[Resistance by oscillometry. Comparison of its behavior in patients with asthma and cystic fibrosis].

This study aims to assess the behavior of the oscillometric parameters in 60 patients with bronchial asthma and in 39 with cystic fibrosis. All of them underwent an impulse oscillometry (IOS) and forced spirometry. The correlations existing between FEV1 and different oscillometric endpoints were assessed. In asthmatic subjects, the oscillometry parameters that correlated best with FEV1 were impedance (Zsr) and resistance to 5 hertz (Rsr5), while it was the Zsr and reactance to 5 hertz (Xsr5) in the individuals with cystic fibrosis. In the last group of patients, no correlation was found between FEV1 and Rsr in most of the frequencies evaluated. We conclude that there are differences in the behavior of the oscillometric parameters in patients with bronchial asthma and cystic fibrosis. The oscillometric parameters having the greatest use in the detection of the obstruction to airflow vary according to the disease studied.