Improvement of Phase Change Materials (PCM) Used for Solar Process Heat Applications.

The high intermittency of solar energy is still a challenge yet to be overcome. The use of thermal storage has proven to be a good option, with phase change materials (PCM) as very promising candidates. Nevertheless, PCM compounds have typically poor thermal conductivity, reducing their attractiveness for commercial uses. This paper demonstrates the viability of increasing the PCM effective thermal conductivity to industrial required values (around 4 W/m·K) by using metal wool infiltrated into the resin under vacuum conditions. To achieve this result, the authors used an inert resin, decoupling the specific PCM material selection from the enhancement effect of the metal wools. To ensure proper behavior of the metal wool under standard industrial environments at a broad range of temperatures, a set of analyses were performed at high temperatures and an inert atmosphere, presenting a thorough analysis of the obtained results.

Automatic Video Analysis for Obstructive Sleep Apnea Diagnosis.

STUDY OBJECTIVES: We investigated the diagnostic accuracy for the identification of obstructive sleep apnea (OSA) and its severity of a noninvasive technology based on image processing (SleepWise). METHODS: This is an observational, prospective study to evaluate the degree of agreement between polysomnography (PSG) and SleepWise. We recruited 56 consecutive subjects with suspected OSA who were referred as outpatients to the Sleep Unit of the Hospital Universitari Germans Trias i Pujol (HUGTiP) from January 2013 to January 2014. All patients underwent laboratory PSG and image processing with SleepWise simultaneously the same night. Both PSG and SleepWise analyses were carried independently and blindly. RESULTS: We analyzed 50 of the 56 patients recruited. OSA was diagnosed through PSG in a total of 44 patients (88%) with a median apnea-hypopnea index (AHI) of 25.35 (24.9). According to SleepWise, 45 patients (90%) met the criteria for a diagnosis of OSA, with a median AHI of 22.8 (22.03). An analysis of the ability of PSG and SleepWise to classify patients by severity on the basis of their AHI shows that the two diagnostic systems distribute the different groups similarly. According to PSG, 23 patients (46%) had a diagnosis of severe OSA, 11 patients (22%) moderate OSA, and 10 patients (20%) mild OSA. According to SleepWise, 20, 13, and 12 patients (40%, 26%, and 24%, respectively) had a diagnosis of severe, moderate, and mild OSA respectively. For OSA diagnosis, SleepWise was found to have sensitivity of 100% and specificity of 83% in relation to PSG. The positive predictive value was 97% and the negative predictive value was 100%. The Bland-Altman plot comparing the mean AHI values obtained through PSG and SleepWise shows very good agreement between the two diagnostic techniques, with a bias of -3.85, a standard error of 12.18, and a confidence interval of -0.39 to -7.31. CONCLUSIONS: SleepWise was reasonably accurate for noninvasive and automatic diagnosis of OSA in outpatients. SleepWise determined the severity of OSA with high reliability. The current study including simultaneous laboratory PSG and SleepWise processing image is proposed as a reasonable validation standard.

Prevalence, Risk Factors and Diagnostic Accuracy of COPD Among Smokers in Primary Care.

The prevalence of COPD is high, and most cases remain undiagnosed. In contrast, some patients labeled and treated as COPD do not have spirometric confirmation. Our objective was to determine the prevalence of COPD among smokers aged 45 years or older and investigate the accuracy of diagnosis of COPD in primary care. A population-based, epidemiological study was conducted in a primary care centre among subjects older than 45 years with a history of smoking. The participants underwent a clinical questionnaire and spirometry with bronchodilator test. Additionally, participants with newly diagnosed COPD, defined as postbronchodilator FEV1/FVC<0.7, underwent 4-week treatment with formoterol and budesonide to rule out reversible airflow obstruction. A total of 1,738 individuals (84.4% male) with a mean age of 59.9 years were included. The prevalence of COPD was 24.3% (95%, CI 22.3-26.4), with an overall underdiagnosis of 56.7%. Patients with COPD were older, more frequently male, with a lower body mass index, a longer history of smoking, lower educational level, previous occupational exposure, and more cardiovascular co-morbidity (all p < 0.001). After 4 weeks of treatment, 16% of initially obstructed patients had normal spirometry; in addition, 15.6% of individuals with a diagnosis of COPD did not have airflow obstruction. One out of four smokers 45 years or older presenting in primary care have airflow obstruction, mostly undiagnosed. However, among those with an initial diagnosis of COPD up to 16% will normalise spirometry after 4 weeks of treatment. There is also a significant number of individuals misdiagnosed with COPD.

