Adaptive smith predictor controller for total intravenous anesthesia automation

Effect of Combined Spinal-Epidural Anesthesia and Total Intravenous Anesthesia on Hemodynamics and Pregnancy Outcomes of Severe Preeclampsia Pregnant Patients Undergoing Cesarean Section

OBJECTIVE

The purpose of the study was to investigate the effect of combined spinal-epidural anesthesia (CSEA) and total intravenous anesthesia (TIVA) on hemodynamics and pregnancy outcomes of severe preeclampsia pregnant patients undergoing cesarean section.

METHODS

126 patients with severe preeclampsia admitted to Zhangqiu District People's Hospital from August 2018 to August 2019 were selected as the study subjects and randomly divided into the experimental group (n = 63) and control group (n = 63). After undergoing cesarean section, the patients in the experimental group received CSEA, while those in the control group were given TIVA. After that, the effect of different anesthesia methods on the hemodynamics and pregnancy outcomes of pregnant women was compared.

RESULTS

There were no significant differences in age, BMI value, weight, height, gestational weeks, SBP, DBP, and residence between the two groups (P > 0.05). The operation duration, the onset time of anesthesia, and delivery time in the experimental group were significantly shorter than those in the control group, with less intraoperative blood loss in the experimental group than that in the control group (P < 0.001). In both groups, MAP and SpO₂ during delivery were significantly lower than those before anesthesia, and HR was significantly higher than that before anesthesia (P < 0.001). In the experimental group, MAP and HR during delivery were significantly lower than those in the control group, and SpO₂ was significantly higher than that in the control group (P < 0.001). The total effective rate of anesthesia in the experimental group was significantly higher than that in the control group (P < 0.05). The Apgar scoring of the newborns in the experimental group was significantly higher than that in the control group (P < 0.001), and the total incidence of postoperative adverse reactions in the experimental group was significantly lower than that in the control group (P < 0.05).

CONCLUSION

CSEA is a reliable anesthesia method for improving the hemodynamics indicators in pregnant patients with severe preeclampsia; such strategy greatly increases the Apgar score of newborns and shortens the anesthesia onset time. Further research will be conducive to establishing a better anesthesia plan for such patients.

Smart syringe using actuator and force sensor for epidural anesthesia injection

The anesthesia process in the epidural space is quite difficult as it requires a high level of skill. Therefore, a medical accident occurs, and intensive training is required. In order to reduce these medical accidents, medical technology is being developed, which provides safe and accurate treatment services. This paper proposes a smart syringe design for safe and accurate anesthesia in the epidural space. The smart syringe is designed to measure the electrical sensing waveform by using a sensor instead of the sense of the hand during anesthesia and show the position of the needle through external monitoring. To design a smart syringe, a force sensor, actuator, and CPU were used, and a 3D printer was used to produce the outer shape. An animal test was conducted to evaluate the performance test of the smart syringe, and satisfactory results were obtained by measuring the needle insertion process of the smart syringe and the position of the needle through the animal experiment.

An enhancement in series cascade control for non-minimum phase system

This work reveals an Internal Model Control (IMC)-based series cascade control for the non-minimum phase and time delay process. The combination of a higher-order fractional IMC filter and inverse response compensator for designing the outer loop controller illustrates the uniqueness of this work. For the time delay term, a higher-order approximation is considered. The standard IMC-PID structure adopts for the inner loop controller design. While the higher-order fractional filter coupled with inverse response compensator takes for the design of the outer loop controller. The suggested scheme demonstrates enhanced exhibition for setpoint tracking and disturbance rejection. Moreover, the sensitivity analysis is also accomplished to determine the robustness of the closed-loop system under process parameter variations.

A comparative study of various Smith predictor configurations for industrial delay processes

Efficient control of industrial delay processes is a challenging problem in the field of process control. Time delays are generally experienced in industrial processes from distance velocity lags, composition analysis loops, recycle time, mass, and energy transportation time. A high time delay adds a large phase lag to the system, thereby affecting the closed-loop control system stability and thus not easily controlled with PID approach. Smith predictor (SP) is a prominent technique based on process model for processes with high time delay. Unfortunately, the performance of SP deteriorates when the plant model is inaccurate. To overcome the problems related to conventional SP, various modifications have been suggested over the years in terms of structure alterations and controller parameters tuning improvements. This paper focuses on a comparative study of various Smith predictor configurations available in the literature for controlling inverse, integrating, stable and unstable industrial processes with time delay.

Control strategy with multivariable fault tolerance module for automatic intravenous anesthesia

In the anesthesia automation, an automatic propofol infusion system uses Bi-spectral Index Signal (BIS) as a primary feedback signal to manipulate propofol dose. However, the BIS signal may be suspended for some time due to poor EEG signal quality, noise, and many other factors. Therefore, BIS signal failure may be the main cause of inadequate propofol infusion. This fact motivates the need for integration of multivariable fault tolerance module (MFTM) and fractional-order Smith predictor controller to avoid adverse reactions of inadequate propofol dosing during BIS failure. Smith Predictor control strategy is sufficiently robust to predict feedback BIS during BIS failure via patient pharmacological modeled BIS. However, modeled BIS may not provide a guarantee of adequate propofol infusion during BIS failure and especially in the presence of hypotension and hypertension. Thus, the proposed control strategy is designed with MFTM to detect BIS sensor fault and to estimate feedback BIS during BIS failure. Further, the proposed control strategy is designed with a multivariable pharmacological patient model to analyze the cross effect of propofol infusion on BIS and hemodynamic variables. The robustness of the proposed control strategy is tested in the presence of noxious surgical stimulation, BIS sensor fault and heavy hemodynamic disturbance. The pharmacological parameters and recorded signals of 30 patients during various surgeries have been used to validate simulated results. The performance of the proposed control strategy assures optimization and smooth propofol infusion during BIS failure. The proposed system provides stability for a wide range of physiological parameters range. The proposed scheme maintains smooth BIS and MAP signal despite the delay, BIS sensor fault, and surgical disturbances.

Multi-model generalised predictive control for intravenous anaesthesia under inter-individual variability

Inter-individual variability possesses a major challenge in the regulation of hypnosis in anesthesia. Understanding the variability towards anesthesia effect is expected to assist the design of controller for anesthesia regulation. However, such studies are still very scarce in the literature. This study aims to analyze the inter-individual variability in propofol pharmacokinetics/pharmacodynamics (PK/PD) model and proposed a suitable controller to tackle the variability. This study employed Sobol' sensitivity analysis to identify significance parameters in propofol PK/PD model that affects the model output Bispectral Index (BIS). Parameters' range is obtained from reported clinical data. Based on the finding, a multi-model generalized predictive controller was proposed to regulate propofol in tackling patient variability. [Formula: see text] (concentration that produces 50% of the maximum effect) was found to have a highly-determining role on the uncertainty of BIS. In addition, the Hill coefficient, [Formula: see text], was found to be significant when there is a drastic input, especially during the induction phase. Both of these parameters only affect the process gain upon model linearization. Therefore, a predictive controller based on switching of model with different process gain is proposed. Simulation result shows that it is able to give a satisfactory performance across a wide population. Both the parameters [Formula: see text] and [Formula: see text], which are unknown before anesthesia procedure, were found to be highly significant in contributing the uncertainty of BIS. Their range of variability must be considered during the design and evaluation of controller. A linear controller may be sufficient to tackle most of the variability since both [Formula: see text] and [Formula: see text] would be translated into process gain upon linearization.