Respiratory Oscillometry in Newborn Infants: Conventional and Intra-Breath Approaches

Bence L Radics; Zita Gyurkovits; Gergely Makan; Zoltán Gingl; Dorottya Czövek; Zoltán Hantos

doi:10.3389/fped.2022.867883

Respiratory Oscillometry in Newborn Infants: Conventional and Intra-Breath Approaches

Front Pediatr. 2022 Apr 4:10:867883. doi: 10.3389/fped.2022.867883. eCollection 2022.

Authors

Bence L Radics¹, Zita Gyurkovits², Gergely Makan³, Zoltán Gingl³, Dorottya Czövek⁴, Zoltán Hantos⁵

Affiliations

¹ Department of Pathology, University of Szeged, Szeged, Hungary.
² Department of Obstetrics and Gynecology, University of Szeged, Szeged, Hungary.
³ Department of Technical Informatics, University of Szeged, Szeged, Hungary.
⁴ 1st Department of Pediatrics, Semmelweis University, Budapest, Hungary.
⁵ Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary.

Abstract

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.

Keywords: infant oscillometry; intra-breath method; nasal resistance; respiratory compliance; respiratory reactance; respiratory resistance.