DEFINITION

• Chronic obstructive pulmonary disease (COPD): condition characterized by “persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases”[9]
  • Classic COPD subtypes include emphysema, chronic bronchitis and small airway disease, though recent research has focused upon understanding many more subtypes of disease based upon clinical, radiologic and other characteristics
  • Emphysema: term describing structural changes (enlargement of airspaces and destruction of alveoli) associated with COPD. Individuals with COPD have varying degrees of emphysema when examined on CT scan, and the degree of emphysema does not always correlate with the severity of the disease as assessed by lung function or symptom scores.
  • Chronic bronchitis: condition characterized by chronic productive cough, or the presence of chronic productive cough in someone with COPD. Though not always present, individuals with COPD often have this condition, and the severity of chronic bronchitis symptoms can vary substantially among individuals.
• Asthma: disease characterized by chronic airway inflammation that is "defined by the history of respiratory symptoms such as wheeze, shortness of breath, chest tightness and cough that vary over time and in intensity together with variable expiratory airflow limitation"[8]
• Some individuals are believed to have characteristics of both asthma and COPD, recently termed "asthma COPD overlap" or ACO.