• Tuberculosis and Respiratory Diseases
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• v.85 no.4
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• pp.302-312
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• 2022

Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous disease. Not all patients with COPD respond to available drugs. Identifying respondents to therapy is critical to delivering the most appropriate treatment and avoiding unnecessary medication. Recognition of individual patients' dominant characteristics by phenotype is a useful tool to better understand their disease and tailor treatment accordingly. To look for a suitable phenotype, it is important to understand what makes COPD complex and heterogeneous. The pathology of COPD includes small airway disease and/or emphysema. Thus, COPD is not a single disease entity. In addition, there are two types (panlobular and centrilobular) of emphysema in COPD. The coexistence of different pathological subtypes could be the reason for the complexity and heterogeneity of COPD. Thus, it is necessary to look for the phenotype based on the difference in the underlying pathology. Review of the literature has shown that clinical manifestation and therapeutic response to pharmacological therapy are different depending on the presence of computed tomography-defined airway wall thickening in COPD patients. Defining the phenotype of COPD based on the underlying pathology is encouraging as most clinical manifestations can be distinguished by the presence of increased airway wall thickness. Pharmacological therapy has shown significant effect on COPD with airway wall thickening. However, it has limited use in COPD without an airway disease. The phenotype of COPD based on the underlying pathology can be a useful tool to better understand the disease and adjust treatment accordingly.

• Tuberculosis and Respiratory Diseases
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• v.76 no.2
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• pp.53-58
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• 2014

Chronic obstructive pulmonary disease (COPD) is a common airway disease that has considerable impact on disease burdens and mortality rates. A large number of articles on COPD are published within the last few years. Many aspects on COPD ranging from risk factors to management have continued to be fertile fields of investigation. This review summarizes 6 clinical articles with regards to the risk factors, phenotype, assessment, exacerbation, management and prognosis of patients with COPD which were being published last year in major medical journals.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1719-1729
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• 2021

Objective: Emphysema and small-airway disease are the two major components of chronic obstructive pulmonary disease (COPD). We propose a novel method of quantitative computed tomography (CT) emphysema air-trapping composite (EAtC) mapping to assess each COPD component. We analyzed the potential use of this method for assessing lung function in patients with COPD. Materials and Methods: A total of 584 patients with COPD underwent inspiration and expiration CTs. Using pairwise analysis of inspiration and expiration CTs with non-rigid registration, EAtC mapping classified lung parenchyma into three areas: Normal, functional air trapping (fAT), and emphysema (Emph). We defined fAT as the area with a density change of less than 60 Hounsfield units (HU) between inspiration and expiration CTs among areas with a density less than -856 HU on inspiration CT. The volume fraction of each area was compared with clinical parameters and pulmonary function tests (PFTs). The results were compared with those of parametric response mapping (PRM) analysis. Results: The relative volumes of the EAtC classes differed according to the Global Initiative for Chronic Obstructive Lung Disease stages (p < 0.001). Each class showed moderate correlations with forced expiratory volume in 1 second (FEV₁) and FEV₁/forced vital capacity (FVC) (r = -0.659-0.674, p < 0.001). Both fAT and Emph were significant predictors of FEV₁ and FEV₁/FVC (R² = 0.352 and 0.488, respectively; p < 0.001). fAT was a significant predictor of mean forced expiratory flow between 25% and 75% and residual volume/total vital capacity (R² = 0.264 and 0.233, respectively; p < 0.001), while Emph and age were significant predictors of carbon monoxide diffusing capacity (R² = 0.303; p < 0.001). fAT showed better correlations with PFTs than with small-airway disease on PRM. Conclusion: The proposed quantitative CT EAtC mapping provides comprehensive lung functional information on each disease component of COPD, which may serve as an imaging biomarker of lung function.

