COMPARISON OF 4 DIFFERENT MEASURES OF BRONCHIAL RESPONSIVENESS IN ASTHMATIC-CHILDREN

Although several tests are available to assess the presence and severi ty of bronchial hyperresponsiveness (BHR), there is no agreement on th e most appropriate stimulus. The most commonly used stimuli are methac holine, histamine, and exercise. Daily peak expiratory now (PEF) varia tion has been reported to correlate with the severity of BHR, and in r ecent years this has been widely used because of its noninvasiveness a nd ease of performance. This study was carried out to determine the re lationship among these four commonly used measures of bronchial respon siveness in asthmatic children. For this purpose, 12 asthmatic childre n of varying disease severity were recruited. Subjects underwent three challenges on 3 separate days in 1 week. During the week preceding th e challenges (methacholine, histamine, and exercise), patients recorde d PEF three times a day. All patients had PC20 less than 8 mg/ml with methacholine and histamine. Patients with PC20 greater than 3.5 mg/ml for both methacholine or histamine had negative exercise challenges. T he strongest correlation was between histamine and methacholine (r=0.9 5). Exercise-induced bronchospasm had substantial and significant corr elation with the other three measures. No significant correlation was observed between PEF variability and histamine or methacholine. The va rying degrees of relationships among the four commonly used measures s uggests that each method yields information on different but related p henomena. More than one measure may be required to detect the differen t aspects of asthmatic bronchial responsiveness.