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Spectral Entropy as a Monitor of Depth of Propofol Induced Sedation

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Abstract

Objective

The aim of this prospective, observational study was to evaluate State and Response entropy (EntropyTM Monitor, GE Healthcare, Finland), indices as measures of moderate (“conscious”) sedation in healthy adult patients receiving a low dose propofol infusion.

Sedation was evaluated using: (I) the responsiveness component of the OAA/S scale␣(Observer’s Assessment of Alertness/Sedation scale) and (II) multi-channel electroencephalogram (EEG) interpretation by a clinical expert.

Methods

12 ASA I patients were recruited. A target-controlled infusion of propofol was administered (using Schnider’s pharmacokinetic model) with␣an initial effect site concentration set to 0.5 µg ml−1. A␣4 minute equilibrium period was allowed. This concentration was increased at 4 minute intervals by 0.5 µg ml−1 to a maximum of 2.0 µg ml−1. State (SE) and Response (RE), entropy values were recorded for each 4 minute epoch together with clinical sedation scores (OAA/S) and continuous multi-channel EEG. The multi-channel EEG recorded during the final minute of each 4 minute epoch or “patient/time unit” was presented to a neurophysiologist who assigned a label “sedated/not sedated”. SE/RE values were compared in patient/time units with clinical or EEG evidence of sedation versus those without.

Results

Mean SE and RE values were less in patient/time units when clinical evidence of sedation was present, [mean = 86.8 (95% CI, 84.0–88.3) and 94.3 (95%CI, 92–96.1)], P = 0.002 and P = 0.001, respectively. In patient/time units assigned the label “sedated” by the clinical neurophysiologist assessing the multi-channel EEG, SE and RE values were less [mean = 87.5 (95% CI, 86.3–88.4) and 95.0 (95% CI, 93.8–96.1)] P = 0.001 and P < 0.001, respectively.

Conclusions

A statistically significant decrease in SE and RE values was demonstrated in patient/time units in which clinical or EEG evidence of sedation was present. We conclude that spectral entropy offers potential as a monitor of propofol induced sedation

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Author information

Authors and Affiliations

  1. Department of Anaesthesia and Intensive Care Medicine, Cork University Hospital, University College Cork, Cork, Ireland

    Padraig Mahon FCARCSI MSc & George D. Shorten MD PhD

  2. University College Cork, Cork, Ireland

    Robert G. Kowalski MSc

  3. Department of Epidemiology and Statistics, University College Cork, Cork, Ireland

    Anthony P. Fitzgerald ScD

  4. Department of Neurophysiology, Cork University Hospital, Cork, Ireland

    Elaine M. Lynch BSc & Brian McNamara MD

  5. School of Medicine, University College Cork, Cork, Ireland

    Geraldine B. Boylan PhD

Authors
  1. Padraig Mahon FCARCSI MSc
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  2. Robert G. Kowalski MSc
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  3. Anthony P. Fitzgerald ScD
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  4. Elaine M. Lynch BSc
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  5. Geraldine B. Boylan PhD
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  6. Brian McNamara MD
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  7. George D. Shorten MD PhD
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Corresponding author

Correspondence to Padraig Mahon FCARCSI MSc.

Additional information

Mahon P, Kowalski RG, Fitzgerald AP, Lynch EM, Boylan GB, McNamara B, Shorten GD. Spectral entropy as a monitor of depth of propofol induced sedation.

Ethical Approval

The Clinical Research Ethics Committee of the Cork Teaching Hospitals, Cork, Ireland approved the study protocol on 1st March 2005. The Clinical Research Ethics Committee of the Cork Teaching Hospitals, is a recognised Ethics Committee under regulation 7 of the European Communities (Clinical Trials on Medicinal Products for Human Use) regulations 2004, and is authorised to carry out the ethical review of clinical trials of investigational medicinal products.

Presentation

This work was presented in part (poster format) at the European Society of Anaesthesia, Annual Congress, Munich, Germany, June 9–12 2007. (Monitoring: equipment and computers poster section).Abstract reference: 3AP9-9. European Journal of Anaesthesia 2007(24) Suppl. 39 p 37.

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Mahon, P., Kowalski, R.G., Fitzgerald, A.P. et al. Spectral Entropy as a Monitor of Depth of Propofol Induced Sedation. J Clin Monit Comput 22, 87–93 (2008). https://doi.org/10.1007/s10877-008-9109-0

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  • DOI: https://doi.org/10.1007/s10877-008-9109-0

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