Lung hyperinflation and its reversibility in patients with airway obstruction of varying severity

Beyond Spirometry: Linking Wasted Ventilation to Exertional Dyspnea in the Initial Stages of COPD

Exertional dyspnea, a key complaint of patients with chronic obstructive pulmonary disease (COPD), ultimately reflects an increased inspiratory neural drive to breathe. In non-hypoxemic patients with largely preserved lung mechanics - as those in the initial stages of the disease - the heightened inspiratory neural drive is strongly associated with an exaggerated ventilatory response to metabolic demand. Several lines of evidence indicate that the so-called excess ventilation (high ventilation-CO2 output relationship) primarily reflects poor gas exchange efficiency, namely increased physiological dead space. Pulmonary function tests estimating the extension of the wasted ventilation and selected cardiopulmonary exercise testing variables can, therefore, shed unique light on the genesis of patients' out-of-proportion dyspnea. After a succinct overview of the basis of gas exchange efficiency in health and inefficiency in COPD, we discuss how wasted ventilation translates into exertional dyspnea in individual patients. We then outline what is currently known about the structural basis of wasted ventilation in "minor/trivial" COPD vis-à-vis the contribution of emphysema versus a potential impairment in lung perfusion across non-emphysematous lung. After summarizing some unanswered questions on the field, we propose that functional imaging be amalgamated with pulmonary function tests beyond spirometry to improve our understanding of this deeply neglected cause of exertional dyspnea. Advances in the field will depend on our ability to develop robust platforms for deeply phenotyping (structurally and functionally), the dyspneic patients showing unordinary high wasted ventilation despite relatively preserved FEV1.

Comprehensive appraisal of lung function in young COPD patients: a single center observational study

PURPOSE

The present study aimed to investigate the clinical characteristics and lung function impairment in young people diagnosed with chronic obstructive pulmonary disease (COPD).

PATIENTS AND METHODS

We retrospectively enrolled patients with COPD who underwent symptom assessment and comprehensive pulmonary function tests at the First Affiliated Hospital of Guangzhou Medical University between August 2017 and March 2022. The patients were categorized into two groups based on age: a young COPD group (aged 20-50 years) and an old COPD group (aged > 50 years).

RESULTS

A total of 1282 patients with COPD were included in the study, with 76 young COPD patients and 1206 old COPD patients. Young COPD patients exhibited a higher likelihood of being asymptomatic, lower rates of smoking, and a lower smoking index compared to old COPD patients. Although young COPD patients had higher median post-bronchodilator forced expiratory volume in 1 s (post-BD FEV1) (1.4 vs.1.2 L, P = 0.019), diffusing capacity of the lung for carbon monoxide (DLCO) (7.2 vs. 4.6, P<0.001), and a lower median residual volume to total lung capacity ratio (RV/TLC) compared to their older counterparts, there were no differences observed in severity distribution by GOLD categories or the proportion of lung hyperinflation (RV/TLC%pred > 120%) between two groups. Surprisingly, the prevalence of reduced DLCO was found to be 71.1% in young COPD, although lower than in old COPD (85.2%).

CONCLUSION

Young COPD showed fewer respiratory symptoms, yet displayed a similar severity distribution by GOLD categories. Furthermore, a majority of them demonstrated lung hyperinflation and reduced DLCO. These results underscore the importance of a comprehensive assessment of lung function in young COPD patients.

Lung Hyperinflation as Treatable Trait in Chronic Obstructive Pulmonary Disease: A Narrative Review

Lung hyperinflation (LH) is a common clinical feature in patients with chronic obstructive pulmonary disease (COPD). It results from a combination of reduced elastic lung recoil as a consequence of irreversible destruction of lung parenchyma and expiratory airflow limitation. LH is an important determinant of morbidity and mortality in COPD, partially independent of the degree of airflow limitation. Therefore, reducing LH has become a major target in the treatment of COPD over the last decades. Advances were made in the diagnostics of LH and several effective interventions became available. Moreover, there is increasing evidence suggesting that LH is not only an isolated feature in COPD but rather part of a distinct clinical phenotype that may require a more integrated management. This narrative review focuses on the pathophysiology and adverse consequences of LH, the assessment of LH with lung function measurements and imaging techniques and highlights LH as a treatable trait in COPD. Finally, several suggestions regarding future studies in this field are made.

Unravelling the complex interplay of factors behind exercise limitations and physical inactivity in COPD

Exercise limitation and physical inactivity are known treatable traits for people with COPD. Maximising exercise capacity and keeping people physically active improves health status and survival rates among people with COPD. However, managing these two treatable traits can be extremely challenging for clinicians due to the complex intersectionality of factors influencing an individual's capacity, opportunity and motivation to engage in physical activity. This review presents the complex factors influencing exercise capacity ("can do"), levels of physical activity ("do do") and sedentary behaviours amongst people with COPD and provides practical recommendations on how clinicians can address some of these factors in practice. Most importantly, it highlights the importance of referring to pulmonary rehabilitation as a way to improve exercise capacity among people with COPD.

Residual reversibility in COPD patients already on long-acting bronchodilator: The OscilloRevers Study

BACKGROUND

Dyspnea is a complex symptom of chronic obstructive pulmonary disease (COPD) which is not strongly correlated with lung function measures. Long-acting bronchodilators (LAB) may reduce this dyspnea, but some patients report persistent chronic dyspnea despite this treatment. This study aims to assess residual reversibility and clinical response after short-acting bronchodilator (SAB) in COPD patients already treated by LAB and reporting persistent dyspnea.

METHODS

COPD patients with a persistent dyspnea (modified Medical Research Council scale (mMRC) ≥1) despite current stable treatment with at least one LAB were included. Spirometry, plethysmography and impulse oscillometry (IOS) were performed at peak effect of their LAB and repeat 45 min after the intake of two SAB (400 µg of salbutamol and 80 µg of ipratropium). Dyspnea improvement was assessed at 45 min after SAB through a comparative two-sided VAS (-100 mm for maximal improvement; +100 mm for maximal degradation).

RESULTS

Twenty-two COPD patients were analyzed, mainly men (59.1 %) with a mean age of 60.6 years and a median FEV1 of 54 % of predicted values. Fifty percent of patients reported a severe basal dyspnea (mMRC ≥2). After SAB, spirometric and plethysmographic measurements were statistically improved. For IOS measurement, reactance at 5 Hz (X5) and area of reactance (AX) were also improved. Fifty percent of patients reported a clinically relevant improvement of their resting dyspnea. However, no correlation was found between dyspnea improvement and functional measures.

CONCLUSIONS

Fifty percent of COPD patients regularly treated with one or two LAB still report a relevant improvement of resting dyspnea after the adjunctive intake of double short-acting bronchodilators. Physiological mechanisms associated with this improvement remain to be determined.

CLINICAL TRIAL REGISTRATION

NCT02928744.

Impact of the new European respiratory (ERS)/American Thoracic Society (ATS) pulmonary function test interpretation guidelines 2021 on the interpretation of bronchodilator responsiveness in subjects with airway obstruction

BACKGROUND

The impact of the new 2021 European Respiratory Society (ERS)/American Thoracic Society (ATS) pulmonary function test interpretation guidelines on the interpretation of bronchodilator responsiveness (BDR) in subjects with airway obstruction is still required. Therefore, the objective of this study was to explore the agreement between the 2005 and 2021 ERS/ATS criteria regarding the interpretation of the BDR. Moreover, we explore the factors that influenced the discordance of positive bronchodilator responsiveness (BDR+) between these two criteria.

METHODS

The agreement regarding the interpretation of BDR + between the two criteria was assessed using kappa (κ). The percentage of agreement in the interpretation of BDR + between the two criteria was calculated. The factors that influenced the discordance of BDR + between these two criteria were also analyzed.

RESULTS

A total of 500 subjects with a mean age of 60.5 ± 15.6 years, 62.2% male were included. The study observed a good level of agreement in the interpretation of BDR + between the two criteria with kappa values = 0.782. The percentages of agreement on the interpretation of BDR + between the two criteria were high, with values = 90.6%. Male sex was the only factor that influenced the discordance of BDR + between these two criteria.

CONCLUSION

A good level of agreement was observed in the interpretation of BDR + between the 2005 and 2021 criteria. Therefore, the 2005 and 2021 ERS/ATS criteria for BDR can be used interchangeably. However, the discordance of BDR + between these two criteria could be affected by sex.

