Relación entre disfunción de los músculos espiratorios e hiperinflación dinámica en la EPOC avanzada

The effect of habitual waterpipe tobacco smoking on pulmonary function and exercise capacity in young healthy males: A pilot study

BACKGROUND

Evidence regarding the health effects of habitual waterpipe smoking is limited, particularly in young smokers. Respiratory health and cardiopulmonary exercise tests were compared in young male habitual waterpipe smokers (WPS) versus non-smokers.

METHODS

69 WPS (≥3 times/week for three years) and 69 non-smokers were studied. Respiratory health was assessed through the American Thoracic Society and the Division of Lung Diseases (ATS-DLD-78) adult questionnaire. Pulmonary function and cardiopulmonary exercise tests were performed. Self-reported respiratory symptoms, forced expiratory volume in first second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, forced expiratory flow between 25 and 75% of FVC (FEF25-75%), peak expiratory flow (PEF), exercise time, peak end-tidal CO2 tension (PetCO2), subject-reported leg fatigue and dyspnea; peak O2 uptake (VO2 max), and end-expiratory lung volume (EELV) change from baseline (at peak exercise) were measured.

RESULTS

WPS were more likely than non-smokers to report respiratory symptoms. WPS also demonstrated: shorter exercise time; lower peak VO2; higher perceived dyspnea at mid-exercise; lower values of the following: FEV1, FVC, PEF, and EELV change.

CONCLUSION

Habitual waterpipe tobacco smoking in young seemingly healthy individuals is associated with a greater burden of respiratory symptoms and impaired exercise capacity.

High Prevalence of Obstructive Sleep Apnea in Patients with Moderate to Severe Chronic Obstructive Pulmonary Disease

RATIONALE

When obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) coexist in the so-called "overlap" syndrome, a high risk for mortality and morbidity has been reported. There is controversy about the prevalence of OSA in people affected by COPD.

OBJECTIVES

The purpose of this study was to investigate objective meaures of sleep-disordered breathing in patients with moderate to severe COPD to test the hypothesis that COPD is associated with an increased prevalence of OSA.

METHODS

Fifty-four patients (54% men) with moderate to severe COPD were enrolled prospectively (mean ± SD, FEV1 = 42.8 ± 19.8% predicted, and FEV1/FVC = 42.3 ± 13.1). Twenty patients (37%) were on supplemental oxygen at baseline. Exercise tolerance; questionnaires related to symptoms, sleep, and quality of life; and home polysomnography were obtained.

MEASUREMENTS AND MAIN RESULTS

Forty-four patients had full polysomnography suitable for analysis. OSA (apnea-hypopnea index > 5/h) was present in 29 subjects (65.9%). Sleep efficiency was poor in 45% of subjects.

CONCLUSIONS

OSA is highly prevalent in patients with moderate to severe COPD referred to pulmonary rehabilitation. Sleep quality is also poor among this selected group. These patients have greater-than-expected sleep-disordered breathing, which could be an important contributory factor to morbidity and mortality. Pulmonary rehabilitation programs should consider including a sleep assessment in patients with moderate to severe COPD and interventions when indicated to help reduce the impact of OSA in COPD.

Muscle dysfunction in chronic obstructive pulmonary disease: update on causes and biological findings

Respiratory and/or limb muscle dysfunction, which are frequently observed in chronic obstructive pulmonary disease (COPD) patients, contribute to their disease prognosis irrespective of the lung function. Muscle dysfunction is caused by the interaction of local and systemic factors. The key deleterious etiologic factors are pulmonary hyperinflation for the respiratory muscles and deconditioning secondary to reduced physical activity for limb muscles. Nonetheless, cigarette smoke, systemic inflammation, nutritional abnormalities, exercise, exacerbations, anabolic insufficiency, drugs and comorbidities also seem to play a relevant role. All these factors modify the phenotype of the muscles, through the induction of several biological phenomena in patients with COPD. While respiratory muscles improve their aerobic phenotype (percentage of oxidative fibers, capillarization, mitochondrial density, enzyme activity in the aerobic pathways, etc.), limb muscles exhibit the opposite phenotype. In addition, both muscle groups show oxidative stress, signs of damage and epigenetic changes. However, fiber atrophy, increased number of inflammatory cells, altered regenerative capacity; signs of apoptosis and autophagy, and an imbalance between protein synthesis and breakdown are rather characteristic features of the limb muscles, mostly in patients with reduced body weight. Despite that significant progress has been achieved in the last decades, full elucidation of the specific roles of the target biological mechanisms involved in COPD muscle dysfunction is still required. Such an achievement will be crucial to adequately tackle with this relevant clinical problem of COPD patients in the near-future.

