Application of impulse oscillometry for within-breath analysis in patients with chronic obstructive pulmonary disease: pilot study

Abstract

BackgroundThe impulse oscillometry is increasingly used for assessing the oscillatory mechanics of the respiratory system. The within-breath behaviour of the oscillatory mechanics in chronic obstructive pulmonary disease (COPD) is a well-known physiological feature. The purpose of this study was to develop a new approach for assessing this feature using impulse oscillometry.MethodsThe oscillatory mechanics were assessed by a commercially available impulse oscillometry device. The respiratory system resistance (Rrs) and reactance (Xrs) were measured during tidal breathing in patients with COPD (n=39) and healthy subjects (n=5). Selected data, the Rrs at 5 Hz (R5), Rrs at 20 Hz (R20), Xrs at 5 Hz (X5), and resonant frequency of Xrs (Fres) every 0.2 s, were extracted from the device. These data were divided into eight time fractions during the respiratory cycle to form averaged respiratory phases.ResultsThe time courses of the R5 and X5 were notably dependent on the respiratory cycles in patients with COPD, while there was little such dependency in healthy subjects. Irrespective of respiratory phase, R5 and Fres increased, and X5 fell to a more negative level in patients with COPD in a severity-dependent fashion. The increase in the R5 and negative level in the X5 were more prominent in the middle of the expiratory phase. The severity dependence in the R20 was relatively small compared with that in the R5.ConclusionsThe results of this study suggest that impulse oscillometry can assess the within-breath behaviour of the oscillatory mechanics with high temporal resolution, which may be helpful for evaluating the severity of COPD. Further studies are needed to reveal which biomarkers obtained with this approach would be suitable for evaluating the airway obstruction.

Clinical Application of the Forced Oscillation Technique

“…The 3D graphic images in MostGraph have an advantage to visualize not only frequency dependence but also respiratory cycle dependence (41)(42)(43). Since airway obstruction is more severe in the expiratory phase, Rrs becomes high and more frequency dependent and Xrs shifts to a more negative direction compared to in the inspiratory phase.…”

Influence of cheek support on respiratory impedance measured by forced oscillation technique

“…Using the FOT, the mechanical properties of the lung have been characterized in humans (Dubois et al 1956;Kaczka et al 1997). As commercially available instruments were developed, the FOT has been used to assess respiratory functions of patients with respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and interstitial lung disease (Yaegashi et al 2007;Kanda et al 2010;Paredi et al 2010;Crim et al 2011;Mori et al 2011;Ohishi et al 2011;Ito et al 2012;Mori et al 2013). …”

Investigating Chronic Obstructive Pulmonary Disease (COPD) in Vietnamese Patients Using Impulse Oscillometry (IOS)

“…IOS is therefore not a replacement for FEV1, but as previously pointed out for classic FOT methods provides complimentary information on respiratory mechanics [4]- [6][23] [24].…”