Mechanisms and measures of exercise intolerance in chronic obstructive pulmonary disease

Effects of inspiratory muscle training on thoracoabdominal volume regulation in older adults: A randomised controlled trial

OBJECTIVES

We investigated the effect of inspiratory muscle training (IMT) on inspiratory muscle strength, functional capacity and respiratory muscle kinematics during exercise in healthy older adults.

METHODS

24 adults were randomised into an IMT or SHAM-IMT group. Both groups performed 30 breaths, twice daily, for 8 weeks, at intensities of ∼50 % maximal inspiratory pressure (PImax; IMT) or <15 % PImax (SHAM-IMT). Measurements of PImax, breathing discomfort during a bout of IMT, six-minute walk distance, physical activity levels, and balance were assessed pre- and post-intervention. Respiratory muscle kinematics were assessed via optoelectronic plethysmography (OEP) during constant work rate cycling.

RESULTS

PImax was significantly improved (by 20.0±11.9 cmH2O; p=0.001) in the IMT group only. Breathing discomfort ratings during IMT significantly decreased (from 3.5±0.9-1.7±0.8). Daily sedentary time was decreased (by 28.0±39.8 min; p=0.042), and reactive balance significantly improved (by 1.2±0.8; p<0.001) in the IMT group only. OEP measures showed a significantly greater contribution of the pulmonary and abdominal rib cage compartments to total tidal volume expansion post-IMT.

CONCLUSIONS

IMT significantly improves inspiratory muscle strength and breathing discomfort in this population. IMT induces greater rib cage expansion and diaphragm descent during exercise, thereby suggesting a less restrictive effect on thoracic expansion and increased diaphragmatic power generation.

Impact of acute exacerbations of COPD on patients' health status beyond pulmonary function: A scoping review

This scoping review summarized the evidence regarding the impact of acute exacerbations of COPD (AECOPD) on patients' health status beyond pulmonary function. PubMed, Embase, and Web of Science were searched. Prospective cohort studies assessing the health status of patients with COPD in a stable phase of the disease and after a follow-up period (where at least one AECOPD occurred) were included. An integrated assessment framework of health status (i.e., physiological functioning, complaints, functional impairment, quality of life) was used. Twenty-two studies were included. AECOPD acutely affected exercise tolerance, quadriceps muscle strength, physical activity levels, symptoms of dyspnoea and fatigue, and impact of the disease. Long-term effects on quadriceps muscle strength, symptoms of dyspnoea and depression, and quality of life were found. Repeated exacerbations negatively impacted the fat-free mass, levels of dyspnoea, impact of the disease and quality of life. Conflicting evidence was found regarding the impact of repeated exacerbations on exercise tolerance and physical activity levels. AECOPD have well-established acute and long-term adverse effects on health status beyond pulmonary function; nevertheless, the recovery trajectory and the impact of repeated exacerbations are still poorly studied. Further prospective research is recommended to draw firm conclusions on these aspects.

Validity and reliability of a new incremental step test for people with chronic obstructive pulmonary disease

BACKGROUND

Incremental step tests (IST) can be used to assess exercise capacity in people with chronic obstructive pulmonary disease (COPD). The development of a new step test based on the characteristics of the incremental shuttle walk test (ISWT) is an important study to explore. We aimed to develop a new IST based on the ISWT in people with COPD, and assess its validity (construct validity) and reliability, according to Consensus-based Standards for the selection of health status Measurement Instruments (COSMIN) recommendations.

METHODS

A cross-sectional study was conducted in participants recruited from hospitals/clinics. During the recruitment, the participants who presented a 6-minute walk test (6MWT) report in the previous month were also identified and the respective data was collected. Subsequently, participants attended two sessions at their homes. IST was conducted on the first visit, along with the 1 min sit-to-stand (1MSTS) test. IST was repeated on a second visit, performed 5-7 days after the first one. Spearman's correlations were used for construct validity, by comparing the IST with the 6MWT and the 1MSTS. Intraclass correlation coefficient (ICC_2,1), SE of measurement (SEM) and minimal detectable change at 95% CI (MDC95) were used for reliability. The learning effect was explored with the Wilcoxon signed-rank test.

RESULTS

50 participants (70.8±7.5 years) were enrolled. IST was significant and moderate correlated with the 6MWT (ρ=0.50, p=0.020), and with the 1MSTS (ρ=0.46, p=0.001). IST presented an ICC_2,1=0.96, SEM=10.1 (16.6%) and MDC95=27.9 (45.8%) for the number of steps. There was a statistically significant difference between the two attempts of the IST (p=0.030).

CONCLUSION

Despite the significant and moderate correlations with the 6MWT and 1MSTS, the inability to full compliance with the COSMIN recommendations does not yet allow the IST to be considered valid in people with COPD. On the other hand, the IST is a reliable test based on its high ICC, but a learning effect and an 'indeterminate' measurement error were shown.

TRIAL REGISTRATION NUMBER

NCT04715659.

Quadriceps physiological response during the 1-min sit-to-stand test in people with severe COPD and healthy controls

We compared quadriceps oxygenation and surface electromyography (sEMG) responses during the 1-min sit-to-stand (1STS) in 14 people with severe COPD and 12 controls, in whom cardiorespiratory response, near-infrared spectroscopy signals (oxy [Hb-Mb], deoxy [Hb-Mb], total [Hb-Mb], and SmO₂) and sEMG signals of the quadriceps were recorded. Time duration of each sit-to-stand cycle and the total work performed during the 1STS were measured. The quadriceps oxygenation parameters were normalized by reporting their values according to the total work during 1STS. The rate of sit-to-stand maneuvers decelerated in people with COPD leading to smaller total work compared with controls. The pattern of quadriceps oxygenation response during 1STS was similar between groups. However, in COPD, the recovery after 1STS was characterized by larger overshoots in oxy [Hb-Mb], total [Hb-Mb], and SmO₂. When corrected for the cumulative total work, the increase in muscle O₂ extraction (deoxy [Hb-Mb]) during the first 30 s of recovery was greater in people with COPD compared to controls. Quadriceps sEMG changes suggestive of a fatiguing contraction pattern was observed only in people with COPD. All together, these results highlighted physiological misadaptation of people with severe COPD to the 1STS.