Index for estimation of muscle force from mechanomyography based on the Lempel-Ziv algorithm.

The study of the amplitude of respiratory muscle mechanomyographic (MMG) signals could be useful in clinical practice as an alternative non-invasive technique to assess respiratory muscle strength. The MMG signal is stochastic in nature, and its amplitude is usually estimated by means of the average rectified value (ARV) or the root mean square (RMS) of the signal. Both parameters can be used to estimate MMG activity, as they correlate well with muscle force. These estimations are, however, greatly affected by the presence of structured impulsive noise that overlaps in frequency with the MMG signal. In this paper, we present a method for assessing muscle activity based on the Lempel-Ziv algorithm: the Multistate Lempel-Ziv (MLZ) index. The behaviour of the MLZ index was tested with synthesised signals, with various amplitude distributions and degrees of complexity, and with recorded diaphragm MMG signals. We found that this index, like the ARV and RMS parameters, is positively correlated with changes in amplitude of the diaphragm MMG components, but is less affected by components that have non-random behaviour (like structured impulsive noise). Therefore, the MLZ index could provide more information to assess the MMG-force relationship.

Documento de consenso sobre el fenotipo mixto EPOC-asma en la EPOC / Consensus Document on the Overlap Phenotype COPD-Asthma in COPD

Introducción: Aunque asma y EPOC son enfermedades distintas, muchos pacientes comparten características de ambas entidades. Estos casos pueden tener una evolución y una respuesta al tratamiento diferente. Sin embargo, la evidencia disponible es escasa, y es necesario valorar si representan un fenotipo diferencial y aportar recomendaciones sobre su diagnóstico y tratamiento, además de identificar posibles lagunas de conocimiento. Método: Consenso nacional de expertos en EPOC en dos etapas: 1) Se establecieron los bloques temáticos a tratar y se elaboró una primera propuesta de aseveraciones, mediante una reunión presencial con metodología de «tormenta de ideas» estructurada. 2) Se realizaron dos rondas de consenso vía correo electrónico, utilizando una escala tipo Likert. Resultados: Se consensua la existencia de un fenotipo clínico diferencial denominado «fenotipo mixto EPOC-asma», cuyo diagnóstico se realizará si se cumplen 2 criterios mayores o uno mayor y 2 menores (criterios mayores: prueba broncodilatadora muy positiva [aumento del FEV1≥15% y≥400ml], eosinofilia en esputo y antecedentes personales de asma; criterios menores: IgE total elevada, antecedentes personales de atopia y prueba broncodilatadora positiva [aumento del FEV1≥12% y≥200ml] en dos o más ocasiones). Se recomienda el uso precoz de corticoides inhalados (CI) ajustados individualmente, ser cautos con la retirada brusca de CI y, en casos graves, valorar el uso de la triple terapia. Finalmente, queda patente la falta de estudios específicos sobre la historia natural y el tratamiento de estos pacientes. Conclusiones: Es preciso profundizar en el conocimiento de este fenotipo para establecer pautas y recomendaciones adecuadas para su diagnóstico y tratamiento(AU)

