[Effects of sevoflurane and propofol on evoked potentials during neurosurgical anesthesia].
BACKGROUND
The effect of anesthetics on somatosensory evoked potential (SEP) and auditory brain stem response (ABR) has been a subject of intense reseach over the last two decades. In fact, volatile anesthetics have been repeatedly shown to decrease cortical amplitude in a dose-dependent fashion but the information regarding the effect of propofol is incomplete. The purpose of this study was to compare the effects of sevoflurane and propofol on evoked potentials during comparable depth of anesthesia guided by bispectral index (BIS).


METHODS
Forty four patients scheduled for neurosurgery were studied. Anesthesia was maintained with intravenous propofol using target controlled infusion (TCI). We measured the change of amplitude and latency of SEP(N20-P25), ABR (V wave) and visual evoked potential (VEP: P100) at three sets of sevoflurane (0%, 1%, 2%) or propofol concentrations (effect site concentration of 1.5, 2.0, 3.0 microug x ml(-1)). BIS monitor was used to measure relative depth of hypnosis.


RESULTS
With increasing concentrations of sevoflurane (0, 1% and 2%), SEP showed dose-related reduction in its amplitude, ABR produced less marked changes and VEP showed a significant reduction at 1%. VEP at the propofol concentration of 3.0 microg x ml(-1) was decreased significantly compared with the amplitude at 1.5 microg x ml(-1) concentration. No significant change was observed with SEP and ABR during the change of propofol dosages. BIS values were almost the same with each anesthetics.


CONCLUSIONS
VEP was most strongly affected with anesthetics, and ABR showed less marked influence of sevoflurane and propofol. Propofol based TIVA technique would induce less change in evoked potentials than sevoflurane.
Nakagawa
Itsuo
I
Department of Anesthesia, Chugoku Rosai General Hospital, Kure.
Hidaka
Syozo
S
Okada
Hironori
H
Kubo
Takashi
T
Okamura
Kenta
K
Kato
Takahiro
T
D000368:Aged; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D005074:Evoked Potentials, Visual / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D019635:Neurosurgical Procedures; D015742:Propofol / Q000494:pharmacology*; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D000077149:Sevoflurane; D015742:Propofol