When a nonlinear biological system is under analysis, one may employ linear and nonlinear tools. Linear tools such as fractional order impedance models have not been previously employed to characterize difference between healthy volunteers and patients diagnosed with cystic fibrosis (CF). Nonlinear tools such as detection lines from nonlinear contributions in frequency domain have also not been employed previously on CF patient data. CF is an irreversible inflammatory disease, of genetic origin. The forced oscillation technique (FOT) is a non-invasive, simple lung function test suitable for this class of patients with breathing difficulties, since it does not require any special maneuvre. In this work we bring additional evidence that the FOT method combined with both linear and nonlinear tools reveals important information which may be used as complementary to the standardized lung function tests. 
Respiratory mechanics in children with cystic fibrosis