Extra-pulmonary manifestations of COPD and the role of pulmonary rehabilitation: a symptom-centered approach

Introduction: Chronic obstructive pulmonary disease (COPD) is a complex and heterogenous disease that is associated with a range of respiratory and non-respiratory symptoms, which highly contribute to the daily burden of the disease. Symptoms burden remains high despite optimal bronchodilator therapy, but pulmonary rehabilitation (PR) is an effective intervention to improve patients' symptoms. A comprehensive interdisciplinary approach within the framework of a PR program is warranted to tackle these complex symptoms and their consequences. Areas covered: This narrative review describes how symptoms of dyspnea, fatigue, cough, sputum, anxiety, depression, pain, sleep disturbances, and cognitive decline arise in COPD and can contribute to several non-pulmonary manifestations of the disease. It also describes evidence of the effectiveness of interdisciplinary PR programs to counteract these symptoms. A literature search was performed on PubMed and Scopus between June and July 2020. Expert opinion: Respiratory and non-respiratory symptoms are highly prevalent, often not comprehensively assessed, and result in several extra-pulmonary manifestations of the disease (physical, emotional and social). Interdisciplinary PR programs can improve these negative manifestations through different pathways, contributing for an effective symptoms' management. A thorough assessment of symptoms (beyond dyspnea) should be routinely performed and may support the identification of treatable traits, allowing the tailoring of PR interventions and assessment of their real-life impact.

Cardiorespiratory Response during the 1-min Sit-to-Stand Test in Chronic Obstructive Pulmonary Disease

PURPOSE

This study aimed to assess the cardiorespiratory response during a 1-min sit-to-stand test (1STS) in comparison with cycling cardiopulmonary exercise test (CPET) in people with chronic obstructive pulmonary disease (COPD) and in healthy subjects and to evaluate whether 1STS may induce leg fatigue in these individuals.

METHODS

Fourteen people with severe COPD and 12 healthy subjects performed a 1STS and a CPET during which cardiorespiratory response, perception of dyspnea, and leg fatigue were assessed. Quadriceps strength was assessed before and after 1STS, and contractile fatigue was defined as a postexercise fall in quadriceps twitch force greater than 15% of resting values.

RESULTS

In COPD, peak V˙O2, V˙E, and HR achieved during 1STS reached 113%, 103%, and 93% of the corresponding values during CPET, respectively. Decrease in SpO2 from preexercise to peak exercise and the magnitude of dynamic hyperinflation were similar between 1STS and CPET. Borg dyspnea and leg fatigue scores were higher for CPET than 1STS. In healthy subjects, peak cardiorespiratory demand and symptom scores were higher during CPET compared with 1STS. A V˙O2 overshoot during recovery was observed only in people with COPD. After 1STS, the V˙O2 half-time recovery of COPD was 152 ± 25 s compared with 74 ± 18 in healthy subjects (P < 0.01). Ten people with COPD and five healthy subjects were considered as fatiguers.

CONCLUSION

The 1STS induced a similar cardiorespiratory stress to that of CPET and was associated with contractile quadriceps fatigue in people with severe COPD. The V˙O2 overshoot and slower recovery time of cardiorespiratory variables seen in COPD demonstrate the clinical relevance of monitoring the recovery phase of exercise.

Mechanisms affecting exercise ventilatory inefficiency-airflow obstruction relationship in male patients with chronic obstructive pulmonary disease

Background

Exercise ventilatory inefficiency is usually defined as high ventilation (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E} $$\end{document}V˙E) versus low CO₂ output (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{CO}2 $$\end{document}V˙CO2). The inefficiency may be lowered when airflow obstruction is severe because \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E} $$\end{document}V˙E cannot be adequately increased in response to exercise. However, the ventilatory inefficiency-airflow obstruction relationship differs to a varying degree. This has been hypothesized to be affected by increased dead space fraction of tidal volume (V_D/V_T), acidity, hypoxemia, and hypercapnia.

Methods

A total of 120 male patients with chronic obstructive pulmonary disease were enrolled. Lung function and incremental exercise tests were conducted, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E} $$\end{document}V˙E versus \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{CO}2 $$\end{document}V˙CO2 slope (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S) and intercept (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I) were obtained by linear regression. Arterial blood gas analysis was also performed in 47 of the participants during exercise tests. V_D/V_T and lactate level were measured.

Results

V_D/V_Tpeak was moderately positively related to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S (r = 0.41) and negatively related to forced expired volume in 1 sec % predicted (FEV₁%) (r = − 0.27), and hence the FEV₁%- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S relationship was paradoxical. The higher the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S, the higher the pH and P_aO₂, and the lower the P_aCO₂ and exercise capacity. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I was marginally related to V_D/V_Trest. The higher the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I, the higher the inspiratory airflow, work rate, and end-tidal PCO_2peak.

Conclusion

1) Dead space ventilation perturbs the airflow- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S relationship, 2) increasing ventilation thereby increases \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S to maintain biological homeostasis, and 3) the physiology- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I relationships are inconsistent in the current and previous studies.

Trial Registration

MOST 106–2314-B-040-025.

Ventilatory limitation and dynamic hyperinflation during exercise testing in Cystic Fibrosis

OBJECTIVE

To investigate the presence of dynamic hyperinflation after the Modified Shuttle Test (MST) and its relationship with lung function, exercise tolerance, and clinical symptoms in Cystic Fibrosis (CF).

