AbstractsMedical & Health Science

Background: The diagnosis of asthma in young children is based mostly on symptoms. The need for objective methods for diagnosing asthma in this age group is therefore obvious. Lung function in preschool children can be assessed with impulse oscillometry (IOS), which involves no voluntary breathing manoeuvers. Because most children with asthma have normal baseline lung function, the use of bronchoprovocative tests may improve diagnostics. Fractional concentration of nitric oxide (FeNO) is suggested to be a good measure for airway inflammation, and the method is also available for preschoolers. Aims: To examine new methods for evaluating airway hyperresresponsiveness and inflammation in young children. Further aims were to study the effect of parental smoking on lung function and airway inflammation in wheezy children and whether children with severe exercise induced bronchoconstriction exhibit small airways dysfunction. Methods: A total of 272 children (3 to 8 years old), 231 with obstructive syndromes and 41 healthy controls, were examined. Children with various clinical characteristics were recruited: troublesome lung symptoms, a history of bronchopulmonary dysplasia (BPD), early wheezing symptoms and multiple-trigger wheezing. Airway hyperresponsiveness was evaluated with exercise test, methacholine and mannitol challenge tests using IOS. FeNO measurements with two different analyzers were examined. Parental reports and children s urinary cotinine measurements served to monitor exposure to environmental tobacco smoke. Results: Exercise test with IOS succesfully identified children with probable asthma, and the methacholine challenge test was able to differentiate children with probable asthma, BPD and early wheezing from the controls. The mannitol challenge test, however, was unable to distinguish between the study groups. Furthermore, children with severe exercise-induced bronchoconstriction (EIB) exhibited small airways dysfunction. A portable FeNO analyzer proved to be more difficult than a stationary device to use in young children. In addition, its poorer accuracy in low FeNO levels diminishes its feasibility in this age group. However, a portable analyzer differentiated children with asthma from the controls. Children with smoking mothers had poorer lung function and higher FeNO than children with non-smoking mothers. Urinary cotinine concentrations closely reflected reported smoking in the family. A father s smoking had no effect on children s FeNO or lung function. Conclusions: The exercise test with IOS succesfully identified children with probable asthma. The methacholine challenge test aids in evaluating airway hyperresponsiveness in young children, although its cut-off value for this age group requires re-evaluation. A portable FeNO analyzer can also serve as a screening tool in young children, because it differentiates asthmatics from the controls with reasonable accuracy. Children with severe exercise induced bronchoconstriction exhibited small airways dysfunction, which suggests that…