Fig. 15.1 Aetiology of COPD
UK (East London COPD Study) with daily diary cards and peak flow readings . The patients were asked to report exacerbations as soon as possible after symptomatic onset . The diagnosis of COPD exacerbation was based on criteria modified from those described by Anthonisen and colleagues , which require two symptoms for diagnosis, one of which must be a major symptom of increased dyspnoea, sputum volume or sputum purulence. Minor exacerbation symptoms included cough, wheeze, sore throat, nasal discharge or fever. The study found that about 50% of exacerbations were un-reported to the research team, despite considerable encouragement being provided and were only diagnosed from diary cards, though there were no differences in major symptoms or physiological parameters between reported and unreported exacerbations . Patients with COPD are accustomed to frequent symptom changes and thus may tend to under-report exacerbations to physicians. These patients have high levels of anxiety and depression and may accept their situation [7,8]. The tendency of patients to under-report exacerbations may explain the higher total rate of exacerbations at 2.7 per patient per year, which is higher than previously reported by Anthonisen and coworkers at 1.1 per patient per year . However, in the latter study, exacerbations were unreported and diagnosed from patients' recall of symptoms.
What is the relation between exacerbation frequency and quality of life?
There is a close relationship between exacerbation frequency and quality of life measures. Using the median number of exacerbations as a cut-off point, COPD patients in the East London Study were classified as frequent and infrequent exacerbators. Quality-of-life scores measured using a validated disease specific scale—the St George's Respiratory Questionnaire (SGRQ), were significantly worse in all of its three component scores (symptoms, activities and impacts) in the frequent, compared to the infrequent, exacerbators. This suggests that exacerbation frequency is an important determinant of health status in COPD and is thus one of the important outcome measures in COPD. Fac tors predictive of frequent exacerbations included daily cough and sputum and frequent exacerbations in the previous year. An earlier study of acute infective exacerbations of chronic bronchitis found that one of the factors predicting exacerbation was also the number in the previous year .
What is the time course of a COPD exacerbation and do all exacerbations recover to baseline symptoms and physiological parameters?
In a study of 504 exacerbations, with daily monitoring being performed, there was some deterioration in symptoms, though no significant peak flow changes . Falls in peak flow and FEVj at exacerbation were generally small and not useful in predicting exacerbations, but larger falls in peak flow were associated with symptoms of dyspnoea, presence of colds and related to a longer recovery time from exacerbations. The median time to recovery of peak flow was 6 days and 7 days for symptoms, but at 35 days peak flow had returned to normal in only 75% of exacerbations, while at 91 days, 7.1% of exacerbations had not returned to baseline lung function. Exacerbations took longer to recover in the presence of increased dyspnoea or symptoms of a common cold at exacerbation, suggesting that respiratory viruses lead to longer and thus more severe exacerbations. Another interesting finding is that the changes observed in lung function at exacerbation were smaller than those observed at asthmatic exacerbations, though the average length of an asthmatic exacerbation was longer at 9.6 days, compared to 6 or 7 days in COPD [11,12].
Are there airway inflammatory changes at COPD exacerbation?
Airway inflammatory changes are an important feature of COPD and it has been assumed that exacerbations are associated with increased airway inflammation. However, there has been little information available on the nature of any inflammatory changes, especially when studied close to an exacerbation, as performing bronchial biopsies at exacerbation is difficult in patients with moderate to severe COPD. The relation of any airway inflammatory changes to symptoms and physiological changes at exacerbations of COPD is also an important factor to consider.
In an Italian study, where biopsies were performed at exacerbation in patients with chronic bronchitis, increased airway eosinophilia was found, though patients described had only mild COPD . With exacerbation, there were more modest increases observed in neutrophils, T lymphocytes (CD3) and TNF-a-positive cells, while there were no changes in CD4 or CD8 T cells, macrophages or mast cells. Sputum induction allows study of these patients at exacerbation and it has been shown that it is a safe and well tolerated
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If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.