Increases in Electroencephalogram and Electromyogram Variability Are Associated with an Increased Incidence of Intraoperative Somatic Response

sBIS, sEMG, and CVI, measures of electroencephalogram and EMG variability, increased when intraoperative somatic events occurred. sBIS, sEMG, and CVI discriminated between 10-minute segments that contained a somatic event and those segments that did not contain an event better than changes in HR and mean arterial blood pressure. Furthermore, CVI increases before somatic events began earlier than HR changes and may provide caregivers with an early warning of potentially inadequate antinociception.