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Updated: Sep 26, 2025
Conducting Respiratory Oscillometry in an Outpatient Setting
Published on: April 8, 2022
Respiratory Oscillometry in Newborn Infants: Conventional and Intra-Breath Approaches
Bence L Radics1, Zita Gyurkovits2, Gergely Makan3
1Department of Pathology, University of Szeged, Szeged, Hungary.
Insights
Respiratory impedance (Zrs) in newborns shows significant within-breath variability, impacting standard oscillometry measurements. Intra-breath analysis offers deeper insights into respiratory system dynamics.
Area of Science:
- Neonatal physiology
- Respiratory mechanics
- Pulmonary function testing
Background:
- Oscillometry is a standard non-invasive method for respiratory function assessment in children and adults.
- Limited data exists on oscillometry in infants, particularly newborns.
Purpose of the Study:
- To determine the within-session variability of respiratory impedance (Zrs) in newborns.
- To characterize intra-breath changes in Zrs and their influence on conventional oscillometry.
- To assess the impact of mechanical non-linearities on Zrs measurements.
Main Methods:
- 109 healthy newborns underwent oscillometry during natural sleep.
- A custom wave-tube setup used spectral (8-48 Hz) and intra-breath (16 Hz) signals.
- Resistance-Compliance-Inertance (R-C-L) models and intra-breath Rrs/Xrs were analyzed.
Main Results:
- Significant within-session variability was observed in mean R, C, and L values (CVs 10.3-26.6%).
- Intra-breath fluctuations in Rrs and Xrs were substantial, reaching 93% and 41% of Zrs magnitude, respectively.
- Mechanical non-linearities significantly affected average Zrs data.
Conclusions:
- Intra-breath tracking of Zrs provides novel insights into respiratory system dynamics in newborns.
- Conventional spectral oscillometry may be biased by mechanical non-linearities in this population.
Background:
Oscillometry has been employed widely as a non-invasive and standardized measurement of respiratory function in children and adults; however, limited information is available on infants.
Aims:
To establish the within-session variability of respiratory impedance (Zrs), to characterize the degree and profile of intra-breath changes in Zrs and to assess their impact on conventional oscillometry in newborns.
Methods:
109 healthy newborns were enrolled in the study conducted in the first 5 postpartum days during natural sleep. A custom-made wave-tube oscillometry setup was used, with an 8-48 Hz pseudorandom and a 16 Hz sinusoidal signal used for spectral and intra-breath oscillometry, respectively. A resistance-compliance-inertance (R-C-L) model was fitted to average Zrs spectra obtained from successive 30-s recordings. Intra-breath measures, such as resistance (Rrs) and reactance (Xrs) at the end-expiratory, end-inspiratory and maximum-flow points were estimated from three 90-s recordings. All natural and artifact-free breaths were included in the analysis.
Results:
Within-session changes in the mean R, C and L values, respectively, were large (mean coefficients of variation: 10.3, 20.3, and 26.6%); the fluctuations of the intra-breath measures were of similar degree (20-24%). Intra-breath analysis also revealed large swings in Rrs and Xrs within the breathing cycle: the peak-to-peak changes amounted to 93% (range: 32-218%) and 41% (9-212%), respectively, of the zero-flow Zrs magnitude.
Discussion:
Intra-breath tracking of Zrs provides new insight into the determinants of the dynamics of respiratory system, and highlights the biasing effects of mechanical non-linearities on the average Zrs data obtained from the conventional spectral oscillometry.
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