Impulse oscillometry and its possibilities in diagnostics of lung mechanics disorders

Abstract

Impulse oscillometry is one of the latest modifications of forced oscillation method. The impedance components such as resistance (R) and reactance (X) are measured simultaneously in the most diagnostically important frequency range from 5 to 35 Hz. It allows to estimate the relative contributions of R, capacitive X and inertial X separately. Measurements were performed in 14 healthy subjects, 14 patients with obstructive ventilatory disorders and 8 with restrictive ones. It was obtained that R, X and resonant frequency were within normal range in healthy subjects and were changed differently in patients with ventilatory disorders. In patients with obstructive disorders R at 5 Hz was significantly enlarged and differed from R at 35 Hz. X was clearly negative, capacitive X predominated and resonant frequency was considerably shifted to the right. In patients with restrictive disorders R and resonant frequency were close to those of healthy persons, inertial X predominated over reactance one. Such differences could be very useful in difficult diagnostic cases.