肺気腫を合併し著明な低酸素血症を来したSwyer-James症候群の1例

Swyer-James Syndrome Showing Severe Hypoxia and Accompanied by Pulmonary Emphysema

　患者は72歳，男性．以前より労作時呼吸困難を自覚していたが増悪したため，当科へ入院となった．入院時，動脈血酸素分圧が著明に低下（PaO₂47.9Torr）しており，胸部X線写真および胸部CT上，右肺の透過性亢進と血管影の減少が認められ，DSAによる肺動脈造影で右肺動脈の狭小化がみられたため，Swyer中James症候群と診断した．換気血流シンチでは，患側である右肺では換気も血流も低下しており，また健側である左肺は換気シンチにおいて換気不均等であり，肺気腫を合併していると考えられた．Swyer-James症候群では，動脈血酸素分圧は通常正常か軽度であるが，本症例では肺気腫を合併していたために著明な低酸素血症を来したと考えられる．本症例はSwyer-James症候群の成因，肺気腫との関連を考えるうえで示唆に富む症例と思われた．

　A seventy-two-year-old man was admitted to ourhospital because of his chief complaint of exacerbationof dyspnea. On admission, arterial blood gas analysisrevealed severe hypoxia (PaO₂ 47.9 Torr), and chest x-ray film demonstrated increased x-ray permeability anddecreased pulmonary marking. Digital subtraction angiography showed scanty distribution and narrowing ofpulmonary arteries in the right lung. From thesefindings, we diagnosed Swyer-James syndrome. Furthermore, emphysema in the left lung was shown on chestCT. In the pulmonary scintigram, both ventilation andperfusion were decreased in the right lung, while, in theleft lung, ventilation-perfusion inequality was shown,indicating chronic obstructive pulmonary disease. It isknown that severe hypoxia is rarely present in cases of Swyer-James syndrome. In the present case, the severehypoxia is considered to be due to the accompanyingpulmonary emphysema. The co-existence of Swyer-James syndrome and pulmonary emphysema is rare.The present case again arouses interest in the pathogenesis of Swyer-James syndrome, which appears tobe independent of chronic pulmonary emphysema.