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Adaptive smith predictor controller for total intravenous anesthesia automation
Bhavina Patel,Hiren Patel,Pragna Vachhrajani,Divyang Shah,Alpesh Sarvaia 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.1
Anesthetic agent propofol needs to be administered at an appropriate rate to prevent hypotension and postoperative adversereactions. To comprehend more suitable anesthetic drug rate during surgery is a crucial aspect. The main objective of thisproposal is to design robust automated control system that work effi ciently in most of the patients with smooth BIS andminimum variations of propofol during surgery to avoid adverse post reactions and instability of anesthetic parameters. And also, to design advanced computer control system that improves the health of patient with short recovery time and lessclinical expenditures. Unlike existing research work, this system administrates propofol as a hypnotic drug to regulate BIS,with fast bolus infusion in induction phase and slow continuous infusion in maintenance phase of anesthesia. The novelty ofthe paper lies in possibility to simplify the drug sensitivity-based adaption with infusion delay approach to achieve closedloopcontrol of hypnosis during surgery. Proposed work uses a brain concentration as a feedback signal in place of the BISsignal. Regression model based estimated sensitivity parameters are used for adaption to avoid BIS signal based frequentadaption procedure and large off set error. Adaptive smith predictor with lead–lag fi lter approach is applied on 22 diff erentpatients’ model identifi ed by actual clinical data. The actual BIS and propofol infusion signals recorded during clinical trialswere used to estimate patient’s sensitivity parameters EC 50 and λ . Simulation results indicate that patient’s drug sensitivityparameters based adaptive strategy facilitates optimal controller performance in most of the patients. Results are obtainedwith proposed scheme having less settling time, BIS oscillations and small off set error leads to adequate depth of anesthesia. A comparison with manual control mode and previously reported system shows that proposed system achieves reductionin the total variations of the propofol dose. Proposed adaptive scheme provides better performance with less oscillation inspite of computation delay, surgical stimulations and patient variability. Proposed scheme also provides improvement inrobustness and may be suitable for clinical practices.
Control strategy with multivariable fault tolerance module for automatic intravenous anesthesia
Patel Bhavina,Patel Hirenkumar,Shah Divyang,Sarvaia Alpesh 대한의용생체공학회 2020 Biomedical Engineering Letters (BMEL) Vol.10 No.4
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.