Reliability of impulse oscillometry parameters in healthy children and in children with cystic fibrosis.

Introduction & Aims: Impulse oscillometry system (IOS) is an instrument developed to evaluate the mechanical lung properties. It has been reported that to analyse the exam in a proper way it is necessary to carry out more than one measure. However, studies addressing the standardisation are still scarce. The objective was to determine within trial reliability of three measures in IOS parameters in healthy children and children with cystic fibrosis (CF).

Method: Weight, height, body mass index, forced spirometric and the oscillometric parameters (resistance, respiratory impedance, respiratory reactance and resonance frequency) data were collected, in a way that all participants performed three IOS measures. To evaluate, the reproducibility was used the intraclass correlation coefficient [two-way mixed model, absolute agreement definition, ICC]. The response stability was appraised using the standard error of measurements (SEM) in three repetitions of the IOS in the healthy children group (HCG) and in the cystic fibrosis group (CFG).

Results: About 95 subjects participated, in each group with a mean age of 10.89 ± 2.21 years old in the HCG and 9.73 ± 2.43 years old in the CFG, having been 41 and 43 boys and 54 and 52 girls, in the respectively group. In both groups, all IOS parameters evaluated in the three measures presented an ICC of 0.9, which is a high reproducibility.

Conclusion: The IOS parameters are reproducible for healthy children and CF children in three measures. However, according to the population studied, the performance of only one measure is sufficient to assess respiratory mechanics, whereas the SEM were low, except for Fres, in both groups.