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Discriminating Measures and Normal Values for Expiratory Obstruction: Pattern Analysis of Current Smokers
We placed each of the currently smoking subjects into 1 of 16 (24) potential categories, depending on whether or not their FEVi, FVC, FEV/FVC, and FEV3/FVC values were below the LLN. This allowed us to decide whether each subject had normal spirometry findins, or had a pattern of obstruction, had probable restriction, or a combination, […]
Discriminating Measures and Normal Values for Expiratory Obstruction: Subjects
Utilizing data from the same NHANES III source, we did the following: (1) calculated the mean and LLN values for FEV3/FVC in these never-smoking and currently smoking groups; (2) compared the variability of FEV1/FVC, FEV3/FVC, and FEF25-75 values in never-smokers and current smokers; and (3) assessed changes associated with aging and smoking. We hypothesized that […]
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Discriminating Measures and Normal Values for Expiratory Obstruction
Since Hutchinson introduced spirometry in 1846, a multitude of measurements, including volumes, flows, time constants, and ratios, have evolved to assess normalcy and disease. Five decades ago Lueallan and Fowler2 added maximal midexpiratory flow, later labeled as forced expiratory flow, midexpiratory phase (FEF25-75), to assess expiratory airway obstruction. In 1967, Macklem and Mead divided airway […]
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