Parametric sensitivity analysis of human respiratory impedance

Measurements of the respiratory impedance in humans are a means to help diagnose underdevelopment and/or pathological conditions. Various models of the human respiratory system of varying complexity and fidelity have been developed for study to enable greater specificity of the diagnosis. In this paper, a parametric sensitivity analysis that was performed on the respiratory impedance of four different respiratory system models is described. The results of this analysis can be used to obtain valuable information on how certain respiratory system parameter variations affect the respiratory impedance at different frequencies. Such an analysis can help determine the optimal input excitation characteristics to more accurately extract particular model component values. Then calculated reference values can be more precise and form a more reliable baseline for diagnosing specific physiologic and pathologic changes in the respiratory system. The sensitivities derived for each parameter of the four models, and their plots using normal values for the lung mechanics of low birth weight newborns are provided. An example of the interpretation and usefulness of sensitivity functions is also presented.