METHODS

Retrospective observational study. Subjects in clinically stable condition with a CF diagnosis based on a positive sweat test (chloride >60 mEq/L) and/or presence of two disease causing mutations, with available data on MST, spirometry, maximal voluntary ventilation, and inspiratory capacity manoeuvres were considered for the analysis. Breathing reserve was calculated and a threshold value of 0.7 was subsequently chosen as a value of pulmonary mechanical limit. Subjects were then categorized into two groups according to the change in the inspiratory capacity from rest to peak exercise. Unconditional logistic regression was used to estimate unadjusted odds ratios, 95% confidence intervals and P-values.

RESULTS

Twenty-two subjects demonstrated evidence of dynamic hyperinflation during the MST. Thirteen out of 22 subjects were ventilatory limited during exercise including 5 of those without evidence of dynamic hyperinflation (P = 0.24). No combination of variables resulted in a parsimonious regression model.

CONCLUSIONS

Dynamic hyperinflation is common in CF and it is not associated with traditionally defined ventilatory limitation parameters during the MST. Pediatr Pulmonol. 2017;52:29-33. © 2016 Wiley Periodicals, Inc.

Reproducibility of NIRS assessment of muscle oxidative capacity in smokers with and without COPD

Low muscle oxidative capacity contributes to exercise intolerance in chronic obstructive pulmonary disease (COPD). Near-infrared spectroscopy (NIRS) allows non-invasive determination of the muscle oxygen consumption (mV̇O₂) recovery rate constant (k), which is proportional to oxidative capacity assuming two conditions are met: 1) exercise intensity is sufficient to fully-activate mitochondrial oxidative enzymes; 2) sufficient O₂ availability. We aimed to determine reproducibility (coefficient of variation, CV; intraclass correlation coefficient, ICC) of NIRS k assessment in the gastrocnemius of 64 participants with (FEV₁ 64±23%predicted) or without COPD (FEV₁ 98±14%predicted). 10-15s dynamic contractions preceded 6min of intermittent arterial occlusions (5-10s each, ∼250mmHg) for k measurement. k was lower (P<0.05) in COPD (1.43±0.4min^-1; CV=9.8±5.9%, ICC=0.88) than controls (1.74±0.69min^-1; CV=9.9±8.4%; ICC=0.93). Poor k reproducibility was more common when post-contraction mV̇O₂ and deoxygenation were low, suggesting insufficient exercise intensity for mitochondrial activation and/or the NIRS signal contained little light reflected from active muscle. The NIRS assessment was well tolerated and reproducible for muscle dysfunction evaluation in COPD.

Diastolic Dysfunction Is a Contributing Factor to Exercise Intolerance in COPD

Right ventricular (RV) systolic failure is rare in patients with COPD, but they often develop RV diastolic dysfunction. Left ventricular (LV) diastolic dysfunction is also common in this population. Nevertheless, data are scarce regarding the effect of diastolic dysfunction on the functional capacity in patients with COPD. We investigated the correlation between echocardiographic parameters of RV and LV diastolic function and the exercise capacity in COPD, by using conventional echocardiographic methods and tissue Doppler imaging. 65 patients with COPD (61 ± 9 years) in stages GOLD II-IV were investigated. Functional capacity was measured with 6-minute walk test (6MWT). Right (RA) and left atrial (LA) area index were measured; collapsibility index inferior vena cava was calculated. Parameters of the mitral and tricuspid inflow (E, A) as well as annular systolic (S), early- (e') and late- (a') diastolic myocardial longitudinal velocities were measured. E/A, E/e' and e'/a' ratios were calculated. 6MWT distance was 330 ± 76 m. LV diastolic dysfunction was found in 48 (74%) patients. LV and RV filling pressures were elevated in 28 (43%) and in 29 (45%) patients, respectively. In the left heart, LA area index showed significant correlation with the functional capacity (r = -0.319; p = 0.011). In stepwise multiple linear regression analysis tricuspid e'/a' (r = 0.611; p = 0.000), collapsibility index (r = 0.505; p = 0.000), RA area index (r = -0.445; p = 0.000) and body surface area (r = 0.314; p = 0.011) were independent predictors of 6MWT distance. Right ventricular diastolic function and filling pressure have strong influence on the functional capacity in patients with COPD.

Respiratory muscle training with normocapnic hyperpnea improves ventilatory pattern and thoracoabdominal coordination, and reduces oxygen desaturation during endurance exercise testing in COPD patients

Background

Few data are available about the effects of respiratory muscle training with normocapnic hyperpnea (NH) in COPD. The aim is to evaluate the effects of 4 weeks of NH (Spirotiger^®) on ventilatory pattern, exercise capacity, and quality of life (QoL) in COPD patients.

Methods

Twenty-six COPD patients (three females), ages 49–82 years, were included in this study. Spirometry and maximal inspiratory pressure, St George Respiratory Questionnaire, 6-minute walk test, and symptom-limited endurance exercise test (endurance test to the limit of tolerance [tLim]) at 75%–80% of peak work rate up to a Borg Score of 8–9/10 were performed before and after NH. Patients were equipped with ambulatory inductive plethysmography (LifeShirt^®) to evaluate ventilatory pattern and thoracoabdominal coordination (phase angle [PhA]) during tLim. After four supervised sessions, subjects trained at home for 4 weeks – 10 minutes twice a day at 50% of maximal voluntary ventilation. The workload was adjusted during the training period to maintain a Borg Score of 5–6/10.

Results

Twenty subjects completed the study. After NH, maximal inspiratory pressure significantly increased (81.5±31.6 vs 91.8±30.6 cmH₂O, P<0.01); exercise endurance time (+150 seconds, P=0.04), 6-minute walk test (+30 meters, P=0.03), and QoL (−8, P<0.01) all increased. During tLim, the ventilatory pattern changed significantly (lower ventilation, lower respiratory rate, higher tidal volume); oxygen desaturation, PhA, and dyspnea Borg Score were lower for the same work intensity (P<0.01, P=0.02, and P<0.01, respectively; one-way ANOVA). The improvement in tidal volume and oxygen saturation after NH were significantly related (R²=0.65, P<0.01).