Introduction: Although asthma and COPD are different pathologies, many patients share characteristics from both entities. These cases can have different evolutions and responses to treatment. Nevertheless, the evidence available is limited, and it is necessary to evaluate whether they represent a differential phenotype and provide recommendations about diagnosis and treatment, in addition to identifying possible gaps in our understanding of asthma and COPD. Methods: A nation-wide consensus of experts in COPD in two stages: 1) during an initial meeting, the topics to be dealt with were established and a first draft of statements was elaborated with a structured «brainstorming» method; 2) consensus was reached with two rounds of e-mails, using a Likert-type scale. Results: Consensus was reached about the existence of a differential clinical phenotype known as «Overlap Phenotype COPD-Asthma», whose diagnosis is made when 2 major criteria and 2 minor criteria are met. The major criteria include very positive bronchodilator test (increase in FEV1 ≥15% and ≥400ml), eosinophilia in sputum and personal history of asthma. Minor criteria include high total IgE, personal history of atopy and positive bronchodilator test (increase in FEV1 ≥12% and ≥200ml) on two or more occasions. The early use of individually-adjusted inhaled corticosteroids is recommended, and caution must be taken with their abrupt withdrawal. Meanwhile, in severe cases the use of triple therapy should be evaluated. Finally, there is an obvious lack of specific studies about the natural history and the treatment of these patients. Conclusions: It is necessary to expand our knowledge about this phenotype in order to establish adequate guidelines and recommendations for its diagnosis and treatment(AU)

Intra- and interobserver agreement among bronchial endosonographers for the description of intrathoracic lymph nodes.

Several sonographic features observed by endobronchial ultrasonography have been suggested to be useful to predict malignancy in mediastinal lymph nodes. To evaluate agreement to describe sonographic features, 28 video images were evaluated twice by eight expert bronchoscopists. The observers reviewed each case for the presence of coagulation necrosis sign (CNS), central hilar structure (CHS), heterogeneity, distinct margin, round shape, size >1 cm and malignancy. Intraobserver agreement was almost perfect for size (κ = 0.826), substantial for CNS (κ = 0.721) and shape (κ = 0.615), and moderate for CHS (κ = 0.565), heterogeneity (κ = 0.441) and margin (κ = 0.407). Interobserver agreement was substantial for size (κ = 0.641), moderate for shape (κ = 0.445), and fair for CNS (κ = 0.340) and margin (κ = 0.274). In conclusion, inter- and intraobserver agreement of the endosonographic features for mediastinal or hilar lymph nodes is good for shape or size but not good enough for the other ultrasonographic features.

Combined Pulmonary Fibrosis and Emphysema Syndrome: A New Phenotype within the Spectrum of Smoking-Related Interstitial Lung Disease.

Combined pulmonary fibrosis and emphysema (CPFE) is a recently defined syndrome, in which centrilobular and/or paraseptal emphysemas in upper lung zones coexist with pulmonary fibrosis in lower lobes in individuals. These patients have a characteristic lung function profile, with unexpected subnormal dynamic and static lung volumes, contrasting with a significant reduction of carbon monoxide transfer (DL(co)) and exercise hypoxemia. Pulmonary hypertension is highly prevalent in CPFE and is the leading determinant of death. Tobacco smoking has been proposed as the main factor in its etiology, though the pathophysiology and its natural history remain to be determined. High-resolution computed axial tomography is the mandatory tool to confirm the diagnosis. Currently, there is no consensus about its treatment since those published to date on this issue are limited to well-characterised series of cases; hence, a better understanding of this entity may help in the development of future therapeutic approaches.

Anemia is a mortality predictor in hospitalized patients for COPD exacerbation.

