Comparing signal concordance of needle electrodes and conventional bispectral index sensors in anesthesia monitoring: a prospective pilot study.

Processed EEG is commonly used for evaluating depth of anesthesia. Conventionally, the adhesive electrodes are applied to the patient’s frontal region. However, it may be unsuitable for certain neurosurgeries. The goal of this study is to assess and compare the performance of needle electrodes and conventional electrodes for intraoperative anesthesia depth monitoring. We developed an in-house interface for connecting needle electrodes to a BIS monitoring system, and simultaneously monitored BIS using needle electrodes and conventional sensor in patients under general anesthesia for elective surgery. Agreement in BIS values between the electrode and sensor was assessed using Bland-Altman analysis, and correlation between the two measurements was assessed using a generalized linear model. We also compared the beta ratio, alpha ratio, 95% spectral edge frequency, and SynchFastSlow index between the needle electrodes and conventional sensor. We analyzed 3,447 pairs of BIS index of 23 patients. Values from the needle electrodes and conventional sensor correlated strongly (r = 0.912 [95% confidence interval, 0.9057 to 0.9170] ) and showed a mean difference (± SD, 95% limits of agreement) of 1.735 (± 5.469, − 8.983 to 12.454). The raw EEG signal obtained with needle electrodes for processed EEG monitoring is comparable to that of conventional electrodes. Therefore, needle electrodes can be an alternative to conventional electrodes.