Conclusion

As expected, NH improves inspiratory muscle performance, exercise capacity, and QoL. New results are significant change in ventilatory pattern, which improves oxygen saturation, and an improvement in thoracoabdominal coordination (lower PhA). These two facts could explain the reduced dyspnea during the endurance test. All these results together may play a role in improving exercise capacity after NH training.

Reduced dynamic hyperinflation after LVRS is associated with improved exercise tolerance

INTRODUCTION

Dynamic hyperinflation (DH) after lung volume reduction surgery (LVRS) has not been well studied. It is not known if reductions in DH correlate with improvements in exercise performance post-LVRS.

METHODS

Forty-two upper-lobe predominant emphysema patients who underwent LVRS were analyzed. Inspiratory capacity was measured every 2 min during symptom-limited cardiopulmonary exercise test (CPET) and end-expiratory lung volumes (EELV) were calculated. The main measure of DH was EELV/TLC ratio matched at metabolic isotimes (based on the post-rehabilitation VCO2max).

RESULTS

Patients had very severe airflow obstruction (FEV1 28.3 ± 7.0% predicted), were hyperinflated (TLC 125 ± 17% predicted) and gas trapped (RV 198 ± 39% predicted). Compared to the post-rehab baseline, dynamic hyperinflation (EELV/TLC) was significantly reduced after LVRS at 6, 12, 24, and 36 months. There were also increases in inspiratory reserve volume at matched isotimes after surgery. Patients adopted a slower, deeper breathing pattern during exercise after LVRS, which strongly correlated to reductions in DH. There were significant correlations between reductions in DH (EELV/TLC @50% VCO2max) and improvements in 6 min walk distance (Pearson r = -0.411, p = 0.02, n = 33) and maximal watts on CPET (Spearman r = -0.536, p = 0.001, n = 33) when comparing post-rehabilitation and 6 month post-LVRS values.

CONCLUSION

Dynamic hyperinflation during exercise was reduced after LVRS (up to 3 years) and there was a strong association between alterations in breathing pattern and reduced DH after LVRS. This is the first study to demonstrate that reductions in DH correlated with improved exercise performance following LVRS.

Identification of three exercise-induced mortality risk factors in patients with COPD

The survival rate of chronic obstructive pulmonary disease (COPD) patients with severely reduced exercise capacity is extremely low. We recently identified three life-threatening pathophysiological conditions during cardiopulmonary exercise testing (CPET): (1) exercise-induced hypoxemia, (2) sympathetic overactivity, and (3) progressive respiratory acidosis at low-intensity exercise. The present prospective observation study aimed to determine whether these parameters constitute risk factors of mortality in moderate-to-very severe COPD. Ninety-six COPD patients were followed-up, monthly, for >3 years. Subsequently, spirometry and CPET were performed to examine parameters of exercise-induced hypoxemia ([PaO2 slope, mmHg/L · min(-1)] = Decrease in PaO2/ΔV˙ O2 (Difference in ΔV˙ O2 between at rest and at peak exercise)), progression of acidosis ([ΔpH/ΔV˙ O2,/L · min(-1)] = Decrease in pH/ΔV˙ O2), and sympathetic overactivity ([Δnorepinephrine (NE)/ΔV˙ O2, ng/mL/L · min(-1)] = Increase in NE/ΔV˙ O2). Univariate analysis revealed a significant association between the three conditions with increased mortality. Kaplan-Meier analysis showed that the quartile combining the steepest PaO2 slope (≤-55 mmHg/ΔV˙ O2 [L/min]), steepest decrease in arterial blood pH (≤ -1.72/ΔV˙ O2 [L/min]), and most rapid increase in plasma NE level (≥ 5.2 ng/VO2 [L/min]) during incremental exercise was associated with higher all-cause mortality. These conditions showed cumulative effects on COPD patients' survival. Multivariate analyses revealed that these three life-threatening factors are also independent predictors of mortality based on age, heart rate and PaO2 at rest, body mass index, and forced expiratory volume in 1 s. Thus, these new exercise-induced mortality risk factors may lead to more efficient pulmonary rehabilitation programs for COPD patients based on patient-specific exercise-induced pathophysiological profiles.

Determinants of exercise capacity in obese and non-obese COPD patients

BACKGROUND

The effects of obesity in combination with chronic obstructive pulmonary disease (COPD) on exercise capacity are receiving increased attention. But, a comprehensive analysis of factors associated with aerobic capacity in obese COPD patients has not been performed.

METHODS

Six-min walking test (6MWT) was performed in 251 COPD patients, and 159 of those also carried out an incremental cardiopulmonary exercise test (CPET) to evaluate exercise capacity. In all patients, anthropometrics, dyspnea and anxiety-depression scores, lung function, daily physical activity, co-morbidities and circulating inflammatory biomarkers were also assessed. Six-min walking distance (6MWD) and peak oxygen uptake (VO2 peak) during CPET were two primary outcome variables.

RESULTS

57% of the patients showed body mass index (BMI) < 30 kg/m2 (COPDN) and the remaining 43% were obese with a BMI ≥ 30 kg/m2 (COPDO). In patients with COPDN, 6MWD showed independent negative associations with age, dyspnea score, sedentarism, depression scores and a positive relationship with arterial oxygenation; whereas in COPDO, 6MWD showed an inverse relationship with BMI. In COPDN, VO2 peak showed a negative association with age and positive relationships with both FEV1 and DLCO. However, in COPDO the dyspnea score was the strongest determinant of VO2 peak.

CONCLUSIONS

Obese and non-obese COPD patients show different determinants of aerobic capacity, including pulmonary and non-pulmonary factors that are also dependent on the type of exercise protocol. These results could be considered in the evaluation of obese patients with COPD.

