Entropy during propofol hypnosis, including an episode of wakefulness.
Depth of anaesthesia has proved to be a complex process to quantify. Monitors based on bispectral analysis of the electroencephalogram and auditory evoked potential have been available, but only recently has a monitor based on entropy become available. This study determined state entropy and response entropy in nine healthy volunteers during propofol hypnosis with a brief intervening period of wakefulness. Both the calculated entropy indices decreased with increasing levels of sedation (r2 = 0.58 and 0.61, respectively) and they showed a high correlation with each other (r2 = 0.94). However, an overlap was observed in real time indices between different stages of the Observer's Assessment of Alertness/Sedation Scale. Only three of the nine volunteers had explicit memories from the episode of wakefulness. Electroencephalographic entropy monitors seem to have potential for staging clinical hypnotic effects.
Anderson
R E
RE
Department of Cardiothoracic Anaesthetics and Intensive Care, Karolinska Hospital, Stockholm, Sweden.
Barr
G
G
Owall
A
A
Jakobsson
Jan
J
D000293:Adolescent; D000328:Adult; D001364:Awareness; D016292:Procedural Sedation / Q000379:methods; D004569:Electroencephalography / Q000187:drug effects; D019277:Entropy; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D011939:Mental Recall / Q000187:drug effects; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D015742:Propofol / Q000494:pharmacology*; D011446:Prospective Studies; D014851:Wakefulness / Q000187:drug effects*
D006993:Hypnotics and Sedatives; D015742:Propofol