Fentanyl-mediated reduction in the bispectral index and 95% spectral edge frequency is age-dependent

Background Inhalational anesthetics produce dose-dependent effects on electroencephalogram-derived parameters, such as 95% spectral edge frequency (SEF) and bispectral index (BIS). The authors analyzed the relationship between end-tidal sevoflurane and isoflurane concentrations (FET) and BIS and SEF and determined the speed of onset and offset of effect (t1/2k(e0)). Methods Twenty-four patients with American Society of Anesthesiologists physical status I or II were randomly assigned to receive anesthesia with sevoflurane or isoflurane. Several transitions between 0.5 and 1.5 minimum alveolar concentration were performed. BIS and SEF data were analyzed with a combination of an effect compartment and an inhibitory sigmoid Emax model, characterized by t1/2k(e0), the concentration at which 50% depression of the electroencephalogram parameters occurred (IC50), and shape parameters. Parameter values estimated are mean +/- SD. Results The model adequately described the FET-BIS relationship. Values for t1/2k(e0), derived from the BIS data, were 3.5 +/- 2.0 and 3.2 +/- 0.7 min for sevoflurane and isoflurane, respectively (NS). Equivalent values derived from SEF were 3.1 +/- 2.4 min (sevoflurane) and 2.3 +/- 1.2 min (isoflurane; NS). Values of t1/2k(e0) derived from the SEF were smaller than those from BIS (P < 0.05). IC50 values derived from the BIS were 1.14 +/- 0.31% (sevoflurane) and 0.60 +/- 0.11% (isoflurane; P < 0.05). Conclusions The speed of onset and offset of anesthetic effect did not differ between isoflurane and sevoflurane; isoflurane was approximately twice as potent as sevoflurane. The greater values of t1/2k(e0) derived from the BIS data compared with those derived from the SEF data may be related to computational and physiologic delays.

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Prediction of movement at laryngeal mask airway insertion: comparison of auditory evoked potential index, bispectral index, spectral edge frequency and median frequency

British Journal of Anaesthesia ◽

10.1093/bja/82.2.203 ◽

1999 ◽

Vol 82 (2) ◽

pp. 203-207 ◽

Cited By ~ 41

Author(s):

M Doi ◽

R J Gajraj ◽

H Mantzaridis ◽

G N Kenny

Keyword(s):

Laryngeal Mask Airway ◽

Bispectral Index ◽

Evoked Potential ◽

Auditory Evoked Potential ◽

Laryngeal Mask ◽

Laryngeal Mask Airway Insertion ◽

Median Frequency ◽

Spectral Edge Frequency ◽

Spectral Edge ◽

Potential Index

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Surgical Stimulation Shifts EEG Concentration–Response Relationship of Desflurane

Anesthesiology ◽

10.1097/00000542-200103000-00006 ◽

2001 ◽

Vol 94 (3) ◽

pp. 390-399 ◽

Cited By ~ 45

Author(s):

Heiko Röpcke ◽

Benno Rehberg ◽

Michael Koenen-Bergmann ◽

Thomas Bouillon ◽

Jörgen Bruhn ◽

...

Keyword(s):

Bispectral Index ◽

Volatile Anesthetic ◽

Pharmacodynamic Modeling ◽

Control Group ◽

Spectral Edge Frequency ◽

Spectral Edge ◽

Desflurane Concentration ◽

Power Frequency ◽

Median Power Frequency ◽

Surgical Stimulation

Background Anesthesiologists routinely increase the delivered anesthetic concentration before surgical stimulation in anticipation of increased anesthetic requirement to achieve certain goals (e.g., amnesia, unconsciousness, and immobility). Electroencephalographic monitoring is one method of determining indirectly anesthetic effect on the brain. The present study investigated the effect of surgical stimuli on the concentration-response relation of desflurane-induced electroencephalographic changes. Methods The electroencephalographic activity was recorded from 24 female patients who received only desflurane after a single induction dose of propofol. Twelve patients served as a control group before surgical stimulation. The other 12 patients, all undergoing lower abdominal surgery, were investigated between opening and closure of the peritoneum. Desflurane vaporizer settings were randomly increased and decreased between 0.5 and 1.6 minimum alveolar concentration as long as anesthesia was considered adequate. Spectral edge frequency 95, median power frequency, and Bispectral Index were calculated. Desflurane effect-site concentrations and the concentration-effect curves for spectral edge frequency 95, median power frequency, and Bispectral Index were determined by simultaneous pharmacokinetic and pharmacodynamic modeling. Results Surgical stimulation shifted the desflurane concentration-electroencephalographic effect curves for spectral edge frequency 95, median power frequency, and Bispectral Index toward higher desflurane concentrations. In the unstimulated group, 2.2 +/- 0.74 vol% desflurane were necessary to achieve a Bispectral Index of 50, whereas during surgery, 6.8 +/- 0.98 vol% (mean +/- SE) were required. Conclusions During surgery, higher concentrations of the volatile anesthetic are required to achieve a desired level of cortical electrical activity and, presumably, anesthesia.

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