Assessing exercise limitation using cardiopulmonary exercise testing

The cardiopulmonary exercise test (CPET) is an important physiological investigation that can aid clinicians in their evaluation of exercise intolerance and dyspnea. Maximal oxygen consumption ([Formula: see text]) is the gold-standard measure of aerobic fitness and is determined by the variables that define oxygen delivery in the Fick equation ([Formula: see text] = cardiac output × arterial-venous O(2) content difference). In healthy subjects, of the variables involved in oxygen delivery, it is the limitations of the cardiovascular system that are most responsible for limiting exercise, as ventilation and gas exchange are sufficient to maintain arterial O(2) content up to peak exercise. Patients with lung disease can develop a pulmonary limitation to exercise which can contribute to exercise intolerance and dyspnea. In these patients, ventilation may be insufficient for metabolic demand, as demonstrated by an inadequate breathing reserve, expiratory flow limitation, dynamic hyperinflation, and/or retention of arterial CO(2). Lung disease patients can also develop gas exchange impairments with exercise as demonstrated by an increased alveolar-to-arterial O(2) pressure difference. CPET testing data, when combined with other clinical/investigation studies, can provide the clinician with an objective method to evaluate cardiopulmonary physiology and determination of exercise intolerance.

Panic attacks and panic disorder in chronic obstructive pulmonary disease: a cognitive behavioral perspective

The prevalence of panic disorder in patients with chronic obstructive pulmonary disease (COPD) is up to 10 times greater than the overall population prevalence of 1.5-3.5%, and panic attacks are commonly experienced. When present, clinically significant anxiety decreases quality of life for COPD patients, and also increases health care costs. Therefore, understanding why COPD patients have such high rates of panic attacks and panic disorder is important for optimal management of COPD. The cognitive model of panic anxiety is the most widely accepted theory of panic attacks and panic disorder in physically healthy adults. According to this model, panic attacks occur when catastrophic misinterpretations of ambiguous physical sensations (such as shortness of breath or increased heart rate) increase arousal, creating a positive feedback loop that results in panic. As the major symptom of a terminal illness that threatens our most basic physical requirement, dyspnea in COPD is open to catastrophic misinterpretation. There is some experimental and clinical evidence for the applicability of the cognitive model of panic anxiety in COPD, and of the utility of cognitive behavior therapy (CBT), based on this model, for treating anxiety symptoms and panic attacks in COPD patients. However, there is much need for further studies. Evidence is increasing that mental health professionals, in collaboration with multi-disciplinary pulmonary teams, potentially have key roles to play in preventing and treating panic attacks and panic disorder in COPD patients. This review addresses diagnosis, epidemiology, theoretical conceptualizations, treatment, and recommendations for future research.

Interval hypoxic training improves autonomic cardiovascular and respiratory control in patients with mild chronic obstructive pulmonary disease

OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is associated with cardiac autonomic nervous system dysregulation. This study evaluates the effects of interval hypoxic training on cardiovascular and respiratory control in patients with mild COPD.

METHODS

In 18 eucapnic normoxic mild COPD patients (age 51.7 +/- 2.4 years, mean +/- SEM), randomly assigned to either training or placebo group, and 14 age-matched healthy controls (47.7 +/- 2.8 years), we monitored end-tidal carbon dioxide, airway flow, arterial oxygen saturation, electrocardiogram, and continuous noninvasive blood pressure at rest, during progressive hypercapnic hyperoxia and isocapnic hypoxia to compare baroreflex sensitivity to hypoxia and hypercapnia before and after 3 weeks of hypoxic training. In double-blind fashion, both groups received 15 sessions of passive intermittent hypoxia (training group) or normoxia (placebo group). For the hypoxia group, each session consisted of three to five hypoxic (15-12% oxygen) periods (3-5 min) with 3-min normoxic intervals. The placebo group inhaled normoxic air.

RESULTS

Before training, COPD patients showed depressed baroreflex sensitivity, as compared with healthy individuals, without evident chemoreflex abnormalities. After training, in contrast to placebo group, the training group showed increased (P < 0.05) baroreflex sensitivity up to normal levels and selectively increased hypercapnic ventilatory response (P < 0.05), without changes in hypoxic ventilatory response.

CONCLUSION

Eucapnic normoxic mild COPD patients already showed signs of cardiovascular autonomic abnormalities at baseline, which normalized with hypoxic training. If confirmed in more severe patients, interval hypoxic training may be a therapeutic strategy to rebalance early autonomic dysfunction in COPD patients.

Long-term repercussions of a pulmonary rehabilitation program on the indices of anxiety, depression, quality of life and physical performance in patients with COPD

OBJECTIVE

To assess the 24-month effects of a pulmonary rehabilitation program (PRP) on anxiety, depression, quality of life and physical performance of COPD patients.

METHODS

Thirty patients with COPD (mean age, 60.8 +/- 10 years; 70% males) participated in a 12-week PRP, which included 24 physical exercise sessions, 24 respiratory rehabilitation sessions, 12 psychotherapy sessions and 3 educational sessions. All patients were evaluated at baseline (pre-PRP), at the end of the treatment (post-PRP) and two years later (current) by means of four instruments: the Beck Anxiety Inventory; the Beck Depression Inventory; Saint George's Respiratory Questionnaire; and the six-minute walk test (6MWT).

RESULTS

The comparison between the pre-PRP and post-PRP values revealed a significant decrease in the levels of anxiety (pre-PRP: 10.7 +/- 6.3; post-PRP: 5.5 +/- 4.4; p = 0.0005) and depression (pre-PRP: 11.7 +/- 6.8; post-PRP: 6.0 +/- 5.8; p = 0.001), as well as significant improvements in the distance covered on the 6MWT (pre-PRP: 428.6 +/- 75.0 m; post-PRP: 474.9 +/- 86.3 m; p = 0.03) and the quality of life index (pre-PRP: 51.0 +/- 15.9; post-PRP: 34.7 +/- 15.1; p = 0.0001). There were no statistically significant differences between the post-PRP and current evaluation values.

