COPD
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Progressive decline in lung function has been widely accepted as the hallmark of chronic obstructive pulmonary disease (COPD); however, recent evidence indicates that the rate of decline measured as decline in forced expiratory volume in one second (FEV1) is higher in mild to moderate COPD than in severe COPD. Usually changes in FEV1 are measured in ml that is "absolute"; however, changes can also be measured "relative" as a percentage of the actual FEV1. We hypothesize that relative measurements could be more appropriate than absolute measurements for describing changes in lung function. ⋯ Measuring changes in relative terms could have important implications for the interpretation of results from clinical trials where FEV1 is the primary outcome. DLCST; www. ClinicalTrials.org , registration number: NCT00496977.
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COPD is often regarded as a smoker's disease. In fact, up to 50% of COPD could be attributable to other causes. Relatively little is known about COPD among nonsmokers, and this group is usually excluded from studies of COPD. ⋯ Asthma is a very common cause of COPD among nonsmokers. Radiological bronchiectasis is common in COPD; the clinical significance of this finding is unclear.
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Oxidative stress is implicated in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Analysis of the expired breath condensate (EBC) has been suggested to provide non-invasive inflammatory markers that reflect oxidative stress in the airways. ⋯ These findings suggest that oxidative stress is involved in the pathogenesis of asthma and COPD and that the H2O2 levels in EBC might reflect the health status in COPD.
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Tidal expiratory flow limitation (EFL) is a step of paramount importance in the functional decline in COPD. Among mechanisms contributing to EFL, loss of airway-parenchymal interdependence could mostly be involved. ⋯ In COPD EFL in sitting position is highly dependent by the severity of airflow obstruction. In contrast, the occurrence of EFL in supine position is associated with worse DLCO and KCO and greater chronic dyspnea, reflecting a prevalent emphysematous phenotype in moderate-to-severe COPD patients.
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Randomized Controlled Trial
Severe chronic bronchitis in advanced emphysema increases mortality and hospitalizations.
Chronic bronchitis in COPD has been associated with an increased exacerbation rate, more hospitalizations, and an accelerated decline in lung function. The clinical characteristics of patients with advanced emphysema and chronic bronchitis have not been well described. ⋯ Severe chronic bronchitis is associated with worse survival, shorter time to hospitalization, and worse health-related quality of life.