Atomization efficacy of a novel micro-dose mesh nebulizer (CVS-100) versus the traditional mesh nebulizer (M102) in adults with chronic obstructive pulmonary disease: A randomized non-inferiority clinical trial

OBJECTIVE

To compare the atomization efficacy of a novel micro-dose mesh nebulizer (CVS-100) versus the traditional mesh nebulizer (M102) in nebulizing a combination of ipratropium bromide and salbutamol for treatment of stable moderate-to-severe chronic obstructive pulmonary disease (COPD).

METHODS

A randomized, parallel, non-inferiority study was conducted. A total of 64 stable COPD patients were randomly assigned to either the experimental group or the control group in a 1:1 ratio. Each the experimental group received nebulized Combivent (Compound Ipratropium Bromide Solution) with CVS-100, while the control group received Combivent with M102. Lung ventilation function was measured before and 30 min after nebulization, and the difference in percentage of forced expiratory volume in the first second (FEV1) of predicted value (FEV1%pred), the forced expiratory flow at 50% (FEF50%), the forced expiratory flow at 75% (FEF75%), the mid-expiratory flow (FEF25-75%), and maximal voluntary ventilation (MVV) was evaluated. The non-inferiority margin for the lower 95% confidence limit was set at 3.5%.

RESULTS

The lower limit of the 95% confidence interval for the difference in FEV1%pred between the two groups was -1.83357, which was greater than -3.5. No significant differences were found in FEF50%, FEF75%, FEF25∼75%, MVV before and after nebulization between the two groups.

CONCLUSION

The novel micro-dose mesh nebulizer (CVS-100) was found to be non-inferior to the traditional mesh nebulizer (M102) in terms of the change in FEV1%pred from baseline after nebulization. Similar results were observed for all other measures of efficacy.

Effectiveness of glycopyrronium bromide in the treatment of small airway dysfunction: A retrospective study

Objective

Glycopyrronium bromide has a quaternary ammonium structure and a low oral bioavailability, which reduces its systemic effects; it acts through a bronchodilating blockade of muscarinic receptors. The aim of this retrospective study was to analyze a possible relationship between the changes in the small airways and the efficacy of a bronchodilation with glycopyrronium bromide; exercise tolerance was also assessed, by performing the six-minute walking test.

Methods

Forty-one patients were identified (23 females/18 males; mean age 66.82 ± 9.75 years), with a normal forced expiratory volume in 1 s (FEV₁)/forced vital capacity ratio of 77.45% ± 4.86%, a reduced forced mid-expiratory flow between 25% and 75% of forced vital capacity (FEF_25-75) of 42.9% ± 10.5%, with an increased residual volume/total lung capacity ratio of 132.68% ± 6.41%, FEV₁ 1.85 ± 0.54 L, forced vital capacity 2.39 ± 0.71 L, airway resistance (sR tot) 168.18% ± 42.5%, total lung capacity 98.28% ± 8.9%, six-minute walking test distance 318.3 ± 36.6 m, modified British Medical Research Council dyspnea scale 1.48 ± 0.77. All patients were initiated with glycopyrronium bromide 50 μg/die and reassessed after 4 months.

Results

After the treatment with glycopyrronium bromide, a significant improvement was noted regarding forced vital capacity (p = 0.04), FEF_25-75 (p < 0.001), sR tot (p < 0.001), residual volume/total lung capacity ratio (p < 0.001) with reduction of dynamic hyperinflation, the significant increase of the distance covered during the six-minute walking test (p < 0.001), and modified British Medical Research Council (p < 0.001) showed enhanced exercise tolerance. FEV₁ improved, but the difference was not statistically significant.

Conclusions

Small airway dysfunction is associated with bronchodilator responsiveness. Glycopyrronium bromide has proven to be capable of inducing favorable effects on lung hyperinflation and its functional and clinical consequences, with a decrease in dyspnea and an increase in exercise capacity. The use of anticholinergic drugs is useful in the management of small airway disease.

Efficacy of Nebulized Glycopyrrolate on Lung Hyperinflation in Patients with COPD

INTRODUCTION

Lung hyperinflation in chronic obstructive pulmonary disease (COPD) is associated with activity limitation, impaired cardiac output, and mortality. Several studies have demonstrated that long-acting muscarinic antagonists (LAMAs) delivered by dry powder inhalers can promote lung deflation; however, the potential of nebulized LAMAs on improving hyperinflation in COPD is currently unknown.

METHODS

This single-center, randomized, double-blind, two-way crossover study (NCT04155047) evaluated the efficacy of a single dose of nebulized LAMA [glycopyrrolate (GLY) 25 µg] versus placebo in patients with COPD and lung hyperinflation. Patients with moderate-to-severe COPD and a residual volume (RV) ≥ 130% of predicted normal were included. The primary endpoint was changed from baseline in RV at 6 h post-treatment. Other endpoints included changes from baseline in spirometric and plethysmographic measures up to 6 h post-treatment.

RESULTS

A total of 22 patients (mean pre-bronchodilator RV, 153.7% of predicted normal) were included. The primary objective of the study was not met; the placebo-adjusted least squares (LS) mean [95% confidence interval (CI) change from baseline in RV with GLY at 6 h post-treatment was - 0.323 l (- 0.711 to 0.066); p = 0.0987]. A post hoc evaluation of the primary analysis was conducted after excluding a single statistical outlier; substantial improvements in RV with GLY compared with placebo was observed after exclusion of this outlier [placebo-adjusted LS mean change from baseline (95% CI) in RV was - 0.446 l (- 0.741 to - 0.150)]. Improvements from baseline were also observed with GLY compared with placebo in spirometric and plethysmographic measures up to 6 h post-treatment. GLY was generally safe, and no new safety signals were detected.

CONCLUSIONS

This is the first study to evaluate the effect of nebulized GLY on lung deflation. Nebulized GLY resulted in marked improvements in RV up to 6 h post-treatment, compared with placebo. Improvements were also observed with GLY in spirometric and plethysmographic parameters of lung function.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04155047.

Normal limits for oscillometric bronchodilator responses and relationships with clinical factors

Introduction

We aimed to determine normal thresholds for positive bronchodilator responses for oscillometry in an Australian general population sample aged ≥40 years, to guide clinical interpretation. We also examined relationships between bronchodilator responses and respiratory symptoms, asthma diagnosis, smoking and baseline lung function.

Methods

Subjects recruited from Sydney, Melbourne and Busselton, Australia, underwent measurements of spirometry, resistance (R_rs6) and reactance (X_rs6) at 6 Hz, before and after inhalation of salbutamol 200 μg. Respiratory symptoms and/or medication use, asthma diagnosis, and smoking were recorded. Threshold bronchodilator responses were defined as the fifth percentile of decrease in R_rs6 and 95th percentile increase in X_rs6 in a healthy subgroup.

Results

Of 1318 participants, 1145 (570 female) were analysed. The lower threshold for ΔR_rs6 was −1.38 cmH₂O·s·L⁻¹ (−30.0% or −1.42 Z-scores) and upper threshold for ΔX_rs6 was 0.57 cmH₂O·s·L⁻¹ (1.36 Z-scores). Respiratory symptoms and/or medication use, asthma diagnosis, and smoking all predicted bronchodilator response, as did baseline oscillometry and spirometry. When categorised into clinically relevant groups according to those predictors, ΔX_rs6 was more sensitive than spirometry in smokers without current asthma or chronic obstructive pulmonary disease (COPD), ∼20% having a positive response. Using absolute or Z-score change provided similar prevalences of responsiveness, except in COPD, in which responsiveness measured by absolute change was twice that for Z-score.

Discussion

This study describes normative thresholds for bronchodilator responses in oscillometry parameters, including intra-breath parameters, as determined by absolute, relative and Z-score changes. Positive bronchodilator response by oscillometry correlated with clinical factors and baseline function, which may inform the clinical interpretation of oscillometry.

Normative values for bronchodilator responses measured by oscillometry were derived. Responsiveness related to clinical factors and baseline function. Reactance was more sensitive in detecting bronchodilator response than spirometry mild airways disease.https://bit.ly/3wtWVeV

Residual Volume Responsiveness Testing May Improve the Detection of Reversible Airway Obstruction in Asthma

BACKGROUND

Residual volume responsiveness to bronchodilator administration has been observed in subjects with chronic obstructive pulmonary disease. However, the prevalence of residual volume (RV) responsiveness has not been formally studied in asthma.

OBJECTIVE

To identify the prevalence and magnitude of RV responsiveness in asthma.

METHODS

Physician-diagnosed adult subjects with asthma on treatment for >12 months were prospectively recruited to perform spirometry and measurement of lung volumes using body plethysmography before and after administration of 360 μg of albuterol.

