Abstract
Noninvasiveness, low cooperation demand and the potential for detailed physiological characterisation have promoted the use of oscillometry in the assessment of lung function. However, concerns have been raised about the comparability of measurement outcomes delivered by the different oscillometry devices. The present study compares the performances of oscillometers in the measurement of mechanical test loads with and without simulated breathing.
Six devices (five were commercially available and one was custom made) were tested with mechanical test loads combining resistors (R), gas compliances (C) and a tube inertance (L), to mimic respiratory resistance (Rrs) and reactance (Xrs) spectra encountered in clinical practice. A ventilator was used to simulate breathing at tidal volumes of 300 and 700 mL at frequencies of 30 and 15 min−1, respectively. Measurements were evaluated in terms of R, C, L, resonance frequency (fres), reactance area (AX) and resistance change between 5 and 20 or 19 Hz (R5–20(19)).
Increasing test loads caused progressive deviations in Rrs and Xrs from calculated values at various degrees in the different oscillometers. While mean values of Rrs were recovered acceptably, some devices exhibited serious distortions in the frequency dependences of Rrs and Xrs, leading to large errors in C, L, fres, AX and R5–20(19). The results were largely independent of the simulated breathing.
Simplistic calibration procedures and mouthpiece corrections, in addition to unknown instrumental and signal processing factors, may be responsible for the large differences in oscillometry measures. Rigorous testing and ongoing harmonisation efforts are necessary to better exploit the diagnostic and scientific potential of oscillometry.
Abstract
The clinical utility of oscillometry is limited by the lack of standardisation of devices. This study tested six oscillometers, and reveals very different performances at higher mechanical impedances observed in children and adults with lung disease. http://bit.ly/317sfjH
Footnotes
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Conflict of interest: R.J. Dandurand reports that he is a 15% shareholder in SpiroTech Medical Inc., which holds the patent for a novel device for the home monitoring of respiratory system resistance; and unrestricted educational grants from AstraZeneca, Boehringer Ingelheim, Novartis, Pfizer and Teva Pharma, outside the submitted work.
Conflict of interest: J-P. Lavoie has nothing to disclose.
Conflict of interest: L.C. Lands has nothing to disclose.
Conflict of interest: Z. Hantos reports that he is named as an inventor on a patent owned by the Telethon Kids Institute entitled “A method of diagnosing a respiratory disease or disorder or monitoring treatment of same and a device for use therein” (Australian patent application number 2005903034). The techniques used in this study are broadly consistent with this patent. He receives no royalties from, nor has he any royalty agreement with, the Telethon Kids Institute under this patent. He also has a consultancy agreement with Thorasys Medical Systems, Inc., which is unrelated to the subject of the present study and was established after the present study was performed.
Support statement: Z. Hantos was supported by Hungarian Scientific Research Fund grant K 128701. Funding information for this article has been deposited with the Crossref Funder Registry.
- Received June 21, 2019.
- Accepted October 7, 2019.
- Copyright ©ERS 2019
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