網膜動脈閉塞症に対するCO2吸入療法

Inhalation of carbon dioxide in the treatment of retinal artery occlusion

　目的：急性期の網膜中心動脈閉塞症の治療として二酸化炭素（CO₂）と酸素の混合吸入療法で，動脈血のCO₂分圧を反映する終末呼気のCO₂濃度を計測しながら吸入CO₂濃度を調節すること。対象と方法：網膜中心動脈閉塞症4例と網膜動脈分枝閉塞症4例を対象とした。年齢は68歳から87歳で，平均76.7歳である。麻酔器を使ったマスク換気下で，CO₂と酸素の混合気体を投与し，終末呼気濃度が動脈拡張に有効で安全と思われる45〜60mmHgの範囲になるように吸入CO₂を調節した。1回の吸入は15分とし，日中は2時間ごと，夜間は3時間ごとに，改善が認められるまで，発症から48時間を限度として行った。全例に眼圧下降療法と血栓溶解剤などの点滴を併用した。結果：適切な吸入CO₂濃度には個人差があり10〜14％で，同一症例でも変動があった。視力は網膜中心動脈閉塞症1例と網膜動脈分枝閉塞症4例で改善した。結論：呼気のCO₂濃度を計測しながらCO₂と酸素の混合気体を投与する新しい方法は，網膜動脈閉塞症の初期治療として有効である。

Purpose: To evaluate carbon dioxide inhalation in treating retinal artery occlusion by monitoring its concentration in the exhaled breath. Cases and Method : Four cases each of central and branch retinal artery occlusion in the early stage were treated. The ages ranged from 68 to 87 years, average 76.7 years. Patients received mixture of carbon dioxide and oxygen through a mask. Concentration of carbon dioxide was controlled to keep its concentration in the breath between 45 and 60mmHg. One session of 15 minutes was repeated every 2 hours in daytime and every 3 hours in nighttime. Treatment was continued until improvement set in and maximally until 48 hours after onset. All the cases also received paracentesis and thrombolytic agents. Results: Optimum concentration of inhaled carbon dioxide ranged from 10% to 14%. Visual acuity improved in 1 case of central retinal artery occlusion and in 4 cases of branch occlusion. Conclusion: Inhalation of carbon dioxide and oxygen by monitoring the concentration the former in the exhaled breath is a novel procedure and may benefit in treating retinal artery occlusions.