CONCLUSIONS

The benefits provided by the PRP in terms of the indices of anxiety, depression and quality of life, as well as the improved 6MWT performance, persisted throughout the 24-month study period.

Comparison of six-minute walking tests conducted with and without supplemental oxygen in patients with chronic obstructive pulmonary disease and exercise-induced oxygen desaturation

BACKGROUND

There are contradictory reports in the literature on the effects of supplemental oxygen administered before or after exercise tests. In light of this, we compared the results of 6-minute walking tests performed in room-air conditions (A6MWT) and with supplemental oxygen (O6MWT) in patients with chronic obstructive pulmonary disease (COPD) and exercise-induced oxygen desaturation.

PATIENTS AND METHODS

Thirty-one patients with COPD were included in the study. The A6MWT and O6MWT were performed in randomized order on each patient. During the tests, severity of dyspnea and tiring of the leg were evaluated by the Modified Borg Scale. Heart rate and pulsed oxygen saturation and blood pressure were measured by pulse oximeter.

RESULTS

Walking distance was longer with the O6MWT than with the A6MWT (P=0.001). The O6MWT resulted in a smaller increase in dyspnea, leg fatigue, and heart rate and a smaller drop in pulsed saturation than the A6MWT (P<0.05). The walking distance with the O6MWT correlated with respiratory function and hemodynamic parameters (P<0.05).

CONCLUSION

The O6MWT, which produced less hemodynamic stress and was safer than the A6MWT, might provide more accurate information on exercise limitation for patients with COPD. These results suggest that the O6MWT can be used as a standard walking exercise test for patients with COPD and exercise-induced oxygen desaturation.

The impact of exercise training intensity on change in physiological function in patients with chronic obstructive pulmonary disease

Pulmonary rehabilitation incorporating exercise training is an effective method of enhancing physiological function and quality of life for patients with chronic obstructive pulmonary disease (COPD). Despite the traditional belief that exercise is primarily limited by the inability to adequately increase ventilation to meet increased metabolic demands in these patients, significant deficiencies in muscle function, oxygen delivery and cardiac function are observed that contribute to exercise limitation. Because of this multifactorial exercise limitation, defining appropriate exercise training intensities is difficult. The lack of a pure cardiovascular limitation to exercise prohibits the use of training guidelines that are based on cardiovascular factors such as oxygen consumption or heart rate. Current recommendations for exercise training intensity for patients with COPD include exercising at a 'maximally tolerable level', at an intensity corresponding with 50% of peak oxygen consumption (V-O2peak), or at 60-80% of peak power output obtained on a symptom-limited exercise tolerance test. In general, it appears that higher intensity training elicits greater physiological change than lower intensity training; however, there is no consensus as to the exercise training intensity that elicits the greatest physiological benefit while remaining tolerable to patients. The 'optimal' intensity of training likely depends upon the individual goals of each patient. If the goal is to increase the ability to sustain tasks that are currently able to be performed, lower to moderate-intensity training is likely to be sufficient. If the goal of training, however, is to increase the ability to perform tasks that are above the current level of tolerance, higher intensity training is likely to elicit greater performance increases. In order to perform higher intensity exercise, an interval training model is likely required. High-intensity interval training involves significant anaerobic energy utilisation and, therefore, may better mimic the physiological requirements of activities of daily living. Also, high-intensity interval training is tolerable to patients and may, in fact, reduce the degree of dyspnoea and dynamic hyperinflation through a reduced ventilatory demand. Another factor that will determine the optimal intensity of training is the relative contribution of ventilatory limitation to exercise tolerance. If peak exercise tolerance is limited by a patient's ability to increase ventilation, it is possible that interval training at an intensity higher than peak will elicit greater muscular adaptation than an intensity at or below peak power on an incremental exercise test. More research is required to determine the optimal training intensity for pulmonary rehabilitation patients.

Exercise Performance Improves in Patients With COPD due to Respiratory Muscle Endurance Training

BACKGROUND

Impaired exercise tolerance is frequently observed in patients with COPD. Respiratory muscle endurance training (RMET) by means of normocapnic hyperpnea can be used to improve respiratory muscle function and probably exercise capacity. RMET is not applied on a large scale because complicated equipment is needed to maintain carbon dioxide homeostasis during hyperpnea, which can also be done by enlarging the dead space of the ventilatory system by breathing through a tube. Therefore, tube breathing might be a new, inexpensive method for home-based RMET. The aim of this study was to assess whether home-based RMET by means of tube breathing improves endurance exercise performance in patients with COPD.

METHODS

We randomized 36 patients with moderate-to-severe COPD to RMET by paced tube breathing (n = 18) or sham training (control, n = 18). Both groups trained twice daily for 15 min, 7 days per week, for 5 weeks.

RESULTS

Patients receiving RMET showed significant improvements in endurance exercise capacity (constant-load exercise on cycle ergometry; 18 min vs 28 min, p < 0.001), in perception of dyspnea (Borg score; 8.4 vs 5.4, p < 0.001), and respiratory muscle endurance capacity (sustainable inspiratory pressure; 25 cm H(2)O vs 31 cm H(2)O, p = 0.005). Quality of life (chronic respiratory disease questionnaire) also improved (78.7 to 86.6, p = 0.001). The control group showed no significant changes.

CONCLUSION

Home-based RMET by means of tube breathing leads to a significant improvement of endurance exercise capacity, a reduction in perception of dyspnea, and an improvement in quality of life in patients with moderate-to-severe COPD.