• Tuberculosis and Respiratory Diseases
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• v.76 no.4
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• pp.169-174
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• 2014

Background: The Korean Obstructive Lung Disease (KOLD) Cohort Study is a prospective longitudinal study of patients with chronic obstructive pulmonary disease (COPD), asthma, or other unclassified obstructive lung diseases. It was designed to develop new classification models and biomarkers that predict clinically relevant outcomes for patients with obstructive lung diseases. Methods: Patients over 18 years old who have chronic respiratory symptoms and airflow limitations or bronchial hyper-responsiveness were enrolled at 17 centers in South Korea. After a baseline visit, the subjects were followed up every 3 months for various assessments. Results: From June 2005 to October 2013, a total of 477 subjects (433 [91%] males; 381 [80%] diagnosed with COPD) were enrolled. Analyses of the KOLD Cohort Study identified distinct phenotypes in patients with COPD, and predictors of therapeutic responses and exacerbations as well as the factors related to pulmonary hypertension in COPD. In addition, several genotypes were associated with radiological phenotypes and therapeutic responses among Korean COPD patients. Conclusion: The KOLD Cohort Study is one of the leading long-term prospective longitudinal studies investigating heterogeneity of the COPD and is expected to provide new insights for pathogenesis and the long-term progression of COPD.

• Tuberculosis and Respiratory Diseases
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• v.86 no.3
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• pp.166-175
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• 2023

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. The lower airways contain a rich and diverse microbiome, which may play a significant regulatory role in both health and disease. In COPD, the microbiome becomes perturbed, causing dysbiosis. Increased representation of members in the Proteobacteria phylum and certain members in the Firmicutes phylum has been associated with increased risk of exacerbations and mortality. Therapies such as inhaled corticosteroids and azithromycin may modulate the airway microbiome or its metabolites in patients with COPD. This paper provides an up-to-date overview of the airway microbiome and its importance in the pathophysiology of COPD and as potential therapeutic target in the future.

• Tuberculosis and Respiratory Diseases
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• v.80 no.4
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• pp.325-335
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• 2017

Chronic obstructive pulmonary disease (COPD) is associated with abnormal inflammatory response and airflow limitation. Acute exacerbation involves increased inflammatory burden leading to worsening respiratory symptoms, including dyspnea and sputum production. Some COPD patients have frequent exacerbations (two or more exacerbations per year). A substantial proportion of COPD patients may remain stable without exacerbation. Bacterial and viral infections are the most common causative factors that breach airway stability and lead to exacerbation. The increasing prevalence of exacerbation is associated with deteriorating lung function, hospitalization, and risk of death. In this review, we summarize the mechanisms of airway inflammation in COPD and discuss how bacterial or viral infection, temperature, air pollution, eosinophilic inflammation, and concomitant chronic diseases increase airway inflammation and the risk of exacerbation.

• Tuberculosis and Respiratory Diseases
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• v.61 no.3
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• pp.218-226
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• 2006

Background: The lung volume and diffusing capacity are influenced by ethnicity. However, there are no equations for predicting the normal lung volume in the adult Korean population, and there is only one equation for diffusing capacity. The aim of this study is to select the most suitable reference equation for the Korean population. Method: 30 men and 33 women at Hanyang University Guri Hospital, and 27 men and 34 women at Asan Medical Center in healthy nonsmoking adults were enrolled in this study. The subject's age, gender, height, weight, lung volume by plethysmography, and diffusing capacity by a single breathing method were obtained. The most suitable equation with the lowest sum of residuals between the observed and predicted values for lung volume and diffusing capacity was selected. Result: At Hanyang University Guri Hospital, the equations with the lowest sum of residuals in the total lung capacity were ECSC's equation in males (sum of residual: 0.04 L) and Crapo/Morris's equation (-1.04) in women. At the Asan Medical Center, the equations with the lowest sum of residuals in the total lung capacity were Goldman/Becklake's equation in males (sum of residual: -2.35) and the ECSC's equation -4.49) in women. The equations with the lowest sum of residuals in the Diffusing capacity were Roca's equation in males (sum of residual: -13.66 ml/min/mmHg) and Park's in women (25.08) in Hanyang University Guri hospital and Park's equation in all cases in the Asan Medical Center (male: -1.65, female: -6.46). Conclusions: Until a reference equstion can be made for healthy Koreans by sampling, ECSC's equation can be used for estimating the lung volume and Park's can be used for estimating the diffusing capacity.

