Journal of Clinical Monitoring and Computing

, Volume 25, Issue 1, pp 81–87 | Cite as

Dynamic behavior of BIS, M-entropy and neuroSENSE brain function monitors

  • Stéphane BibianEmail author
  • Guy A. Dumont
  • Tatjana Zikov



The objective of this paper is to assess the suitability of brain function monitors for use in closed-loop anesthesia or sedation delivery. In such systems, monitors used as feedback sensors should preferably be Linear and Time Invariant (LTI) in order to limit sensor-induced uncertainty which can cause degraded performance. In this paper, we evaluate the suitability of the BIS A2000 (Aspect Medical Systems, MA), the M-Entropy Monitor (GE HealthCare), and the NeuroSENSE Monitor (NeuroWave Systems Inc, OH), by verifying whether their dynamic behavior conforms to the LTI hypothesis.


We subjected each monitor to two different composite EEG signals containing step-wise changes in cortical activity. The first signal was used to identify Linear Time-Invariant (LTI) models that mathematically capture the dynamic behavior of each monitor. The identification of the model parameters was carried out using standard Recursive Least Squares (RLS) estimation. The second signal was used to assess the performance of the model, by comparing the output of the monitor to the simulated output predicted by the model.


While a LTI model was successfully derived for each monitor using the first signal, only the model derived for NeuroSENSE was capable to reliably predict the monitor output for the second input signals. This indicates that some algorithmic processes within the BIS A2000 and M-Entropy are non-linear and/or time variant.


While both BIS and M-Entropy monitors have been successfully used in closed-loop systems, we were unable to obtain a unique LTI model that could capture their dynamic behavior during step-wise changes in cortical activity. The uncertainty in their output during rapid changes in cortical activity impose limitations in the ability of the controller to compensate for rapid changes in patients’ cortical state, and pose additional difficulties in being able to provide mathematically proof for the stability of the overall closed-loop system. Conversely, the NeuroSENSE dynamic behavior can be fully captured by a linear and time invariant transfer function, which makes it better suited for closed-loop applications.


brain monitors electroencephalography modeling anesthesia closed-loop 


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  1. 1.
    Struys MMRF, Mortier EP, De Smet T. Closed loops in anaesthesia. Best Pract Res Clin Anaesthesiol. 2006;20(1):211–20.CrossRefPubMedGoogle Scholar
  2. 2.
    Zikov T, Bibian S, Dumont GA, Huzmezan M, Ries CR. Quantifying cortical activity during general anesthesia using wavelet analysis. IEEE Transact Biomed Eng. 2006;53:617–32.CrossRefGoogle Scholar
  3. 3.
    Liu N, Chazot T, Genty A, Landais A, Restoux A, McGee K, Laloë P-A, Trillat B, Barvais L, Fischler M. Titration of Propofol for anesthetic induction and maintenance guided by the bispectral index: closed-loop versus manual control: a prospective, randomized, multicenter study. Anesthesiology. 2006;104:686–95.CrossRefPubMedGoogle Scholar
  4. 4.
    De Smet T, Struys MMRF, Neckebroek MM, Van den Hauwe K, Bonte S, Mortier EP. The accuracy and clinical feasibility of a new Bayesian-based closed-loop control system for Propofol administration using the bispectral index as a controlled variable. Anesth Analg. 2008;107(4):1200–10.CrossRefPubMedGoogle Scholar
  5. 5.
    Absalom A, Kenny G. Closed-loop control of Propofol anaesthesia using bispectral index: performance assessment in patients receiving computer controlled propofol and manually controlled Remifentanil infusions for minor surgeries. Br J Anaesth. 2003;90(6):738–41.CrossRefGoogle Scholar
  6. 6.
    Locher S, Stadler K, Boehlen T, Bouillon T, Leibundgut D, Schumacher P, Wymann R, Zbinden A. A new closed-loop control system for isoflurane using bispectral index outperforms manual control. Anesthesiology. 2004;101:591–602.CrossRefPubMedGoogle Scholar
  7. 7.
    Struys MM, De Smet T, Versichelen LF, Van De Velde S, Van den Broecke R, Mortier EP. Comparison of closed-loop controlled administration of propofol using bispectral index as the controlled variable versus “standard practice” controlled administration. Anesthesiology. 2001;95(1):6–17.CrossRefPubMedGoogle Scholar
  8. 8.
    Liu N, Fatima B, Chazot T, Trillat B, Fischler M (2007) Closed-loop titration of Propofol and Remifentanil guided by spectral entropy: a controlled study. Anesthesiology A1881.Google Scholar
  9. 9.
    Liu N, Chazot T, Le Guen M, Trillat B, Fischler M (2010) Closed-loop administration of Propofol and Remifentanil guided by the BIS index in 1594 patients. Anesthesiology A1694.Google Scholar
  10. 10.
    Liu N, Chazot T, Trillat B, Michel-Cherqui M, Marandon J, Law-Koune J, Rives B, Fischler M. Closed-loop control of consciousness during lung transplantation: an observational study. J Cardiothorac Vasc Anesth. 2008;22:611–5.CrossRefPubMedGoogle Scholar
  11. 11.
    Hegde HV, Puri GD, Kumar B, Behera A. Bi-spectral index guided closed-loop anaesthesia delivery system (CLADS™) in pheochromocytoma. J Clin Monit Comput. 2009;23:189–96.CrossRefPubMedGoogle Scholar
  12. 12.
    Haddad WM, Bailey JM. Closed-loop control for ICU sedation. Best Pract Res Clin Anaesthesiol. 2009;23:95–114.CrossRefPubMedGoogle Scholar
  13. 13.
    Pauldine R, Beck G, Salinas J, Kaczka D. Closed-loop strategies for patient care systems. J Trauma Inj Infect Crit Care. 2008;64:S289–94.CrossRefGoogle Scholar
  14. 14.
    Bibian S, Ries CR, Huzmezan M, Dumont GA. Introduction to automated drug delivery in clinical anesthesia. Eur J Control. 2005;11:535–57.CrossRefGoogle Scholar
  15. 15.
    Bibian S, Zikov T (2010) NeuroSENSETM monitor with WAVCNS cortical quantifier: a deterministic approach to EEG analysis. White paper,
  16. 16.
    Absalom AR, Sutcliffe N, Kenny GN. Closed-loop control of anesthesia using bispectral index: performance assessment in patients undergoing major orthopedic surgery under combined general and regional anesthesia. Anesthesiology. 2002;96:67–73.CrossRefPubMedGoogle Scholar
  17. 17.
    Bibian S, Dumont GA, Huzmezan M, Ries CR. Quantifying uncertainty bounds in anesthetic PKPD models. Proc IEEE Eng Med Biol Soc Conf. 2004;1:786–9.Google Scholar
  18. 18.
    Dumont GA, Martinez A, Ansermino M. Robust control of depth of anesthesia. Int J Adapt Control Signal Process. 2009;23:435–54.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Stéphane Bibian
    • 1
    Email author
  • Guy A. Dumont
    • 2
  • Tatjana Zikov
    • 1
  1. 1.Neurowave Systems Inc.Cleveland HeightsUSA
  2. 2.Department of Electrical and Computer EngineeringThe University of British ColumbiaVancouverCanada

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