Heterogeneity of bronchial response to exercise among children with asthma

Abstract

Exercise-induced broncho-obstruction (EIB) is common among asthmatic children with a prevalence rate of 40–90. It is one of the leading causes of the deterioration of the general condition of asthmatics and the limitation of physical activity. Therefore, early recognition and provision of adequate therapy is necessary. However, it is not possible to achieve this without first having information about the features of the bronchial response. The aim of the present study was to determine the bronchial response to exercise and to establish a connection between bronchial response and the clinical features of the disease in asthmatic children. One hundred and three clinically stable children with different clinical severities of asthma were studied with a standardized step-up exercise test. The airway response to exercise was investigated by peak flowmetry to measure the peak expiratory flow rate (PEFR). Bronchial permeability was determined before and after exercise at 0, 5, 10, 15, 30 and 60 min and then hourly for the next 11 h. These determinations were repeated at the same time points on a non- exercise (control) day. The test resulted in four types of response to exercise: (i) non-obstructive; (ii) isolated early airway response (EAR); (iii) dual-waved; and (iv) prolonged EAR. The frequency of these responses in the study population was 33.0, 39.81, 26.21 and 0.97%, respectively. No significant difference in clinical features, such as severity and duration of disease, baseline values for PEFR, atopic status, age and gender, was observed with different forms of response to exercise. However, children with moderate and severe asthma had significantly more frequent EIB- positive type responses than children with a mild form of asthma. Responses to exercise in asthmatic children are heterogeneous and, quite possibly, are particular to each individual patient.