Authors: Dragovic SZ et al.
Anesthesia & Analgesia, Volume 142, Issue 2, pages 249–260, February 2026
Summary:
This retrospective study examines whether commonly used processed EEG metrics obscure meaningful differences between anesthetic agents, particularly propofol versus volatile fluranes (sevoflurane and desflurane). The authors challenge the “one-size-fits-all” assumption that equivalent processed EEG targets reflect comparable anesthetic brain states across agents. Using frontal EEG data from 108 surgical patients under general anesthesia, they compared conventional spectral analysis with two newer analytical approaches: fitting oscillations with one-over-f modeling and variational mode decomposition. Analyses were performed at clinically guided hypnotic and analgesic states, with further subgroup evaluation using two spectral edge frequency (SEF) ranges (8–15 Hz and 15–21 Hz).
Both fluranes demonstrated similar EEG spectral profiles across methods, supporting their treatment as a single group. In contrast, propofol anesthesia showed consistently higher central EEG frequencies compared with fluranes across both novel analytical techniques. Variational mode decomposition identified approximately a 1.5 Hz higher central frequency under propofol, while fitting oscillations and one-over-f modeling demonstrated an even larger shift of about 2 Hz. Additionally, propofol was associated with a lower one-over-f exponent, indicating a different balance between oscillatory and nonoscillatory EEG components. These differences persisted across both low and high SEF ranges, though exponent differences were less consistent at higher SEF values.
Overall, the study demonstrates that newer EEG analysis techniques can sensitively detect anesthetic-specific spectral signatures that are not apparent with conventional monitoring parameters. The findings suggest that anesthetic agents produce fundamentally distinct brain states even when titrated to similar processed EEG targets, underscoring limitations of current depth-of-anesthesia indices.
What You Should Know:
Propofol and volatile anesthetics produce distinguishable EEG signatures despite equivalent processed EEG targets.
Novel EEG analysis methods reveal agent-specific differences in oscillatory frequency and background spectral structure.
Relying solely on standard processed EEG indices may introduce bias when comparing or titrating different anesthetics.
These findings support the concept of future agent-specific EEG-based anesthetic monitoring rather than universal indices.
Key Points:
Processed EEG parameters may mask meaningful anesthetic-specific brain dynamics.
Propofol is associated with higher central EEG frequencies than fluranes at similar anesthetic depths.
Fitting oscillations with one-over-f and variational mode decomposition outperform conventional spectral measures in detecting these differences.
The study provides a foundation for developing anesthetic agent–specific EEG monitoring strategies.
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