Abstract
The coherent frequency (CF) of the auditory evoked response (AER) is derived using auditory clicks presented at frequencies in the range 5-47 Hz. CF and psychological performance were measured while seven subjects breathed isoflurane in doses increasing from 0% to 0.2%, 0.4% and 0.8% end-tidal concentration and then decreasing to 0%. With increasing doses of isoflurane, CF decreased and there was a decrease in within-list recognition (WLR) and category recognition (CR) scores. There was a correlation between changes in CF and WLR (P < 0.05) and between CF and category recognition (CR) (P < 0.05). A painful stimulus given in conjunction with 0.4% isoflurane caused an increase in CF, WLR and CR in some subjects. This did not reach statistical significance for the group as a whole, apart from the short word interval scores in the WLR which indicated an increase in attention (P < 0.01). Subjects did not respond with 0.8% isoflurane, either before or after painful stimulation. Reduction of end-tidal isoflurane from 0.8% to 0% caused an increase in the CF and improved performance on the psychological tests. A category generation task on recovery showed no evidence of implicit learning of words presented in conjunction with 0.8% isoflurane.(ABSTRACT TRUNCATED AT 250 WORDS)
Original language | English |
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Pages (from-to) | 633-641 |
Number of pages | 0 |
Journal | Br J Anaesth |
Volume | 71 |
Issue number | 5 |
DOIs | |
Publication status | Published - Nov 1993 |
Keywords
- Anesthesia
- Inhalation
- Awareness
- Cognition
- Consciousness
- Evoked Potentials
- Auditory
- Female
- Humans
- Isoflurane
- Male
- Memory
- Psychological Tests
- Time Factors