Small Airways Obstruction Syndrome

Study objectives To clarify the significance of a functional lung pattern characterized by a decreased vital capacity (VC) and an increased residual volume (RV), but with a normal FEV1/VC ratio. Setting A university teaching hospital. Subjects Patients with bronchial asthma, pulmonary emphysema, and small airways disease, and older subjects. Measurements Measurements of static and dynamic lung volumes, diffusing capacity of the lung for carbon monoxide (as measured by the single-breath method), nitrogen slope of the alveolar plateau, and closing volume (as measured by the single-breath O2 test). Conclusion A functional pattern characterized by a decreased VC and FEV1and increased RV, but with a normal FEV1/VC ratio and total lung capacity, reflects an obstructive impairment of small airways. To clarify the significance of a functional lung pattern characterized by a decreased vital capacity (VC) and an increased residual volume (RV), but with a normal FEV1/VC ratio. A university teaching hospital. Patients with bronchial asthma, pulmonary emphysema, and small airways disease, and older subjects. Measurements of static and dynamic lung volumes, diffusing capacity of the lung for carbon monoxide (as measured by the single-breath method), nitrogen slope of the alveolar plateau, and closing volume (as measured by the single-breath O2 test). A functional pattern characterized by a decreased VC and FEV1and increased RV, but with a normal FEV1/VC ratio and total lung capacity, reflects an obstructive impairment of small airways.