RESULTS

Among 120 subjects, 76% were women. The ethnic composition was 64% Caucasian, 32% Hispanic, and 13% African American. The mean age was 52 ± 15 years. The mean duration of asthma was 16 ± 15 years. The mean RV% responsiveness was -7.74 ± 14. Whereas patients with the lowest baseline forced expiratory volume in 1 second (FEV1) value showed the highest mean responsiveness (P = .001), the baseline RV value had minimal influence on RV responsiveness. Using -7.74% to define significant RV responsiveness, and ≥12% and ≥200 mL to define significant FEV1 responsiveness, more subjects showed isolated RV responsiveness (37%) compared with 6% with isolated FEV1 responsiveness and 14% with both FEV1 and RV responsiveness (P = .04). There was a minimal correlation between FEV1 responsiveness and RV responsiveness (r = 0.17, P = .06). The RV responsiveness was significantly associated with the wheeze score (P = .006) and dyspnea score (P = .029).

CONCLUSION

The addition of RV responsiveness testing to spirometry based responsiveness testing can improve the identification of reversible airway obstruction in asthma. RV responsiveness may be useful in monitoring symptoms associated with air trapping in asthma.

Pulmonary function testing in COPD: looking beyond the curtain of FEV1

Chronic obstructive pulmonary disease (COPD) management remains challenging due to the high heterogeneity of clinical symptoms and the complex pathophysiological basis of the disease. Airflow limitation, diagnosed by spirometry, remains the cornerstone of the diagnosis. However, the calculation of the forced expiratory volume in the first second (FEV1) alone, has limitations in uncovering the underlying complexity of the disease. Incorporating additional pulmonary function tests (PFTs) in the everyday clinical evaluation of COPD patients, like resting volume, capacity and airway resistance measurements, diffusion capacity measurements, forced oscillation technique, field and cardiopulmonary exercise testing and muscle strength evaluation, may prove essential in tailoring medical management to meet the needs of such a heterogeneous patient population. We aimed to provide a comprehensive overview of the available PFTs, which can be incorporated into the primary care physician's practice to enhance the efficiency of COPD management.

Diagnostic performance of lung volumes in assessment of reversibility in chronic obstructive pulmonary disease

Background

Reversibility measured by spirometry in chronic obstructive pulmonary disease (COPD) is defined as an increase in forced expiratory volume in first second (FEV1) that is both more than 12% and 200 mL above the pre-bronchodilator value in response to inhaled bronchodilators. FEV1 only may not fully reverberate the changes caused by reduction in air trapping or hyperinflation. To date, the studies that examined the effect of inhaled bronchodilators (BD) on residual volume (RV) and total lung capacity (TLC) are limited. This study was carried out to assess the differences between flow and volume responses after bronchodilator reversibility testing in patients with different COPD GOLD stages (GOLD stage I to stage IV). Spirometry and whole body plethysmography were done before and 15 min after inhalation of 400 μg salbutamol.

Results

Majority (53.3%) of cases were volume responders, 18.7% were flow responders, 20% were flow and volume responders, and 8% were non responders. Significant increase in Δ FEV1% was found in 15% of cases while 55% showed a significant increase in Δ FVC (P= < 0.001). Mean difference of Δ FVC (L) post BD was significantly increased with advancing GOLD stage (P= 0.03). A cutoff point > 20% for Δ RV% had 70% sensitivity and 60% specificity and > 12% for Δ TLC% showed 90% sensitivity and 45% specificity for prediction of clinically significant response to BD based on FEV1. A cutoff point > 18% for Δ RV% had 78% sensitivity and 29% specificity and > 14% for Δ TLC% had 50% sensitivity and 70% specificity for prediction of clinically significant response to BD based on FVC.

Conclusion

ΔFEV1 underestimates the true effect of bronchodilators with advancing GOLD stage. Measurement of lung volumes in addition to the standard spirometric indices is recommended when determining bronchodilator response in COPD patients.

Diagnosis and Treatment of Early Chronic Obstructive Lung Disease (COPD)

Chronic obstructive lung disease (COPD) is responsible for substantial rates of mortality and economic burden, and is one of the most important public-health concerns. As the disease characteristics include irreversible airway obstruction and progressive lung function decline, there has been a great deal of interest in detection at the early stages of COPD during the “at risk” or undiagnosed preclinical stage to prevent the disease from progressing to the overt stage. Previous studies have used various definitions of early COPD, and the term mild COPD has also often been used. There has been a great deal of recent effort to establish a definition of early COPD, but comprehensive evaluation is still required, including identification of risk factors, various physiological and radiological tests, and clinical manifestations for diagnosis of early COPD, considering the heterogeneity of the disease. The treatment of early COPD should be considered from the perspective of prevention of disease progression and management of clinical deterioration. There has been a lack of studies on this topic as the definition of early COPD has been proposed only recently, and therefore further clinical studies are needed.

Clinical and Physiologic Implications of Negative Cardiopulmonary Interactions in Coexisting Chronic Obstructive Pulmonary Disease-Heart Failure

Chronic obstructive pulmonary disease (COPD) and heart failure with reduced ejection fraction (HF) frequently coexist in the elderly. Expiratory flow limitation and lung hyperinflation due to COPD may adversely affect central hemodynamics in HF. Low lung compliance, increased alveolar-capillary membrane thickness, and abnormalities in pulmonary perfusion because of HF further deteriorates lung function in COPD. We discuss how those negative cardiopulmonary interactions create challenges in clinical interpretation of pulmonary function and cardiopulmonary exercise tests in coexisting COPD-HF. In the light of physiologic concepts, we also discuss the influence of COPD or HF on the current medical treatment of each disease.

A New Bronchodilator Response Grading Strategy Identifies Distinct Patient Populations

Rationale: A positive bronchodilator response (BDR) according to American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines require both 200 ml and 12% increase in forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC) after bronchodilator inhalation. This dual criterion is insensitive in those with high or low FEV1.Objectives: To establish BDR criteria with volume or percentage FEV1 change.Methods: The largest FEV1 and FVC were identified from three pre- and three post-bronchodilator maneuvers in COPDGene (Genetic Epidemiology of COPD) participants. A total of 7,741 individuals with coefficient of variation less than 15% for both FEV1 and FVC formed bronchodilator categories of FEV1 response: negative (≤0.00% or ≤0.00 L), minimal (>0.00% to ≤9.00% or >0.00 L to ≤0.09 L), mild (>9.00% to ≤16.00% or >0.09 L to ≤0.16 L), moderate (>16.00% to ≤26.00% or >0.16 L to ≤0.26 L), and marked (>26.00% or >0.26 L). These response size categories are based on empirical limits considering average FEV1 increase of approximately 160 ml and the clinically important difference for FEV1. To compare flow and volume response characteristics, BDR-FEV1 category assignments were applied for the BDR-FVC response.Results: Twenty percent met mild and 31% met moderate or marked BDR-FEV1 criteria, whereas 12% met mild and 33% met moderate or marked BDR-FVC criteria. In contrast, only 20.6% met ATS/ERS positive criteria. Compared with the negative BDR-FEV1 category, the minimal, mild, moderate, and marked BDR-FEV1 categories were associated with greater 6-minute-walk distance and lower St. George's Respiratory Questionnaire and modified Medical Research Council dyspnea scale scores. Compared with negative BDR, moderate and marked BDR-FEV1 categories were associated with fewer exacerbations, and minimal BDR was associated with lower computed tomography airway wall thickness. Compared with the negative category, all BDR-FVC categories were associated with increasing emphysema percentage and gas trapping percentage. Moderate and marked BDR-FVC categories were associated with higher St. George's Respiratory Questionnaire scores but fewer exacerbations and lower dyspnea scores.Conclusions: BDR grading by FEV1 volume or percentage response identified subjects otherwise missed by ATS/ERS criteria. BDR grades were associated with functional exercise performance, quality of life, exacerbation frequency, dyspnea, and radiological airway measures. BDR grades in FEV1 and FVC indicate different clinical and radiological characteristics.

Lung air trapping lowers respiratory arousal threshold and contributes to sleep apnea pathogenesis in COPD patients with overlap syndrome

STUDY OBJECTIVES

Overlap syndrome occurs when obstructive sleep apnea (OSA) and chronic obstructive pulmonary disorder (COPD) coexist in the same patient. Although several studies highlighted the importance of clinical phenotyping in OSA, the trait contribution to OSA pathogenesis in overlap syndrome has not been investigated. With this pilot study, we aimed to measure OSA determinants and their relationship with functional respiratory parameters in a sample of patients with overlap syndrome. In particular, we hypothesize that patients with COPD have in the low arousal threshold a major contributor for the development of OSA.

