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Use of cluster analysis to describe desaturator phenotypes in COPD: correlations between pulmonary function tests and nocturnal oxygen desaturation. (full freetext)

Significant heterogeneity of clinical presentation and disease progression exists within chronic obstructive pulmonary disease (COPD). Although forced expiratory volume in 1 second (FEV(1)) inadequately describes this heterogeneity, a clear alternative has not emerged. This article discusses and refines the concept of phenotyping desaturators in COPD and shows a possible pattern which could be used as a framework for future research.

RECENT FINDINGS: COPD is a complex condition with pulmonary and extrapulmonary manifestations. We suggest that COPD phenotypes should be associated with clinically meaningful outcomes. The innovation of COPD phenotyping is defined as COPD desaturators. Sleep-related hypoxemia and hypercapnia are well recognized in COPD and the development of systemic inflammation during sleep. These sleep-related changes predispose to nocturnal cardiac arrhythmias, pulmonary hypertension, and possibly death, particularly during acute exacerbations.

CONCLUSION: A more focused definition makes possible a classification of patients into two distinct subgroups for both clinical and research purposes. Establishing a common language for future research will facilitate our understanding and management of such diseases. Even if different treatment strategies have different outcomes for these groups, we will have confirmation, or otherwise, of the clinical value of cluster analysis. This knowledge could lead to pharmacological treatment and other interventions directed to specific phenotypic groups.

Asthma, chronic obstructive pulmonary disease, or both? Diagnostic labeling and spirometry in primary care patients aged 40 years or more. (full freetext)

AIMS: To describe symptoms and lung function in patients registered with asthma or chronic obstructive pulmonary disease (COPD) in primary care and to examine how spirometry findings fit with general practitioners' (GPs) diagnoses.

METHODS: Patients aged ≥40 years with a diagnosis of asthma or COPD registered in the electronic medical record during the previous 5 years were recruited at seven GP offices in Norway in 2009-2010. Registered diagnosis, spirometry results, comorbidity, and reported symptoms were compared.

RESULTS: Among 376 patients, 62% were women. Based on Global Initiative for Chronic Obstructive Lung Diseases criteria, a spirometry diagnosis of COPD could be made in 68.1% of the patients with a previous COPD diagnosis and in 17.1% of those diagnosed with asthma only (P < 0.001). The κ agreement between last clinical diagnosis of COPD and COPD based on spirometry was 0.50. A restrictive spirometry pattern was found in 19.4% and more frequently in patients diagnosed with both asthma and COPD (23.9%) than in patients diagnosed with COPD only (6.8%, P = 0.003).

CONCLUSION: The ability of GPs to differentiate between asthma and COPD seems to have considerably improved during the last decade, probably due to the dissemination of spirometry and guidelines for COPD diagnosis. A diagnosis of COPD that cannot be confirmed by spirometry represents a challenge in clinical practice, in particular when a restrictive pattern on spirometry is found.

The effects of long-term noninvasive ventilation in hypercapnic COPD patients: a randomized controlled pilot study. (full freetext)

Noninvasive ventilation (NIV) is a well-established treatment for acute-on- chronic respiratory failure in hypercapnic COPD patients. Less is known about the effects of a long-term treatment with NIV in hypercapnic COPD patients and about the factors that may predict response in terms of improved oxygenation and lowered CO(2) retention.

METHODS: In this study, we randomized 15 patients to a routine pharmacological treatment (n = 5, age 66 [standard deviation ± 6] years, FEV(1) 30.5 [±5.1] %pred, PaO(2) 65 [±6] mmHg, PaCO(2) 52.4 [±6.0] mmHg) or to a routine treatment and NIV (using the Synchrony BiPAP device [Respironics, Inc, Murrsville, PA]) (n = 10, age 65 [±7] years, FEV(1) 29.5 [±9.0] %pred, PaO(2) 59 [±13] mmHg, PaCO(2) 55.4 [±7.7] mmHg) for 6 months. We looked at arterial blood gasses, lung function parameters and performed a low-dose computed tomography of the thorax, which was later used for segmentation (providing lobe and airway volumes, iVlobe and iVaw) and post-processing with computer methods (providing airway resistance, iRaw) giving overall a functional image of the separate airways and lobes.

