Respiratory impedance in healthy subjects: baseline values and bronchodilator response

Ellie Oostveen1, Krisztina Boda2, Chris P.M. van der Grinten3, Alan L. James4, Sally Young4, Hans Nieland5 and Zoltán Hantos2


Affiliations: ¹Dept of Respiratory Medicine, Antwerp University Hospital and University of Antwerp, Antwerp, Belgium. ²Dept of Medical Physics and Informatics, University of Szeged, Szeged, Hungary. ³Dept of Respiratory Medicine, Maastricht University Medical Centre, Maastricht, and 5Dept of Lung Function, Medisch Spectrum Twente, Enschede, The Netherlands. 4Dept of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, Australia.

Correspondence: E. Oostveen, Antwerp University Hospital, Wilrijkstraat 10, Edegem-Antwerp, B-2650, Belgium. E-mail: email hidden; JavaScript is requiredemail hidden; JavaScript is required


ABSTRACT Because of the minimal demand for cooperation by the subject, the forced oscillation technique is increasingly employed in routine lung function testing. However, comprehensive and device- independent values of respiratory impedance at baseline and after bronchodilation have not been established for healthy adults.

The aim of this multicentre study was to collect impedance data from 4 to 26 Hz in healthy Caucasian subjects between 18 and 80 years of age. Five different devices were employed to assess baseline values and the bronchodilator response.

Altogether, 368 subjects were examined. Despite adjustment for anthropometry, the impedance spectra differed in frequency dependence between the centres, and hence could not be pooled. However, resistance at all frequencies except 20 and 25 Hz, and the low-frequency (f14 Hz) values of reactance did not exhibit a centre dependence. The regression equations for resistance reflected a greater height dependence in males and a greater weight dependence in both males and females than those published previously. Bronchodilation resulted in a statistically significant decrease (11%) in resistance and a 95th percentile equal to a 32% decrease in resistance at low frequency.

We conclude that rigorous calibration procedures should be developed to ensure data compatibility. Furthermore, new reference equations based on different setups are recommended to replace those established with a single device.


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Received: Aug 10 2012 | Accepted after revision: Feb 06 2013 | First published online: April 18 2013 Conflict of interest: None declared.

Copyright ©ERS 2013

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