Should mild COPD be treated? Evidence for early pharmacological intervention

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.

Recent Advances in the Physiological Assessment of Dyspneic Patients with Mild COPD

There is growing recognition that a sizable fraction of COPD patients with forced expiratory volume in one second (FEV₁)/forced vital capacity ratio below the lower limit of normal but preserved FEV₁ reports out-of-proportion dyspnea relative to the severity of airflow limitation. Most physicians, however, assume that patients' breathlessness is unlikely to reflect the negative physiological consequences of COPD vis-à-vis FEV₁ normalcy. This concise review integrates the findings of recent studies which uncovered the key pathophysiological features shared by these patients: poor pulmonary gas exchange efficiency (increased "wasted" ventilation) and gas trapping. These abnormalities are associated with two well-known causes of exertional dyspnea: heightened ventilation relative to metabolic demand and critically low inspiratory reserves, respectively. From a clinical standpoint, a low diffusion capacity associated with increased residual volume (RV) and/or RV/total lung capacity ratio might uncover these disturbances, identifying the subset of patients in whom exertional dyspnea is causally related to "mild" COPD.

The Economic Effect of Early Management in Patients with Early Chronic Obstructive Pulmonary Disease: Results from a Population-Based Nationwide Survey

PURPOSE

The economic effect of regular follow-up and early management in patients with early chronic obstructive pulmonary disease (COPD) has not yet been clarified. Therefore, this study aimed to estimate the economic effect of regular follow-up and early management in these patients.

METHODS

Patients with early COPD were identified from the Korea National Health and Nutrition Examination Survey. We analyzed medical utilization and cost for 2 years without any missing data by using the Korean National Health Insurance data. Patients with routine healthcare maintenance were defined as, after diagnosis, those with regular visits to the hospital and receiving early management of COPD.

RESULTS

Among 1204 patients with early COPD, the patients who were classified as the group with routine healthcare maintenance (69/146; 47.3%) and the group with intermittent healthcare user (79/1058; 7.5%) visited to hospital for the next 2 years. The patients with routine healthcare maintenance had lower cost of inpatient service and frequencies of emergency room (ER) visit and intensive care unit (ICU) admission than intermittent healthcare users (cost of inpatient service, $4595 vs. $4953 per person; ER visit, 7.2 vs. 11.5; ICU admission, 4.3 vs. 7.7). Even in patients with COPD and FEV₁ ≥ 80, early intervention through follow-up reduced the cost of inpatient service because these patients could have had less severe acute exacerbations than intermittent healthcare users.

CONCLUSION

Patients with early COPD, even those with FEV₁ ≥ 80, need regular follow-up for early management and disease control as well as for reducing the socioeconomic burden of the disease.

Outcomes for symptomatic non-obstructed individuals and individuals with mild (GOLD stage 1) COPD in a population based cohort

BACKGROUND

We aimed to study the adverse outcomes of symptomatic and asymptomatic non-obstructed individuals and those with mild COPD longitudinally in participants from three Latin-American cities.

METHODS

Two population-based surveys of adults with spirometry were conducted for these same individuals with a 5- to 9-year interval. We evaluated the impact of respiratory symptoms (cough, phlegm, wheezing or dyspnea) in non-obstructed individuals, and among those classified as Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 1, COPD on exacerbation frequency, mortality and FEV1 decline, compared with asymptomatic individuals without airflow obstruction or restriction.

RESULTS

Non-obstructed symptomatic individuals had a marginal increased risk of mortality (HR 1.3; 95% CI 0.9-1.94), increased FEV1 decline (-4.5 mL/year; 95% CI -8.6, -0.4) and increased risk of 2+ exacerbations in the previous year (OR 2.6; 95% CI 1.2-6.5). Individuals with GOLD stage 1 had a marginal increase in mortality (HR 1.5; 95% CI 0.93-2.3) but a non-significant impact on FEV1 decline or exacerbations compared with non-obstructed individuals.

CONCLUSIONS

The presence of respiratory symptoms in non-obstructed individuals was a predictor of mortality, lung-function decline and exacerbations, whereas the impact of GOLD stage 1 was mild and inconsistent. Respiratory symptoms were associated with asthma, current smoking, and the report of heart disease. Spirometric case-finding and treatment should target individuals with moderate-to-severe airflow obstruction and those with restriction, the groups with consistent increased mortality.

Physiological and clinical relevance of exercise ventilatory efficiency in COPD

Exercise ventilation (V'_E) relative to carbon dioxide output (V'_CO2 ) is particularly relevant to patients limited by the respiratory system, e.g. those with chronic obstructive pulmonary disease (COPD). High V'_E-V'_CO2 (poor ventilatory efficiency) has been found to be a key physiological abnormality in symptomatic patients with largely preserved forced expiratory volume in 1 s (FEV₁). Establishing an association between high V'_E-V'_CO2 and exertional dyspnoea in mild COPD provides evidence that exercise intolerance is not a mere consequence of detraining. As the disease evolves, poor ventilatory efficiency might help explaining "out-of-proportion" breathlessness (to FEV₁ impairment). Regardless, disease severity, cardiocirculatory co-morbidities such as heart failure and pulmonary hypertension have been found to increase V'_E-V'_CO2 In fact, a high V'_E-V'_CO2 has been found to be a powerful predictor of poor outcome in lung resection surgery. Moreover, a high V'_E-V'_CO2 has added value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of COPD severity. Documenting improved ventilatory efficiency after lung transplantation and lung volume reduction surgery provides objective evidence of treatment efficacy. Considering the usefulness of exercise ventilatory efficiency in different clinical scenarios, the V'_E-V'_CO2 relationship should be valued in the interpretation of cardiopulmonary exercise tests in patients with mild-to-end-stage COPD.

