Background Subjective measurement of physical activity using questionnaires has prognostic value in COPD. However, their lack of accuracy and large individual variability limit their use for ...evaluation on an individual basis. We evaluated the capacity of the objective measurement of daily physical activity in patients with COPD using accelerometers to estimate their prognostic value. Methods In 173 consecutive subjects with moderate to very severe COPD, daily physical activity was measured using a triaxial accelerometer providing a mean of 1-min movement epochs as vector magnitude units (VMUs). Patients were evaluated by lung function testing and 6-min walk, incremental exercise, and constant work rate tests. Patients were followed for 5 to 8 years, and the end points were all-cause mortality, hospitalization for COPD exacerbation, and annual declining FEV1. Results After adjusting for relevant confounders, a high VMU decreased the mortality risk (adjusted hazard ratio HR, 0.986; 95% CI, 0.981-0.992), and in a multivariate model, comorbidity, endurance time, and VMU were retained as independent predictors of mortality. The time until first admission due to COPD exacerbation was shorter for the patients with lower levels of VMU (adjusted HR, 0.989; 95% CI, 0.983-0.995). Moreover, patients with higher VMU had a lower hospitalization risk than those with a low VMU (adjusted incidence rate ratio, 0.099; 95% CI, 0.033-0.293). In contrast, VMU was not identified as an independent predictor of the annual FEV1 decline. Conclusion The objective measurement of the daily physical activity in patients with COPD using an accelerometer constitutes an independent prognostic factor for mortality and hospitalization due to severe exacerbation.
Background There are a variable number of obese subjects with self-reported diagnosis of asthma but without current or previous evidence of airflow limitation, bronchial reversibility, or airway ...hyperresponsiveness (misdiagnosed asthma). However, the mechanisms of asthma-like symptoms in obesity remain unclear. Objectives We sought to evaluate the perception of dyspnea during bronchial challenge and exercise testing in obese patients with asthma and misdiagnosed asthma compared with obese control subjects to identify the mechanisms of asthma-like symptoms in obesity. Methods In a cross-sectional study we included obese subjects with asthma (n = 25), misdiagnosed asthma (n = 23), and no asthma or respiratory symptoms (n = 27). Spirometry, lung volumes, exhaled nitric oxide levels, and systemic biomarker levels were measured. Dyspnea scores during adenosine bronchial challenge and incremental exercise testing were obtained. Results During bronchial challenge, patients with asthma or misdiagnosed asthma reached a higher Borg-FEV1 slope than control subjects. Moreover, maximum dyspnea and the Borg–oxygen uptake (V′O2 ) slope were significantly greater during exercise in subjects with asthma or misdiagnosed asthma than in control subjects. The maximum dyspnea achieved during bronchial challenge correlated with IL-1β levels, whereas peak respiratory frequency, ventilatory equivalent for CO2 , and IL-6 and IL-1β levels were independent predictors of the Borg-V′O2 slope during exercise ( r 2 = 0.853, P < .001). Conclusions A false diagnosis of asthma (misdiagnosed asthma) in obese subjects is attributable to an increased perception of dyspnea, which, during exercise, is mainly associated with systemic inflammation and excessive ventilation for metabolic demands.
Background In senior subjects, diffusing capacity of the lung for carbon monoxide (D lco ) is interpreted using prediction equations derived from primarily younger adult populations. Our objectives ...were to provide reference equations for single-breath D lco for a cohort of healthy, never-smoking, white, European adults between 65 and 85 years of age and to compare the predicted values of this sample with those from other studies involving middle-aged adults. Methods Reference equations were derived from a randomly selected sample from the general population of 431 healthy never smoker subjects aged 65 to 85 years (262 women and 169 men). Spirometry, lung volume determinations by plethysmography, and single-breath D lco (corrected for hemoglobin) were performed following the American Thoracic Society/European Respiratory Society guidelines. Reference values and lower and upper limits of normal were derived using a piecewise polynomial model. Results In addition to age, our reference equations confirmed the height and body size dependence of D lco and diffusing capacity for alveolar volume (D lco /V a ) in older subjects. Practically all of the reference values obtained by extrapolating reference equations of middle-aged adults underestimated the true diffusing capacity of the healthy elderly volunteers. Middle-aged reference equations underestimated D lco by 2.1% to 22.3% in women and 2.8% to 37.8% in men. In addition, D lco /V a was overestimated up to 18% and 39.8% in women and men, respectively, whereas other equations underestimated D lco /V a up to 22.2% and 11.9% in women and men, respectively. Conclusions These results underscore the importance of using prediction equations appropriate to the origin and age characteristics of the subjects being studied.
Background There is considerable evidence that oxidative stress is increased in patients with COPD, although little information is available about its relationship with the structural and functional ...alterations produced by COPD. In this study, we evaluated the relationship between 8-isoprostane in exhaled breath condensate (EBC) of stable patients with COPD and the main parameters of the disease (such as dyspnea), stages of severity, lung parenchyma densities, lung function impairment, and exercise tolerance in order to identify the predictors of airway oxidative stress. Methods In a cross-sectional study, we included 76 men with moderate to very severe COPD. 8-Isoprostane levels in EBC were measured by enzyme immunoassay. Regional lung densities were measured by lung densitometry with high-resolution CT scanning. Arterial blood gas levels, lung volumes, and diffusing capacity were determined. Patients performed a 6-min walk test and an incremental exercise test with measurement of breathing pattern and operating lung volumes. Results Significant severity-related differences in 8-isoprostane were identified according to the BMI, obstruction, dyspnea, and exercise (BODE) index. 8-Isoprostane levels were related to smoking intensity, lung densities in expiration, static lung volumes, Pa o2 , diffusion capacity, distance walked in 6 min, peak oxygen uptake, and anaerobic threshold. Concentration of 8-isoprostane was higher in the 60 patients (79%) who developed dynamic hyperinflation than in the remaining 16 (21%) who did not. In a multivariate linear regression analysis using 8-isoprostane as a dependent variable, end-expiratory lung volume change and Pa o2 were retained in the prediction model ( r2 = 0.734, P < .001). Conclusions In stable patients with COPD, oxygen level and dynamic hyperinflation are related to airway oxidative stress.
Little is known about the behavior of operative lung volumes during exercise in patients with asthma and exercise-induced bronchoconstriction (EIB).
To compare the presence of dynamic hyperinflation ...(DH) in patients with mild asthma with and without EIB and in healthy individuals and to relate the changes in end-expiratory lung volume (EELV) with postexercise airflow reduction.
A total of 122 consecutive stable patients (>12 years of age) with mild asthma and 38 controls were studied. Baseline lung volumes were measured, and all patients performed an exercise bronchial challenge. At each minute of exercise, EELV and end-inspiratory lung volume (EILV) were estimated from inspiratory capacity measurements to align the tidal breathing flow-volume loops to within the maximal expiratory curve.
DH was more frequent in patients with asthma and EIB (76%) than in patients with asthma but without EIB (11%) or controls (18%). The EELV increased in patients with asthma and EIB and decreased in patients with asthma without EIB and controls during exercise. In the patients with asthma, the decrease in forced expiratory volume in 1 second after the exercise challenge correlated with age (r = -0.179, P = .05), baseline forced vital capacity (r = 0.255, P = .005), EELV increase (r = 0.447, P < .001), and EILV increase (r = 0.246, P = .007). Age, baseline forced vital capacity, and magnitude of DH were retained as independent predictors of EIB intensity.
In patients with asthma and EIB, the development of DH is very frequent and related to the intensity of postexercise bronchoconstriction. This finding could implicate DH in the development of EIB.
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