Middle latency auditory evoked potentials during repeated transitions from consciousness to unconsciousness

Summary We have investigated the relationship between changes in the middle latency auditory evoked potentials during alternating periods of consciousness and unconsciousness produced by propofol infusion combined with spinal anaesthesia for total knee replacement. Eleven patients completed the stud...

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Bibliographic Details
Published in:Anaesthesia 1996-02, Vol.51 (2), p.107-113
Main Authors: DAVIES, F. W., MANTZARIDIS, H., KENNY, G. N. C., FISHER, A. C.
Format: Article
Language:English
Subjects:
Aged
Anaesthetics, intravenous
propofol
Anesthesia
Anesthesia, Intravenous
Anesthesia, Spinal
Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy
Anesthetics, Intravenous - pharmacology
Biological and medical sciences
Consciousness - drug effects
Evoked Potentials, Auditory - drug effects
Female
General anesthesia. Technics. Complications. Neuromuscular blocking. Premedication. Surgical preparation. Sedation
Humans
Knee Prosthesis
Male
Measurement techniques
auditory evoked potentials
Medical sciences
Middle Aged
Monitoring, Intraoperative - methods
Propofol - pharmacology
Reaction Time - drug effects
Signal Processing, Computer-Assisted
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Summary:Summary We have investigated the relationship between changes in the middle latency auditory evoked potentials during alternating periods of consciousness and unconsciousness produced by propofol infusion combined with spinal anaesthesia for total knee replacement. Eleven patients completed the study, of whom two had recollection of events after the onset of the anaesthetic. There were no significant differences in heart rate or systolic arterial pressure between any conscious and unconscious period. With the first change from consciousness to unconsciousness, latencies of Na, Pa and Nb increased from mean (SD) starting values of 20.0 (1.4), 31.7 (1.0) and 42.8 (1.6)ms to 22.5 (2.0), 39.3 (2.1) and 57.8 (4.4)ms, respectively. During successive transitions from unconsciousness to consciousness, awake latencies were slightly higher than those of baseline awake, whereas anaesthetised latencies were similar to the ones obtained during the first period of unconsciousness. The consistent changes demonstrated, suggest that the auditory evoked potentials could represent a reliable indicator of potential awareness during anaesthesia.
ISSN:0003-2409
1365-2044
DOI:10.1111/j.1365-2044.1996.tb07694.x