A novel electronic algorithm for detecting potentially insufficient anesthesia: implications for the prevention of intraoperative awareness.
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.
Mashour
George A
GA
Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, 48109-5048, USA. gmashour@umich.edu
Esaki
Roy K
RK
Vandervest
John C
JC
Shanks
Amy
A
Kheterpal
Sachin
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018681:Anesthetics, General / Q000008:administration & dosage* / Q000032:analysis; D001364:Awareness / Q000187:drug effects*; D001944:Breath Tests / Q000379:methods*; D020000:Decision Support Systems, Clinical; D004360:Drug Therapy, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D007431:Intraoperative Complications / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
D018681:Anesthetics, General