BACKGROUND: Anemia is a recognized prognostic factor in many chronic illnesses, but there is limited information about its impact on outcomes in patients hospitalized for acute COPD exacerbation (AECOPD). AIM: To investigate whether anemia exerts an effect on mortality in patients admitted for AECOPD after one year of follow-up. Methods. From November 2007 to November 2009 we recruited 117 patients who required hospitalization due to an AECOPD. Clinical, functional and laboratory parameters on admission were prospectively assessed. Patients were followed up during one year. Mortality and days-to-death were collected. RESULTS: Mean age 72 (SD ± 9); FEV1 37.4 (SD ± 12); mortality after 1 year was 22.2%. Mean survival: 339 days. Comparing patients who died to those who survived we found significant differences (p < 0,000) in hemoglobin (Hb) (12.4 vs 13.8 mg/dl) and hematocrit (Ht) (38 vs 41%). Anemia (Hb < 13 g.dl⁻¹) prevalence was 33%. Those who died had experienced 3.5 exacerbations in previous year vs 1.5 exacerbations in the case of the survivors (p = 0.000). Lung function and nutritional status were similar, except for percentage of muscle mass (%) (35 vs 39%; p = 0.015) and albumin (33 vs 37 mg/dl; p = 0.039). These variables were included in a Multivariate Cox Proportional Hazards Model; anemia and previous exacerbations resulted as independent factors for mortality. Mortality risk for patients with anemia was 5.9(CI: 1.9-19); for patients with > 1 exacerbation in the previous year was 5.9(CI: 1.3-26.5). CONCLUSION: Anemia and previous exacerbations were independent predictors of mortality after one year in patients hospitalized for AECOPD.

Consensus document on the overlap phenotype COPD-asthma in COPD.

INTRODUCTION: Although asthma and COPD are different pathologies, many patients share characteristics from both entities. These cases can have different evolutions and responses to treatment. Nevertheless, the evidence available is limited, and it is necessary to evaluate whether they represent a differential phenotype and provide recommendations about diagnosis and treatment, in addition to identifying possible gaps in our understanding of asthma and COPD. METHODS: A nation-wide consensus of experts in COPD in two stages: 1) during an initial meeting, the topics to be dealt with were established and a first draft of statements was elaborated with a structured "brainstorming" method; 2) consensus was reached with two rounds of e-mails, using a Likert-type scale. RESULTS: Consensus was reached about the existence of a differential clinical phenotype known as"Overlap Phenotype COPD-Asthma", whose diagnosis is made when 2 major criteria and 2 minor criteria are met. The major criteria include very positive bronchodilator test (increase in FEV(1) ≥ 15% and ≥ 400ml), eosinophilia in sputum and personal history of asthma. Minor criteria include high total IgE, personal history of atopy and positive bronchodilator test (increase in FEV(1) ≥ 12% and ≥ 200ml) on two or more occasions. The early use of individually-adjusted inhaled corticosteroids is recommended, and caution must be taken with their abrupt withdrawal. Meanwhile, in severe cases the use of triple therapy should be evaluated. Finally, there is an obvious lack of specific studies about the natural history and the treatment of these patients. CONCLUSIONS: It is necessary to expand our knowledge about this phenotype in order to establish adequate guidelines and recommendations for its diagnosis and treatment.

Nutritional status and eating disorders: neglected risks factor for nontuberculous mycobacterial lung disease?

Nontuberculous mycobacterial lung disease (NTMLD) in immunocompetent patients is an increasingly important epidemiologic concern. However, risk factors associated with susceptibility to NTMLD are not completely known. A prevalence of NTMLD appears to be rising, mainly in some populations such as middle-aged or elderly thin women, (a group including those with Lady Windermere syndrome) with neither remarkable history of respiratory disease nor smoking habit. Right middle lobe (RML) and lingula are often involved. Various predisposing factors and genetic defects have been described as possible causes of development of NTMLD, namely: voluntary suppression of cough, RML anatomical factors, menopause and mutations in cystic fibrosis transmembrane conductance regulator (CFTR). Malnutrition is also an important and common risk factor associated with other mycobacterial disease like tuberculosis (TB) and its probable association with NTMLD as have been pointed out for some authors. However, a real description of all nutritional aspects and eating habits of patients prior to NTMLD diagnosis is lacking. We hypothesized that malnutrition and eating disorders like anorexia nervosa could be risk factors that may promoting NTMLD. From a clinical viewpoint, if this hypothesis proves to be correct, eating habits and nutritional aspects should be taken into account in the diagnosis process of suspected NTMLD, since they are easily identifiable and treatable conditions.

