[Effects of sevoflurane on mid-latency auditory evoked potentials and the 95% spectral frequency limit].
OBJECTIVE
To investigate the effects of sevoflurane on mid-latency auditory evoked potentials (MLAEP) and compare them to changes in the encephalographic 95% spectral edge frequency (SEF95).


METHODS
The effect of sevoflurane on MLAEP and SEF95 was studied in 15 patients. Anesthetic induction was carried out with propofol, remifentanil, and cisatracurium. After anesthetic induction, the patients were ventilated to achieve different expired concentrations of sevoflurane (1%, 1.5%, and 2%) during 3 consecutive 10-minute periods before the start of surgery. SEF95 and the amplitude and latency of the Na, Pa and Nb MLAEP waves were recorded. All the parameters were measured at baseline and during the different expired fractions of sevoflurane.


RESULTS
The increase in sevoflurane concentration was accompanied by a significant decrease in amplitude and a statistically significant increase in latency of the Na, Pa and Nb waves. Likewise, SEF95 decreased significantly. A linear relation was demonstrated between sevoflurane concentration and the variables Na, Pa, Nb and SEF95.


CONCLUSIONS
Our results indicate that the effect of sevoflurane on the MLEAP of Na, Pa and Nb is similar to that of other anesthetic gases. Even though the amplitude of the Na, Pa and Nb waves decreased in a dose-dependent way, SEF95 correlated more strongly with sevoflurane concentration.
Hernández-Palazón
J
J
Servicio de Anestesiología y Reanimación, Hospital Universitario Virgen de la Arrixaca, Murcia. joapal@ono.com
Falcón-Araña
L F
LF
Doménech-Asensi
P
P
Giménez-Viudes
J
J
Nuño de la Rosa-Carrillo
V
V
Martínez
I
I
D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D017558:Elective Surgical Procedures; D004569:Electroencephalography / Q000187:drug effects; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D008875:Middle Aged; D011930:Reaction Time / Q000187:drug effects; D000077149:Sevoflurane; D013057:Spectrum Analysis
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane