Broadband frequency dependence of respiratory impedance in rats

Thamrin, Cindy, Sly, Peter D. and Hantos, Zoltán (2005) Broadband frequency dependence of respiratory impedance in rats. Journal of Applied Physiology, 99 4: 1364-1371. doi:10.1152/japplphysiol.00383.2005

Author Thamrin, Cindy
Sly, Peter D.
Hantos, Zoltán
Title Broadband frequency dependence of respiratory impedance in rats
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 8750-7587
Publication date 2005-10
Sub-type Article (original research)
DOI 10.1152/japplphysiol.00383.2005
Volume 99
Issue 4
Start page 1364
End page 1371
Total pages 8
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Language eng
Formatted abstract
Past studies in humans and other species have revealed the presence of resonances and antiresonances, i.e., minima and maxima in respiratory system impedance (Zrs), at frequencies much higher than those commonly employed in clinical applications of the forced oscillation technique (FOT). To help understand the mechanisms behind the first occurrence of antiresonance in the Zrs spectrum, the frequency response of the rat was studied by using FOT at both low and high frequencies. We measured Zrs in both Wistar and PVG/c rats using the wave tube technique, with a FOT signal ranging from 2 to 900 Hz. We then compared the high-frequency parameters, i.e., the first antiresonant frequency (far,1) and the resistive part of Zrs at that frequency [Rrs(far,1)], with parameters obtained by fitting a modified constant-phase model to low-frequency Zrs spectra. The far,1 was 570 ± 43 (SD) Hz and 456 ± 16 Hz in Wistar and PVG/c rats, respectively, and it did not shift with respiratory gases of different densities (air, heliox, and a mixture of SF6). The far,1 and Rrs(far,1) were relatively independent of methacholine-induced bronchoconstriction but changed significantly with increasing transrespiratory pressures up to 20 cmH2O, in the same way as airway resistance but independently of changes to tissue parameters. These results suggest that, unlike the human situation, the first antiresonance in the rat is not primarily dependent on the acoustic dimensions of the respiratory system and can be explained by interactions between compliances and inertances localized to the airways, but this most likely does not include airway wall compliance.
Keyword Antiresonance
Forced oscillation
High frequency
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Faculty of Health and Behavioural Sciences -- Publications
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Created: Wed, 17 Nov 2010, 11:54:11 EST