| Abstract | 「要旨」気管内チューブより心拍動に伴う気体の流量変化を呼吸気流計で測定すると, 心収縮により生ずると思われる陰性波(A-B), と肺循環系の関与が考えられる陽性波(B-C)からなる気管内心機図(ITCG-F)がえられる. はじめにA-B, B-Cの発生機序を知る目的で, 7頭の雑種成犬に, 肺動脈閉塞用カテーテルを用い, 上行大動脈を閉塞すると, A-Bは50%(P<0.01)減少し, 心収縮との関連を示したが, 肺動脈閉塞では, B-Cが18.6%(P<0.2)の減少傾向を示すのみで有意の変化はえられず, 肺動脈閉塞実験からは肺循環系の関与が明らかにできなかった. 次に10頭の雑種成犬にイソプロテレノール, フェニレフリソ, デキストラン, プロプラノロールを投与, 他の12頭に静脈内空気注入を行い, 肺空気塞栓を作成し, B-Cの発生メカニズム, およびA-Bの心機能評価について更に検討を加えた. フェニレフリン, デキストラン, 肺空気塞栓により肺動脈圧を上昇させると, B-C成分はそれぞれ51%(P<0.01), 44%(P<0.01), 126%(P<0.01)と増加し, 平均肺動脈圧とB-Cのあいだに相関が認められ(r=0.625, P<0.05), B-Cの形成に肺動脈圧の影響が大きく関与していることがわかった. A-Bと心機能との関連について, ITCG-FのA-Bの一次微分値max dF/dtはイソプロテレノール投与により68%(P<0.01)増加し, プロプラノロール投与では43%(P<0.01)減少したが, デキストラン, フェニレフリンでは有意な変化は示さなかった. 臨床では, ハロセン吸入濃度1.0%でmax dF/dtは136%, (P<0.05), 2.0%で54%(P<0.01)減少しており, ITCG-Fのmax dF/dtは心筋の収縮性の変化を反映する. |
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| Abstract | 「Abstract」During endotracheal anesthesia there is a movement of gas through the trachea with cardiac cycle. We have measured this change by pneumotachograph and named this an intratracheal cardiogram (ITCG-F). We have analyzed ITCG as a non-invasive means of assessing cardiac function during anesthesia. In order to evaluate the genesis of ITCG, experimental study was performed using canine. Seven mongrel dogs were prepared with Dotter Lucas balloon catheter for aortic and pulmonary arterial occlusion. Isoproterenol, phenylephrine, dextran and propranolol were given respectively to ten other mongrel dogs when hemodynamic parameters were stabilized to control value after administration of each drug. Twelve other dogs were infused air causing experimental pulmonary air embolism. In clinical study, six patients were anesthetized with nitrous oxide, oxygen and 1.0 per cent or 2.0 per cent halothane for ten minutes in order to evaluate cardiac performance by the ITCG. The negative wave was reduced by ascending aortic occlusion, so, it was considered that this wave concerned left ventricular contraction. On the other hand, pulmonary arterial occlusion yielded no significant change on ITCG-F, but the positive wave correlated with elevation of pulmonary arterial pressure by administration of phenylephrine, dxtran and air. As a result, the positive wave of ITCG-F revealed more augmented pulsation of the precapillary arteries potentiated by high PAP than capillary pulsation. Maximum differential value (max dF/dt) increased by isoproterenol and decreased by halothane or propranolol, but phenylephrine and dextran did not show any significant changes. This evidence revealed the possibility of the negative wave of ITCG-F being related to left ventricular contraction velocity. |
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