Pathology and pathophysiology COPD

Main points

1 COPD is not a discrete clinical entity, but a combination of emphysema, chronic bronchitis, small airways disease and chronic asthma.
2 The most important risk factor is cigarette smoking.
3 Treating persistent asthma early and aggressively with inhaled steroids may reduce the development of chronic airflow limitation.
4 Chronic mucus production alone is not always associated with the development of progressive airflow limitation;however, when there is progressive airflow limitation,chronic mucus production may accelerate the decline in lung function.
5 Emphysema is thought to develop as a result of an imbalance between elastase and anti-elastase activity in the lung.
6 Loss of lung elastin, such as occurs in emphysema,contributes to airway collapse, particularly during exercise.
7 Hyperinflation of the lungs leads to increased breathlessness on exertion.
8 Disruption of gas exchange leads to polycythaemia, cor pulmonale and respiratory failure.