Evaluation and adaptive attenuation of the cardiac vibration interference in mechanomyographic signals.

The study of the mechanomyographic signal of the diaphragm muscle (MMGdi) is a promising technique in order to evaluate the respiratory muscles effort. The relationship between amplitude and frequency parameters of this signal with the respiratory effort performed during respiration is of great interest for researchers and physicians due to its diagnostic potentials. However, MMGdi signals are frequently contaminated by a cardiac vibration or mechanocardiographic (MCG) signal. An adaptive noise cancellation (ANC) can be used to reduce the MCG interference in the recorded MMGdi activity. In this paper, it is evaluated the proposed ANC scheme by means of a synthetic MMGdi signal with a controlled MCG interference. The Pearson's correlation coefficient (PCC) between both root mean square (RMS) and mean frequency (fm) of the synthetic MMGdi signal are considerably reduced with the presence of cardiac vibration noise (from 0.95 to 0.87, and from 0.97 to 0.76, respectively). With the ANC algorithm proposed the effect of the MCG noise on the amplitude and frequency of MMG parameters is reduced considerably (PCC of 0.93 and 0.97 for the RMS and fm, respectively). The ANC method proposed in this work is an interesting technique to attenuate the cardiac interference in respiratory MMG signals. Further investigation should be carried out to evaluate the performance of the ANC algorithm in real MMGdi signals.

Evaluation of the respiratory muscles efficiency during an incremental flow respiratory test.

The aim of this study was to evaluate the respiratory muscles efficiency during a progressive incremental flow (IF) respiratory test in healthy and Chronic Obstructive Pulmonary Disease (COPD) subjects. To achieve this, the relationship between mouth Inspiratory Pressure (IP) increment, which is a measure of the force produced by respiratory muscles, and respiratory muscular activity increment, evaluated by means of Mechanomyografic (MMG) signals of the diaphragm muscle, was analyzed. Moreover, the correlation between the respiratory efficiency measure and the obstruction severity of the subjects was also examined. Data from two groups of subjects were analyzed. One group consisted of four female subjects (two healthy subjects and two moderate COPD patients) and the other consisted of ten male subjects (six severe and four very severe COPD patients). All subjects performed an easy IF respiratory test, in which small IP values were reached. We have found that there is an increase of amplitude and a displacement towards low frequencies in the MMG signals when the IP increases. Furthermore, it has also been found that respiratory muscles efficiency is lower when greater the obstructive severity of the patients is, and it is lower in women than in men. These results suggest that the information provided by MMG signals could be used to evaluate the muscular efficiency in healthy and COPD subjects.

Snoring analysis for the screening of Sleep Apnea Hypopnea Syndrome with a single-channel device developed using polysomnographic and snoring databases.

Several studies have shown differences in acoustic snoring characteristics between patients with Sleep Apnea-Hypopnea Syndrome (SAHS) and simple snorers. Usually a few manually isolated snores are analyzed, with an emphasis on postapneic snores in SAHS patients. Automatic analysis of snores can provide objective information over a longer period of sleep. Although some snore detection methods have recently been proposed, they have not yet been applied to full-night analysis devices for screening purposes. We used a new automatic snoring detection and analysis system to monitor snoring during full-night studies to assess whether the acoustic characteristics of snores differ in relation to the Apnea-Hypopnea Index (AHI) and to classify snoring subjects according to their AHI. A complete procedure for device development was designed, using databases with polysomnography (PSG) and snoring signals. This included annotation of many types of episodes by an expert physician: snores, inspiration and exhalation breath sounds, speech and noise artifacts, The AHI of each subject was estimated with classical PSG analysis, as a gold standard. The system was able to correctly classify 77% of subjects in 4 severity levels, based on snoring analysis and sound-based apnea detection. The sensitivity and specificity of the system, to identify healthy subjects from pathologic patients (mild to severe SAHS), were 83% and 100%, respectively. Besides, the Apnea Index (AI) obtained with the system correlated with the obtained by PSG or Respiratory Polygraphy (RP) (r=0.87, p<0.05).

