COPD is characterised by airflow limitation that is not fully reversible with the use of medication. People with COPD may also have a persistent cough with sputum due to excessive mucus production in the airways (known as chronic bronchitis) or evidence of lung tissue destruction, enlargement of the air sacs and further impaired lung function (known as emphysema). The terms COPD, emphysema and chronic bronchitis are often used interchangeably.
