Anesthesia, Closed-Circuit

Publication Title: 
Tierärztliche Praxis

Using the Stephens anaesthetic apparatus-which is a closed system with an in-circuit, nonprecision vaporizer-and isoflurane as anaesthetic gas, 18 rabbits were anaesthetized and showed sufficient hypnosis, analgesia, and muscle relaxation during bone surgery. Induction of anaesthesia was achieved with intravenous propofol and all rabbits were intubated afterwards.

Author(s): 
Henke, J.
Koch, M.
Brill, T.
Bolkart, B.
Janczewski, M.
Erhardt, W.
Publication Title: 
IEEE transactions on bio-medical engineering

A model-based closed-loop control system is presented to regulate hypnosis with the volatile anesthetic isoflurane. Hypnosis is assessed by means of the bispectral index (BIS), a processed parameter derived from the electroencephalogram. Isoflurane is administered through a closed-circuit respiratory system. The model for control was identified on a population of 20 healthy volunteers. It consists of three parts: a model for the respiratory system, a pharmacokinetic model and a pharmacodynamic model to predict BIS at the effect compartment. A cascaded internal model controller is employed.

Author(s): 
Gentilini, A.
Rossoni-Gerosa, M.
Frei, C. W.
Wymann, R.
Morari, M.
Zbinden, A. M.
Schnider, T. W.
Publication Title: 
Anesthesiology

BACKGROUND: Automatic control of depth of hypnosis using the Bispectral Index (BIS) can help to reduce phases of inadequate control. Automated BIS control with propofol or isoflurane administration via an infusion system has recently been described, a comparable study with isoflurane administration via a vaporizer had not been conducted yet. Our hypothesis was that our new model based closed-loop control system can safely be applied clinically and maintains the BIS within a defined target range better than manual control.

Author(s): 
Locher, Stephan
Stadler, Konrad S.
Boehlen, Thomas
Bouillon, Thomas
Leibundgut, Daniel
Schumacher, Peter M.
Wymann, Rolf
Zbinden, Alex M.
Publication Title: 
Anesthesiology

BACKGROUND: In contrast to hypnosis, there is no surrogate parameter for analgesia in anesthetized patients. Opioids are titrated to suppress blood pressure response to noxious stimulation. The authors evaluated a novel model predictive controller for closed-loop administration of alfentanil using mean arterial blood pressure and predicted plasma alfentanil concentration (Cp Alf) as input parameters. METHODS: The authors studied 13 healthy patients scheduled to undergo minor lumbar and cervical spine surgery.

Author(s): 
Luginbühl, Martin
Bieniok, Christian
Leibundgut, Daniel
Wymann, Rolf
Gentilini, Andrea
Schnider, Thomas W.
Publication Title: 
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference

Research has demonstrated the efficacy of closed-loop control of anesthesia using bispectral index (BIS) as the controlled variable, and the recent development of model-based, patient-adaptive systems has considerably improved anesthetic control. To further explore the use of model-based control in anesthesia, we investigated the application of fuzzy control in the delivery of patient-specific propofol-induced hypnosis. In simulated intraoperative patients, the fuzzy controller demonstrated clinically acceptable performance, suggesting that further study is warranted.

Author(s): 
Moore, Brett L.
Pyeatt, Larry D.
Doufas, Anthony G.
Publication Title: 
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference

This paper presents a robust closed-loop strategy for control of depth of hypnosis. The proposed method regulates the electroencephalogram (EEG)-derived WAVCNS index as a hypnosis measure by manipulating intravenous propofol administration.

Author(s): 
Hahn, Jin-Oh
Dumont, Guy A.
Ansermino, J.
Publication Title: 
Anesthesia and Analgesia

BACKGROUND: Research has demonstrated the efficacy of closed-loop control of anesthesia using bispectral index (BIS) as the controlled variable. Model-based and proportional-integral-derivative (PID) controllers outperform manual control. We investigated the application of reinforcement learning (RL), an intelligent systems control method, to closed-loop BIS-guided, propofol-induced hypnosis in simulated intraoperative patients. We also compared the performance of the RL agent against that of a conventional PID controller.

Author(s): 
Moore, Brett L.
Quasny, Todd M.
Doufas, Anthony G.
Publication Title: 
Anesthesia and Analgesia

Reinforcement learning (RL) is an intelligent systems technique with a history of success in difficult robotic control problems. Similar machine learning techniques, such as artificial neural networks and fuzzy logic, have been successfully applied to clinical control problems. Although RL presents a mathematically robust method of achieving optimal control in systems challenged with noise, nonlinearity, time delay, and uncertainty, no application of RL in clinical anesthesia has been reported.

Author(s): 
Moore, Brett L.
Doufas, Anthony G.
Pyeatt, Larry D.
Publication Title: 
Anesthesiology

BACKGROUND: This randomized controlled trial describes automated coadministration of propofol and remifentanil, guided by M-Entropy analysis of the electroencephalogram. The authors tested the hypothesis that a novel dual-loop controller with an M-Entropy monitor increases time spent within predetermined target entropy ranges.

Author(s): 
Liu, Ngai
Le Guen, Morgan
Benabbes-Lambert, Fatima
Chazot, Thierry
Trillat, Bernard
Sessler, Daniel I.
Fischler, Marc
Publication Title: 
Journal of Clinical Monitoring and Computing

To control the three components of general anesthesia (hypnosis, analgesia, and neuromuscular blockade), an automated closed-loop, anesthesia-drug delivery system (McSleepy) was developed. Bispectral index was used as the control variable for hypnosis, the analgoscore for analgesia, and phonomyography for neuromuscular blockade. McSleepy can be used to control the induction, maintenance and emergence from general anesthesia.

Author(s): 
Wehbe, Mohamad
Arbeid, Erik
Cyr, Shantale
Mathieu, Pierre A.
Taddei, Riccardo
Morse, Joshua
Hemmerling, Thomas M.
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