Use of pulmonary function tests in the diagnosis of occupational asthma

To discuss the different methods of assessing lung function measurements for the diagnosis of occupational asthma, focusing in particular on serial peak expiratory flow rate (PEFR) monitoring, including details on how PEFR records should be kept, plotted, and analyzed and limitations of the method. Published studies on the use of diagnostic methods in occupational asthma, expert opinion, and recently obtained data from studies performed at a large occupational lung disease clinic. The expert opinion of the author was used to select the relevant data for review. Objective methods are necessary for the diagnosis of occupational asthma, since clinical history alone is not a satisfactory means of diagnosis. Serial PEFR monitoring has a high diagnostic sensitivity and specificity for occupational asthma and is more useful than evaluation of cross-shift change in forced expiratory volume in 1 second or change in nonspecific bronchial hyperresponsiveness. Interpretation is best performed by expert visual evaluation of plots of maximum, mean, and minimum daily PEFR readings. Despite some limitations of the method, serial PEFR monitoring is usually the most appropriate first-line investigation in workers suspected of having occupational asthma.