RESULTS: In both groups there was a nonsignificant change in FEV(1) (NIV group 29.5 [9.0] to 38.5 [14.6] %pred, control group 30.5 [5.1] to 36.8 [8.7] mmHg). PaCO(2) dropped significantly only in the NIV group (NIV: 55.4 [7.7] → 44.5 [4.70], P = 0.0076; control: 52.4 [6.0] → 47.6 [8.2], NS). Patients actively treated with NIV developed a more inhomogeneous redistribution of mass flow than control patients. Subsequent analysis indicated that in NIV-treated patients that improve their blood gases, mass flow was also redistributed towards areas with higher vessel density and less emphysema, indicating that flow was redistributed towards areas with better perfusion. There was a highly significant correlation between the % increase in mass flow towards lobes with a blood vessel density of >9% and the increase in PaO(2). Improved ventilation-perfusion match and recruitment of previously occluded small airways can explain the improvement in blood gases.

CONCLUSION: We can conclude that in hypercapnic COPD patients treated with long-term NIV over 6 months, a mass flow redistribution occurs, providing a better ventilation-perfusion match and hence better blood gases and lung function. Control patients improve homogeneously in iVaw and iRaw, without improvement in gas exchange since there is no improved ventilation/perfusion ratio or increased alveolar ventilation. These differences in response can be detected through functional imaging, which gives a more detailed report on regional lung volumes and resistances than classical lung function tests do. Possibly only patients with localized small airway disease are good candidates for long-term NIV treatment. To confirm this and to see if better arterial blood gases also lead to better health related quality of life and longer survival, we have to study a larger population.

Impaired lung function in individuals chronically exposed to biomass combustion.

BACKGROUND: The use of biomass for cooking and heating is considered an important factor associated with respiratory diseases. However, few studies evaluate the amount of particulate matter less than 2.5μm in diameter (PM2.5), symptoms and lung function in the same population.

OBJECTIVES: To evaluate the respiratory effects of biomass combustion and compare the results with those of individuals from the same community in Brazil using liquefied petroleum gas (Gas).

METHODS: 1402 individuals in 260 residences were divided into three groups according to exposure (Gas, Indoor-Biomass, Outside-Biomass). Respiratory symptoms were assessed using questionnaires. Reflectance of paper filters was used to assess particulate matter exposure. In 48 residences the amount of PM2.5 was also quantified. Pulmonary function tests were performed in 120 individuals.

RESULTS: Reflectance index correlated directly with PM2.5 (r=0.92) and was used to estimate exposure (ePM2.5). There was a significant increase in ePM2.5 in Indoor-Biomass and Outside-Biomass, compared to Gas. There was a significantly increased odds ratio (OR) for cough, wheezing and dyspnea in adults exposed to Indoor-Biomass (OR=2.93, 2.33, 2.59, respectively) and Outside-Biomass (OR=1.78, 1.78, 1.80, respectively) compared to Gas. Pulmonary function tests revealed both Non-Smoker-Biomass and Smoker-Gas individuals to have decreased %predicted-forced expiratory volume in the first second (FEV1) and FEV1/forced vital capacity (FVC) as compared to Non-Smoker-Gas . Pulmonary function tests data was inversely correlated with duration and ePM2.5. The prevalence of airway obstruction was 20% in both Non-Smoker-Biomass and Smoker-Gas subjects.

CONCLUSION: Chronic exposure to biomass combustion is associated with increased prevalence of respiratory symptoms, reduced lung function and development of chronic obstructive pulmonary disease. These effects are associated with the duration and magnitude of exposure and are exacerbated by tobacco smoke.

Is chronic obstructive pulmonary disease associated with increased arterial stiffness?

OBJECTIVE: We hypothesize that airflow limitation is associated with increasing arterial stiffness and that having COPD increases a non-invasive measure of arterial stiffness - the aortic augmentation index (AIx) - independently of other CVD risk factors.

METHODS: This population study is based on 3374 subjects from the Copenhagen City Heart Study; 494 had COPD. We used multiple linear regression analyses to examine the association between COPD and AIx adjusted for CVD risk factors. Furthermore, we analyzed the association between AIx and FEV(1), FVC and FEV(1)/FVC in the entire population.

RESULTS: AIx was higher in subjects with COPD than in subjects without: 25.7 vs. 21.0 (p < 0.001) in men and 33.6 vs. 29.4 (p < 0.001) in women. We found no increase in AIx with COPD adjusted for CVD risk factors: difference 0.63 (-0.26 to 1.52, p = 0.16). In sensitivity analyses in subjects younger than 60 years with exclusion of mild COPD from the analyses, COPD was associated with an increase in AIx in men only of 4.1 (0.88-7.22, p = 0.007). AIx had a curvilinear association with FEV(1) and FVC but no association with the FEV(1)/FVC ratio.

CONCLUSION: AIx and COPD are only weakly associated. In the general population, this finding argues against increased arterial stiffness, as measured by AIx, being a complication of COPD.

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