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I was interested to read Dr Morgan’s review of dysfunctional breathing in asthma in the 2002 Year in Review,1 but the problem may be even greater in COPD.
Dr Morgan suggests that the problem may have serious consequences in terms of morbidity, but we have published indirect evidence of an association with mortality. In the 10 year follow up of the Darlington and Northallerton Asthma Study the odds ratio for the risk of dying in those who had no best function recorded was 2.5, equivalent to a risk of best function of 60% predicted.2 Although failure to obtain best function was sometimes associated with steroid phobia, by far the most frequent cause was an inability to complete spirometric tests which is a sensitive indicator of dysfunctional breathing.
In non-clinical practice one sees large numbers of patients managed in primary care who have breathlessness attributed to COPD which may or may not exist objectively. By the time they are seen the subjects usually are genuinely breathless because of deconditioning. There is an urgent need to correct this under recognition of the problem. Perhaps a change in the approach to history taking might be helpful. Breathlessness is usually regarded not only as a symptom of COPD—which it may be—but also as a measure of disability due to physiological limitation —which it certainly is not in moderate airway obstruction. The prime measure of disability in chronic cardiorespiratory dysfunction is exercise limitation. If this is physiologically mediated through failure of oxygen delivery, then the natural limiting symptom is muscle failure and not breathlessness. This is well recognised in athletes, where breathlessness is accepted as incidental. In as much as breathlessness is due to moderate airway obstruction, it is mechanical in origin and should be regarded as a contributory factor to exercise limitation rather than its prime cause. Moreover, breathlessness is the initiator of the vicious circle of decreased physical activity, deconditioning, and breathlessness which leads to the prime cause of exercise limitation deconditioning. A shift in history taking first to establish the extent of exercise limitation and then to ask about the associated symptoms would lead to a much better approach to the management of chronic respiratory disease, particularly in patients with other chronic diseases that themselves lead to exercise limitation. Perhaps respiratory physicians should train themselves to introduce breathlessness last rather than first when talking to a patient.