估了他们的意识程度。

这组作者发现了与无意识和由异丙酚诱导产生的镇静的不同状态有联系的具有高度结构的脑电图(EEG)特征。在深度无意识期间,alpha和beta脑电波在低频振荡的峰上的幅度最大,而在失去和恢复意识的时候这些振幅在低频振荡的谷上最大。

这两种状态之间的转变可能用于预测个体何时失去和恢复意识。

该研究的技术可能用于准确监测接受全身麻醉的病人的意识程度。

了解更多:

Electroencephalogram signatures of loss and recovery of consciousness from propofol

PNAS, March 4, 2013 | doi:10.1073/pnas.1221180110

Unconsciousness is a fundamental component of general anesthesia (GA), but anesthesiologists have no reliable ways to be certain that a patient is unconscious. To develop EEG signatures that track loss and recovery of consciousness under GA, we recorded high-density EEGs in humans during gradual induction of and emergence from unconsciousness with propofol. The subjects executed an auditory task at 4-s intervals consisting of interleaved verbal and click stimuli to identify loss and recovery of consciousness. During induction, subjects lost responsiveness to the less salient clicks before losing responsiveness to the more salient verbal stimuli; during emergence they recovered responsiveness to the verbal stimuli before recovering responsiveness to the clicks. The median frequency and bandwidth of the frontal EEG power tracked the probability of response to the verbal stimuli during the transitions in consciousness. Loss of consciousness was marked simultaneously by an increase in low-frequency EEG power (<1 Hz), the loss of spatially coherent occipital alpha oscillations (8–12 Hz), and the appearance of spatially coherent frontal alpha oscillations. These dynamics reversed with recovery of consciousness. The low-frequency phase modulated alpha amplitude in two distinct patterns. During profound unconsciousness, alpha amplitudes were maximal at low-frequency peaks, whereas during the transition into and out of unconsciousness, alpha amplitudes were maximal at low-frequency nadirs. This latter phase–amplitude relationship predicted recovery of consciousness. Our results provide insights into the mechanisms of propofol-induced unconsciousness, establish EEG signatures of this brain state that track transitions in consciousness precisely, and suggest strategies for monitoring the brain activity of patients receiving GA.

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