Pulmonary function tests fail to predict exercise intolerance in sheep with emphysema

PURPOSE

The purpose of this study was to examine ventilatory parameters, gas exchange, and exercise tolerance in sheep undergoing cardiopulmonary exercise testing and pulmonary function testing at baseline and after induction of emphysema using nebulized papain, to improve our understanding of the contributions of parenchymal emphysema with minimal airway disease to exertional dysfunction in mild-to-moderate emphysema.

METHODS

Static lung physiology (total lung capacity, residual volume, static elastance, and diffusing capacity of carbon monoxide) and lung (ZL) input impedance were measured, and cardiopulmonary exercise testing (CPET) was performed in 12 sheep before and after induction of emphysema. Papain treatment was delivered over a 12-wk period, as a single dose per week, to induce mild-to-moderate emphysema without airway disease. Static and dynamic lung physiology, as well as CPET, were then repeated.

RESULTS

At the emphysema time point (EMPH), all animals were asymptomatic for emphysema at rest. There was a 60% increase in residual volume and a 57% decrease in static elastance, accompanied by a 36% reduction in diffusing capacity. Airway resistance was consistently, mildly increased, resulting in an increased expiratory time constant for all sheep at EMPH. There were no significant differences at EMPH versus baseline for any measured physiological variables during CPET (VO2peak, VCO2peak, RER, anaerobic threshold, O2 pulse, tidal volume, peak flow, peak VE/VO2, or peak VE).

CONCLUSION

There is notable conservation of exercise capacity in sheep with mild-to-moderate parenchymal emphysema; this is not predicted by pulmonary function tests. In the absence of significant airway narrowing, mild-to-moderate emphysema is unlikely to result in airflow limitation.

Exercise responses during endurance testing at different intensities in patients with COPD

Endurance time on submaximal exercise tests is a sensitive measure in detecting changes after medical intervention and is used as an outcome in clinical trials, although there has been little discussion regarding the appropriate intensity. Therefore, we investigated whether there were differences in exercise responses between endurance tests at high versus moderate intensity, and analyzed which test was more appropriate. Thirty-seven patients with chronic obstructive pulmonary disease participated in the study. They performed cycle endurance tests at high and moderate submaximal workloads representing 80% and 60% of the maximum work rate reached on progressive cycle ergometry, respectively. Each type of exercise test was performed after inhaling salbutamol 400 microg, ipratropium bromide 80 microg or an identical placebo. Endurance time on the 80% endurance test was much shorter than on the 60% endurance test. The coefficients of variation for the endurance time were lower on the 80% test. Statistically significant improvements in the endurance time after bronchodilators in comparison to placebo were found only on the 80% test. When using the endurance time as an outcome, the high intensity endurance test is preferable to the moderate intensity endurance test, as the high intensity test demonstrated shorter exercise time, less variability and higher sensitivity.

[Exercise limitation in patients with chronic obstructive pulmonary disease at the altitude of Bogota (2640 m). Breathing pattern and arterial gases at rest and peak exercise]

OBJECTIVE

To describe the response to exercise of normal subjects and patients with chronic obstructive pulmonary disease (COPD) in Bogota, Colombia (altitude: 2640 m; atmospheric pressure: 560 mm Hg) and compare it with data published on COPD patients at sea level. Healthy people increase their minute ventilation to attenuate hypoxemia (PaCO2: 30 mm Hg; PaO2: 63 mm Hg).

MATERIAL AND METHOD

A descriptive study was carried out on healthy subjects and COPD patients. Exercise limitation was determined by an incremental test on a cycle ergometer.

RESULTS

The study enrolled 16 healthy subjects and 25 COPD patients (forced expiratory volume in 1 second: 43.3% [SD 13%]). Minute ventilation at rest was greater in COPD patients compared with healthy subjects, it was not adequately sustained during exercise, and there was a reduction in peak oxygen uptake (53.0% [15%]). At peak exercise, inspiratory capacity decreased (-0.62 [0.34] L), the ratio of minute ventilation to maximal voluntary ventilation increased, and severe hypoxemia occurred (PaO2: 49.9 [9.9] mm Hg). There was significant correlation between hypoxemia and the percentage of predicted peak oxygen uptake (r=0.60), leg fatigue (r=-0.62), percentage of predicted peak inspiratory capacity (r=0.61), and the percentage of predicted peak tidal volume (r=0.49). Minute ventilation at rest was shown to be higher, there was a greater reduction in the inspiratory capacity during exercise, and hypoxemia was more severe at rest and during exercise for patients with COPD in Bogota, compared with those at sea level.

CONCLUSIONS

Patients with COPD living in Bogota were shown to have lower tolerance to exercise evidenced by ventilatory limitation and severe hypoxemia. Increased minute ventilation at rest, greater reduction in inspiratory capacity, and severity of hypoxemia during exercise were the main differences between COPD in Bogota and at sea level.

Clinical implications of Hoover's sign in chronic obstructive pulmonary disease

Background: The objective of the study was to evaluate whether Hoover's sign-the paradoxical inspiratory movement of the lateral rib margin-may have clinical implications in patients with COPD. Methods: The study included two groups of male patients with stable COPD-30 with and 30 without Hoover's sign-who were matched for age and smoking habits. Spirometric values were assessed for both groups. Degree of dyspnea, measured for normal activities with the Medical Research Council (MRC) scale and for climbing two flights of stairs with the Borg scale, and utilization of health resources, including hospitalization, were compared. Results: Patients with Hoover's sign had a higher degree of dyspnea [MRC 2.2 (S.D.: 1.2) and 1.0 (0.8), p<0.0001; Borg 5.6 (2.4) and 3.1 (2.3), p=0.0001] and a higher number of hospitalizations [0.87 (1.0) and 0.27 (0.5), p=0.005] and emergency visits [2.5 (2.3) and 0.9 (2.3), p=0.01] than patient's without it. FEV(1) significantly correlated with dyspnea scales only in patients with Hoover's sign (MRC r=0.48; Borg r=0.49; p<0.05). Conclusions: Our study shows that Hoover's sign in COPD identifies a group of patients with a higher level of dyspnea and a higher use of health care resources, regardless of the degree of functional impairment. Consequently, establishing the presence of Hoover's sign would appear to be valuable in treating patients with COPD.

