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Clin Neurophysiol. 2002 Aug;113(8):1357-64.

Evidence of auditory processing during postoperative propofol sedation.

Author information

1
Department of Clinical Neurophysiology, Kuopio University Hospital, University of Kuopio, Kuopio, Finland. heidi.ypparila@kuh.fi

Abstract

OBJECTIVES:

Our aim was to characterize cerebral event-related responses, which index the detection of auditory stimuli during postoperative sedation.

METHODS:

We monitored auditory event-related potentials (ERPs) before and after elective cardiac operation in 29 patients. Sedation levels, induced with propofol, were evaluated clinically with Ramsay score (RS).

RESULTS:

During deep sedation (RS 6), patients could be categorized into 3 groups according to ERP responses evoked by a standard 'oddball' paradigm. In one group, there were no cortical responses indexing the detection of a sound (N100), another group showed clear responses, and the third group was characterized by a later P300a component which was taken to reflect orienting to a novel stimulus in adults who were awake. However, in deep sedation, P300a did not show behaviour characteristic to an orienting reaction. In moderate sedation (RS 4), all the patients showed a visible N100. Total sedative propofol dose, hemodynamics and the spontaneous electroencephalography (EEG) were not connected to the category of an individual's responses.

CONCLUSIONS:

The results of our study suggest that the detection and automatic auditory information processing function during postoperative sedation, and may signal the individual stages of awakening in a sensitive way. In addition, the findings suggest a deficit in sensory memory function during sedation.

PMID:
12140017
[Indexed for MEDLINE]

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