Clinical application of impulse oscillometry

Abstract

OBJECTIVE: To discuss the clinical significance of impulse oscillometry(IOS) to determine the resistance of large and small airways and the compliance of lung. METHODS: The IOS indices of 40 normal cases, 50 cases of chronic obstructive pulmonary diseases (COPD) and 60 cases of pleural effusion were determined at 5-35 Hz. Their FEV1/FVC and maximal expiratory flow-volume curve (MEFV curve) were measured in conventional method at the same time. RESULTS: Compared with normal cases, the peripheral resistance of the 50 patients with COPD rose obviously and the central airway resistance rose in some of them, the resonance frequency increased, but the peripheral reactance descended at the same time (P < 0.01). Resistance curve show markedly nonlinear decreasing course with increasing frequency. The resistance increased and the reactance descended in end-expiration. FEV1/FVC < 50%, MEFV curve showed severe obstructive shape. 60 patients with pleural effusion were found the resistance increasing and reactance descending to negative values in end-inpiration at low frequencies (inverse values relation at low frequencies). FEV1/FVC were nearly normal, MEFV curve showed restrictive dysfunction shape only in half of them. CONCLUSIONS: IOS can reflect variation of airway resistance and lung compliance. The future development of IOS could be prosperous.