METHODS

Ten consecutive non-hypercapnic COPD patients (body mass index<35 kg/m²) suffering from overlap syndrome with no other relevant comorbidities underwent a phenotyping polysomnography. Traits were measured with CPAP dial-downs.

RESULTS

Arousal threshold was found to be inversely associated to functional measures of lung air trapping and static hyperinflation. Particularly, correlations with residual volume (r² = 0.49, p =  0.024) and residual volume to total lung capacity ratio (r² = 0.48, p =  0.026) were evident. Only 20% of patients showed a high upper airway passive collapsibility as single pathological trait. In contrast, among those patients with multiple altered traits (6 out of 10), all had an elevated loop gain and 4 (∼65%) a low arousal threshold.

CONCLUSIONS

High loop gain and particularly low arousal threshold seem important contributors to OSA pathogenesis and severity in patients with COPD. Recognizing in COPD patients these features as key traits may open avenues for personalized medicine in the field of overlap syndrome.

Investigating the relationships among lung function variables in chronic obstructive pulmonary disease in men

Background

In patients with chronic obstructive pulmonary disease (COPD), the independent contributions of individual lung function variables to outcomes may be lower when they are modelled together if they are collinear. In addition, lung volume measurements may not be necessary after spirometry data have been obtained. However, these hypotheses depend on whether forced vital capacity (FVC) can predict total lung capacity (TLC). Moreover, the definitions of hyperinflation and air trapping according to lung function variables overlap and need be clarified. Therefore, the aim of this study was to evaluate the relationships among various lung function parameters to elucidate these issues.

Methods

Demographic data and 26 parameters of full lung function were measured in 94 men with COPD and analyzed using factor and correlation analyses.

Results

Factor analysis revealed five latent factors. Inspiratory capacity (IC)/TLC and residual volume (RV)/TLC were most strongly correlated with all other lung volumes. IC/TLC, RV/TLC, and functional residual capacity (FRC)/TLC were collinear and were potential markers of air trapping, whereas TLC%, FRC%, and RV% were collinear and were potential markers of hyperinflation. RV/TLC >0.4 (or IC/TLC <0.4) was comparable with the ratio of forced expiratory volume in one second (FEV₁) and FVC <0.7. FVC% and FEV₁% were poorly correlated with TLC%. The correlation study showed that TLC%, RV/TLC, and FEV₁% could be used to represent individual latent factors for hyperinflation, air trapping, inspiration, expiration, and obstruction. Combined with diffusion capacity%, these four factors could be used to represent comprehensive lung function.

Conclusions

This study identified collinear relationships among individual lung function variables and thus selecting variables with close relationships for correlation studies should be performed with caution. This study also differentiated variables for air trapping and lung hyperinflation. Lung volume measurements are still required even when spirometry data are available. Four out of 26 lung function variables from individual latent factors could be used to concisely represent lung function.

Effect of tiotropium/olodaterol on sedentary and active time in patients with COPD: post hoc analysis of the VESUTO® study

Background

Patients with COPD are less physically active. This post hoc analysis of a randomized, double-blind, active-controlled, crossover trial assessed the efficacy of once-daily tiotropium/olodaterol combination therapy versus tiotropium monotherapy in Japanese patients with COPD.

Patients and methods

Patients were provided with a three-axis accelerometer to measure sedentary and active behavior defined as 1.0-1.5 metabolic equivalents (METs), ≥2.0 METs, and ≥3.0 METs, respectively. Of the 182 patients enrolled, 131 satisfied the conditions for the present analysis and were randomized to tiotropium monotherapy (n=62) or tiotropium/olodaterol combination therapy (n=69).

Results

Tiotropium/olodaterol combination therapy significantly reduced the duration of 1.0-1.5 MET activity by 8.64 mins (p=0.040) and significantly increased the duration of ≥2.0 MET and ≥3.0 MET activity by 6.51 mins (p=0.017) and 2.60 mins (p=0.008), respectively, compared with tiotropium alone. Subgroup analyses showed that better lung function, milder dyspnea, and higher levels of physical activity at baseline were associated with reduced sedentary time and increased duration of physical activity.

Conclusion

Tiotropium/olodaterol combination therapy significantly reduced sedentary time and improved physical activity compared with tiotropium monotherapy. This trial was registered in ClinicalTrials.gov (NCT02629965).

New insights into early intervention of chronic obstructive pulmonary disease with mild airflow limitation

Chronic obstructive pulmonary disease (COPD) has become one of the major public health problems worldwide due to its high morbidity and mortality. Up until now, COPD is still under-diagnosed and under-treated, especially for mild or moderate patients. It is widely accepted that the majority of patients with COPD are in the early stages, yet this subpopulation is underestimated. In recent years, growing evidence indicates that substantial physiological and clinical abnormalities exist in patients with mild COPD compared with healthy controls. Furthermore, recent studies suggest that pharmacologic intervention in early COPD has the potential to alter clinical outcomes. The main objective of this review is to summarize recent research regarding the heterogeneous pathophysiology, clinical features, and treatment of mild and moderate COPD. We also discuss promising markers of disease progression, which may contribute to the development of precision medicine in early COPD.

Area under the forced expiratory flow-volume loop in spirometry indicates severe hyperinflation in COPD patients

BACKGROUND

Severe hyperinflation causes detrimental effects such as dyspnea and reduced exercise capacity and is an independent predictor of mortality in COPD patients. Static lung volumes are required to diagnose severe hyperinflation, which are not always accessible in primary care. Several studies have shown that the area under the forced expiratory flow-volume loop (AreaFE) is highly sensitive to bronchodilator response and is correlated with residual volume/total lung capacity (RV/TLC), a common index of air trapping. In this study, we investigate the role of AreaFE% (AreaFE expressed as a percentage of reference value) and conventional spirometry parameters in indicating severe hyperinflation.

MATERIALS AND METHODS

We used a cohort of 215 individuals with COPD. The presence of severe hyperinflation was defined as elevated air trapping (RV/TLC >60%) or reduced inspiratory fraction (inspiratory capacity [IC]/TLC <25%) measured using body plethysmography. AreaFE% was calculated by integrating the maximal expiratory flow-volume loop with the trapezoidal rule and expressing it as a percentage of the reference value estimated using predicted values of FVC, peak expiratory flow and forced expiratory flow at 25%, 50% and 75% of FVC. Receiver operating characteristics (ROC) curve analysis was used to identify cut-offs that were used to indicate severe hyperinflation, which were then validated in a separate group of 104 COPD subjects.

RESULTS

ROC analysis identified cut-offs of 15% and 20% for AreaFE% in indicating RV/TLC >60% and IC/TLC <25%, respectively (N=215). On validation (N=104), these cut-offs consistently registered the highest accuracy (80% each), sensitivity (68% and 75%) and specificity (83% and 80%) among conventional parameters in both criteria of severe hyperinflation.

CONCLUSION

AreaFE% consistently provides a superior estimation of severe hyperinflation using different indices, and may provide a convenient way to refer COPD patients for body plethysmography to address static lung volumes.

Lung hyperinflation and functional exercise capacity in patients with COPD - a three-year longitudinal study

Background

Lung hyperinflation contributes to dyspnea, morbidity and mortality in chronic obstructive pulmonary disease (COPD). The inspiratory-to-total lung capacity (IC/TLC) ratio is a measure of lung hyperinflation and is associated with exercise intolerance. However, knowledge of its effect on longitudinal change in the 6-min walk distance (6MWD) in patients with COPD is scarce. We aimed to study whether the IC/TLC ratio predicts longitudinal change in 6MWD in patients with COPD.

Methods

This prospective cohort study included 389 patients aged 40–75 years with clinically stable COPD in Global Initiative for Chronic Obstructive Lung Disease stages II-IV. The 6MWD was measured at baseline, and after one and 3 years. We performed generalized estimating equation regression analyses to examine predictors for longitudinal change in 6MWD. Predictors at baseline were: IC/TLC ratio, age, gender, pack years, fat mass index (FMI), fat-free mass index (FFMI), number of exacerbations within 12 months prior to inclusion, Charlson index for comorbidities, forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and light and hard self-reported physical activity.

Results

Reduced IC/TLC ratio (p < 0.001) was a statistically significant predictor for decline in 6MWD. With a 0.1-unit decrease in baseline IC/TLC ratio, the annual decline in 6MWD was 12.7 m (p < 0.001). Study participants with an IC/TLC ratio in the upper quartiles maintained their 6MWD from baseline to year 3, while it was significantly reduced for the patients with an IC/TLC ratio in the lower quartiles. Absence of light and hard physical activity, increased age and FMI, decreased FEV₁ and FVC, more frequent exacerbations and higher Charlson comorbidity index were also predictors for lower 6MWD at any given time, but did not predict higher rate of decline over the timespan of the study.

