Forced oscillometry is applicable to epidemiological settings to detect asthmatic children.

Forced oscillometry (FOT) has been reported as a simple method to detect respiratory resistance (Rrs) changes. The aim of this study was to evaluate FOT capacity to detect children with clinical characteristics of asthma in a school setting. One thousand thirty children, 6-7 years old, were investigated by questionnaire. Children with wheezing symptoms in the last 12 months but without previous diagnosis of asthma were selected and underwent evaluations. FOT measurements were performed pre- and post-salbutamol administration, with a level of significant reduction of Rrs of >29%. Patients were further investigated for atopy by skin-prick tests (SPTs) and for bronchial hyperreactivity (BHR) by exercise free-running test. Of 1030 children participating in the study, 120 were selected by questionnaire responses for respiratory symptoms. Twenty-two children had a significant reduction of Rrs of 6 Hz (p < 0.001; group 1); 98 children presented no variation of Rrs to bronchodilator (group 2). Prick test positivity and significant bronchoconstriction after exercise tests were significantly more frequent in group 1 than in group 2 (77% and 64% versus 8% and 12%, respectively; p < 0.001). In a school setting FOT changes after bronchodilator are able to detect airway obstruction in children with wheezing symptoms. Children with significant FOT variability present more significantly atopy and BHR and therefore more probable asthma.