Oral N-acetylcysteine and exercise tolerance in mild chronic obstructive pulmonary disease

Heightened oxidative stress is implicated in the progressive impairment of skeletal muscle vascular and mitochondrial function in chronic obstructive pulmonary disease (COPD). Whether accumulation of reactive oxygen species contributes to exercise intolerance in the early stages of COPD is unknown. The purpose of the present study was to determine the effects of oral antioxidant treatment with N-acetylcysteine (NAC) on respiratory, cardiovascular, and locomotor muscle function and exercise tolerance in patients with mild COPD. Thirteen patients [forced expiratory volume in 1 s (FEV₁)-to-forced vital capacity ratio < lower limit of normal (LLN) and FEV₁ ≥ LLN) were enrolled in a double-blind, randomized crossover study to receive NAC (1,800 mg/day) or placebo for 4 days. Severe-intensity constant-load exercise tests were performed with noninvasive measurements of central hemodynamics (stroke volume, heart rate, and cardiac output via impedance cardiography), arterial blood pressure, pulmonary ventilation and gas exchange, quadriceps muscle oxygenation (near-infrared spectroscopy), and estimated capillary blood flow. Nine patients completed the study with no major adverse clinical effects. Although NAC elevated plasma glutathione by ~27% compared with placebo (P < 0.05), there were no differences in exercise tolerance (placebo: 325 ± 47 s, NAC: 336 ± 51 s), central hemodynamics, arterial blood pressure, pulmonary ventilation or gas exchange, locomotor muscle oxygenation, or capillary blood flow from rest to exercise between conditions (P > 0.05 for all). In conclusion, modulation of plasma redox status with oral NAC treatment was not translated into beneficial effects on central or peripheral components of the oxygen transport pathway, thereby failing to improve exercise tolerance in nonhypoxemic patients with mild COPD.NEW & NOTEWORTHY Acute antioxidant treatment with N-acetylcysteine (NAC) elevated plasma glutathione but did not modulate central or peripheral components of the O₂ transport pathway, thereby failing to improve exercise tolerance in patients with mild chronic obstructive pulmonary disease (COPD).

Early detection of COPD patients in GOLD 0 population: an observational non-interventional cohort study - MARKO study

BACKGROUND

Main risk factor for the development of chronic obstructive pulmonary disease (COPD) is smoking, although only less than 1/3 of smokers develop clinically manifest COPD. COPD's progressive nature with high disability and mortality makes it plausible to detect it as early as possible thus allowing for an early intervention. The only tool for an early diagnosis that could be used on the global scale is spirometry, even though symptoms and deprivation of health related quality of life (HRQoL) precede relevant spirometric changes. Existing HRQoL questionnaires are too complicated or not developed for an early detection of COPD. The aim of our study was to develop a new simple HRQoL tool that will allow (alone or in combination with other markers) early detection of patients with COPD.

METHODS

A multicenter prospective cohort study recruiting 500 subjects at risk for COPD (smokers/ex-smokers ≥20 pack-years, 40-65 years, both sexes, with no prior diagnosis of COPD) will be carried out in two phases: (1) cross-sectional - development and validation of a new questionnaire; and (2) prospective - follow-up of a cohort of patients at risk for COPD. Subjects were recruited by 25 GPs and assessed for COPD by dedicated pulmonologists in 7 hospital centers using a predefined protocol: HRQoL, history, physical, blood sampling, exhaled breath temperature (EBT), lung function, 6-min walk test (6MWT). Patients without COPD and those in GOLD stage 1 at initial assessment will be reassessed for disease progression by the same pulmonologist after 2 and 5 years.

DISCUSSION

This is one of the first cohort studies attempting to establish the incidence of COPD in the pre-symptomatic stage before significant end organ damage. We intend to assess the validity, predictability and discriminative power ('healthy' smokers vs. pre-symptomatic phase in newly developed COPD) of newly developed HRQoL tool alone or in combination with other markers; EBT, lung function, 6MWT, genomics, transcriptomics, proteomics). We expect that the results of this study can improve our understanding of the development of COPD, identify some new underlying pathophysiological pathways, and offer to sensitive smokers/ex-smokers new preventive and early intervention measures thus improving the management of COPD.

TRIAL REGISTRATION

Clinicaltrial.gov NCT01550679 retrospectively registered February 28, 2012.

