Investigation of changes in EEG at sedation level and development of the monitor for sedation

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K10557
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Anesthesiology
• Research Institution: Kansai Medical University (2017-2018); Osaka University (2015-2016)
• Principal Investigator: HAGIHIRA SATOSHI 関西医科大学, 医学部, 教授 (90243229)
• Co-Investigator(Kenkyū-buntansha): 高階 雅紀 大阪大学, 医学部附属病院, 講師 (30221352)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 脳波 / 鎮静 / 睡眠紡錘波 / 脳波バイコヒーレンス

Outline of Final Research Achievements

Electroencephalogram (EEG) at awake state is generally β wave dominant. During induction of anesthesia β power transiently increased ("β activation"), after that spindle activity (α power) then became predominant at surgical level of anesthesia. In deeper anesthetic level, θ and δ activity became dominant. This was simply described by watching the changes of power spectrum of EEG. Currently, we carefully observed the changes of raw EEG as well as EEG power spectrum, when we gradually increased or decreased the concentration of propofol during induction or recovery from anesthesia. We found that "β activation" was the beginning of increase in spindle activity, but not the simple increase of the power of β wave observed in awake state. Changing pattern of the peaks in EEG bicoherence obtained from bispectral analysis revealed that peak frequency of EEG bicoherence changed in relation with power spectrum. At the rising edge of EEG bicoehrence, its peak was in β range.

Free Research Field

麻酔・蘇生学

Academic Significance and Societal Importance of the Research Achievements

鎮静は侵襲的な検査や，区域麻酔などに併用して広く行われているが，適切な鎮静を保つことは容易ではない．浅すぎる鎮静では患者が不穏になったりする一方で過度の鎮静は呼吸抑制など重篤な問題を生じる危険性がある．客観的な鎮静の指標を作ることは適切な鎮静を得るために非常に重要である．今回の研究では十分に有用な指標を作る所までは到達できなかったが，鎮静レベルにおいて麻酔薬濃度に対する脳波変化を注意深く観察し解析することで，ある程度まで鎮静レベルを判断するための基礎データを得ることができたと考えている．