Evaluating NeuroSENSE for assessing depth of hypnosis during desflurane anesthesia: an adaptive, randomized-controlled trial

  • Matthias GörgesEmail author
  • Nicholas C. West
  • Erin M. Cooke
  • Shanshan Pi
  • Rollin F. Brant
  • Guy A. Dumont
  • J. Mark Ansermino
  • Richard N. Merchant
Reports of Original Investigations



Processed electroencephalography (EEG) monitors support depth-of-hypnosis assessment during anesthesia. This randomized-controlled trial investigated the performance of the NeuroSENSE electroencephalography (EEG) monitor to determine whether its wavelet anesthetic value for central nervous system (WAVCNS) index distinguishes consciousness from unconsciousness during induction of anesthesia (as assessed by the anesthesiologist) and emergence from anesthesia (indicated by patient responsiveness), and whether it correlates with changes in desflurane minimum alveolar concentration (MAC) during maintenance of anesthesia.


EEG was collected using a fronto-temporal bilateral montage. The WAVCNS was continuously recorded by the NeuroSENSE monitor, to which the anesthesiologist was blinded. Anesthesia was induced with propofol/remifentanil and maintained with desflurane, with randomized changes of −0.4, 0, or +0.4 MAC every 7.5 min within the 0.8–1.6 MAC range, if clinically acceptable to the anesthesiologist. During emergence from anesthesia, desflurane was stepped down by 0.2 MAC every five minutes.


Data from 75 patients with a median [interquartile range] age of 41[35-52] yr were obtained. The WAVCNS distinguished consciousness from unconsciousness as assessed by the anesthesiologist, with area under the receiver operating characteristic curve of 99.5% (95% confidence interval [CI], 98.5 to 100.0) at loss of consciousness and 99.4% (95% CI, 98.5 to 100.0) at return of consciousness. Bilateral WAVCNS changes correlated with desflurane concentrations, with −8.0 and −8.6 WAVCNS units, respectively, per 1 MAC change in the 0.8–1.6 MAC range during maintenance of anesthesia and −10.0 and −10.5 WAVCNS units, respectively, in the 0.4–1.6 MAC range including emergence from anesthesia.


The NeuroSENSE monitor can reliably discriminate between consciousness and unconsciousness, as assessed by the anesthesiologist, during induction of anesthesia and with a lower level of reliability during emergence from anesthesia. The WAVCNS correlates with desflurane concentration but plateaus at higher concentrations, similar to other EEG monitors, which suggests limited utility to titrate higher concentrations of anesthetic vapour.

Trial registration, NCT02088671; registered 17 March, 2014.

Une évaluation du moniteur NeuroSENSE pour mesurer la profondeur de l’hypnose pendant une anesthésie au desflurane : une étude randomisée contrôlée adaptable



Cette étude randomisée contrôlée a évalué la performance du moniteur d’électroencéphalographie (EEG) NeuroSENSE afin de déterminer si sa valeur anesthésique d’ondelette pour l’indice du système nerveux central (wavelet anesthetic value for central nervous system, WAVSNC) était capable de distinguer la conscience de l’inconscience pendant l’induction de l’anesthésie (telle qu’évaluée par l’anesthésiologiste) et le réveil de l’anesthésie (tel qu’indiqué par la réactivité du patient), et si cette valeur était corrélée aux modifications de la concentration alvéolaire minimale (MAC) de desflurane pendant le maintien de l’anesthésie.


Les données électro-encéphalographiques ont été récoltées à l’aide d’un monitorage fronto-temporal bilatéral. La WAVSNC a été enregistrée en continu par le moniteur NeuroSENSE, dont les données étaient tenues cachées de l’anesthésiologiste. L’anesthésie a été induite à l’aide de propofol / rémifentanil et maintenue avec du desflurane, avec des modifications randomisées de -0,4, 0 ou +0,4 MAC toutes les 7,5 min dans une plage de MAC de 0,8-1,6. Pendant le réveil de l’anesthésie, le desflurane a été réduit de 0,2 MAC toutes les cinq minutes.


