Abstract

The depth of anesthesia is contingent upon the concentration of administered hypnotics, but establishing an exact relationship proves challenging, given its variability among individual patients. To elucidate the connection between the depth of anesthesia and hypnotic concentration, we leverage transient EEG patterns—specifically, iso-electric suppressions and power distributions within the α and δ frequency bands—at constant concentrations. Our investigation focuses on two hypnotics: propofol and sevoflurane. In a cohort encompassing children and young adults undergoing general anesthesia, we employ segmentation algorithms to extract a diverse range of spectral representations in EEG profiles. However, as we systematically alter hypnotic concentrations, a consistent trend emerges: heightened hypnotic concentration predominantly aligns with increased δ-band power and reduced α-band power. Notably, the occurrence of iso-electric suppressions is primarily associated with elevated propofol concentrations and infrequently observed with high levels of sevoflurane. Furthermore, we observe a decrease in the maximal power frequency of the α-band as hypnotic concentrations increase. In summary, this study offers a systematic quantification of EEG patterns corresponding to distinct concentrations of propofol and sevoflurane. These observed patterns contribute to a nuanced EEG representation of brain activity, laying the groundwork for personalized anesthesia strategies.

Competing Interest Statement

The authors have declared no competing interest.

Clinical Trial

NCT02893904

Funding Statement

DH research is supported by Fondation pour la Recherche Medicale (Postdoctorat en France SPF201909009284), an ANR grant NEUC-0001 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation programme (grant agreement No 882673) and a CNRS Pre-maturation Grant.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The protocol has been therefore performed in accordance with the ethical standards laid down in 1964 declaration of Helsinki and its later amendments. A group of 89 patients ranging from 6 to 38 years old, ASA 1 or 2, was used in this study. Data were collected between 2005 and 2006. The trial was later on registered and completed on September 2016 (ClinicalTrials.gov ID: NCT02893904). This study was approved by the Ethics Committee CPP Saint Antoine, Paris, France (Approval number: 04605).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data availability

The datasets generated and analysis in the current study are available from the corresponding authors upon reasonable request.

AbbreviationsEEGElectroEncephaloGramGAGeneral AnesthesiaTCITarget Controlled InfusionαSAlpha-SuppressionIESIso-Electric Suppression;