1,720,973 research outputs found
Experimental Results of an Optimized PID Controller for General Anesthesia with Adjustable Opioid-Hypnotic Balance
No full textClosed-loop control of total intravenous anesthesia (TIVA) is an emerging technology expected to have a significant impact on clinical practice in the upcoming years. However, for these systems to become widely acceptable in clinical practice, they should not aim to replace the anesthesiologist; instead, they must act as tools capable of enhancing the abilities of the clinician. Thus, it is important to develop control structures that allow the human operator to adjust the behavior of the controller based on clinical considerations. In the clinical practice of TIVA, balanced anesthesia is a technique that involves properly dosing the administration of propofol and remifentanil to optimize the therapeutic effect of each drug while minimizing their individual side effects. The anesthesiologists perform this technique by regulating the ratio between the infusion rates of these two drugs, known as the opioid-hypnotic balance. In this paper, we present and discuss the experimental results obtained with a PID-based control architecture for propofol and remifentanil co-administration where such a controller has a tuning parameter that can be regulated by the anesthesiologist to achieve the desired opioid-hypnotic balance
On the practical use of a PID-based control scheme for automatic control of general anesthesia
No full textDespite 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
Event-based MPC for propofol administration in anesthesia
Full text linkBackground 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
On the use of the Eleveld PK/PD model for the design of PID control of anesthesia
No full textThis paper investigates the use of different pharmacokinetic/parmacodynamic models for the design of a PID-based control structure for total intravenous anesthesia. In particular, a PID controller tuned by exploiting the Schnider model for propofol administration (which has been developed for adults) in order to ensure the required robustness and performance is evaluated by considering patients modelled by using the recently developed Eleveld model. The latter is more general and, in principle, takes into account children, adults and elderly people. Simulation results show that clinically acceptable performance are obtained, disregarding the adopted model, for children and adults. On the contrary, the use of the Eleveld model to tune the controller for elderly people, for which a significant delay emerges, requires further investigation
MPC for Propofol Anesthesia: the Noise Issue
Full text linkThe 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
Experimental Evaluation of Analgesia With an Event-Based PID Control Strategy for Anesthesia
Full text linkThe recent introduction of the Conox monitoring system in the clinical practice of total intravenous anesthesia (TIVA) has opened new research opportunities. Indeed, it provides the qCON and the qNOX indexes, which give a measure of hypnosis and analgesia, respectively. This letter presents the first experimental results of closed-loop anesthesia performed by using the Conox monitoring system. In particular, we exploited the qCON as the feedback variable for an event-based PID multiple-input single-output (MISO) controller and we recorded the qNOX to evaluate analgesia. Clinical experiments have been performed on four patients undergoing general anesthesia for elective plastic surgery. The controller demonstrated a satisfactory performance in maintaining qCON within the desired range for all patients. An optimal qNOX level has also been achieved in three out of four cases, while, in one patient, the qNOX level indicated a slight excess of analgesia. These findings suggest that the proposed MISO architecture is effective in providing adequate levels of hypnosis and analgesia and that, in future works, the qNOX information could be leveraged in the controller design to enhance analgesia control
Blending Physics and Data to Model Hemodynamic Effects Under General Anesthesia
No full textGeneral anesthesia, typically induced using a combination of hypnotic (propofol) and analgesic
(remifentanil) drugs, is crucial for the success of surgical procedures, but it can cause dangerous
cardiovascular side effects. In this context, models and simulations offer new opportunities to
address the intrinsic complexity of the process, accelerating advances and innovation in the
technology of anesthesia. This study aims to improve the modeling of hemodynamic effects under
general anesthesia by expanding the applicability of a recent mechanistic model in combination
with data-driven modules. In particular, we use a dataset related to plastic surgery for both
model calibration and testing, preserving the physical interpretability of the mechanistic model
while integrating it with data-driven components to enhance its predictive capabilities. The
results demonstrate a significant improvement in the model ability to simulate hemodynamic
variables under surgical conditions, offering potential applications for anesthesia monitoring and
control systems design that consider the patient’s cardiovascular safety. This enhanced hybrid
model provides a more accurate representation of the complex interactions between anesthetic
drugs and cardiovascular dynamics in real surgical settings
Performance evaluation of an optimized PID controller for propofol and remifentanil coadministration in general anesthesia
No full textIn 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
No full textThis 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
In Vivo Performance Evaluation of an FOPID Controller for Closed-Loop Anesthesia
No full textIn this article, we design and evaluate a fractional-order proportional-integral-derivative (FOPID) controller for the regulation of total intravenous anesthesia (TIVA). In particular, the FOPID controller has been designed to regulate the patient’s depth of hypnosis (DoH), measured via the bispectral index (BIS) monitor, by coadministrating both the hypnotic and analgesic drugs used in TIVA. Separate tunings are obtained for the induction phase and for the maintenance phase. For the former, a methodology based on the minimization of the integrated absolute error (IAE) has been employed, while for the latter, the isodamping design approach has been applied. Experiments carried out on ten patients undergoing plastic surgery show that the FOPID controller meets the clinical requirements for each one of the ten patients without requiring any manual intervention from the anesthesiologist. Notably, the controller provided a fast rejection of disturbances without provoking harmful overdosing episodes
- …