Les données de 75 patients d’un âge médian [écart interquartile] de 41 [35-52] ans ont été obtenues. La WAVSNC a différencié la conscience de l’inconscience avec une surface sous la courbe de fonction d’efficacité de l’observateur de 99,5 % (intervalle de confiance [IC] 95 %, 98,5 à 100,0) au moment de la perte de conscience et de 99,4 % (IC 95 %, 98,5 à 100,0) au rétablissement de la conscience. Les modifications bilatérales de la WAVSNC étaient corrélées aux concentrations de desflurane, avec des unités de WAVSNC de -8,0 et -8,6, respectivement par unité de MAC dans la plage de MAC de 0,8-1,6 pendant le maintien de l’anesthésie et de -10,0 et -10,5 unités WAVSNC, respectivement, dans la plage de MAC de 0,4-1,6, incluant le réveil de l’anesthésie.


Le moniteur NeuroSENSE peut distinguer de façon fiable un état de conscience d’un état d’inconscience pendant l’induction de l’anesthésie et, à un degré de fiabilité moindre, pendant le réveil de l’anesthésie. La WAVSNC est corrélée à la concentration de desflurane mais atteint un plateau à des concentrations plus élevées, tout comme les autres moniteurs EEG, ce qui suggère une utilité limitée pour titrer de plus fortes concentrations de gaz anesthésiques.

Enregistrement de l’étude, NCT02088671; enregistrée le 17 mars 2014.


Author contributions

Matthias Görges conducted the literature review, designed the study, obtained the ethical approval to conduct the research, analyzed and interpreted the findings, and drafted the manuscript. Nicholas C. West collected the data and drafted the manuscript. Erin M. Cooke conducted the literature review, designed the study, obtained the ethical approval to conduct the research, and collected the data. Shanshan Pi analyzed and interpreted the findings and drafted the manuscript. Rollin F. Brant analyzed and interpreted the findings. Guy A. Dumont conducted the literature review, designed the study, and obtained the ethical approval to conduct the research. J. Mark Ansermino conducted the literature review, designed the study, and obtained the ethical approval to conduct the research. Richard N. Merchant conducted the literature review, designed the study, and obtained the ethical approval to conduct the research. All authors critically reviewed the manuscript.


The authors wish to thank all the participating patients, anesthesiologists, the surgical and nursing teams in the operating theatre, as well as Aryannah Rollinson and Sonia Brodie for their help with the data collection.

Declaration of interests

Guy A. Dumont is a co-inventor of the NeuroSENSE monitor (NeuroWave Systems Inc., Cleveland Heights, OH, USA). J. Mark Ansermino and Guy A. Dumont have consulted for NeuroWave Systems Inc. Matthias Görges, J. Mark Ansermino, Guy A. Dumont, and Richard N. Merchant are party to a licensing agreement between NeuroWave Systems Inc. and the University of British Columbia for control technology. The remaining authors have no disclosures.


This study was funded by NeuroWave Systems Inc. (Cleveland Heights, OH, USA), under contract from the US Army (W81XWH-06-C-0016).

Editorial responsibility

This submission was handled by Dr. Gregory L. Bryson, Deputy Editor-in-Chief, Canadian Journal of Anesthesia.


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Copyright information

© Canadian Anesthesiologists' Society 2019

Authors and Affiliations

  1. 1.Department of Anesthesiology, Pharmacology & TherapeuticsUniversity of British ColumbiaVancouverCanada
  2. 2.BC Children’s Hospital Research InstituteVancouverCanada
  3. 3.Department of StatisticsUniversity of British ColumbiaVancouverCanada
  4. 4.Department of Electrical EngineeringUniversity of British ColumbiaVancouverCanada
  5. 5.Department of AnesthesiaRoyal Columbian Hospital, Fraser Health AuthorityNew WestminsterCanada

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