The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts


Yohei Yatagai1, Takeo Saito1, Yoshiya Tsunoda1, Toru Tanaka1, Shigen Lin1, Yukiko Miura1, Kunihiko Miyazaki1, Akimasa Sekine1, Kenji Hayashihara1, Yasuhiro Umetsu2; 1respiratory medicine, Ibarakihigashi hospital, Naka-gun Tokai-mura, Japan; 2clinical laboratory, Ibarakihigashi hospital, Naka-gun Tokai-mura, Japan

Background: Robert E. Hyatt and his colleague defined a nonspecific pattern (NSP) of pulmonary function test results as a reduced FEV1 and FVC, a normal FEV1/FVC, and a normal total lung capacity (TLC). They encountered the NSP in 9.5% of their subjects. Fifty percent of the subjects were obese and sixty-eight percent had airway hypersensitivity or chronic lung disease. Stanescu suggested the NSP be called the small airways obstruction syndrome. We performed a similar study among Japanese patients showing decreased body mass index, compared to those in the original study. Methods: We undertook a retrospective analysis of subjects studied in our pulmonary function laboratory between Jun 2009 and May 2010. Selection criteria for the NSP were that subjects be more than 20 years old with an FEV1 and FVC below the lower limit of normal, and the FEV1/FVC and TLC above the lower limit of normal. And then, these subjects had received a bronchodilator challenge. A positive bronchodilator response was an increase in FEV1 and/or FVC of at least 12% or of at least 200mL. A TLC was examined in the gas dilution method. Results: From 399 test results, the NSP was found in 25 subjects (6.3%). We classified the NSP subjects into five groups. Group A consisted of airway hyperresponsiveness, defined as a clinical diagnosis of asthma and/or positive bronchodilator response (n=3). Group B consisted of airway disease without AHR, i.e. COPD (n=2), bronchiectasis (n=2), diffuse panbronchiolitis (n=2) and undifferentiated connective tissue disease with bronchiolitis (n=2). Group C were obese subjects without airway disease (n=4). Group D were other diagnosis, i.e. nontuberculous mycobacteriosis (n=3), idiopathic pulmonary fibrosis (n=2), nonspecific interstitial pneumonia (n=2) and so on. In the NSP subjects (normal FEV1/FVC, reduced FEV1 and FVC, normal TLC), the value of V50/V25 were higher than other subjects with normal FEV1/FVC, reduced FEV1 and FVC, reduced TLC (p=0.0147). Conclusion: We found the NSP subjects in Japanese population at a little lower rate than in the original study. One of the probable underlying cause of the pattern might be small airway disease. So, even in Japan, when the subjects showed normal FEV1/FVC with reduced FEV1 and FVC, we shouldnÂ’t automatically rule out airway obstruction, and shouldnÂ’t rule in pulmonary restriction. Sponsored Research - None