Japanese
Title胸部交感神経遮断下における心臓刺激伝導系に及ぼす各種吸入麻酔薬の影響
Subtitle原著
Authors村上富裕美*
Authors(kana)
Organization*北海道大学医学部麻酔学講座
Journal循環制御
Volume13
Number1
Page125-137
Year/Month1992/
Article原著
Publisher日本循環制御医学会
Abstract「要旨」交感神経(心臓枝)遮断下の心臓刺激伝導系に及ぼす吸入麻酔薬の影響を検討する目的で, イヌ59頭を使用して以下の2つの実験を行った. 実験1：胸部硬膜外麻酔による房室伝導抑制作用の要因を検討する. 実験2：星状神経節切除による交感神経遮断下で, 吸入麻酔薬が房室伝導に及ぼす影響を濃度依存性に検討する. フェンタニール5μg/kgおよび酸素(50%), 窒素(50%)投与下に以下のパラメータ：自発洞周期(SCL), 房室結節内興奮伝導時間(AH時間), ヒス-プルキンエ系興奮伝導時間(HV時間), 房室結節有効不応期(ERP), 房室結節機能的不応期(FRP)を測定し, 対照値とした. 実験1より1%リドカイン溶液0. 2ml/kg(2mg/kg)硬膜外注入では30分後にSCLは9%, AH時間は11%それぞれ延長し, FRPは15分後に5%以上の延長が認められた. 同程度の血中濃度を得るようにリドカインを静脈内に投与しても, SCL, AH時間, FRPは有意な変化を認めなかった. これらの結果より胸部硬膜外麻酔による房室伝導抑制作用は交感神経(心臓枝)遮断作用によるもので, 血中局所麻酔薬の直接作用ではないと考えられた. 実験2からは, 両側の星状神経節切除による交感神経遮断によって抑制された房室伝導は各種吸入麻酔薬の投与によりさらに抑制され, 両者併用の効果は相加的効果と考えられた. 吸入麻酔薬の種類では, エンフルレン, イソフルレン, ハロセンはその抑制効果に濃度依存性が認められたが, セボフルレンの抑制効果は軽度であり濃度依存性は認められなかった. 以上の結果から, 胸部硬膜外麻酔などにより胸部交感神経が遮断された状態での吸入麻酔薬の投与は, 胸部交感神経遮断と吸入麻酔薬の効果が相加的に作用し, 麻酔薬の種類によっては濃度が濃い場合には房室伝導はより強力に抑制されるため, 十分な注意が必要であることが示唆された.
Practice基礎医学・関連科学
Keywordsvolatile anesthetics, epidural anesthesia, thoracic sympathetic nerve block, stellate ganglion, ectomy, atrio-ventricular conduction
English
TitleEffects of volatile anesthetics on atrioventricular conduction during thoracic sympathetic nerve block
Subtitle
AuthorsFuyumi Murakami
Authors(kana)
OrganizationDepartment of Anesthesiology Holrkaido University School of Medicine
JournalCirculation Control
Volume13
Number1
Page125-137
Year/Month1992/
ArticleOriginal article
PublisherJapan Society of Circulation Control
AbstractThoracic epidural anesthesia (TEA) has usually been combined with volatile anesthetics in clinical practice. lt is well known that both TEA and volatile anesthetics have depressant effects on atrioventricular (AV) conduction and sinus node automaticity. Therefore, the present study was designed to investigate combined effects of either sevoflurane, isoflurane, enflurane or ha1othane and thoracic sym, pathetic nerve block on AV conduction. The following 2 sets of experiments were performed using 59 mongrel dogs anesthetized with thiamylal 25 mg/kg iv and fentanyl 5 μg/kg iv. Experiment 1：the author evaluated what causes the effects of TEA on cardiac electrophysiology, diminished cardiac sympathetic activity or direct pharmacological action of the circulating drug. Experiment 2：the author evaluated the combined effects of four different volatile anesthetics and thoracic sympathetic nerve block. The following variables were measured utilizing His bundle electrocardiogram：Sinus cycle length (SCL), AV conduction time (AV interval), His-ventricle conduction time (HV interval), effective and functional refractory period of AV node (ERP and FRP). From experiment 1, it was confirmed that the depressant effects of TEA on intracardiac conduction were caused by not direct pharmacological action of the circulating drug, but blocking of the sympathetic efferent activity. In experiment 2, the author performed bilateral stellate ganglionectomy (SGn) to obtain stable and continuous effects of thoracic sympathetic nerve block. From the comparison between bilateral SGn and bilateral stellate ganglion block (SGB) with 1% lidocaine 2 ml, the effects of SGn was similar to those of SGB on AV conduction. The combined effects of volatile anesthetics and thoracic sympathetic nerve block by SGB were evaluated and proved to be additive on AV conduction. Isoflurane, enflurane and halothane suppressed intracardiac conduction in a concentration-dependent manner, and their effects were more than sevoflurane. It may be suggested that caution should be necessary in administering high cont centrations of volatile anesthetics when thoracic sympathetic nerve is already blocked.
PracticeBasic medicine
Keywordsvolatile anesthetics, epidural anesthesia, thoracic sympathetic nerve block, stellate ganglion, ectomy, atrio-ventricular conduction

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