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Discriminating Measures and Normal Values for Expiratory Obstruction: Physiologic Defects in Current Smokers
Figure 2 shows marked differences in the variability of FEV1/FVC, FEV3/FVC, and FEF25-75 in never-smokers and current smokers for each fifth percentile of the respective populations when plotted against the percentage of the mean predicted values. The legend emphasizes misclassifications that would result if 80% of mean values was used as the threshold. Figure 3 […]
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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The Bronchial Response, but not the Pulmonary Response to Inhaled Methacholine Is Dependent on the Aerosol Deposition Pattern: Conclusion
Theoretically, differences in regional deposition of a vasoactive drug might then elicit different responses or time courses of effects, dependent on the deposition pattern. Experimental studies have suggested that a compound may be rapidly redistributed throughout the lung by bronchial blood flow This ability may have a role in airway homeostasis by enhancing the clearance […]
The Bronchial Response, but not the Pulmonary Response to Inhaled Methacholine Is Dependent on the Aerosol Deposition Pattern: Conclusion
Similarly, collateral ventilation may also be more effective at a segmental level than when a whole lobe is obstructed, at least in the dog Our findings further support the previously reported discrepancy in time courses of Va/Q mismatch and bronchial constriction, and the discrepancy occurred independently of whether the aerosol was deposited in the central […]
The Bronchial Response, but not the Pulmonary Response to Inhaled Methacholine Is Dependent on the Aerosol Deposition Pattern: Comment
Similar to the conditions reported there, we postulated that mixing of the two water-soluble compounds, methacholine and DTPA, was homogeneous, both in the nebulizing chamber and in the separate aerosol particles. We, therefore, assumed that the differences in amounts of methacholine deposited within the various sections of the airways were proportional to the differences in […]