• asthma
• peak

I read with interest the editorial by Dr Brusasco on the usefulness of peak expiratory flow measurements¹ in which he suggests that they may become obsolete. As a pioneer of the use of regular peak flow measurements in hospital patients in the 1970s,^2,3 it might seem natural that I would be reluctant to see them go, but I do think I can rationally defend their place for two purposes—one dating from the start and the other from the end of my career.

The characteristic of asthma is variable airway obstruction. Despite the potential difficulties, variation in peak flow is of value in patients in whom asthma has been diagnosed as an adjunct to establishing the pattern of disease in the contexts of causation and management. Much of Dr Brusasco’s argument is dichotomous, which is inappropriate in developing an overall strategy when there are limitations to all approaches—for example, under-perception and over-perception of symptoms. Cheating does occur, but blinded readings may be used to obtain useful results. Symptoms may precede deterioration in peak flow but, in practice, a relevantly lower reading on the second attempt is one of the best early indications of onset of a deterioration in a consistent performer. Guidelines suggest that serial recordings may have a place in the diagnosis of occupational asthma⁴—for …