Chronic obstructive pulmonary disease: COPD
COPD is characterized by decreased maximal expiratory flow and delayed lung emptying which are fairly stable over a period of a few months. Flow limitation increases in time and is largely irreversible (see references). The most important pathological features are:
- diminished airway patency due to thickening of the airway walls, accumulation of secretions and to changes in the fluid lining of small airways;
- pulmonary emphysema, characterized by enlarged air spaces due to loss of alveolar walls, the loss of alveolar attachments to intrapulmonary airways contributing to airway obstruction.
COPD is usually accompanied by chronic cough and phlegm, i.e. 3 months a year for at least two consecutive years. It is often also associated with some extent of bronchial hyperreactivity to various stimuli. There is usually only a minimal response to bronchodilator drugs. The physician is usually first consulted because of progressive dyspnea and chronic cough; the previous history often reveals wheezing, and particularly during the winter time there are repeated episodes of respiratory infections. Chronic cough is often productive and worse in the morning; sputum volume may increase during exacerbations, and it may be blood-streaked. Large volumes of sputum, particularly if purulent, are a feature of bronchiectasis.
Chronic bronchitis is accompanied
by chronic hypersecretion, which in turn bears little relation
to the presence of airflow limitation.
It may be difficult to differentiate COPD from persistent asthma in older subjects. A history of heavy smoking, radiological evidence of lung emphysema, chronic hypoxemia and diminished diffusing capacity are points in favor of COPD. Marked improvement in spirometric indices with administration of bronchodilators or corticosteroids, and atopy, favor the diagnosis of asthma.
Apart from textbooks, consult these sources of information:
1. ERS Consensus statement. Optimal assessment and management of chronic obstructive pulmonary disease (COPD). Eur Respir J 1995; 8: 1398-1420.
2. ATS Statement. Standards for the diagnosis and care of patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1995; 152: S77-S120.
3. NHG Standaard COPD: Huisarts en Wetenschap 1997; 40: 416-429.
4. BTS. Diagnosis and management of stable COPD. Thorax 1997; 52: S2-S15.