Colour of sputum is a marker for bacterial colonisation in chronic obstructive pulmonary disease.

BACKGROUND: Bacterial colonisation in chronic obstructive pulmonary disease (COPD) contributes to airway inflammation and modulates exacerbations. We assessed risk factors for bacterial colonisation in COPD. METHODS: Patients with stable COPD consecutively recruited over 1 year gave consent to provide a sputum sample for microbiologic analysis. Bronchial colonisation by potentially pathogenic microorganisms (PPMs) was defined as the isolation of PPMs at concentrations of > or =102 colony-forming units (CFU)/mL on quantitative bacterial culture. Colonised patients were divided into high (>105 CFU/mL) or low (<105 CFU/mL) bacterial load. RESULTS: A total of 119 patients (92.5% men, mean age 68 years, mean forced expiratory volume in one second [FEV1] [% predicted] 46.4%) were evaluated. Bacterial colonisation was demonstrated in 58 (48.7%) patients. Patients with and without bacterial colonisation showed significant differences in smoking history, cough, dyspnoea, COPD exacerbations and hospitalisations in the previous year, and sputum colour. Thirty-six patients (62% of those colonised) had a high bacterial load. More than 80% of the sputum samples with a dark yellow or greenish colour yielded PPMs in culture. In contrast, only 5.9% of white and 44.7% of light yellow sputum samples were positive (P < 0.001). Multivariate analysis showed an increased degree of dyspnoea (odds ratio [OR] = 2.63, 95% confidence interval [CI] 1.53-5.09, P = 0.004) and a darker sputum colour (OR = 4.11, 95% CI 2.30-7.29, P < 0.001) as factors associated with the presence of PPMs in sputum. CONCLUSIONS: Almost half of our population of ambulatory moderate to very severe COPD patients were colonised with PPMs. Patients colonised present more severe dyspnoea, and a darker colour of sputum allows identification of individuals more likely to be colonised.

Diels-Alder reaction between cyclopentadiene and C60: an analysis of the performance of the ONIOM method for the study of chemical reactivity in fullerenes and nanotubes.

In this article, we theoretically analyze the Diels-Alder cycloaddition between cyclopentadiene and C60 for which experimental results on energy barriers and reaction energies are known. The comparison of the results obtained with the two-layered ONIOM approach using different partitions for the high- and low-level layers with those obtained employing the B3LYP/6-31G(d) method for the entire system allows us to conclude that the partition including a pyracylene unit of C60 in the description of the high-level layer is enough to get excellent results. Using this partition in the two-layered ONIOM approach, we have computed the energy barriers and reaction energies for this Diels-Alder reaction for different functionals, and we have compared them with experimental data. From this comparison, both the ONIOM2(M06-2X/6-31G(d):SVWN/STO-3G) and the M06-2X/6-31G(d)//ONIOM2(B3LYP/6-31G(d):SVWN/STO-3G) methods are recommended as reliable and computationally affordable approaches to be exploited for the study of the chemical reactivity of [6,6]-bonds in fullerenes and nanotubes.

