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

Abstract

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.

A Response Surface Model Approach for Continuous Measures of Hypnotic and Analgesic Effect during Sevoflurane–Remifentanil Interaction

“…"U" can be used as if it was a drug concentration of that virtual new drug on the x-axis of a two-dimensional concentration-response curve (figs. [2][3][4][5]. With the selected interaction models, the combined potency "U" predicted the effect on BIS, SE, and RE with an error of approximately 10%, which is comparable to that reported in the previous studies.…”

“…3 More recently, new continuous measures with different neurophysiological background, such as the Surgical Pleth Index (SPI; GE Healthcare) and the Composite Variability Index (CVI; Covidien), attempt to quantify the balance between nociception and antinociception. 4,5 All these continuous surrogate measures of hypnotic or analgesic effect are influenced by the interaction between hypnotic and analgesic drugs and should therefore be studied with this multidrug reality in mind. Eventually, the ultimate goal of continuous monitoring is to effectively counter deviating measurements with an adequate change in the balance between opioids and hypnotics so that better clinical results are obtained.…”

“…The raw electroencephalographic signal was captured by the BIS™ monitor with a 128-Hz sample rate and allowed post hoc calculation of CVI. The calculation of CVI has been described by Mathews et al 5 The CVI is a composite index that combines the variability in BIS with frontal electromyographic changes over time. A high CVI reflects activation of the frontal electromyography and increased input of sensory information from deep brain structures to the cortex.…”

Monitoring depth of anesthesia: from consciousness to nociception. A window on subcortical brain activity

“…Nociceptive stimulations can induce changes in cortical EEG in lightly anesthetized subjects, by producing a sort of cortical awakening. In the same way, increase in EEG and EMG variability seems to be associated with the occurrence of intraoperative somatic events in anesthetized adults Some authors have proposed a composite index (CVI) derived from the standard deviations of the bispectral index and the electromyogram, to assess the level of analgesia/nociception during general anesthesia . However, if the CVI appears to correlate with somatic responses to noxious stimuli, the unstimulated CVI depends more on the hypnotic drug effect than on opioid concentration .…”

Comparisons of Electroencephalographically Derived Measures of Hypnosis and Antinociception in Response to Standardized Stimuli During Target-Controlled Propofol-Remifentanil Anesthesia

“…8,9 A derived calculation of analgesic state, the composite variability index (CVI), has therefore been developed as a function of BIS and EMG variability and is associated with an increased incidence of intraoperative somatic responses to noxious stimulation. 10 In contrast to BIS and CVI, which are both heuristically derived, Liley and Bojak 11 and Liley et al 12,13 have taken a more physiologically based approach to modeling the effects of anesthetic drugs on brain electrical activity, by using a detailed mathematical model of human EEG. This model aims to describe the electrical dynamics of coupled populations of excitatory and inhibitory neurons within the cerebral cortex that are driven by external inputs.…”