Correlation between pulmonary function and low attenuation area (LAA) on HRCT III patients with asthma in relation to smoking

The influence of smoking on pulmonary function and emphysematous changes of the lung (percentage of attenuation area < -950 HU (% LAA) on high resolution computed tomography (HRCT) was examined in 49 patients with bronchial asthma. 1. In patients with asthma, the % residual volume (RV) in many nonsmokers was less than 129%, in contrast, the % RV in many smokers was between 130% and 189% , which was higher than that in nonsmokers. 2. Significant correlations between % RV and 96LAA value, and between % RV and CT number were observed both in nonsmokers and smokers with asthma, in which as % RV more increased, % LAA value was larger, and CT number was lower. 3. % DLco value was lower in smoking patients with asthma, whose % RV was between 130% and 189% and larger than 190% , however, the % DLco value did not change in nonsmoking patients despite of higher valure in % RV. 4. A significant correlation was also observed between % FEV1.0 value and % RV both in smoking and nonsmoking patients with asthma; as % RV value more increased, % FEV1.0 value was lower. 5. Any correlation between % FVC value and % RV was not observed. These results suggest that smoking affects the % LAA of the lung on HRCT and % DLco in patients with asthma.

気管支喘息49例を対象に､肺機能およびHigh resolution computed tomography(HRCT)上のLow attenuation are (LAA) <-950HUで示される肺気腫様変化に及ぼす喫煙の影響について検討した｡　 1.気管支喘息患者のうち､非喫煙例では% 残気量(% RV)は多くの症例(65.6% )で129% 以下であったが､一方喫煙症例では130% から189% を示す症例が最も多く見られた(60.0% )｡非喫煙例および喫煙例いずれにおいても､ 2.% RVと% LAA､% RVとCT number 間に有意の相関が見られた: % RVが上昇するにつれて､% LAA値は増加し､CT numberは低下する傾向が見られた｡　 3.喫煙例では､% RVが130-189% あるいは190% 以上の症例で､% DLco値 が明かに低値を示す症例が見られたが､非喫煙症例では% RVが高い値を示しても% DLcoの低下はみられなかった｡　 4.喫煙例､非喫煙例いずれにおいても､% FEV1.0倍と% RV値の問には有意の相関が見られ､% RV値が上昇するにつれて､% FEV1.0値は低下する傾向が見られた｡　 5.% FVCと% RVの問には相関は見られなかった｡以上の結果より､喫煙は気管支喘息患者のHRCT上の% LAAおよび% DLcoに影響を与えることが示唆された｡