Bronchial responsiveness to methacholine and adenosine 5'-monophosphate in preschool children with bronchopulmonary dysplasia

Bronchial hyperresponsiveness (BHR) is a characteristic feature of asthma, but it is also frequently present in children and adults with chronic obstructive lung diseases. Bronchopulmonary dysplasia (BPD) is a chronic lung disease, most commonly developing after mechanical ventilation and oxygen therapy in premature infants. BHR is usually measured by bronchial challenges, using direct or indirect stimuli. The aim of this study was to evaluate BHR to direct and indirect stimuli in young children with BPD. Methacholine and adenosine 5'-monophosphate (AMP) bronchial challenges were performed on preschool children with BPD (n = 19), using a modified auscultation method. The endpoint was defined as the appearance of wheezing and/or oxygen desaturation. The results obtained were then compared with those of asthmatic (n = 25) and control (n = 23) preschool children. A positive response to methacholine (endpoint concentration, < or = 8 mg/ml) was observed in 89.5% (17/19) of patients with BPD, but a positive response to AMP (endpoint concentration, < or = 200 mg/ml) was observed only in 21.1% (4/19). All patients with asthma responded positively to methacholine, and most (23/25, 92.0%) of them also responded positively to AMP. The majority of controls were unresponsive to both challenges. BHR to methacholine is a frequent finding in preschool-age survivors of BPD, but is usually not accompanied by BHR to AMP. This suggests that most patients with BPD do not have the inflammatory airway response which is characteristic of asthmatic patients