Event-based MPC for propofol administration in anesthesia

Background and Objective : The automatic control of anesthesia is a demanding task mostly due to the presence of nonlinearities, intra- and inter-patient variability and specific clinical requirements to be meet. The traditional approach to achieve the desired depth of hypnosis level is based on knowledge and experience of the anesthesiologist. In contrast to a typical automatic control system, their actions are based on events that are related to the effect of the administrated drug. Thus, it is interesting to build a control system that will be able to mimic the behavior of the human way of actuation, simultaneously keeping the advantages of an automatic system.Methods : In this work, an event-based model predictive control system is proposed and analyzed. The nonlinear patient model is used to form the predictor structure and its linear part is exploited to design the predictive controller, resulting in an individualized approach. In such a scenario, the BIS is the controlled variable and the propofol infusion rate is the control variable. The event generator governs the computation of control action applying a dead-band sampling technique. The proposed control architecture has been tested in simulation considering process noise and unmeasurable disturbances. The evaluation has been made for a set of patients using nonlinear pharmacokinetic/pharmacodynamic models allowing realistic tests scenarios, including inter- and intra-patient variability.Results For the considered patients dataset the number of control signal changes has been reduced of about 55% when compared to the classical control system approach and the drug usage has been reduced of about 2%. At the same time the control performance expressed by the integrated absolute error has been degraded of about 11%.Conclusions : The event-based MPC control system meets all the clinical requirements. The robustness analysis also demonstrates that the event-based architecture is able to satisfy the specifications in the presence of significant process noise and modelling errors related to inter- and intra-patient variability, providing a balanced solution between complexity and performance. (c) 2022 Elsevier B.V. All rights reserved

MPC for Propofol Anesthesia: the Noise Issue

The design of automatic control systems for general anesthesia is a challenging task due to the severe safety requirements and process constraints. This is even more complex when model-based control techniques are used due to the significant variability of the process model. Additionally, issues like noisy measurements and interference also influence the control system overall performance. In this context, adequate filtering and control system sampling period selection should be analyzed to test their influence on the controller. In this paper, an MPC system for the depth of hypnosis, where the BIS signal is used as a controlled variable, is analyzed. The main purpose is to test and evaluate how the process noise affects the performance of the control system. The analysis is performed in a simulation study using a dataset of virtual patients representative of a wide population. Results show that a satisfactory performance is obtained when the noise is explicitly taken into account in the controller tuning procedure for a specific sampling period

On the practical use of a PID-based control scheme for automatic control of general anesthesia

Despite promising results have been obtained in clinical trials, closed-loop control systems for general anesthesia are not routinely used in the clinical practice yet. One of the possible reasons is that problems related to their practical implementation are not fully solved. In particular, a control system must be able to cope with manual interventions from the anesthesiologist and to operate with different devices commonly available in surgery rooms. In this paper we present experimental results where a PID-based control system has been tested when drug boluses are manually administered by the anesthesiologist and when different syringe pumps are used. The performance of the control system has been assessed on a group of nine patients undergoing elective plastic surgery. Results demonstrate that the control system is capable to handle these practical issues and it is therefore suitable to be used in the clinical practice

Experimental Results of an MPC Strategy for Total Intravenous Anesthesia

In this paper we present experimental results obtained by applying a Model Predictive Control strategy for the control of Depth of Hypnosis in general anesthesia. In particular, the Bispectral Index Scale is employed as the controlled variable and the administration of the hypnotic drug propofol is determined by applying a Generalized Predictive Control algorithm, which considers a process model that is linearized by means of an external predictor. The results of four patients who underwent elective plastic surgeries are analyzed and discussed, showing the feasibility of the approach in a practical context

Performance evaluation of an optimized PID controller for propofol and remifentanil coadministration in general anesthesia

In this paper we present the preliminary clinical results obtained with a PID control scheme for propofol and remifentanil coadministration during general anesthesia. The bispectral index scale is the only process variable, and the extra degree of freedom in the control architecture is handled by introducing an appropriate ratio between the infusion rates of the two drugs. The parameters of the PID controller are selected by means of an optimization procedure. The proposed control system automatically handles both the induction and the maintenance phase by using two different set of tuning parameters, specifically optimized for each phase, and a gain scheduling approach. The preliminary clinical evaluation of our controller has been obtained on ten patients undergoing general anesthesia during plastic surgery. The system has been able to satisfactorily induce and maintain anesthesia in the entire population of patients, without requiring any manual intervention by the anesthesiologist, thus confirming the effectiveness of the overall design approach

Event-based PID Control for Anesthesia Administration: Effect on Hemodynamic Variables

This paper aims to investigate the effects of an event-based Proportional-Integral-Derivative control system for propofol and remifentanil coadministration on hemodynamics variables in general anesthesia. The validity of the considered control system with respect the anesthetic variables has already been proven in previous works. Here hemodynamic variables are also analyzed by using a specifically devised simulator. In general anesthesia, the balance between propofol and remifentanil is a key factor to optimize the automatic infusion of anesthesia during long and invasive surgical procedures. Indeed, the possibility given by the control system to change the ratio between the infusion rates of the two drugs during the surgery allows the anesthesiologist to handle the patient's hemodynamics in each situation, thus, providing an improved healthcare. Results obtained from simulations suggest that the devised control solution can provide a suitable depth of hypnosis of the patients by always keeping the hemodynamic variables inside their recommended values

Randomized Evidence for Reduction of Perioperative Mortality: An Updated Consensus Process

Of the 230 million patients undergoing major surgical procedures every year, more than 1 million will die within 30 days. Thus, any nonsurgical interventions that help reduce perioperative mortality might save thousands of lives. The authors have updated a previous consensus process to identify all the nonsurgical interventions, supported by randomized evidence, that may help reduce perioperative mortality

Optimized PID control of propofol and remifentanil coadministration for general anesthesia

© 2018 Elsevier B.V. A closed-loop control system for the control of the depth of hypnosis in anesthesia by using propofol-remifentanil coadministration and the Bispectral Index as feedback signal is proposed. A PID controller is employed together with a fixed ratio between propofol and remifentanil infusions. The ratio allows the anesthesiologist to control the opioid-hypnotic balance during surgery. Optimal tuning rules for the proposed controller are obtained off-line by using the particle swarm optimization method and by considering a given dataset of patients and a wide range of infusion ratios that covers a rich set of scenarios that might occur in clinical practice. Finally, a gain scheduling strategy guarantees the optimality of the performance both for the induction and the maintenance phase. A Monte Carlo approach is used to evaluate the robustness of the method with respect to intra- and inter-patient variability