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Brain and Nerve No to Shinkei Volume 44, Issue 2 （February 1992）

Brain and Nerve 脳と神経 44巻2号（1992年2月発行）

Japanese English

原著

"高周波脳波ゆらぎ解析"によるDiazepamのヒト麻酔効果の評価 Electrophysiological Evaluation of Diazepam Anesthetic Effect by "Automated Fluctuation Analysis" of High Frequency EEG in Human 中田宗朝 ¹ , 六川二郎 ¹ , 湯佐祚子 ² , 奥田佳朗 ² Munetomo Nakata ¹ , Jiro Mukawa ¹ , Tosiko Yusa ² , Yoshiaki Okuda ² ¹琉球大学医学部脳神経外科 ²琉球大学医学部脳神経麻酔科 ¹Department of Neurosurgery, University of the Ryukyus School of Medicine ²Department of Anesthesiology, University of the Ryukyus School of Medicine キーワード： automated fluctuation analysis , high frequency EEG , Fast Fourier Transform , Lorentzian fluctuation , diazepam Keyword: automated fluctuation analysis , high frequency EEG , Fast Fourier Transform , Lorentzian fluctuation , diazepam pp.117-124

発行日 1992年2月1日 Published Date 1992/2/1

DOI https://doi.org/10.11477/mf.1406900294

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Abstract 文献概要
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　意識障害のない7名の脳神経外科患者を対象に，"高周波脳波ゆらぎ解析"により，ジアゼパム静注の麻酔効果を評価した。

　1.2Hzから1kHzの周波数帯域の頭皮脳波をフーリエ解析し，得られたPower Spectral Density（PSD）を両対数表示した。次にこのPSDを以下のダブルローレンツ数式にあてはめパラメーターを抽出した。S（f）＝S1／［1＋（f／f^c1）²］＋S2／［1＋（f／f^c2）²］｛S（f）；PSD．S1，S2：plateau level of the Initial andSecond Lorentz．f_c1，f_c2；corner or half power frequency of the Initial and Second Lorentz．｝

　ジアゼパム静注によりSecond Lorentzは経時的，用量依存的に低下し，入眠とともに消失し，覚醒とともに回復した。Initial Lorentzは皮質高次機能（言語，計算能力）が低下した時点で前頭優位のトポグラフィーパターンが消失し，睡眠深度の深まりとともに上昇し，覚醒とともに低下した。

"Automated fluctuation analysis" of human scalp EEG was made in order to evaluate anaesthetic effect of intravenous diazepam injection.

Seven patients without disturbed consciousness were utilized for this study. Analytical system is composed of high fidelity pre-amplifier and signal processor. After 10,000 amplification of the signal, A/D conversion and Fast Fourier Transform were programmed with following parameters, sweep time ; 12sec., frequency resolvability ; 1.2Hz, fre-quency limit ; lkHz, Fourier points : 2048 and Four-ier time ; 15. Power spectral density (PSD) was displayed on log-log graph. The best curve fitting program was next applied to the following equation, S (f)=S1/[1+(f/fc1)²]+S2/[1+(f/fc2)²] (S (f) : power spectral density, S1,S2 : plateau levels of the initial and the second Lorentz, fcl, fc2 : the corner or half power frequencies of the initial and the second Lorentz).

As results, 1) PSDs of high frequency EEG up to 1kHz were composed of double Lorentzian fluctua-tions. 2) From our previous animal study, it is sug-gested that the initial and the second Lorentz reflect the cortical and subcortical functions, respectively. 3) After diazepam injection, the second Lorentz was suppressed according to the time and dose and disappeared when the subjects fell asleep, and reappeared when waked up. There was excellentcorrelation between the consciousness level and the second Lorentz. 4) The initial Lorentz reflected higher cortical function ; the ability of calculation or language were reduced after diazepam injection, and the hyperfrontal activity of the initial Lorentz disappeared.

These results may suggest that "Automated Fluc-tuation Analysis" of high frequency EEG may have a potential to develop a new field in clinical neuro-electrophysiology.