• Tuberculosis and Respiratory Diseases
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• v.80 no.4
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• pp.317-324
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• 2017

Small airway disease (SAD) has been recognized for many years as a central feature of chronic obstructive pulmonary disease (COPD). Histopathology studies have shown that the narrowing and destruction of small airways in COPD combined with inflammatory cell infiltration in the submucosa increases the severity of the disease. SAD is present in the early stages of COPD and becomes more widespread over time as the disease progresses to more severe COPD. The development of inhalers containing extra-fine particles allows the small airways to be pharmacologically targeted. Recent clinical trials have shown the efficacy of extra-fine triple therapy that targets the small airways in patients with COPD. This article reviews the importance and treatment of SAD in COPD.

• Tuberculosis and Respiratory Diseases
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• v.60 no.5
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• pp.510-515
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• 2006

Background : Although 17% of Korean adults over the age of 45 years have chronic obstructive pulmonary disease (COPD), there is only limited data on the cause of death in COPD patients in Korea. Therefore, this retrospective study was performed to examine the cause of death in COPD patients at a referral hospital in Korea. Methods : The medical records of 28 deceased patients diagnosed as COPD in Asan Medical Center from January to December 2003 were reviewed patients had died in Asan Medical Center and 16 patients had died outside the hospital. The Korean National Statistical Office confirmed 88 deceased patients out of 1,078 patients diagnosed as COPD in Asan Medical Center in 2003. After excluding those with tuberculous destroyed lung, bronchiectasis, and lung cancer, 28 COPD patients were evaluated. Results : The causes of death were pulmonary disease including pneumonia in 16 patients (57%), cardiac disease in 5 patients (18%), sudden death in 3 patients (11%), and other causes in 4 patients (14%). The cause of death was pulmonary disease in 83% (10 out of 12 patients) and 38% (6 out of 16 patients) of patients who died in Asan Medical Center and outside the center, respectively (P=0.05). The cause of death was pulmonary disease in 43% of patients with $FEV_1$ more than 50 % of the predicted value and in 55% of patients with $FEV_1$ less than 50 % of the predicted value (P=0.89). Conclusion : Pulmonary disease is the leading cause of death in COPD patients in Korea.

• Tuberculosis and Respiratory Diseases
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• v.60 no.2
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• pp.215-220
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• 2006

Background : A spirometric reference equation was recently developed for the general population in Korea. The applicability of the new Korean equation to clinical practice was examined by comparing it with the Morris equation, which is one of the most popular reference equations used for interpreting the spirometric patterns and for grading the disease severity in Korea. Methods : Spirometry was performed on 926 men and 694 women, aged 20 years or older, in November 2004 at the Asan Medical Center, Seoul, Korea. The subjects' age, gender, height, weight, and spirometric values ($FEV_1$ [forced expiratory volume in one second], FVC [forced vital capacity], and $FEV_1/FVC$) were obtained. The spirometric patterns and disease severity were evaluated using both equations, and the results of the Korean equation were compared with the Morris equation. The spirometric patterns were defined as normal, restrictive, obstructive, and undetermined according to the level of $FEV_1/FVC$ and FVC. The disease severity was defined according to the level of $FEV_1$ level for subjects with an airflow limitation, and according to the FVC level for those subjects without an airflow limitation. Results : Spirometric patterns were differently interpreted in 22.5% (208/926) of the men and 24.8% (172/694) of the women after the application of the Korean equation compared with the Morris equation. Of the subjects with airflow limitation, disease severity was differently graded in 30.2% (114/378) of the men and 39.4% (37/94) of the women after the application of the Korean equation. Of the subjects without airflow limitation, disease severity was differently graded in 27.9% (153/548) of the men and 30.2% (181/600) of the women after the application of the Korean equation. Conclusion : Achange in the reference equation for spirometry could have an effect on the interpretation of spirometric patterns and on the grading of disease severity.