Long-term cigarette smoking influences low attenuation area of the lungs on high-resolution CT in elderly patients with asthma, compared with pulmonary emphysema.

The influence of cigarette smoking on the pathophysiology in elderly patients with asthma. Forty asthmatics over the age of 70 years (20 ex-smokers and 20 never-smokers), and 20 patients with pulmonary emphysema over age 70 (all ever-smokers) were studied to determine the influence of cigarette smoke on the low attenuation area (LAA) <-950 HU (RA950) of the lungs on high resolution CT (HRCT) scans, and the ratio of expiratory LAA to inspiratory LAA of the lungs in relation to pulmonary function. The LAA value was significantly higher in patients with pulmonary emphysema compared with ever-smokers of asthmatics. The LAA ratio was significantly higher in ever-smokers than in never-smokers of asthmatics, and the ratio was less than 0.5 in all never-smokers, and the ratio was more than 0.5 in 10 of 20 ever-smokers of asthmatics and in all patients with pulmonary emphysema. The % RV (residual volume) was significaltly larger and % DLco (diffusing capacity for carbon monoxide) was significantly lower in subjects with the ratio more than 0.5 than in those with the ratio less than 0.5. These results suggest that cigarette smoke influences LAA of the lungs in relation to % RV value and % DLco value.

70歳以上の気管支喘息40例(20例喫煙者,20例非喫煙者)および肺気腫20例を対象に,長期間喫煙のHRCT上の-950 HU以下の肺のlow atenuation area(LAA)に及ぼす影響について検討した。 HRCT上の肺の% LAAは,喘息の喫煙例で非喫煙例に比べ有意に高い値を示した｡また,この% LAAは,肺気腫症例で喘息の喫煙例に比べさらに高い値を示した｡LAA比(呼気時LAA/吸気時LAA)は,職息症例では喫煙例で非喫煙例比べ有意に高い値を示したが,肺気腫症例ではさらに高い値を示した｡LAA比0.5以上を示す症例は,喘息の非喫煙例では見られず,喫煙例で20例中10例,肺気腫症例では全例に見られた｡そして,喘息喫煙例でLAA比が0.5以上を示す症例は,0.5以下の症例に比べ,% RVは有意に高く,また% DLcoは有意に低い値を示した｡しかし,% RV,% DLco値いずれも喘息のLAA比0.5以上の症例と肺気腫の間には有意差は見られず,喘息における喫煙の影響の高いことが示唆された｡