마취심도 평가지표 개선을 위한 뇌파 신호의 품질지수에 관한 연구

Abstract

Anesthesia is a treatment that induces temporary loss of cognitive ability to numbness or pain by drugs, and with the continuous development of various drugs since the successful anesthesia of surgical patients by using the first ether in the 18th century, anesthesia has been continuously researched and developed into a field of medical science The main purpose of performing anesthesia procedures during surgery is to relieve patients of psychological anxiety and fear of surgery, and to induce muscle relaxation to prevent them from recognizing labor pains despite strong external stimuli during surgery and to proceed with smooth treatment smoothly. Changes in the body by anesthesia are known as factors such as unconsciousness, numbness, muscle relaxation, and reflex suppression. As anesthesia progresses, there is no response to external stimuli or reflexes of the autonomic nervous system. Anesthesia can be largely divided into general anesthesia and general anesthesia. Part anesthesia is an anesthetic method that chemically blocks nerve conduction at the nerve end of the nerve traveling in the area by administering a local anesthetic to a specific part of the body while the patient's consciousness is awake, while general anesthesia, usually used in surgical operations, is an anesthesia method that eliminates consciousness or systemic perception by administering one or more anesthetic agents to suppress central nervousness. In the general anesthesia process, controlling effective sedation and loss of consciousness to the desired depth of the patient is a very important factor: the process of sedating the patient, i.e. controlling the depth of the anesthesia, which fails to control the depth of the anesthesia, resulting in a recall with pain, or unconsciousness of the occurrence of a recall without pain, or unconsciousness. In general, anesthetics expand blood vessels, and there are side effects that cause low blood pressure. Since these side effects can cause unexpected situations during medical procedures, the selection of the type of anesthetic and the amount of administration to control the anesthesia depth are of considerable importance, depending on the patient's condition and the type of surgery. To this end, quantitative measurement of anesthesia depth is highly necessary and important in that it can properly administer drugs needed for anesthesia and minimize side effects from over-capacity use. In the case of general anesthesia, since the level of anesthesia cannot be accurately determined through unconscious patients, the medical team evaluated and adjusted the level of anesthesia by using abnormal criteria such as response to verbal commands to check the loss of consciousness of the patient, loss of eyelid reflex, etc., and methods of determining clinical conditions, such as vital signs of the patient's ECG and body temperature. However, these methods had disadvantages that it was difficult to evaluate objective anesthesia depth because they could vary in response from individual patient to individual patient and were evaluated by clinical experience of the clinical workforce. The recent expansion of medical services not only at home but also abroad has led to an increase in the supply and demand of various medical services, resulting in more surgical procedures. Under these circumstances, the demand for quantitative anesthesia depth measurement is increasing, and research on the development of anesthesia depth parameters using bio-signals is also being actively carried out. Among them, methods for measuring the brain waves of patients during surgery to assess the anesthesia depth, such as SEF, Delta Ratio, and MF, have been developed and used in clinical trials such as the SEF, Delta Ratio, and MF, and Spectral index(BIS), of which BIS measures the changes in the brain waves objectively based on the results of research that inhalation anesthetic agent causes changes in brain waves. BIS can evaluate the anesthetic depth of anesthetized patients, especially the sedative sleep state, and is evaluated as a useful tool to evaluate the pain of patients during surgery, the anesthetic depth of anesthetized patients, especially the sedative sleep state, and has features that real-time observation of anesthetic depth is possible. However, BIS and various clinical indicators based on brain waves, which are small in size from several μV to tens of μV, are difficult to measure accurate brain waves because they can easily be affected by high frequencies during operation, such as electro-surgical devices used for incision or haemostasis during surgery, and also have problems that easily affect brain waves even if the effect is caused by various medical devices operated together. In this paper, a study was conducted to improve the extraction efficiency of parameters for quantitative anesthesia depth assessment during surgery, and to this end, experiments were conducted on the following series of processes. Research was conducted on the selection of groups subject to experiment, classification by anesthesia phase, brain wave data acquisition system, parameter extraction with frequency analysis method and nonlinear analysis method, classification for anesthesia depth assessment by anesthesia phase, and clinical significance assessment of classification results. This paper is composed of: Chapter 2 described the background of the research, including the study related to brain waves and the definition of anesthesia depth, and Chapter 3 described the methods of brain wave measurement and experimental methods for pre-treatment of signals. Chapter 4 dealt with the analysis of experimental results and the consideration of parameter extraction for the elimination of artifact. Finally, Chapter 5 describes the conclusion of this paper.