Fiberoptic Pulmonary Artery Catheterを用いた運動負荷時，混合静脈血酸素飽和度の連続測定の意義—陳旧性心筋梗塞例を対象として

Continuous monitoring of mixed venous oxygen saturation during exercise using fiberoptic pulmonary artery catheter

　混合静脈血酸素飽和度（SvO₂）をphotodetectorつきのthermodilution,balloon tipped flowdirected catheter（opti-catheter）を用いて連続して測定することにより，運動中のSvO₂の変化を詳細に検討し，さらにSvO₂値より外的負荷最が実際に生体に及ぼしている運動強度を検討することを目的とした。陳旧性心筋梗塞5例および健常例1例を対象とし，自転車エルゴメータにて多段階定常漸増運動負荷を行い，opti-catheterによりSvO₂を連続測定した。SvO₂は負荷開始後平均43.4秒後より急激に減少を開始し，各負荷量約1.5分でほぼ定常状態に達した。60W負荷時SvO₂は44.7％と乳酸産性レベルより低下した。各々の症例でSvO₂値と心拍出量間には良い相関が得られた。opti-catheterは運動中のSvO₂変化の詳細な検討を可能とし，負荷の生体に対する影響を解析する有用な方法と考えられた。

We measured the mixed venous oxygen saturation (SvO₂) continuously using a fiberoptic thermodilution pulmonary artery catheter to analyze the time course of SvO₂ during exercise, and evaluated the relation-ship between SvO₂ and exercise load, SvO₂ and car-diac output. Five patients with old myocardial in-farction and one healthy man underwent pulmonary arterial catheterization and then performed an in- cremental steady state exercise test using a supine cycle ergometer. There was a rapid fall in SvO₂ 43.4±10.6 seconds after the start of exercise and new steady state were achieved 92.6±22.5 seconds after changing the exercise load. The value of SvO₂ at exercise load 60 watts were 44.7±9.8% and this value was under the level of lactic acid accumulation. SvO₂ correlates well with cardiac output by the thermodilution method in individual patienst. We conclude that a fiberoptic thermodilu-tion pulmonary artery catheter was useful to evaluate the dynamic changes of SvO₂ during exercise.