EEG signatures at ascending vs descending propofol vs sevoflurane concentrations analyzed with BIS and a State-Chart Score
- 1ENS
Abstract
BackgroundDepth of anesthesia is routinely monitored using electroencephalo-graphic (EEG) indices such as the Bispectral Index (BIS), which reduce cortical activity to a single numerical real-time series. However, these scalar descriptors fail to capture inter-individual variability, drug-specific EEG signatures, and transitions between brain states.
MethodsWe analyzed transient EEG patterns during general anesthesia induced by propofol and sevoflurane in 89 patients. Iso-electric suppressions (IES), -suppressions, and spectral power in the and{delta} bands were quantified across controlled concentration plateaus. We compared conventional BIS monitoring with a novel State-Chart representation mapping EEG activity into discrete depth states.
ResultsIncreasing hypnotic concentration produced a consistent shift from -dominant to{delta} -dominant activity and a reduction in maximal frequency. IES occurred predominantly at high propofol concentrations and remained infrequent under sevoflurane. Compared with BIS, the State-Chart showed a marked reduction in temporal variability (0.5 {+/-} 0.6 vs 4.0 {+/-} 2.9; p < 10-90). Importantly, our State-Chart separates stable from transition regimes and discriminates identical concentration levels. Statistics computed over prior dosing (ascending vs descending), reveals refined clustering not captured by BIS.
ConclusionsAnesthesia depth drugs concentrations vs EEG effects is more accurately described by structured EEG state transitions than by a single numerical index. The State-Chart provides a stable, physiologically interpretable representation of brain activity and reveals transition states preceding deep cortical suppression, supporting individualized and predictive monitoring of anesthesia.
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BibTeX
@misc{sun2026signatures,
title = {{EEG signatures at ascending vs descending propofol vs sevoflurane concentrations analyzed with BIS and a State-Chart Score}},
author = {C. Sun and P.-O. Michel and A. rigouzzo and J. Loh and d. longrois and I. Constant and D. holcman},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.03.26364648},
url = {https://www.medrxiv.org/content/10.64898/2026.10.03.26364648v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - EEG signatures at ascending vs descending propofol vs sevoflurane concentrations analyzed with BIS and a State-Chart Score
AU - C. Sun
AU - P.-O. Michel
AU - A. rigouzzo
AU - J. Loh
AU - d. longrois
AU - I. Constant
AU - D. holcman
PY - 2026
DA - 2026/10/03
PB - medRxiv
DO - 10.64898/2026.10.03.26364648
UR - https://www.medrxiv.org/content/10.64898/2026.10.03.26364648v1
AB - BackgroundDepth of anesthesia is routinely monitored using electroencephalo-graphic (EEG) indices such as the Bispectral Index (BIS), which reduce cortical activity to a single numerical real-time series. However, these scalar descriptors fail to capture inter-individual variability, drug-specific EEG signatures, and transitions between brain states. MethodsWe analyzed transient EEG patterns during general anesthesia induced by propofol and sevoflurane in 89 patients. Iso-electric suppressions (IES), -suppressions, and spectral power in the and{delta} bands were quantified across controlled concentration plateaus. We compared conventional BIS monitoring with a novel State-Chart representation mapping EEG activity into discrete depth states. ResultsIncreasing hypnotic concentration produced a consistent shift from -dominant to{delta} -dominant activity and a reduction in maximal frequency. IES occurred predominantly at high propofol concentrations and remained infrequent under sevoflurane. Compared with BIS, the State-Chart showed a marked reduction in temporal variability (0.5 {+/-} 0.6 vs 4.0 {+/-} 2.9; p < 10-90). Importantly, our State-Chart separates stable from transition regimes and discriminates identical concentration levels. Statistics computed over prior dosing (ascending vs descending), reveals refined clustering not captured by BIS. ConclusionsAnesthesia depth drugs concentrations vs EEG effects is more accurately described by structured EEG state transitions than by a single numerical index. The State-Chart provides a stable, physiologically interpretable representation of brain activity and reveals transition states preceding deep cortical suppression, supporting individualized and predictive monitoring of anesthesia.
ER -