Acute Exacerbations of COPD

There has been considerable recent interest into the causes and mechanisms of exacerbations of chronic obstructive pulmonary disease (COPD) as COPD exacerbations are an important cause of the considerable morbidity and mortality found in COPD. COPD exacerbations increase with increasing severity of COPD. Earlier descriptions of COPD exacerbations had concentrated mainly on studies of hospital admission, though most COPD exacerbations are treated in the community and not associated with hospital admission. Exacerbation frequency is an important determinant of health status in COPD and is thus one of the important outcome measures in COPD. Factors predictive of frequent exacerbations included daily cough and sputum and frequent exacerbations in the previous year. In a further prospective analysis of 504 exacerbations, where daily monitoring was performed, there was some deterioration in symptoms, though no there were significant peak expiratory flow changes. Recovery was longer in the presence of increased dyspnoea or symptoms of a common cold at exacerbation. The changes observed in lung function at exacerbation were smaller than those observed at asthmatic exacerbations. The reasons for the incomplete recovery of symptoms and lung function are not clear, but may involve inadequate treatment or persistence of the causative agent. The incomplete physiological recovery after an exacerbation could contribute to the decline in lung function with time in patients with COPD. The association of the symptoms of increased dyspnoea and of the common cold at exacerbation with a prolonged recovery suggests that viral infections may lead to more prolonged exacerbations.