Power spectral analysis of the electroencephalogram during increasing end‐expiratory concentrations of isoflurane, desflurane and sevoflurane

Abstract

SummaryWe studied the effects of increasing end-expiratory concentrations of isoflurane (0.3, 0.6, 0.9, 1.2 vol.%) (n ¼ 12 patients), desflurane (1.5, 3.0, 4.5, 6.0 vol.%) (n ¼ 12 patients) and sevoflurane (0.5, 1.0, 1.5, 2.0 vol.%) (n ¼ 12 patients) on power spectral analysis of the electroencephalogram (EEG). Spectral edge frequency (SEF), total power (TP) and relative power in the delta, theta, alpha and beta band were calculated. EEG changes were very similar within the three groups. SEF decreased, TP and relative power in the delta and theta band increased, power in the beta band decreased in a dose-dependent fashion with comparable regression lines. This indicates that MAC equivalent administration of isoflurane, desflurane and sevoflurane in clinically applied dose ranges is associated with equipotent EEG suppression.

Avaliação dos parâmetros derivados do eletroencefalograma durante administração de diferentes concentrações de óxido nitroso

“…BIS variations are compatible with the weak sedative effect of 30% and 50% N 2 O / SEF1 and SEF2 analysis has shown higher potency density in low frequency ranges, showing that N 2 O had an important slowing-down effect in brain waves frequency. Power energy, another EEG parameter, had a statistical behavior similar to that described by other authors, who have shown an increase in PE as anesthesia goes deeper 17 . Values different than zero in burst suppression variables were not observed, showing that in such concentrations, N 2 O is unable to decrease EEG voltage amplitude to below 5 µV 18 .…”

“…Adjustment time for 30% and 50% FeN 2 O was established in five minutes. T h e f o l l o w i n g p a r a m e t e r s w e r e e v a l u a t e d : a ) electroencephalographic: BIS SEF1, SEF2 and power energy (PE), defined as total absolute potency measurement in the frequency range of 0.5 to 30 Hz, with variation values between 40 and 100 db 17 ; b) burst suppression (BS), defined as time percentage in the last 63 seconds in which EEG recorded amplitudes below 5 µV (low amplitude compatible with deep anesthesia) 18 ; c) hemodynamic: heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). Lowest hemodynamic parameters levels were SBP = 80 mmHg and DBP = 60 mmHg.…”

“…A análi-se de SEF1 e SEF2 demonstrou maior densidade de potên-cia em bandas de freqüência baixa, mostrando que o N 2 O apresentou importante efeito lentificador da freqüência das ondas cerebrais. A potência total, outro parâmetro eletroencefalográfico, teve comportamento estatístico semelhante ao descrito por outros autores, que demonstraram um aumento da mesma, à medida que a anestesia se aprofunda 17 .…”

Effects of halothane on the electroencephalogram of the chicken

“…While P TOT has not been reported by studies investigating the EEG effects of halothane, the increase in P TOT observed with increasing halothane concentration in chickens is consistent with that reported in humans anaesthetized with isoflurane, desflurane or sevoflurane (Schwender et al . 1998). …”

EEG power spectrum analysis for monitoring depth of anaesthesia during experimental surgery

“…These QEEG variables include EEG median frequency (MF; 50% quantile) (Schwilden & Stoeckel 1980, Otto et al 1996, spectral edge frequency (SEF) as the 80% (White & Boyle 1989, Otto & Short 1991, 90% (Schwender et al 1998) or 95% quantile (Hudson et al 1983, Johnson et al 1994, total power (mV 2 ) (Schwender et al 1996, Haga et al 2000, percentage distribution of total power (relative power) into the d, u, a and b frequency bands (De Beer et al 1996, Otto et al 1996 and power band ratios u/d, a/d, b/d (Schwilden & Stoeckel 1980, Haga et al 2001 derived from relative power. Reliable correlations between QEEG variables and clinical signs demonstrate that certain aspects of brain electrical activity are sensitive to the level of consciousness.…”