A randomized controlled trial of the effect of psychotherapy on anxiety and depression in chronic obstructive pulmonary disease

OBJECTIVE

To assess the effect of psychotherapy on the anxiety and depression levels of patients with chronic obstructive pulmonary disease (COPD).

DESIGN

A blind, randomized, controlled trial.

SETTING

Outpatient university pulmonary rehabilitation program in Brazil.

PARTICIPANTS

Thirty patients with COPD (mean age, 60.33y; 22 men) attending a pulmonary rehabilitation program were randomized into 2 groups: experimental group (G1) and control group (G2). Both groups underwent a 12-week treatment program.

INTERVENTIONS

Group 1 (n=14) participated in 24 sessions of physical exercise, 24 sessions of physiotherapy, 12 psychologic sessions, and 3 educational sessions. Group 2 did not participate in psychotherapy sessions.

MAIN OUTCOME MEASURES

All patients were evaluated at baseline and at completion of the pulmonary rehabilitation program by using 3 instruments: the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), and 6-minute walk distance (6MWD).

RESULTS

Both groups showed statistically significant improvements on the 6MWD (G1, P<.001; G2, P=.03). Only G1 had a significant reduction in anxiety and depression levels (G1: BAI, P<.001; BDI, P<.001; G2: BAI, P=.156; BDI, P=.142). Statistically significant differences existed between G1 and G2 for BAI (P<.001) and BDI (P=.02).

CONCLUSIONS

Including psychotherapy in a pulmonary rehabilitation program for COPD reduced patients' anxiety and depression levels but did not modify 6MWD performance.

Analysis of the factors related to mortality in chronic obstructive pulmonary disease: role of exercise capacity and health status

In this study, we analyzed the relationships of exercise capacity and health status to mortality in patients with chronic obstructive pulmonary disease (COPD). We recruited 150 male outpatients with stable COPD with a mean postbronchodilator FEV1 at 47.4% of predicted. Their pulmonary function, progressive cycle ergometry, and health status using the Chronic Respiratory Disease Questionnaire, the St. George's Respiratory Questionnaire (SGRQ), and the Breathing Problems Questionnaire were measured at entry. Among 144 patients who were available for the 5-year follow-up, 31 had died. Univariate Cox proportional hazards analysis revealed that the SGRQ total score and the Breathing Problems Questionnaire were significantly correlated with mortality; however, with the Chronic Respiratory Disease Questionnaire, the total score was not significantly correlated. Multivariate Cox proportional hazards analysis revealed that the peak oxygen uptake and the SGRQ total score were both predictive of mortality, independent of FEV1 and age. Stepwise Cox proportional hazards analysis revealed that the peak oxygen uptake was the most significant predictor of mortality. We found that exercise capacity and health status were significantly correlated with mortality, although different health status measures had different abilities to predict mortality. These results will have a potentially great impact on the multidimensional evaluation of disease severity in COPD.

Relationship between different indices of exercise capacity and clinical measures in patients with chronic obstructive pulmonary disease

PURPOSE

The purpose of this study was to make comparisons between different types of exercise tests used in chronic obstructive pulmonary disease (COPD) to better interpret the results and to select the most suitable testing procedure. Therefore, we evaluated the relationship between exercise capacity and other clinical measures and their relative contributions to exercise capacity in patients with COPD.

METHOD

We studied 36 patients with stable COPD. All patients underwent baseline pulmonary function testing. Dyspnea during activities of daily living was assessed with the Oxygen Cost Diagram (OCD). The Hospital Anxiety and Depression Scale and the St George's Respiratory Questionnaire were used to assess psychologic status and health-related quality of life, respectively. All patients performed the 6-minute walking test, progressive cycle ergometry, and the cycle endurance test.

RESULTS

Each exercise capacity result correlated significantly with pulmonary function, the OCD, and the Activity and Total scores of the St George's Respiratory Questionnaire. Multiple regression analyses revealed that the OCD was an important predictor of exercise capacity, especially for the walking test. Diffusing capacity was also a significant predictor on progressive cycle ergometry. Body mass index was the most significant predictor of the endurance time.

CONCLUSION

The 3 different exercise tests had similar characteristics in relation to pulmonary function, dyspnea, and health-related quality of life in patients with COPD. However, some differences were found in the aspects they evaluated.

Recent advances in diagnosis and management of chronic bronchitis and emphysema

Chronic obstructive pulmonary disease is a progressive inflammatory disease of the airways and lung parenchyma. Expiratory airflow limitation is the hallmark of chronic obstructive pulmonary disease. It is a significant cause of morbidity and mortality in the United States and worldwide and results in a large consumption of health care resources. Unfortunately, despite efforts to curb this disease, its prevalence is increasing. The diagnosis is usually made when the patient complains of dyspnea on exertion; by this time, irreversible structural damage to the lung has already occurred. Given the nonspecific symptoms of the disease and the inability to effectively treat and reverse the damage, it is essential to diagnose the disease in its early stages and take the necessary preventive measures, thus avoiding disability or death. This review summarizes the latest developments in the diagnosis and management of chronic obstructive pulmonary disease. The first half of the review discusses functional, radiographic, biochemical, and cellular/histopathologic issues in the diagnosis of chronic obstructive pulmonary disease. The second half focuses on the current pharmacologic and nonpharmacologic advances in chronic obstructive pulmonary disease, including the role of respiratory support and surgical treatment. Based on the research on the cellular mechanisms of chronic obstructive pulmonary disease, the review also makes a reference to novel and experimental therapies for chronic obstructive pulmonary disease.