[The mechanics of forced oscillation--principles and use]

The technique of forced oscillation is a basic method of investigation of electrical and mechanical systems. Various modifications may be used in the field of respiratory physiology and pathology. When applying the oscillations at the mouth, we will measure respiratory input impedance; when applying the oscillations at total body surface, we will measure respiratory transfer impedance. Combining both methods one can calculate airway impedance and tissue impedance separately. Despite of the large number of studies which have already been carried out, I am convinced that the potential of the method is not yet exhausted.