Conclusion

Our findings demonstrated that patients with less lung hyperinflation at baseline maintained their functional exercise capacity during the follow-up period, and that it was significantly reduced for patients with increased lung hyperinflation.

Lung volume indices predict morbidity in smokers with preserved spirometry

BACKGROUND

Abnormal lung volumes that reflect air trapping are common in COPD. However, their significance in smokers with preserved spirometry (normal FEV₁ to FVC ratio) is unclear.

METHODS

Using the Veterans Administration Informatics and Computing Infrastructure database, we identified 7479 patients at risk for COPD (ever smokers >40 years of age without restrictive lung disease) who had preserved spirometry and concomitant lung volume measurements, and examined their subsequent health records for clinical diagnoses of COPD, healthcare utilisation, follow-up spirometry and mortality.

RESULTS

Air trapping was prevalent, with 31% of patients having residual volume to total lung capacity ratio (RV:TLC) greater than the upper limit of normal (ULN). RV:TLC varied widely from 14% to 77% (51% to 204% of predicted) across the normal ranges of FEV₁:FVC and FEV₁. Patients with RV:TLC greater than the ULN were more likely to receive subsequent clinical diagnoses of COPD (HR (95% CI)=1.55 (1.42 to 1.70), p<0.001) and had higher all-cause mortality (HR (95% CI)=1.41 (1.29 to 1.54), p<0.001). They had higher rates of respiratory medication prescriptions and hospital and intensive care unit admissions. Other air trapping and static hyperinflation indices showed similar associations with health outcomes. Additionally, high-normal RV:TLC was associated with intermediate adverse health outcomes compared with low-normal and abnormal RV:TLC. Abnormal RV:TLC predicted higher likelihood of progression to spirometric COPD (OR (95% CI)=1.30 (1.03 to 1.65), p=0.027).

CONCLUSION

In this study of the Veterans Affairs electronic health records, air trapping was common in smokers with preserved spirometry and predicted adverse respiratory outcomes and progression to overt COPD.

Bronchodilator Responses in Respiratory Impedance, Hyperinflation and Gas Trapping in COPD

Hyperinflation, gas trapping and their responses to long-acting bronchodilator are clinically important in COPD. The forced oscillation technique (FOT) measures of respiratory system resistance and reactance are sensitive markers of bronchodilator response in COPD. The relationships between changes in resistance and reactance, and changes in hyperinflation and gas trapping, following long-acting bronchodilator (LA-BD) have not been studied. 15 subjects with mild-moderate COPD underwent FOT, spirometry then body plethysmography, before and 2 hours after a single 150 microg dose of the LA-BD indacaterol. Hyperinflation was quantified as the inspiratory capacity to total lung capacity ratio (IC/TLC), and gas trapping as residual volume to TLC ratio (RV/TLC). At baseline, FOT parameters were moderately correlated with IC/TLC (|r| 0.53-0.73, p < 0.05). At 2 hours post-LA-BD, there were moderate correlations between change in FOT and change in RV/TLC (|r| 0.60-0.82, p < 0.05). Baseline FOT parameters also correlated with the subsequent post-LA-BD change in both IC/TLC (|r| 0.54-0.62, p < 0.05) and RV/TLC (|r| 0.57-0.76, p < 0.05). FOT impedance reflects hyperinflation and gas trapping in COPD, and the potential for long-acting bronchodilator responsiveness. These results provide us with further insight into the physiological mechanisms of action of long-acting bronchodilator treatment, and may be clinically useful for predicting treatment responses.

The Link between Reduced Inspiratory Capacity and Exercise Intolerance in Chronic Obstructive Pulmonary Disease

Low inspiratory capacity (IC), chronic dyspnea, and reduced exercise capacity are inextricably linked and are independent predictors of increased mortality in chronic obstructive pulmonary disease. It is no surprise, therefore, that a major goal of management is to improve IC by reducing lung hyperinflation to improve respiratory symptoms and health-related quality of life. The negative effects of lung hyperinflation on respiratory muscle and cardiocirculatory function during exercise are now well established. Moreover, there is growing appreciation that a key mechanism of exertional dyspnea in chronic obstructive pulmonary disease is critical mechanical constraints on tidal volume expansion during exercise when resting IC is reduced. Further evidence for the importance of lung hyperinflation comes from multiple studies, which have reported the clinical benefits of therapeutic interventions that reduce lung hyperinflation and increase IC. A reduced IC in obstructive pulmonary disease is further eroded by exercise and contributes to ventilatory limitation and dyspnea. It is an important outcome for both clinical and research studies.

Chronic obstructive pulmonary disease with mild airflow limitation: current knowledge and proposal for future research - a consensus document from six scientific societies

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality and morbidity worldwide, with high and growing prevalence. Its underdiagnosis and hence under-treatment is a general feature across all countries. This is particularly true for the mild or early stages of the disease, when symptoms do not yet interfere with daily living activities and both patients and doctors are likely to underestimate the presence of the disease. A diagnosis of COPD requires spirometry in subjects with a history of exposure to known risk factors and symptoms. Postbronchodilator forced expiratory volume in 1 second (FEV₁)/forced vital capacity <0.7 or less than the lower limit of normal confirms the presence of airflow limitation, the severity of which can be measured by FEV₁% predicted: stage 1 defines COPD with mild airflow limitation, which means postbronchodilator FEV₁ ≥80% predicted. In recent years, an elegant series of studies has shown that "exclusive reliance on spirometry, in patients with mild airflow limitation, may result in underestimation of clinically important physiologic impairment". In fact, exercise tolerance, diffusing capacity, and gas exchange can be impaired in subjects at a mild stage of airflow limitation. Furthermore, growing evidence indicates that smokers without overt abnormal spirometry have respiratory symptoms and undergo therapy. This is an essential issue in COPD. In fact, on one hand, airflow limitation, even mild, can unduly limit the patient's physical activity, with deleterious consequences on quality of life and even survival; on the other hand, particularly in younger subjects, mild airflow limitation might coincide with the early stage of the disease. Therefore, we thought that it was worthwhile to analyze further and discuss this stage of "mild COPD". To this end, representatives of scientific societies from five European countries have met and developed this document to stimulate the attention of the scientific community on COPD with "mild" airflow limitation. The aim of this document is to highlight some key features of this important concept and help the practicing physician to understand better what is behind "mild" COPD. Future research should address two major issues: first, whether mild airflow limitation represents an early stage of COPD and what the mechanisms underlying the evolution to more severe stages of the disease are; and second, not far removed from the first, whether regular treatment should be considered for COPD patients with mild airflow limitation, either to prevent progression of the disease or to encourage and improve physical activity or both.

CONTROL LEVEL AND ASSESSMENT OF THE CLINICAL COURSE IN PATIENTS WITH THE ASSOCIATED PATHOLOGY OF BRONCHIAL ASTHMA AND COPD

The notion “asthma-COPD cross” (ACC) for patients with clinical signs of bronchial asthma and COPD was introduced. From 15 to 45 % of population with bronchial obstructive diseases suffer from ACC and its prevalence increases with age. According to the data of epidemiological studies, in average a half of patients with BA in the world cannot reach a control of BA or keep it for a long time. The aim of our research was the determination of the control level and also assessment of symptoms of the disease of patients with BA and COPD. Patients. The study included patients with ACC, older than 30 years. The control included patients with the bronchial asthma and COPD without any signs of these pathologies combination. Methods. All patients underwent the spirography with the analysis of the curve “flow-volume” of a force exhalation and also bodypletizmography (“MasterScreenPneumo”, "CardinalHealth" (Germany)). Al patients were interrogated by the questionnaires: questionnaire for BA symptoms control (ACQ-7), test for BA control (ACT), test for COPD assessment CAT). Results. At comparing parameters of BA control was revealed the reliably worse control in the group of patients with the associated pathology by data of the questionnaire ACQ-7 comparing with patients with BA. The influence of COPD symptoms was also more essential in patients with ACC comparing with one with COPD. At the more expressed degree of the bronchial obstruction, BA control was reliably weaker, whereas the influence of COPD symptoms was more essential. In patients with ACC with the unsatisfactory control of BA (АСQ-7 ≥1,5 points) the mortality prognosis, expressed by BODE index, grows almost in 3 times; inpatients with the severe and very severe influence of the disease effect (САТ > 20 points), the mortality prognosis grows more than in 2 times. The reliable positive correlation was revealed between the results of CAT and ratio of the internal thoracic volume of gases to the total capacity of lungs (ITGV/TLС), that reflects the degree of lungs hyperinflation - (r=0,35; p<0,05). Conclusions. At BA and COPD combination the indices of the disease control are worse than at the bronchial asthma and a bit similar to ones at COPD. Indices of BA control and influence of COPD symptoms on the condition of patients with the associated pathology were mainly negatively changed at the increase of the bronchial obstruction degree. The essential negative influence of the insufficient BA control and the high influence of COPD symptoms on the disease prognosis in patients with associated pathology (BA+COPD) were revealed.

