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Title: Interpatient and Intra-Patient Variability Compensation in Regulation of Hypnosis based on Modern Control of Propofol Anaesthesia Administration
Authors: Ilyas, Muhammad
Keywords: Engineering & Technology
Issue Date: 2019
Publisher: COMSATS University, Islamabad.
Abstract: Regulation of hypnosis level on bispectral index monitor (BIS) during surgical procedure in Propofol anesthesia administration is a challenging task for anesthesiologist in multi-tasking environment of operation theatre. As the surgical procedure gets prolonged due to medical complications, the responsibility of anesthesiologist is increased due to variations in the physiological conditions of the patient. Patients of different age, height, weight and gender shows different responses to anesthetics due to sensitivity and medical disorders. Manual administration of anesthetics causes severe medical issues due to overdosing and underdosing of these drugs during surgery. If the amount of drug infusion exceeds beyond the certain limits, it causes increase in heart rates, blood pressure variation and glucose level distress. Similarly in case of insufficient infusion causes vomiting, anxiety and consciousness during surgery. All these variations beyond the certain limit are intolerable for successful conduction of surgery. In the current thesis control strategy is developed to keep the hypnosis level between required bounds on BIS and to compensate different challenges like interpatient and intra-patient variability as well. The designed control mechanism is based on a set of states equations derived from pharmacokinetic and pharmacodynamic models, which describes different behaviours and responses of the patient to propofol infusion. Induction and maintenance of anesthesia in feedback control system depends on the wavelet anesthetic value for central nervous system (𝑊𝐴𝑉 ). The first order SMC is designed and shows considerable performances and their limitations is discussed in term of steady state error. Super-twisting sliding mode control (STSMC) is applied due to its less sensitivity towards patient parameters. Second advantage of STSMC is its robustness as compared to other control techniques such as predicative control in the presence of bleeding, which is a surgical stimulus. STSMC shows optimum results and removes the chattering problem in hypnosis level on BIS. The performance of STSMC is investigated to achieve the desired hypnosis level during xi induction, maintenance and emergence phase of anesthesia. The metabolism shown in results presents the plasma drug concentration in different compartment of the body. The controller input is analyzed clinically for different silico patient shows pulsating behaviour. The states of the system in three compartmental models are the plasma drug concentration not measurable parameters. The luenburger observer is designed based on different algorithems provides optimum results to estimates the states of compartmental model accurately. Performance of observer is analyzed in terms of error convergence based on gain scheduling mechanism. Intra-patient variability consists of surgical stimuli is perturbation occurred during surgery reduces the depth of anesthesia directs to consciousness of the patient including skin incision, surgical diathermy and larnogscopy. The achieved results are evaluated and analyzed clinically considering all complications as well as limitations during regulation of the hypnosis level in the presence of surgical stimuli by designing STSMC. The depth of hypnosis level is maintained to 50 on BIS level in maintenance phase after improving the induction phase to 40 seconds with STSMC. Moreover, the surgical stimuli direct the hypnosis level toward the state of consciousness, stimulates the controller to provide continuous drug infusion in interval 80 to 90 seconds. Simulation results witness that an oscillatory behaviour is observed in drug infusion to ensure the moderate level of hypnosis (40-60) for general surgery. The results achieved in presence of surgical stimulus being compared with BIS level investigated in open loop surgical procedure conducted in Hayatabad Medical Complex.
Gov't Doc #: 18771
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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