Chest
Original ResearchCOPDThe Relationship Between Airflow Obstruction, Emphysema Extent, and Small Airways Function in COPD
Section snippets
Subject Characteristics
Subjects were recruited from a volunteer database at Royal North Shore Hospital and advertisements in a local newspaper. Inclusion criteria were age ≥ 40 years, a physician diagnosis of COPD, smoking history of > 10 pack-years, a postbronchodilator FEV1/FVC < 0.7, and symptoms of shortness of breath on exertion or chronic cough for at least 12 months. Subjects were excluded if they had coexistent asthma or other respiratory disease or an exacerbation of COPD within the past 6 weeks defined as
Results
Subject baseline demographic characteristics and lung function data are provided in Table 1. Twenty-six subjects participated in the study and had moderate COPD, although there was a wide range of severities. Dlco was severely impaired, and subjects had mild to moderate hyperinflation (Table 1). Rrs was increased at 173.5 ± 45.1% predicted, and Xrs was increased at 653.05 ± 371.7% predicted. Six subjects were not taking any medications, 17 were taking long-acting muscarinic antagonists, 13 were
Discussion
In this COPD cohort, we found airflow obstruction and FEV1/FVC to be independently predicted by both small airways disease as measured by CV/VC and the extent of emphysema as measured by %LAA on CT scan. The severity of COPD as determined by FEV1 % predicted was independently predicted by EFL measured by FOT (EFL index) and by emphysema. The results of the present study are consistent with the notion that airflow limitation in COPD measured by spirometry is a global measure that has separable
Acknowledgments
Author contributions: Dr Timmins had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Dr Timmins: contributed to the study design, data analysis and interpretation, and writing of the manuscript.
Dr Diba: contributed to the data analysis and interpretation and writing of the manuscript.
Ms Farrow: contributed to the data collection and critical review of the manuscript and final draft.
Ms Schoeffel: contributed
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Funding/Support: The research was funded by the Australian Lung Foundation Webster Memorial Award and the Cooperative Research Centre for Asthma and Airways Project 2.1.
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