Oscillometry reference values for children and adolescents

Abstract

Background: Oscillometry devices allow quantification of respiratory function at tidal breathing but device-specific reference equations are scarce: the present study aims to create sex-specific oscillometric reference values for children and adolescents using the Resmon PRO FULL device.

Methods: Healthy participants (n=981) aged 6 to 17 years of the Austrian LEAD general population cohort were included. Subjects had normal weight (body mass index ≤99th percentile) and normal lung volumes (total lung capacity (TLC) ≥ lower limit of normal). Oscillometry data were collected using a single frequency mode of 8 Hz. Sex-specific prediction equations were developed for total, inspiratory and expiratory resistance (R) and reactance (X) as well as for the modulus of impedance (Z) value using the LMS (lambda, mu, sigma) method. Height was used as a single covariate.

Results: Reference equations for all oscillometry parameters were created for Caucasian children aged 6 to 17 years with a height span from 101 to 183 cm and a lung volume span from 1.7 to 8.8 L TLC. R and Z values progressively decrease and X values increase with increasing height. Oscillometry parameters versus lung volume curves differ from those versus height curves. Stratified for lung size, no sex differences are found for oscillometry parameters.

Conclusion: Our study provides reference values for oscillometry parameters in children and adolescents using strictly defined criteria for weight and lung volumes. No sex-related differences in oscillometry parameters corrected for height or lung size are found.

FIGURE 1

Flow chart of sample size used in the analysis. Z_rs: respiratory impedance; R: respiratory resistance; R_tot: respiratory resistance (total part); TLC: total lung capacity; LLN: lower limit of normal; BMI: body mass index; CoV: coefficient of variation.

FIGURE 2

Relationship between TLC and height stratified by sex. r²=0.808 for boys, r²=0.798 for girls. TLC: total lung capacity.

FIGURE 3

Relationship between R_rs/X_rs and age stratified by sex. R: respiratory resistance; X: respiratory reactance; R_rs: respiratory resistance; X_rs: respiratory reactance; R_exp: expiratory resistance; R_insp: inspiratory resistance; R_tot: total resistance; X_exp: expiratory reactance; X_insp: inspiratory reactance; X_tot: total reactance.

FIGURE 4

Relationship between R, X and Z and height and TLC stratified by sex. a) R_exp, R_insp, R_tot versus height (cm) by sex, b) R_exp, R_insp, R_tot versus TLC (L) by sex, c) X_exp, X_insp, X_tot versus height (cm) by sex, d) X_exp, X_insp, X_tot versus TLC (L) by sex, e) Z_tot versus height (cm) by sex, and f) Z_tot versus TLC (L) by sex. R: respiratory resistance; X: respiratory reactance; R_rs: respiratory resistance; X_rs: respiratory reactance; R_exp: expiratory resistance; R_insp: inspiratory resistance; R_tot: total resistance; X_exp: expiratory reactance; X_insp: inspiratory reactance; X_tot: total reactance; TLC: total lung capacity; Z_tot: total impedance.

FIGURE 5

Centiles of height adapted reference values for R_tot, X_tot and Z_tot for male and female children and adolescents. X parameters were preliminarily shifted with the following function: f(x)=X × (−1)+0.1. R_tot: total resistance at 8 Hz; X_tot: total reactance at 8 Hz; Z_tot: total impedance (overall impedance) at 8 Hz.

FIGURE 6

Comparison of mean and sd of a) R_tot and b) X_tot parameters at 8 Hz of the current reference values and those from already published reference values (Ducharme et al. 2022 [17]). R_tot: total resistance; X_tot: total reactance.