Normal limits for oscillometric bronchodilator responses and relationships with clinical factors

Kanika Jetmalani, Nathan J. Brown, Chantale Boustany, Brett G. Toelle, Guy B. Marks, Michael J. Abramson, David P. Johns, Alan L. James, Michael Hunter, Arthur W. Musk, Norbert Berend, Claude S. Farah, David G. Chapman, Cindy Thamrin, Gregory G. King*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
45 Downloads (Pure)

Abstract

Introduction We aimed to determine normal thresholds for positive bronchodilator responses for oscillometry in an Australian general population sample aged ⩾40 years, to guide clinical interpretation. We also examined relationships between bronchodilator responses and respiratory symptoms, asthma diagnosis, smoking and baseline lung function. Methods Subjects recruited from Sydney, Melbourne and Busselton, Australia, underwent measurements of spirometry, resistance (Rrs6) and reactance (Xrs6) at 6 Hz, before and after inhalation of salbutamol 200 μg. Respiratory symptoms and/or medication use, asthma diagnosis, and smoking were recorded. Threshold bronchodilator responses were defined as the fifth percentile of decrease in Rrs6 and 95th percentile increase in Xrs6 in a healthy subgroup. Results Of 1318 participants, 1145 (570 female) were analysed. The lower threshold for ΔRrs6 was −1.38 cmH2O·s·L−1 (−30.0% or −1.42 Z-scores) and upper threshold for ΔXrs6 was 0.57 cmH2O·s·L−1 (1.36 Z-scores). Respiratory symptoms and/or medication use, asthma diagnosis, and smoking all predicted bronchodilator response, as did baseline oscillometry and spirometry. When categorised into clinically relevant groups according to those predictors, ΔXrs6 was more sensitive than spirometry in smokers without current asthma or chronic obstructive pulmonary disease (COPD), ∼20% having a positive response. Using absolute or Z-score change provided similar prevalences of responsiveness, except in COPD, in which responsiveness measured by absolute change was twice that for Z-score. Discussion This study describes normative thresholds for bronchodilator responses in oscillometry parameters, including intra-breath parameters, as determined by absolute, relative and Z-score changes. Positive bronchodilator response by oscillometry correlated with clinical factors and baseline function, which may inform the clinical interpretation of oscillometry.

Original languageEnglish
Article number00439-2021
Pages (from-to)1-10
Number of pages10
JournalERJ Open Research
Volume7
Issue number4
DOIs
Publication statusPublished - 9 Oct 2021
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2021. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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