Physiologic Determinants of Exercise Capacity in Pulmonary Langerhans Cell Histiocytosis: A Multidimensional Analysis

BACKGROUND

Reduced exercise capacity severely impacts quality of life in pulmonary Langerhans cell histiocytosis. Ascertaining mechanisms that impair exercise capacity is necessary to identify targets for symptomatic treatments.

METHODS

Dyspnea, pulmonary function tests and cardiopulmonary exercise test were analysed in 62 study participants. Data were compared between subjects with impaired and normal aerobic capacity (V'O2 peak less than 84% versus 84% predicted or more). Data were reduced using a principal component analysis. Multivariate analysis included V'O2 peak as the dependent variable and principal components as covariates.

RESULTS

V'O2 peak was reduced in 44 subjects (71%). Subjects with impaired aerobic capacity presented: (i) decreased FEV1, FVC, FEV1/FVC, DLCO and DLCO/VA and increased AaDO2, (ii) increased ventilatory equivalents at ventilatory threshold, VD/VT peak, AaDO2 peak and PaCO2 peak and decreased ventilatory reserve and PaO2 peak. There was no difference between groups in dyspnea scores. Principal component analysis extracted 4 principal components interpreted as follows: PC1: gas exchange; PC2: "pseudorestriction"; PC3: exercise-induced hyperpnea; PC4: air trapping. Multivariate analysis explained 65% of V'O2 peak. The 4 principal components were independently associated with V'O2 peak (βcoefficients: PC1: 9.3 [4.6; 14], PC2: 7.5 [3; 11.9], PC3: -5.3 [-9.6;-1.], PC4: -9.8 [-14,9;-4.7]).

CONCLUSION

Impaired exercise capacity is frequent in pulmonary Langerhans cell histiocytosis. It is mainly caused by pulmonary changes but is not associated with increased dyspnea intensity. Therefore, treating the lung represents a relevant approach for improving exercise capacity, even in patients experiencing mild dyspnea.

Veterans Airflow Obstruction Screening Questionnaire: A Survey to Identify Veterans with Airflow Obstruction

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality within the Veterans Healthcare Administration (VHA) and is frequently under-diagnosed. We developed the Veterans Airflow Screening Questionnaire (VAFOSQ) to improve the identification of Veterans with airflow obstruction (AFO), the most commonly used criterion for the diagnosis of COPD.We created an initial survey with 78 variables that have been associated with AFO. A total of 825 patients in 3 primary care clinics performed spirometry after bronchodilator administration and completed the initial survey. Best sets regression was used to build a model that predicted AFO optimally. A total of 195 of 825 (23.3%) patients had AFO and 7 items positively predicted AFO. When the questionnaire score was greater than 25, the VAFOSQ accurately identified AFO with an area under the receiver operating curve of 0.72. In a prospective validation cohort of 376 participants, the positive predictive value was 32% and negative predictive value 81%. The VAFOSQ is a reliable and valid instrument for the identification of veterans at risk for AFO who would benefit from further evaluation with spirometry and assessment for COPD. The VAFOSQ is straightforward to use and can be easily self-administered and self-scored enabling widespread application within the VHA.

A gene therapy induced emphysema model and the protective role of stem cells

BACKGROUND

Chronic obstructive pulmonary disease presents with two different phenotypes: chronic bronchitis and emphysema with parenchymal destruction. Decreased expression of vascular endothelial growth factor and increased endothelial cell apoptosis are considered major factors for emphysema. Stem cells have the ability of vascular regeneration and function as a repair mechanism for the damaged endothelial cells. Currently, minimally invasive interventional procedures such as placement of valves, bio-foam or coils are performed in order to improve the disturbed mechanical function in emphysema patients. However, these procedures cannot restore functional lung tissue. Additionally stem cell instillation into the parenchyma has been used in clinical studies aiming to improve overall respiratory function and quality of life.

METHODS

In our current experiment we induced emphysema with a DDMC non-viral vector in BALBC mice and simultaneously instilled stem cells testing the hyposthesis that they might have a protective role against the development of emphysema. The mice were divided into four groups: a) control, b) 50.000 cells, c) 75.000 and d) 100.000 cells.

RESULTS

Lung pathological findings revealed that all treatment groups had less damage compared to the control group. Additionally, we observed that emphysema lesions were less around vessels in an area of 10 μm.

CONCLUSIONS

Our findings indicate that stem cell instillation can have a regenerative role if applied upon a tissue scaffold with vessel around.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_195.

A multifactoral analysis of 1452 patients for smoking sensation. An outpatient lab experience

Smoking habit is held responsible for several respiratory and metabolic diseases. Data from 1452 patients were recorded from our outpatient laboratory. The following parameters were recorded within several follow ups of our patients; smoking habit, respiratory functions, smoking cessation questionnaires, and administered drugs. The treatment administered to smokers throughout the period of inspection seems to also have a significant effect on dependence. In fact, varelicline causes a 50% reduction in smoking dependence in regards to nicotine substitutes (odds ratio: 0.48 (0.31-0,74), p=0.001) so displaying a substantial preponderance on the choice to fight smoking dependence.