17.01.2 Introduction to COPD

COPD is associated with chronic bronchitis and in the later stages, emphysema. In chronic bronchitis there is excessive production of sputum, breathlessness and cough. In chronic bronchitis, there is alveolar hypoventilation, hypercapnia and hypoxia. There is also an airway narrowing and mucus plug, and the mucus plugs provide an environment suitable for secondary infection.

In emphysema, there is a permanent, destructive enlargement of air spaces distal to the terminal bronchiole. There is progressive airflow limitation largely due to enzymatic destruction of elastin fibres in the lung parenchyma.

COPD occurs mainly in smokers, develops over years with a progressive decline in lung function. COPD is the fourth leading cause of death in the US, and the leading cause of preventable death. Smoking cessation is the only intervention that has been shown to slow decline in pulmonary function, and the drug interventions to promote smoking cessation are discussed in Chapter 35. Unfortunately, only 20-40% of COPD patients quit smoking.