Journal of Clinical Monitoring and Computing

, Volume 23, Issue 5, pp 273–277

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

  • George A. Mashour
  • Roy K. Esaki
  • John C. Vandervest
  • Amy Shanks
  • Sachin Kheterpal
Article

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.

Keywords

intraoperative awareness anesthesia awareness awareness during general anesthesia minimum alveolar concentration anesthesia information management system 

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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • George A. Mashour
    • 1
  • Roy K. Esaki
    • 1
  • John C. Vandervest
    • 1
  • Amy Shanks
    • 1
  • Sachin Kheterpal
    • 1
  1. 1.Division of Neuroanesthesiology, Department of AnesthesiologyUniversity of Michigan Medical SchoolAnn ArborUSA

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