慢性心不全患者における運動時動脈血酸素飽和度測定の意義—Pulse oxymeterを用いて

Significance of Arterial Oxygen Saturation Estimations during Exercise in Patients with Chronic Heart Failure:Using Pulse Oxymeter

　慢性心不全患者の運動時に連続的に動脈血酸素飽和度（SaO₂）を測定し，その測定意義について検討した．対象は心不全患者16名（平均年齢63±11歳）で，健常者12名（平均年齢60±12歳）を対照とした．方法は全例にトレッドミルによる多段階運動負荷試験を行い，同時にパルスオキシメーターを用いSaO₂を連続測定した．また，心不全群では安静時の血中ノルアドレナリン濃度とANP濃度を測定した．心不全患者は，運動時に3％以上のSaO₂下降を示す高度低下群（6名）と3％未満の軽度低下群（10名）に分類できた．一方，対照群では運動にて変化しなかった．高度低下群は軽度低下群に比しNYHA心機能分類III度の頻度が多く，血中ノルアドレナリン濃度とANP濃度が有意に上昇しており，重症例と推察された．したがって，今回の検討では，慢性心不全患者の運動時のSaO₂下降を非観血的に測定することが可能で，心肺機能障害の重症度の評価に有用であることを明らかにした．

Serial changes in arterial oxygen saturation during treadmill exercise was measured with a pulse oxymeter in 16 patients with chronic heart failure and in 12 con-trols. Control subjects showed no appreciable changes in oxygen saturation during exercise. In patients with heart failure, 6 showed a fall in oxygen saturation by 3% or more during exercise, while the remaining 10 patients did not show any exercise-induced fall in oxy-gen saturation. As compared with those showing no fall in oxygen saturation, patients with a fall in oxygen saturation were more frequently associated with short-ness of breath as end-point. Plasma level of ANP and norepinephrine at rest were significantly higher in patients with a fall in oxygen saturation.

These observations suggest that exercise-induced fall in arterial saturation could be detected by a pulse oxymeter in patients with chronic heart failure and is a useful index of the severity of heart failure.