Chronic obstructive pulmonary disease (COPD) is characterized by persistent slowing of the airflow during expiration in patients who do not have more specific conditions such as asthma, bronchiectasis or cystic fibrosis. It is sometimes diagnosed as chronic bronchitis or emphysema, or both. The degree of emphysema present and the severity of airflow obstruction do not correlate well. However, emphysema is an important cause of airflow obstruction, and probably basic to the condition, with exacerbations produced by a flare-up in the inflammatory component - bronchitis. .
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