Chest
Clinical InvestigationsAirwaysAssessing the Reversibility of Airway Obstruction
Section snippets
Subjects
The study participants were 78 outpatients with chronic airflow obstruction who were referred to a pulmonary function laboratory by their family physician. Fifty patients (37 men) met the American Thoracic Society criteria for bronchial asthma and 28 patients (27 men) met the criteria for COPD.9 To enter the study, the patients were required to have an FEV1/FVC below the lower normal limit,10 not to have suffered from exacerbations in the previous month, and to be able to abstain from
Results
Under control conditions (Table 1), all patients were obstructed, with a mean (±SD) FEV1 63 ± 19% of predicted and FVC 86 ± 18% of predicted, and moderately hyperinflated (FRC 136 ± 29% of predicted). The FEV1 was slightly but significantly less in COPD patients than in asthma patients (58 ± 20% vs 67 ± 18%; p < 0.05). m30 was on average similar to p30, though their ratio (M/P) was slightly greater in asthma patients than in COPD patients (1.05 ± 0.42 vs 0.88 ± 0.24; p < 0.06).
Discussion
The FEV1 is the traditional measure for the diagnosis of COPD and detection of reversibility of airway obstruction. Normal values are well established from population-based studies and the FEV1 is quite reproducible.1 Flow at 50% of FVC and below on both MEFV and PEFV is more variable because it is sensitive to changes in the depth of inhalation3, 4, 5 and compression of intrathoracic gas during a forced expiration.12 Furthermore, normal values are not well established. Until recently,
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Alternative functional criteria to assess airflow-limitation reversibility in asthma
2015, Revista Portuguesa de PneumologiaPartial versus maximal forced exhalations in COPD: Enhanced signal detection for novel therapies
2014, Pulmonary Pharmacology and TherapeuticsAssessment of acute bronchodilator effects from specific airway resistance changes in stable COPD patients
2014, Respiratory Physiology and NeurobiologyCitation Excerpt :Despite the practical relevance of the improvements of lung volume parameters produced by bronchodilators, the use of FEV1 is still recommended as the primary efficacy end-point in assessing the response to COPD medications, whereas volume-based measures are not (Guidance for Industry, 2007). Although both FEV1 and sRAW changed substantially with indacaterol (Table 2), and the FEV1 vs sRAW relationships obtained before and after bronchodilation did not differ significantly, no relation was found between the changes of these variables produced by bronchodilator administration (Fig. 2), supporting the notion that FEV1 is a poor evaluator of intrapulmonary airway resistance (Pride, 1971; Pellegrino et al., 1998). Furthermore, the changes of FEV1 did not correlate with those of lung volume variables, except FVC (Figs. 3 and 4), thus indicating that the increase of FEV1 is mainly due to that of FVC, as previously suggested (Sourk and Nugent, 1983; Deesomchok et al., 2010).