Technical Aspects of Closing the Loop in Depth-of-Anesthesia Control
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32918
Technical Aspects of Closing the Loop in Depth-of-Anesthesia Control

Authors: Gorazd Karer


When performing a diagnostic procedure or surgery in general anesthesia (GA), a proper introduction and dosing of anesthetic agents is one of the main tasks of the anesthesiologist. That being said, depth of anesthesia (DoA) also seems to be a suitable process for closed-loop control implementation. To implement such a system, one must be able to acquire the relevant signals online and in real-time, as well as stream the calculated control signal to the infusion pump. However, during a procedure, patient monitors and infusion pumps are purposely unable to connect to an external (possibly medically unapproved) device for safety reasons, thus preventing closed-loop control. This paper proposes a conceptual solution to the aforementioned problem. First, it presents some important aspects of contemporary clinical practice. Next, it introduces the closed-loop-control-system structure and the relevant information flow. Focusing on transferring the data from the patient to the computer, it presents a non-invasive image-based system for signal acquisition from a patient monitor for online depth-of-anesthesia assessment. Furthermore, it introduces a User-Datagram-Protocol-based (UDP-based) communication method that can be used for transmitting the calculated anesthetic inflow to the infusion pump. The proposed system is independent of medical-device manufacturer and is implemented in MATLAB-Simulink, which can be conveniently used for DoA control implementation. The proposed scheme has been tested in a simulated GA setting and is ready to be evaluated in an operating theatre. However, the proposed system is only a step towards a proper closed-loop control system for DoA, which could routinely be used in clinical practice.

Keywords: Closed-loop control, Depth of Anesthesia, DoA, optical signal acquisition, Patient State index, PSi, UDP communication protocol.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 468


[1] C. M. Ionescu, M. Neckebroek, M. Ghita, and D. Copot, “An Open Source Patient Simulator for Design and Evaluation of Computer Based Multiple Drug Dosing Control for Anesthetic and Hemodynamic Variables,” IEEE Access, pp. 1–1, Jan. 2021, doi: 10.1109/access.2021.3049880.
[2] G. A. Dumont, “Closed-loop control of anesthesia - A review,” in IFAC Proceedings Volumes (IFAC-PapersOnline), Jan. 2012, vol. 45, no. 18, pp. 373–378, doi: 10.3182/20120829-3-HU-2029.00102.
[3] I. Potočnik, V. N. Janković, T. Štupnik, and B. Kremžar, “Haemodynamic changes after induction of anaesthesia with sevoflurane vs. propofol,” Signa Vitae, vol. 6, no. 2, pp. 52–57, 2011.
[4] D. Drover and H. R. R. Ortega, “Patient state index,” Best Practice and Research: Clinical Anaesthesiology, vol. 20, no. 1. Best Pract Res Clin Anaesthesiol, pp. 121–128, Mar. 2006, doi: 10.1016/j.bpa.2005.07.008.
[5] F. A. Lobo and S. Schraag, “Limitations of anaesthesia depth monitoring,” Curr. Opin. Anaesthesiol., vol. 24, no. 6, pp. 657–664, Dec. 2011, doi: 10.1097/ACO.0b013e32834c7aba.
[6] B. Marsh, M. White, N. Morton, and G. N. Kenny, “Pharmacokinetic model driven infusion of propofol in children,” Br J Anaesth, vol. 67, pp. 41–48, 1991.
[7] T. W. Schnider et al., “The influence of method of administration and covariates on the pharmacokinetics of propofol in adult volunteers,” Anesthesiology, vol. 88, no. 5, pp. 1170–1182, 1998, doi: 10.1097/00000542-199805000-00006.
[8] T. W. Schnider et al., “The influence of age on propofol pharmacodynamics,” Anesthesiology, vol. 90, no. 6, pp. 1502–1516, Jun. 1999, doi: 10.1097/00000542-199906000-00003.
[9] J. Schüttler and H. Ihmsen, “Population pharmacokinetics of propofol: A multicenter study,” Anesthesiology, vol. 92, no. 3, pp. 727–738, 2000, doi: 10.1097/00000542-200003000-00017.
[10] G. N. Kenny and M. White, “Intravenous propofol anaesthesia using a computerised infusion system,” Anaesthesia, vol. 46, pp. 204–209, 1990.
[11] D. J. Eleveld, P. Colin, A. R. Absalom, and M. M. R. F. Struys, “Pharmacokinetic–pharmacodynamic model for propofol for broad application in anaesthesia and sedation,” Br. J. Anaesth., vol. 120, no. 5, pp. 942–959, May 2018, doi: 10.1016/j.bja.2018.01.018.
[12] S. Goutelle et al., “The Hill equation: A review of its capabilities in pharmacological modelling,” Fundamental and Clinical Pharmacology, vol. 22, no. 6. Blackwell Publishing Ltd, pp. 633–648, 2008, doi: 10.1111/j.1472-8206.2008.00633.x.
[13] G. Karer, V. Novak-Jankovič, A. Stecher, and I. Potočnik, “Modelling of BIS-Index Dynamics for Total Intravenous Anesthesia Simulation in Matlab-Simulink,” IFAC Pap., vol. 51, no. 2, pp. 355–360, 2018, doi: 10.1016/j.ifacol.2018.03.061.
[14] G. Karer, “Image-Based PSi Signal Acquisition from a Patient Monitor During a Medical Procedure,” Int. J. Priv. Heal. Inf. Manag., vol. 8, no. 1, pp. 70–87, Jan. 2020, doi: 10.4018/IJPHIM.2020010104:
[15] R. Smith, “An overview of the tesseract OCR engine,” in Proceedings of the International Conference on Document Analysis and Recognition, ICDAR, 2007, vol. 2, pp. 629–633, doi: 10.1109/ICDAR.2007.4376991.
[16] P. J. Manberg, C. M. Vozella, and S. D. Kelley, “Regulatory challenges facing closed-loop anesthetic drug infusion devices,” Clinical Pharmacology and Therapeutics, vol. 84, no. 1. Clin Pharmacol Ther, pp. 166–169, Jul. 2008, doi: 10.1038/clpt.2008.79.
[17] G. A. Dumont and J. M. Ansermino, “Closed-Loop Control of Anesthesia,” Anesth. Analg., vol. 117, no. 5, pp. 1130–1138, Nov. 2013, doi: 10.1213/ANE.0b013e3182973687.