Intra-breath oscillometry for assessing respiratory outcomes

Respiratory oscillometry (also known as the forced oscillation technique) is increasingly contributing to lung function studies in clinical routine and research, as a result of its sophistication, non-invasiveness and minimal interaction with normal breathing. Oscillometry has focused traditionally on the frequency dependence of respiratory impedance (Zrs) obtained as average spectra over several respiratory cycles, and several linear models have been investigated to interpret Zrs in terms of biomechanical descriptors, such as the resistive and elastic properties of the respiratory tract. In contrast, recent advances in oscillometry address the changes in Zrs during the breathing cycle with high temporal resolution, in order to characterise the dependences of Zrs components on respiratory flow and volume and their alterations in different respiratory disorders. In the context of the development of respiratory oscillometry, this article discusses the emerging intra-breath approach and its potential in the characterisation of respiratory mechanical disorders.