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Comparative Study
. 2019 Aug;197(4):473-481.
doi: 10.1007/s00408-019-00247-y. Epub 2019 Jul 4.

I Say IOS You Say AOS: Comparative Bias in Respiratory Impedance Measurements

Chris RuiWen Kuo  1 , Sunny Jabbal  1 , Brian Lipworth  2
Affiliations
Comparative Study

I Say IOS You Say AOS: Comparative Bias in Respiratory Impedance Measurements

Chris RuiWen Kuo et al. Lung. 2019 Aug.

Abstract

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

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

Methods: 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.

Results: 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) were significantly higher using AOS but to a much larger extent. The difference in AX between devices was more pronounced in COPD than in asthma. Salbutamol reversibility as % change was greater in asthma than COPD patients with AX but not FEV1.

Conclusion: Our study showed evidence of better agreement for resistance than reactance when comparing IOS and AOS, perhaps inferring that AOS may be more sensitive at measuring reactance in patients with airflow obstruction.

Keywords: Airwave oscillometry; Asthma; Asthma control questionnaire; COPD; Impulse oscillometry; Spirometry.

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Conflict of interest statement

Dr. Kuo reports personal fees from Pfizer and Bristol-Myers Squibb, personal fees from Circassia, personal fees from AstraZeneca, outside the submitted work. Dr. Jabbal reports personal fees and non-financial support from Chiesi Pharma, personal fees and non-financial support from Pfizer, non-financial support and other from Napp, personal fees and non-financial support from AstraZeneca, non-financial support from Teva, personal fees and non-financial support from Mylan, personal fees from Boehringer Ingelheim, outside the submitted work. Dr. Lipworth reports personal fees and non-financial support from Thorasys, during the conduct of the study; grants, personal fees and non-financial support from Chiesi; grants, personal fees and non-financial support from Boerhinger; grants, personal fees and non-financial support from AstraZeneca, outside the submitted work.

Figures

Fig. 1
Fig. 1
Bland–Altman plots in all patients (i.e. asthma and COPD) showing post-bronchodilator values of a R5; b R20 (19); c AX; d X5 and e Fres. The conversion factor from kPa to cmH2O is × 10.2
Fig. 2
Fig. 2
Scatter plot in all patients (i.e. asthma and COPD) of a R5; b R20(19); c AX; d X5 and e Fres showing linear regression line of best fit and 95% CI for IOS versus AOS. R2 and intra-class correlation coefficient (ICC) values were R5 R2 = 0.79, ICC = 0.94; R20(19) R2 = 0.77, ICC = 0.93; AX R2 = 0.78, ICC = 0.85; X5 R2 = 0.65, ICC = 0.8; Fres R2 = 0.82, ICC = 0.93 (p < 0.001 for all regression models). The conversion factor from kPa to cmH2O is × 10.2
See this image and copyright information in PMC

References

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