Monitoring hypnotic effect and nociception with two EEG-derived indices, qCON and qNOX, during general anaesthesia

Abstract

The qCON was able to reliably detect LOC during general anaesthesia with propofol and remifentanil. The qNOX showed significant overlap between movers and non-movers, but it was able to predict whether or not the patient would move as a response to noxious stimulation, although the anaesthetic concentrations were similar.

Time delay of the qCON monitor and its performance during state transitions

“…These issues may hinder the indices to reliably separate conscious or responsive states from unconscious or unresponsive states on-line at the state transitions [14][15][16]. Specific information regarding the performance of a relatively new index, the qCON (Quantium Medical, Mataro, Spain) [17], that is now integrated in the CONOX monitor (Fresenius Kabi AG, Bad Homburg, Germany) [18], is not available to a great extent. Here we present the results regarding the time delay of the qCON as well as its ability to distinguish (goal-directed) responsiveness from unresponsiveness [19,20] state transitions.…”

“…The qCON processes frontal EEG information and reflects the estimated anesthetic level as a dimensionless number between 99 (fully awake) and 0 (isoelectric EEG) and the detailed algorithm is described in the article by Jensen et al [17] In short, the index is based on four spectral parameters that are calculated from the signal energy of different EEG frequency bands. Prior to the calculation of these parameters the recorded EEG is checked for artefacts using an artefact rejection routine.…”

EEG Based Monitoring of General Anesthesia: Taking the Next Steps

“…State and Response entropy (GE Healthcare, Chicago, IL) evaluate changes in the shape of the power spectrum (Viertio-Oja et al, 2004). Other devices like the CSI (Danmeter, Odense, Denmark), IoC (Morpheus Medical, Barcelona, Spain), or qCON (Quantium Medical, Mataro, Spain) use ratios of EEG band power (Jensen et al, 2006, 2014; Revuelta et al, 2008). The IoC also processes information from the EEG after transformation to a time series of symbols (Revuelta et al, 2008).…”

“…But these observations have not been used for current monitors of nociception. These devices use processed EEG like the BIS as subparameters (Ellerkmann et al, 2013; Castro et al, 2016), a wide range of spectral band power (Jensen et al, 2014), or non EEG information from heart rate variability (Ledowski et al, 2013), modeled drug and opioid concentrations (Luginbühl et al, 2010), or the polysynaptic spinal withdrawal reflex (Von Dincklage et al, 2012). One exception is the BAR.…”

Assessment of Nociceptive Responsiveness Levels during Sedation-Analgesia by Entropy Analysis of EEG

“…There is not consensus in the relationship between different levels of analgesia and changes in EEG features, and therefore methods based on EEG signals tend to be unspecific. The AEP signals are weakly coupled to the levels of analgesia and its amplitude is very small, being difficult to record in clinical practice without significant noise levels [16]. Recently, studies based on time-frequency representation [17] and auto-mutual information function (AMIF) [18] were applied in order to determine associated changes between EEG spectrum and EEG complexity with the prediction of the levels of unconsciousness as measured via the Ramsay Sedation Scale (RSS).…”