La heterogeneidad fenotípica de la EPOC / Phenotypic Heterogeneity of Chronic Obstructive Pulmonary Disease

La definición funcional de la enfermedad pulmonar obstructiva crónica (EPOC), basada en la limitación al flujo aéreo, ha predominado durante largo tiempo en el ámbito de la neumología. Sin embargo, ha surgido una nueva perspectiva que establece que en la EPOC tiene lugar una compleja variedad de manifestaciones celulares, orgánicas, funcionales y clínicas, y se ha incrementado el interés por desentrañar la heterogeneidad fenotípica de dicha enfermedad. La presente revisión se basa en la opinión de unos autores que tienen una amplia experiencia en la investigación de los diversos aspectos de la EPOC. La revisión parte de la base de que el conocimiento actual sobre la fisiopatología y el cuadro clínico de la EPOC permite clasificar la información fenotípica en función de las siguientes dimensiones: síntomas respiratorios y estado de salud, exacerbaciones agudas, función pulmonar, cambios estructurales, inflamación local y sistémica, y efectos sistémicos. Se han identificado 26 rasgos fenotípicos que se han asignado a alguna de las 6 dimensiones. Para cada dimensión se proporciona un resumen de la mejor evidencia sobre la relación existente entre los rasgos fenotípicos —en concreto, entre aquellos que corresponden a diferentes dimensiones— y sobre la relación entre dichos rasgos y las manifestaciones relevantes en la evolución natural de la EPOC. Toda la información se ha organizado gráficamente en una matriz fenotípica donde cada celda que representa un par de rasgos fenotípicos está vinculada a referencias bibliográficas relevantes. La información podría ayudar a comprender mejor la heterogeneidad de los fenotipos de la EPOC y a planificar estudios futuros sobre aspectos que todavía no se han investigado(AU)

A functional definition of chronic obstructive pulmonary disease (COPD) based on airflow limitation has largely dominated the field. However, a view has emerged that COPD involves a complex array of cellular, organic, functional, and clinical events, with a growing interest in disentangling the phenotypic heterogeneity of COPD. The present review is based on the opinion of the authors, who have extensive research experience in several aspects of COPD. The starting assumption of the review is that current knowledge on the pathophysiology and clinical features of COPD allows us to classify phenotypic information in terms of the following dimensions: respiratory symptoms and health status, acute exacerbations, lung function, structural changes, local and systemic inflammation, and systemic effects. Twenty-six phenotypic traits were identified and assigned to one of the 6 dimensions. For each dimension, a summary is provided of the best evidence on the relationships among phenotypic traits, in particular among those corresponding to different dimensions, and on the relationship between these traits and relevant events in the natural history of COPD. The information has been organized graphically into a phenotypic matrix where each cell representing a pair of phenotypic traits is linked to relevant references. The information provided has the potential to increase our understanding of the heterogeneity of COPD phenotypes and help us plan future studies on aspects that are as yet unexplored(AU)

[Phenotypic heterogeneity of chronic obstructive pulmonary disease]. / La heterogeneidad fenotípica de la EPOC.

A functional definition of chronic obstructive pulmonary disease (COPD) based on airflow limitation has largely dominated the field. However, a view has emerged that COPD involves a complex array of cellular, organic, functional, and clinical events, with a growing interest in disentangling the phenotypic heterogeneity of COPD. The present review is based on the opinion of the authors, who have extensive research experience in several aspects of COPD. The starting assumption of the review is that current knowledge on the pathophysiology and clinical features of COPD allows us to classify phenotypic information in terms of the following dimensions: respiratory symptoms and health status, acute exacerbations, lung function, structural changes, local and systemic inflammation, and systemic effects. Twenty-six phenotypic traits were identified and assigned to one of the 6 dimensions. For each dimension, a summary is provided of the best evidence on the relationships among phenotypic traits, in particular among those corresponding to different dimensions, and on the relationship between these traits and relevant events in the natural history of COPD. The information has been organized graphically into a phenotypic matrix where each cell representing a pair of phenotypic traits is linked to relevant references. The information provided has the potential to increase our understanding of the heterogeneity of COPD phenotypes and help us plan future studies on aspects that are as yet unexplored.