Assessment of dyspnea and dynamic hyperinflation in male patients with chronic obstructive pulmonary disease during a six minute walk test and an incremental treadmill cardiorespiratory exercise test

The six minute walk test (6MWT) is a standardized test that provides information on exercise capacity in patients with COPD. It is considered a submaximal test in opposition to incremental cardiopulmonary exercise tests (CPET) that provide valuable information on all the systems involved in exercise.

OBJECTIVES

1. To compare the perceptive, physiological responses and degree of dynamic hyperinflation during two exercise tests: the 6MWT and the incremental CPET on a treadmill. 2. To evaluate how dyspnea is related to dynamic hyperinflation (DH) and other functional parameters in both tests.

METHODS

29 stable COPD male patients, age 68±5.8 years, mean post-bronchodilator FEV1 57±11%, were recruited. To evaluate dynamic hyperinflation, inspiratory capacity (IC) was measured at rest and upon completing each one of the tests. At the same time, perceived dyspnea and leg discomfort were rated on specific modified Borg scales.

RESULTS

The mean walk distance in 6MWT was 494±88m. The Borg scale rating for shortness of breath upon completing the test was 4.7±2, whilst 2.9±2 for leg discomfort. IC changed from 2.53±0.63l before to 2.34±0.60l after completion of the test. In the treadmill CPET, maximal oxygen consumption (V˙O₂max) was 21.8±5mL/kg/min with 6.6±2 dyspnea and 4.3±2 leg discomfort on Borg scales. IC changed from 2.17±0.53l to 1.20±0.43l.

CONCLUSIONS

Dynamic hyperinflation occurs in male COPD patients during submaximal exercise such as the 6MWT. This phenomenon is more pronounced after incremental CPET on a treadmill. Despite being dyspnea the dominant limiting symptom for both tests, we observed different physiological responses.

Exertional dyspnoea in COPD: the clinical utility of cardiopulmonary exercise testing

Activity-related dyspnoea is often the most distressing symptom experienced by patients with chronic obstructive pulmonary disease (COPD) and can persist despite comprehensive medical management. It is now clear that dyspnoea during physical activity occurs across the spectrum of disease severity, even in those with mild airway obstruction. Our understanding of the nature and source of dyspnoea is incomplete, but current aetiological concepts emphasise the importance of increased central neural drive to breathe in the setting of a reduced ability of the respiratory system to appropriately respond. Since dyspnoea is provoked or aggravated by physical activity, its concurrent measurement during standardised laboratory exercise testing is clearly important. Combining measurement of perceptual and physiological responses during exercise can provide valuable insights into symptom severity and its pathophysiological underpinnings. This review summarises the abnormal physiological responses to exercise in COPD, as these form the basis for modern constructs of the neurobiology of exertional dyspnoea. The main objectives are: 1) to examine the role of cardiopulmonary exercise testing (CPET) in uncovering the physiological mechanisms of exertional dyspnoea in patients with mild-to-moderate COPD; 2) to examine the escalating negative sensory consequences of progressive respiratory impairment with disease advancement; and 3) to build a physiological rationale for individualised treatment optimisation based on CPET.

The effect of obesity on patients with mild chronic obstructive pulmonary disease: results from KNHANES 2010 to 2012

PURPOSE

A low body mass index has been associated with high mortalities in patients with chronic obstructive pulmonary disease (COPD), and studies reveal that obesity aggravates the clinical effects of COPD. We investigated the impact of obesity on patients newly identified with COPD.

PATIENTS AND METHODS

This population-based, cross-sectional study, used data from the Korea National Health and Nutrition Examination Survey (KNHANES) conducted from 2010 to 2012. Through analyses of data from this survey, we compared concurrent comorbid diseases, symptoms, and lung functions between an obese and nonobese group of patients with COPD.

RESULTS

In total, 618 participants were diagnosed with COPD and the average forced expired volume in 1 s (FEV1) was 79.47%±0.69%. Of the total, 30.5% of the subjects were categorized into an obese group. Subjects in the obese group were likely to have metabolic syndrome (P<0.001), hypertension (P=0.02), and a higher number of comorbidities compared to the nonobese group (2.3±0.1 vs 2.0±0.1, P=0.02). In addition, subjects in the obese group showed a lower forced vital capacity (FVC) than subjects in the nonobese group, even after adjusting for covariates (average FVC%, 89.32±1.26 vs 92.52%±0.72%, P=0.037). There were no significant differences in the adjusted FEV1% and adjusted FEV1/FVC between the groups.

CONCLUSIONS

Among subjects newly identified with mild COPD, participants in the obese group had more comorbid conditions and showed a lower FVC compared with subjects in the nonobese group, even after adjustment of covariates. These findings show that a combination of obesity and COPD may be a severe phenotype; therefore, early attention should be paid to obesity for the management of COPD patients.

Advances in the Evaluation of Respiratory Pathophysiology during Exercise in Chronic Lung Diseases

Dyspnea and exercise limitation are among the most common symptoms experienced by patients with various chronic lung diseases and are linked to poor quality of life. Our understanding of the source and nature of perceived respiratory discomfort and exercise intolerance in chronic lung diseases has increased substantially in recent years. These new mechanistic insights are the primary focus of the current review. Cardiopulmonary exercise testing (CPET) provides a unique opportunity to objectively evaluate the ability of the respiratory system to respond to imposed incremental physiological stress. In addition to measuring aerobic capacity and quantifying an individual's cardiac and ventilatory reserves, we have expanded the role of CPET to include evaluation of symptom intensity, together with a simple "non-invasive" assessment of relevant ventilatory control parameters and dynamic respiratory mechanics during standardized incremental tests to tolerance. This review explores the application of the new advances in the clinical evaluation of the pathophysiology of exercise intolerance in chronic obstructive pulmonary disease (COPD), chronic asthma, interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH). We hope to demonstrate how this novel approach to CPET interpretation, which includes a quantification of activity-related dyspnea and evaluation of its underlying mechanisms, enhances our ability to meaningfully intervene to improve quality of life in these pathologically-distinct conditions.

Longitudinal changes in lung hyperinflation in COPD

Purpose

COPD is characterized by an accelerated and progressive decline in forced expiratory volume in 1 second (FEV₁) and lung hyperinflation. Although lung hyperinflation is the hallmark of COPD, data on the longitudinal changes in lung hyperinflation and any association with the decline in FEV₁ are lacking. The aim of this study was to evaluate the longitudinal changes in lung hyperinflation and to investigate its relationship with FEV₁ decline.

Patients and methods

We conducted a prospective cohort study and studied 176 COPD patients with annual lung volume measurements over a period of 5 years or more. We used a random coefficient model to calculate the annual changes in lung volumes and to evaluate the factors associated with changes in lung hyperinflation. Additionally, the relationship between the change in lung hyperinflation and FEV₁ was assessed.

Results

Residual volume (RV), inspiratory capacity (IC), and total lung capacity (TLC) declined at a mean rate of 39.5, 49.6, and 63.8 mL/year, respectively. While IC/TLC declined at 0.70%/year, RV/TLC also declined at 0.35%/year. Changes in both IC/TLC and RV/TLC varied significantly. Frequent exacerbations led to an increase in RV/TLC and faster decline in IC/TLC over time. RV/TLC declined in 59.7% and increased in 40.3% of the patients. A significant negative correlation was found between the rates of change in FEV₁ and RV/TLC, and the rate of decline in FEV₁ was greater in patients with an increase in RV/TLC than in those with a decline in RV/TLC (54.2 vs 10.7 mL/year, P<0.001).

Conclusion

The rate of change in lung hyperinflation varied greatly among COPD patients. Progression of hyperinflation was associated with frequent exacerbations and a faster decline in FEV₁.

Bronchodilator Response in FVC Is Larger and More Relevant Than in FEV1 in Severe Airflow Obstruction

BACKGROUND

Recommendations on interpreting tests of bronchodilator responsiveness (BDR) are conflicting. We investigated the dependence of BDR criteria on sex, age, height, ethnicity, and severity of respiratory impairment.

