The Definition of COPD

COPD actually comprises two related diseases, chronic bronchitis and emphysema, one rarely occurring without a degree of the other. The definition of COPD is a disorder that is characterized by reduced maximal expiratory flow and slow forced emptying of the lungs; features that do not change markedly over several months. This limitation in airflow is only minimally reversible with bronchodilators.

Emphysema has a pathological definition, which is a condition where there is permanent destructive enlargement of of the airspaces distal to the terminal bronchioles without obvious fibrosis. Chronic bronchitis is defined clinically by the presence of chronic bronchial secretions, enough to cause expectoration, occurring on most days for a minimum of 3 months of the year for 2 consecutive years.