Expiratory muscle fatigue does not regulate operating lung volumes during high-intensity exercise in healthy humans

To determine whether expiratory muscle fatigue (EMF) is involved in regulating operating lung volumes during exercise, nine recreationally active subjects cycled at 90% of peak work rate to the limit of tolerance with prior induction of EMF (EMF-ex) and for a time equal to that achieved in EMF-ex without prior induction of EMF (ISO-ex). EMF was assessed by measuring changes in magnetically evoked gastric twitch pressure. Changes in end-expiratory and end-inspiratory lung volume (EELV and EILV) and the degree of expiratory flow limitation (EFL) were quantified using maximal expiratory flow-volume curves and inspiratory capacity maneuvers. Resistive breathing reduced gastric twitch pressure (−24 ± 14%, P = 0.004). During EMF-ex, EELV decreased from rest to the 3rd min of exercise [39 ± 8 vs. 27 ± 7% of forced vital capacity (FVC), P = 0.001] before increasing toward baseline (34 ± 8% of FVC end exercise, P = 0.073 vs. rest). EILV increased from rest to the 3rd min of exercise (54 ± 8 vs. 84 ± 9% of FVC, P = 0.006) and remained elevated to end exercise (88 ± 9% of FVC). Neither EELV ( P = 0.18) nor EILV ( P = 0.26) was different at any time point during EMF-ex vs. ISO-ex. Four subjects became expiratory flow limited during the final minute of EMF-ex and ISO-ex; the degree of EFL was not different between trials (37 ± 18 vs. 35 ± 16% of tidal volume, P = 0.38). At end exercise in both trials, EELV was greater in subjects without vs. subjects with EFL. These findings suggest that 1) contractile fatigue of the expiratory muscles in healthy humans does not regulate operating lung volumes during high-intensity sustained cycle exercise; and 2) factors other than “frank” EFL cause the terminal increase in EELV.

[Physical activity and its relationship with the state of health of stable COPD patients]

INTRODUCTION

Previous studies have shown that physical activity (PA) in COPD is associated with a better quality of life and less morbidity and mortality. Our aim was to study the daily PA in the lives of stable COPD patients, outside the setting of a pulmonary rehabilitation program.

MATERIAL AND METHODS

Observational, descriptive and transversal multi-center study in patients with stable COPD controlled in an outpatient clinic by pneumologists. In order to determine the Physical Activity Index (PAI), the Minnesota Leisure Time Physical Activity Questionnaire (MLTPAQ) was used to differentiate the following groups according to the energy expenditure: inactive (less than 1,000 kilocalories per week), moderately active (between 1,000 and 3,000 kilocalories per week) and very active (more than 3,000 kilocalories per week). We analyzed the relationship between PAI and disease severity, health level and socioeconomic variables of the patients.

RESULTS

A total of 132 patients (121 men) were included in the study. Mean age was 66; mean FEV1 was 45%. Regarding PA, 32.6% had energy expenditures of less than 1,000 kilocalories/week, 38.6% between 1,000 and 3,000 and 28.8% more than 3,000. The most inactive COPD patients had more bronchial obstruction, more severe disease, more dyspnea and walked fewer meters in the 6MWT.

CONCLUSIONS

Stable COPD patients perform low levels of PA. Lower PA is associated with poorer health and with more severe disease.