Suppression of brain electrical activity in general anesthesia: the dose-effect relationship

Abstract

The purpose of this study was to determine to mean effective dosage for propofol and sevoflurane that leads to the generation of burst-suppression pattern on electroencephalogram and electrocorticogram in general anesthesia. It is established that effective dosages that cause the generation of intermittent activity on electroencephalogram exceed those for electrocorticogram. This trend is common both for sevoflurane and for propofol. Discrepancies in the dosage for general anesthetics causing the suppression of electrical activity on electroencephalogram and electrocorticogram defined the «dissociation» of recorded patterns. Simultaneous recording of electroencephalogram and electrocorticogram showed cortical burst-suppression pattern together with the continuous pattern on scalp electrodes. It is concluded that rating and systematization for suppression patterns on electroencephalogram and electrocorticogram should be built upon the common foundation, but with allowances made for technical specifics. Categorization of suppression phenomenon on electrocorticogram implies the critical amplitude to be 20 mkV, whereas for electroencephalogram it is 10 mkV. More formal proposed methods for assessment of intermittent patterns of brain electrical activity during general anesthesia are based on the specific tasks for intraoperative neuromonitoring. Excessive levels of sedation causing rough depression of electrical activity should be avoided, since they may lead to false-negative results of the neuromonitoring.