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A novel electronic algorithm for detecting potentially insufficient anesthesia: implications for the prevention of intraoperative awareness

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Abstract

Objective

A recent clinical trial compared a minimum alveolar concentration (MAC)-based protocol to an electroencephalography (EEG)-based protocol for the prevention of intraoperative awareness. One limitation of this study design is that MAC-based protocols are not sensitive to the use of intravenous agents, while EEG-based protocols are. Our objective was to develop a MAC alert that incorporates intravenous agents.

Methods

We developed an electronic algorithm and alerting system that calculates a total age-adjusted MAC value based on inhalational agents, but also incorporates intravenous agents. We retrospectively applied the algorithm to adult general anesthesia cases over a 1 year period to assess the frequency of alert triggers, using thresholds of <0.8, <0.7, <0.6, <0.5 and <0.4 age-adjusted MAC. We also electronically analyzed 12 cases of intraoperative awareness that occurred over a 4-year period for the frequency of alert triggers using the same thresholds. Finally, we calculated positive and negative likelihood ratios based on these analyses.

Results

Over a 1-year period we identified 15,091 cases without self-reported awareness that were valid for analysis. At all age-adjusted MAC thresholds, the incidence of triggered alerts was higher in the awareness cases. The threshold of<0.8 age-adjusted MAC was associated with the highest negative likelihood ratio; the<0.5 age-adjusted MAC was associated with the highest positive likelihood ratio.

Conclusions

Our novel electronic alerting system incorporates both age-adjusted MAC and intravenous anesthesia, and triggers with a higher frequency in cases of awareness. These data suggest the potential for our system to alert clinicians to insufficient anesthesia.

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Acknowledgments

This work was supported, in part, by a grant from the Foundation for Anesthesia Education and Research (GAM, Principal Investigator).

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Authors and Affiliations

  1. Division of Neuroanesthesiology, Department of Anesthesiology, University of Michigan Medical School, 1H247 UH/Box 5048, 1500 East Medical Center Drive, Ann Arbor, MI, 48109-5048, USA

    George A. Mashour MD, PhD, Roy K. Esaki MD, MS, John C. Vandervest BS, Amy Shanks MS & Sachin Kheterpal MD, MBA

Authors
  1. George A. Mashour MD, PhD
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  2. Roy K. Esaki MD, MS
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  3. John C. Vandervest BS
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  4. Amy Shanks MS
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  5. Sachin Kheterpal MD, MBA
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Corresponding author

Correspondence to George A. Mashour MD, PhD.

Additional information

Mashour GA, Esaki RK, Vandervest JC, Shanks A, Kheterpal S. A novel electronic algorithm for detecting potentially insufficient anesthesia: implications for the prevention of intraoperative awareness.

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Mashour, G.A., Esaki, R.K., Vandervest, J.C. et al. A novel electronic algorithm for detecting potentially insufficient anesthesia: implications for the prevention of intraoperative awareness. J Clin Monit Comput 23, 273–277 (2009). https://doi.org/10.1007/s10877-009-9193-9

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  • DOI: https://doi.org/10.1007/s10877-009-9193-9

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