IOS vs AOS: Comparative Bias in Respiratory Impedance Measurements

May 6, 2020 / in Scientific articles / by Eve-Gabrielle Bissonnette


The forced oscillation technique (FOT) measures respiratory impedance during normal tidal breathing and requires minimal patient cooperation.


To compare IOS and AOS devices in patients with asthma and COPD.


We compared two different FOT devices, namely impulse oscillometry using a loudspeaker (IOS: Jaeger Masterscreen) and airwave oscillometry using a vibrating mesh (AOS: Thorasys Tremoflo) for pre- and post-bronchodilator measurements in 84 patients with asthma and COPD.


The overall pattern of measurement bias was for higher resistance with IOS and higher reactance with AOS, this being the case in asthma and COPD separately. There were small but significantly higher values using IOS for resistance at 5 Hz (R5) and 20(19) Hz (R20(19)). In converse, values for reactance at 5 Hz (X5), reactance area (AX) and resonant frequency (Fres)


Impulse oscillometry, Airwave oscillometry, Asthma, COPD, Spirometry, Asthma control questionnaire

Kuo CR, Jabbal S, Lipworth B. I Say IOS You Say AOS: Comparative Bias in Respiratory Impedance Measurements. Lung. 2019