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Observational Study
. 2025 Jan 24;25(1):37.
doi: 10.1186/s12871-024-02859-1.

Anesthesia depth monitoring during opioid free anesthesia - a prospective observational study

Krister Mogianos  1   2 , Anna Km Persson  3   4
Affiliations
Observational Study

Anesthesia depth monitoring during opioid free anesthesia - a prospective observational study

Krister Mogianos et al. BMC Anesthesiol. .

Abstract

Background: Patients undergoing general anesthesia are more frequently monitored for depth of anesthesia using processed electroencephalography. Opioid-free anesthesia is nowadays an accepted modality for general anesthesia, however it is unclear how to interpret data from processed electroencephalography when using a mixture of non-opioid anesthetic drugs. Our objective was to describe density spectral array patterns and compare processed encephalographic data indices between opioid-free and routine opioid based anesthesia.

Methods: This prospective observational cohort study was conducted on 30 adult patients undergoing laparoscopic surgery in a non-tertiary regional hospital. The patients underwent general anesthesia with three different methods and were monitored for anesthesia depth using processed encephalography and density spectral array. Primary outcome is a group-derived mean difference in patient state index and spectral edge frequency. As a secondary outcome a descriptive comparison of the spectral power, derived from the density spectral array, was done between groups.

Results: The opioid-free anesthesia group had significantly higher patient state index and spectral edge frequency compared to routine anesthesia. Density spectral array patterns were also different, most notably lacking the high power in alpha frequency spectrum seen in the other routine anesthesia methods.

Conclusions: Processed electroencephalography monitoring can be used in opioid-free anesthesia, however clinicians should expect higher values in monitoring indices. The density spectral array pattern using a common protocol for opioid-free anesthesia, with mainly sevoflurane combined with low doses of dexmedetomidine and esketamine, differs from well described opioid and GABA-ergic anesthesia methods. These findings should be further validated using other protocols for opioid-free anesthesia in order to safely monitor anesthesia depth.

Trial registration: Clinicaltrials.gov registration number NCT06227143, registration date; 26th of January 2024.

Keywords: Density spectral array; Opioid-based anesthesia; Opioid-free anesthesia; Patient state index; Processed electroencephalography; Spectral edge frequency.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This study was performed in line with the principles of the Declaration of Helsinki. Oral and written informed consent was given from all participants in this study. Approval was granted by the Swedish Ethical Review Authority of Uppsala University lead by chairman Anna Önell (Date 2023-01-18/ Dnr 2022-07156-02). Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Description of Sedline Monitor indices. (A) The four channels of electroencephalography (EEG) representing two locations on right and left frontal lobes respectively. (B) Patient state index (PSI), algorithm-based quantitative index for monitoring of brain function to determine anesthesia depth during general anesthesia. (C) Spectral edge frequency (SEF95) containing 95% of the electric activity, also separated for left and right side. (D) Electromyography (EMG), which is an index over temporal muscle relaxation. Suppression ratio (SR) represents percentage of isoelectric electrical activity (+/- 0.5 µV) per minute in prefrontal and frontal cortex. Artefacts (ARTF) reflect environmental noise as artifacts, conveyed as vertical white lines in DSA. (E) Density spectral array (DSA) showing the power of frequencies over time as a color-scale. The upper and lower part reflects left and right frontal lobes
Fig. 2
Fig. 2
Primary outcome. Bar chart illustrating difference in mean patient state index (PSI) between total intravenous anesthesia (TIVA), volatile and opioid-free anesthesia (OFA) groups. The whiskers represent the 95% confidence interval. A single asterisk (*) indicates a statistically significant difference between groups
Fig. 3
Fig. 3
Secondary quantitative outcome. Bar chart illustrating difference in mean spectral edge frequency (SEF) between total intravenous anesthesia (TIVA), volatile and opioid-free anesthesia (OFA) groups. The whiskers represent the 95% confidence interval. A single asterisk (*) indicates a statistically significant difference between groups
Fig. 4
Fig. 4
Secondary quantitative outcome. Data from processed electroencephalography and density spectral array (DSA) for all ten patients in opioid-free anesthesia (OFA) group. Patients in this figure were labeled a1 - j1 starting on top left to bottom right. All patients were considered to be in anesthetic steady state after skin incision
Fig. 5
Fig. 5
Secondary quantitative outcome. Data from processed electroencephalography of anesthesia and density spectral array for all ten patients in total intravenous anesthesia (TIVA) group. Patients in this figure were labeled a2 - j2 starting on top left to bottom right. All patients were considered to be in anesthetic steady state after skin incision
Fig. 6
Fig. 6
Secondary quantitative outcome. Data from processed electroencephalography of anesthesia and density spectral array for all ten patients in volatile group. Patients in this figure were labeled a3 - j3 starting on top left to bottom right. All patients were in anesthetic steady state after skin incision
See this image and copyright information in PMC

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