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Comparison of forced and impulse oscillometry measurements: a clinical population and printed airway model study

Soares, Marcia; Richardson, Matthew; Thorpe, James; Owers-Bradley, John; Siddiqui, Salman


Marcia Soares

Matthew Richardson

James Thorpe

John Owers-Bradley

Salman Siddiqui


The use of commercialised forced oscillation (FOT) devices to assess impedance in obstructive diseases such as asthma has gained popularity. However, it has yet to be fully established whether resistance and reactance measurements are comparable across different FOT devices, particularly in disease. We compared two commercially available FOT devices: Impulse Oscillometry (IOS) and TremoFlo FOT (Thorasys) in a) clinical adult population of healthy controls (n?=?14), asymptomatic smokers (n?=?17) and individuals with asthma (n?=?73) and b) a 3D printed CT-derived airway tree model resistance, as well as a 3?L standardised volume reactance. Bland-Altman Plots and linear regressions were used to evaluate bias between the devices. Resistance measurements at both 5 and 20?Hz were numerically higher with IOS compared to FOT, with evidence of small and statistically significant proportional systematic bias and a positive Bland-Altman regression slope at both 5 and 20?Hz. In contrast, the IOS device recorded reactances that were less negative at both 5?Hz and 20?Hz and significantly smaller reactance areas when compared to TremoFlo. Larger statistically significant proportional systematic biases were demonstrated with both reactance at 5?Hz and reactance area (AX) between the devices with a negative Bland-Altman regression slope. The printed airway resistance and standardised volume reactance confirmed the observations seen in patients. We have demonstrated that the impulse oscillation system and TremoFlo FOT demonstrate comparative bias, particularly when comparing airway reactance in patients. Our results highlight the need for further standardisation across FOT measurement devices, specifically using variable test loads for reactance standardisation.


Soares, M., Richardson, M., Thorpe, J., Owers-Bradley, J., & Siddiqui, S. (2019). Comparison of forced and impulse oscillometry measurements: a clinical population and printed airway model study. Scientific Reports, 9,

Journal Article Type Article
Acceptance Date Nov 26, 2018
Online Publication Date Feb 14, 2019
Publication Date 2019-12
Deposit Date Mar 13, 2019
Publicly Available Date Mar 15, 2019
Journal Scientific Reports
Print ISSN 2045-2322
Electronic ISSN 2045-2322
Publisher Nature Publishing Group
Peer Reviewed Peer Reviewed
Volume 9
Article Number 2130
Public URL
Publisher URL
Additional Information Received: 1 March 2018; Accepted: 26 November 2018; First Online: 14 February 2019; : Salman Siddiqui has received grants from NIHR, Chiesi and European Union FP7 Scheme: AirPROM-FP7 during the conduct of the study. Salman Siddiqui also reports personal fees from Advisory boards (AZ, GSK, Roche, Boehringer Ingelheim, NAPP, Owlstone and ERT) outside the submitted work. Marcia Soares, James Thorpe, John Owers-Bradley and Matthew Richardson have no competing interests to declare.


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Figure 1 Main Manuscript (545 Kb)

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