title: Comparison of the qCON and qNOX indices for the assessment of unconsciousness level and noxious stimulation response during surgery.
abstract: The objective of this work is to compare the performances of two electroencephalogram based indices for detecting loss of consciousness and loss of response to nociceptive stimulation. Specifically, their behaviour after drug induction and during recovery of consciousness was pointed out. Data was recorded from 140 patients scheduled for general anaesthesia with a combination of propofol and remifentanil. The qCON 2000 monitor (Quantium Medical, Barcelona, Spain) was used to calculate the qCON and qNOX. Loss of response to verbal command and loss of eye-lash reflex were assessed during the transition from awake to anesthetized, defining the state of loss of consciousness. Movement as a response to laryngeal mask (LMA) insertion was interpreted as the response to the nociceptive stimuli. The patients were classified as movers or non-movers. The values of qCON and qNOX were statistically compared. Their fall times and rise times defined at the start and at the end of the surgery were calculated and compared. The results showed that the qCON was able to predict loss of consciousness such as loss of verbal command and eyelash reflex better than qNOX, while the qNOX has a better predictive value for response to noxious stimulation such as LMA insertion. From the analysis of the fall and rise times, it was found that the qNOX fall time (median: 217 s) was significantly longer (p value <0.05) than the qCON fall time (median: 150 s). At the end of the surgery, the qNOX started to increase in median at 45 s before the first annotation related to response to stimuli or recovery of consciousness, while the qCON at 88 s after the first annotation related to response to stimuli or recovery of consciousness (p value <0.05). The indices qCON and qNOX showed different performances in the detection of loss of consciousness and loss of response to stimuli during induction and recovery of consciousness. Furthermore, the qCON showed faster decrease during induction. This behaviour is associated with the hypothesis that the loss of response to stimuli (analgesic effect) might be reached after the loss of consciousness (hypnotic effect). On the contrary, the qNOX showed a faster increase at the end of the surgery, associated with the hypothesis that a higher probability of response to stimuli might be reached before the recovery of consciousness.
authors.affiliation: R&D Department, Quantium Medical, Barcelona, Spain. umg@quantiummedical.com.
authors.forename: Umberto
authors.identifier: http://orcid.org/0000-0003-3033-0505
authors.initials: U
authors.lastname: Melia
authors.affiliation: R&D Department, Quantium Medical, Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Gabarron
authors.affiliation: Systems Pharmacology Effect Control and Modeling (SPEC-M) Research Group, Anesthesiology Department, Hospital CLINIC de Barcelona, Barcelona, Spain.
authors.forename: Mercé
authors.initials: M
authors.lastname: Agustí
authors.affiliation: Systems Pharmacology Effect Control and Modeling (SPEC-M) Research Group, Anesthesiology Department, Hospital CLINIC de Barcelona, Barcelona, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Souto
authors.affiliation: R&D Department, Quantium Medical, Barcelona, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Pineda
authors.affiliation: R&D Department, Quantium Medical, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Fontanet
authors.affiliation: Automatic Control and Informatic (ESAII) Department, Centre for Biomedical Research (CREB), UPC-Barcelonatech, Barcelona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Vallverdu
authors.affiliation: R&D Department, Quantium Medical, Barcelona, Spain.|Systems Pharmacology Effect Control and Modeling (SPEC-M) Research Group, Anesthesiology Department, Hospital CLINIC de Barcelona, Barcelona, Spain.|Automatic Control and Informatic (ESAII) Department, Centre for Biomedical Research (CREB), UPC-Barcelonatech, Barcelona, Spain.
authors.forename: Erik Weber
authors.initials: EW
authors.lastname: Jensen
authors.affiliation: Systems Pharmacology Effect Control and Modeling (SPEC-M) Research Group, Anesthesiology Department, Hospital CLINIC de Barcelona, Barcelona, Spain.|Neuroimmunology Research Program Institut de Investigacions Biomèdiques August Pi Sunyer (IDIBAPS), Barcelona, Spain.|Department of Anesthesia and Perioperative Medicine, University of California San Francisco (UCSF), San Francisco, CA, USA.
authors.forename: Pedro
authors.initials: P
authors.lastname: Gambus
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D000776:Anesthesiology / Q000379:methods*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D001767:Blinking / Q000187:drug effects; D003243:Consciousness / Q000187:drug effects; D004569:Electroencephalography; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D059225:Nociception; D010880:Piperidines / Q000008:administration & dosage*; D011336:Probability; D015742:Propofol / Q000008:administration & dosage*; D000077208:Remifentanil; D015203:Reproducibility of Results; D013997:Time Factors; D014474:Unconsciousness; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol
keywords: Anesthesia monitor; Clinical indices; Electroencephalography; Nociception