The depth of anesthesia under sevoflurane can be monitored based on calling names language paradigm and Ag/AgCl electrooculogram electrode

Abstract

In the depth of anesthesia monitoring, electrooculogram is usually treated as an artifact of EEG. However, the amplitude of the electrooculogram is much greater than that of electroencephalography. Its requirements for electrode materials and detection circuits are also far lower than electroencephalography. In this prospective cohort study, we use a new language paradigm that elicited rhythmic ocular muscle activity to explore whether the electrooculogram can be used for monitoring the depth of anesthesia. Thirty-three patients inhaled sevoflurane via a laryngeal mask for induction of anesthesia. According to the end-tidal sevoflurane concentration, patients were studied under three depth of sedation. Throughout all periods, the rhythmic calling of the patient’s own name script was sporadically played at a frequency of 0.5 Hz. We found that the electrooculogram was synchronized to the language paradigm during induction with sevoflurane, and the Ag/AgCl electrode has a significantly higher signal-to-noise ratio and 0.5 hz spectral peak value than other electrode. With the increase in the sevoflurane concentration, the synchronizing ability gradually weakened and eventually disappeared. Based on this evidence, we proposed a new method that can improve the performance of the anesthesia prediction monitoring model.