METHODS

BDR test data were available from clinical patients in the Netherlands, New Zealand, and the United States (n = 15,278; female subjects, 51.7%) and from surveys in Canada, Norway, and five Latin-American countries (n = 16,250; female subjects, 54.7%). BDR calculated according to FEV₁, FVC, and FEV₁/FVC was expressed as absolute change, a percentage of the baseline level (% baseline), a percentage of the predicted value (% predicted), and z score.

RESULTS

Change (Δ) in FEV₁ and FVC, in milliliters, was unrelated to the baseline value but was biased toward age, height, sex, and level of airways obstruction; ΔFEV₁ was significantly lower in African Americans. In 1,106 subjects with low FEV₁ (200-1,621 mL) the FEV₁ increased by 12% to 44.7% relative to baseline but < 200 mL. Expressing BDR as a percentage of the predicted value or as a z score attenuated the bias and made the 200-mL criterion redundant, but reduced positive responses by half. ΔFEV₁ % baseline increased with the level of airflow obstruction but decreased with severe obstruction when expressed as z scores or % predicted; ΔFVC, however expressed, increased with the level of airflow obstruction.

CONCLUSIONS

Expressing FEV₁ responsiveness as % baseline spuriously suggests that responsiveness increases with the severity of respiratory impairment. Expressing change in FEV₁ or FVC as % predicted or as z scores eliminates this artifact and renders the required 200-mL minimum increase redundant. In severe airways obstruction ΔFVC should be critically evaluated as an index of clinically important relief of hyperinflation, with implications for bronchodilator drug trials.

Bronchoscopic Lung Volume Reduction with Endobronchial Valves in Low-FEV1 Patients

BACKGROUND

Bronchoscopic lung volume reduction (BLVR) with valves has been shown to improve lung function, exercise capacity, and quality of life in patients with emphysema, but only few patients with forced expiratory volume in 1 s (FEV1) ≤20% predicted have been included in former studies. Although the procedure can be performed safely, pneumothorax is a frequent complication, which can be critical for these very severely diseased patients.

OBJECTIVES

The aim of the study was to assess the safety of BLVR in patients with a very advanced stage of emphysema, as indicated by FEV1 ≤20% predicted.

PATIENTS AND METHODS

Patients in whom BLVR was performed between January 2013 and August 2015 were included in this analysis if their baseline predicted FEV1 was ≤20%. BLVR, performed only if collateral ventilation was absent, achieved complete occlusion of the target lobe. All patients were closely monitored and were not discharged before the fourth day after BLVR.

RESULTS

Twenty patients with FEV1 ≤20% predicted were included in the analysis. Lung volume reduction was achieved in 65% of the cases. Pneumothorax occurred in 4 cases (20%). No patient died. Lung function and exercise tolerance improved after 1 and 3 months, respectively.

CONCLUSIONS

BLVR with valves can be safely performed in patients with FEV1 ≤20% predicted when close postprocedural monitoring is provided. Improvement in lung function and exercise capacity can be achieved.

Early COPD patients with lung hyperinflation associated with poorer lung function but better bronchodilator responsiveness

Background

It is unknown whether aggressive medication strategies should be used for early COPD with or without lung hyperinflation. We aimed to explore the characteristics and bronchodilator responsiveness of early COPD patients (stages I and II) with/without lung hyperinflation.

Methods

Four hundred and six patients with COPD who performed both lung volume and bronchodilation tests were retrospectively analyzed. Residual volume to total lung capacity >120% of predicted values indicated lung hyperinflation. The characteristics and bronchodilator responsiveness were compared between the patients with and without lung hyperinflation across all stages of COPD.

Results

The percentages of patients with lung hyperinflation were 72.7% in the entire cohort, 19.4% in stage I, 68.5% in stage II, 95.3% in stage III, and 100.0% in stage IV. The patients with lung hyperinflation exhibited poorer lung function but better bronchodilator responsiveness of both forced expiratory volume in 1 second and forced vital capacity than those without lung hyperinflation during early COPD (t=2.21–5.70, P=0.000–0.029), especially in stage I, while age, body mass index, smoking status, smoking history, and disease duration were similar between the two subgroups in the same stages. From stages I to IV of subgroups with lung hyperinflation, stage I patients had the best bronchodilator responsiveness. Use of bronchodilator responsiveness of forced vital capacity to detect the presence of lung hyperinflation in COPD patients showed relatively high sensitivities (69.5%–75.3%) and specificities (70.3%–75.7%).

Conclusion

We demonstrated the novel finding that early COPD patients with lung hyperinflation are associated with poorer lung function but better bronchodilator responsiveness and established a simple method for detecting lung hyperinflation.

Pharmacological management of breathlessness in COPD: recent advances and hopes for the future

INTRODUCTION

Activity-related breathlessness is often the dominant symptom in patients with chronic obstructive pulmonary disease (COPD) and usually persists despite optimal medical therapy. Currently, our inability to meaningfully alter the pathophysiology of the underlying disease means that we must focus our attention on relieving this distressing symptom so as to improve exercise tolerance and quality of life.

AREAS COVERED

The current review examines the neurobiology of breathlessness and constructs a solid physiological rationale for amelioration of this distressing symptom. We will examine the efficacy of interventions which: 1) reduce the increased central drive to breathe (opioids); 2) improve the respiratory system's ability to appropriately respond to this increased demand (bronchodilators); and 3) address the important affective dimension of breathlessness (anxiolytics). Expert commentary: Advances in our understanding of the mechanisms of activity-related breathlessness in COPD, and its measurement in the clinical domain, now set the stage for the development of effective management strategies on an individual patient basis.

Current methods to diagnose small airway disease in patients with COPD

The small airways are characterized by an internal diameter < 2 mm and absence of cartilage. Approximately 10-25% of total airway resistance in healthy lungs is due to the small airways, with their contribution to total airway resistance increasing substantially in chronic obstructive pulmonary disease (COPD). As the small airways are located in the lung periphery, they are not easily evaluable, which can potentially interfere with the diagnosis (especially at early stages), monitoring, detection of responses to clinical interventions, and prognostic evaluation in COPD. Here, we will discuss the currently available methods in clinical practice to evaluate small airway disease in COPD, focusing on the concept, advantages, and disadvantages of each method.

Diagnosis, assessment, and phenotyping of COPD: beyond FEV₁

COPD is now widely recognized as a complex heterogeneous syndrome, having both pulmonary and extrapulmonary features. In clinical practice, the diagnosis of COPD is based on the presence of chronic airflow limitation, as assessed by post-bronchodilator spirometry. The severity of the airflow limitation, as measured by percent predicted FEV1, provides important information to the physician to enable optimization of management. However, in order to accurately assess the complexity of COPD, there need to be other measures made beyond FEV1. At present, there is a lack of reliable and simple blood biomarkers to confirm and further assess the diagnosis of COPD. However, it is possible to identify patients who display different phenotypic characteristics of COPD that relate to clinically relevant outcomes. Currently, validated phenotypes of COPD include alpha-1 antitrypsin deficiency, and "frequent exacerbators". Recently, a definition and assessment of a new phenotype comprising patients with overlapping features of asthma and COPD has been suggested and is known as "asthma COPD overlap syndrome". Several other phenotypes have been proposed, but require validation against clinical outcomes. Defining phenotypes requires the assessment of multiple factors indicating disease severity, its impact, and its activity. Recognition and validation of COPD phenotypes has an important role to play in the selection of evidence-based targeted therapy in the future management of COPD, but regardless of the diagnostic terms, patients with COPD should be assessed and treated according to their individual treatable characteristics.

Prevalence and reversibility of lung hyperinflation in adult asthmatics with poorly controlled disease or significant dyspnea

BACKGROUND

In asthma, inflammation affects both the proximal and distal airways and may induce significant hyperinflation (HI). This study sought to evaluate the prevalence of HI in asthmatic patients with poorly controlled disease and/or dyspnea.

METHODS

Poor asthma control was defined by an Asthma Control Test (ACT) score <20 (n = 287), and dyspnea was defined as a modified Medical Research Council score ≥1 (n = 18). HI was defined as either a residual volume/total lung capacity (RV/TLC) above the upper limit of normal (RV-HI) or a functional residual capacity (FRC) >120% predicted (FRC-HI). HI reversibility after administration of salbutamol (400 μg) was defined as a decrease in RV >20% or a reduction in FRC >10%. Changes in dyspnea and chest tightness were evaluated on a visual analogue scale.

