Background: Bispectral index has been introduced to provide optimal level of anesthesia. However, Bispectral index monitoring may not be cost effective in a relatively short procedures due to the high costs of the electrode. The authors conducted the present study to compare the feasibility of commercially available electrocardiogram (ECG) electrodes instead of the Bispectral index (BIS) monitoring.
Material and Method: The authors evaluated the difference in signal quality index (SQI) and BIS values collected from two BIS monitors, using ECG electrodes and BIS electrodes on the same patients before anesthesia, during light anesthesia, deep anesthesia and the emergence period. Both sets of electrodes were placed at bifrontal areas throughout the procedure. Statistical analysis was evaluated by mean difference 95% confidence limits of agreement and visualized by Bland-Altman plot. A parametric analysis was analyzed using paired t-test.
Results: There were 390 parallel signal quality index and BIS values recorded in the present study. During anesthesia the mean BIS values were 58.63 18.77 in the ECG electrode group and 56.99 19.84 in the BIS electrode group, which were not statistically different. The mean SQI values were 79.2 24.8 and 82.8 21.6 using ECG electrodes and BIS electrodes, respectively. The mean difference between BIS values was 1.65 with 95% confidence limits of agreement between 0.91 and 2.38.
Conclusion: Commercial ECG electrodes could be used for monitoring depth of anesthesia with clinically acceptable mean bias and 95% confidencelimits of agreement of BIS value obtained from BIS electrode.

Keywords: Electroencephalogram, Signal quality index, Bispectral index Depth, Equipment, Electrodes