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. Author manuscript; available in PMC: 2014 Aug 1.
Published in final edited form as: Crit Care Med. 2013 Aug;41(8):10.1097/CCM.0b013e31828a3f75. doi: 10.1097/CCM.0b013e31828a3f75

Figure 2.

Figure 2

Dissociation between observed wakefulness or level of consciousness and electroencephalography (EEG) patterns. A, EEG demonstrating delta waves (indicated by circle) suggestive of slow wave sleep in a patient with evidence of wakefulness by following simple commands. This epoch would be scored as pathologic wakefulness by the proposed scoring criteria. B, EEG demonstrating theta frequency EEG activity, normally seen in light (stage N1) sleep, in a patient who was unresponsive. Short periods of isoelectric activity can be seen (indicated by arrow) in this example, which can alert the polysomnography reader that this is not normal stage N1. This epoch would be scored as At4 by the proposed scoring criteria..