RESULTS

Both RV-HI and FRC-HI were observed in 48% of the 305 patients (mean ± SD age: 49 ± 17; FEV1 : 75 ± 18% predicted) included in the study. The prevalence of HI was higher in patients with a FEV1 <60% predicted (93% for RV-HI and 71% for FRC-HI, vs 21% and 41% in patients with a FEV1 > 80%). In patients with HI, the ACT score was lower and chest tightness higher. HI reversibility was obtained in 38% of the asthmatics with FRC-HI and 29% of the asthmatics with RV-HI, whereas FEV1 reversibility was obtained in half of these patients.

CONCLUSIONS

HI is highly prevalent in poorly controlled asthmatics suggesting small airway dysfunction and may represent an additional criteria for evaluating responsiveness to bronchodilators.

Physiological impairment in mild COPD

Chronic obstructive pulmonary disease (COPD) is a common and often progressive inflammatory disease of the airways, alveoli and microvasculature that is both preventable and treatable. It is well established that smokers with mild airway obstruction, as spirometrically defined, represent the vast majority of patients with COPD, yet this population has not been extensively studied. An insidious preclinical course means that mild COPD is both underdiagnosed and undertreated. In this context, recent studies have confirmed that even patients with mild COPD can have extensive physiological impairment, which contributes to poor perceived health status compared with non-smoking healthy controls. This review describes the heterogeneous pathophysiology that can exist in COPD patients with only mild airway obstruction on spirometry. It exposes the compensatory adaptations that develop in such patients to ensure that the respiratory system fulfils its primary task of maintaining adequate pulmonary gas exchange for the prevailing metabolic demand. It demonstrates that adaptations such as increased inspiratory neural drive to the diaphragm due to combined effects of increased mechanical loading and chemostimulation underscore the increased dyspnoea and exercise intolerance in this population. Finally, based on available evidence, we present what we believe is a sound physiological rationale for earlier diagnosis in this population.

Airways resistance and specific conductance for the diagnosis of obstructive airways diseases

BACKGROUND

Airway resistance (RAW) and specific airway conductance (sGAW) are measures that reflect the patency of airways. Little is known of the variability of these measures between different lung diseases. This study investigated the contribution of RAW and sGAW to a diagnosis of obstructive airways disease and their role in differentiating asthma from COPD.

METHODS

976 subjects admitted for the first time to a pulmonary practice in Belgium were included. Clinical diagnoses were based on complete pulmonary function tests and supported by investigations of physicians' discretion. 651 subjects had a final diagnosis of obstructive diseases, 168 had another respiratory disease and 157 subjects had no respiratory disease (healthy controls).

RESULTS

RAW and sGAW were significantly different (p < 0.0001) between obstructive and other groups. Abnormal RAW and sGAW were found in 39 % and 18 % of the population, respectively, in which 81 % and 90 % had diagnosed airway obstruction. Multiple regression revealed sGAW to be a significant and independent predictor of an obstructive disorder. To differentiate asthma from COPD, RAW was found to be more relevant and statistically significant. In asthma patients with normal FEV1/FVC ratio, both RAW and sGAW were more specific than sensitive diagnostic tests in differentiating asthma from healthy subjects.

CONCLUSIONS

RAW and sGAW are significant factors that contribute to the diagnosis and differentiation of obstructive airways diseases.

Small airway dysfunction and flow and volume bronchodilator responsiveness in patients with chronic obstructive pulmonary disease

Background

We investigated whether a relationship between small airways dysfunction and bronchodilator responsiveness exists in patients with chronic obstructive pulmonary disease (COPD).

Methods

We studied 100 (20 female; mean age: 68±10 years) patients with COPD (forced expiratory volume in 1 second [FEV₁]: 55% pred ±21%; FEV₁/forced vital capacity [FVC]: 53%±10%) by impulse oscillometry system. Resistance at 5 Hz and 20 Hz (R5 and R20, in kPa·s·L⁻¹) and the fall in resistance from 5 Hz to 20 Hz (R5 – R20) were used as indices of total, proximal, and peripheral airway resistance; reactance at 5 Hz (X5, in kPa·s·L⁻¹) was also measured. Significant response to bronchodilator (salbutamol 400 μg) was expressed as absolute (≥0.2 L) and percentage (≥12%) change relative to the prebronchodilator value of FEV₁ (flow responders, FRs) and FVC (volume responders, VRs).

Results

Eighty out of 100 participants had R5 – R20 >0.03 kPa·s·L⁻¹ (> upper normal limit) and, compared to patients with R5 – R20 ≤0.030 kPa·s·L⁻¹, showed a poorer health status, lower values of FEV₁, FVC, FEV₁/FVC, and X5, along with higher values of residual volume/total lung capacity and R5 (P<0.05 for all comparisons). Compared to the 69 nonresponders and the 8 FRs, the 16 VRs had significantly higher R5 and R5 – R20 values (P<0.05), lower X5 values (P<0.05), and greater airflow obstruction and lung hyperinflation.

Conclusion

This study shows that peripheral airway resistance is increased in the vast majority of patients with COPD, who showed worse respiratory reactance, worse spirometry results, more severe lung hyperinflation, and poorer health status. Small airway dysfunction was also associated with the bronchodilator responsiveness in terms of FVC, but not in terms of FEV₁.

Cluster Analysis in Patients with GOLD 1 Chronic Obstructive Pulmonary Disease

Background

We hypothesized that heterogeneity exists within the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 spirometric category and that different subgroups could be identified within this GOLD category.

Methods

Pre-randomization study participants from two clinical trials were symptomatic/asymptomatic GOLD 1 chronic obstructive pulmonary disease (COPD) patients and healthy controls. A hierarchical cluster analysis used pre-randomization demographics, symptom scores, lung function, peak exercise response and daily physical activity levels to derive population subgroups.

Results

Considerable heterogeneity existed for clinical variables among patients with GOLD 1 COPD. All parameters, except forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC), had considerable overlap between GOLD 1 COPD and controls. Three-clusters were identified: cluster I (18 [15%] COPD patients; 105 [85%] controls); cluster II (45 [80%] COPD patients; 11 [20%] controls); and cluster III (22 [92%] COPD patients; 2 [8%] controls). Apart from reduced diffusion capacity and lower baseline dyspnea index versus controls, cluster I COPD patients had otherwise preserved lung volumes, exercise capacity and physical activity levels. Cluster II COPD patients had a higher smoking history and greater hyperinflation versus cluster I COPD patients. Cluster III COPD patients had reduced physical activity versus controls and clusters I and II COPD patients, and lower FEV₁/FVC versus clusters I and II COPD patients.

Conclusions

The results emphasize heterogeneity within GOLD 1 COPD, supporting an individualized therapeutic approach to patients.

Trial registration

www.clinicaltrials.gov. NCT01360788 and NCT01072396.

Not all measures of hyperinflation are created equal: lung structure and clinical correlates of gas trapping and hyperexpansion in COPD: the Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study

BACKGROUND

Hyperinflation refers to a nonspecific increase in absolute lung volumes and has a poor prognosis in COPD. The relative contribution of increased airways resistance and increased parenchymal compliance to hyperinflation of each absolute lung volume is poorly understood. We hypothesized that increased residual volume (RV) and RV/total lung capacity (TLC) would be associated with reduced airway lumen dimensions, whereas increased functional residual capacity (FRC), TLC, and reduced inspiratory capacity (IC)/TLC would be associated with emphysema on CT scan. We examined whether clinical characteristics differed accordingly.

METHODS

The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited smokers aged 50 to 79 years who were free of clinical cardiovascular disease. Gas trapping was defined as RV or RV/TLC greater than the upper limit of normal and hyperexpansion as FRC or TLC greater than the upper limit of normal or IC/TLC less than the lower limit of normal. Airway lumen diameters and percent emphysema &lt; -950 Hounsfield units were quantified on CT images. Analyses were adjusted for age, sex, body size, race/ethnicity, education, and smoking.

RESULTS

Among 116 participants completing plethysmography, 15% had gas trapping, 18% has hyperexpansion, and 22% had both. Gas trapping was associated with smaller airway lumen diameters (P = .001), greater dyspnea (P = .01), and chronic bronchitis (P = .03). Hyperexpansion was associated with percent emphysema (P &lt; .001), lower BMI (P = .04), and higher hemoglobin concentration (P = .001).

CONCLUSIONS

Gas trapping and hyperexpansion on plethysmography were associated with distinct differences in lung structure and clinical characteristics. Absolute lung volumes should not be considered equivalent in their estimation of hyperinflation and provide insight into the extent of airway and parenchymal abnormalities in COPD.