Radics Bence L, Gyurkovits Zita, Makan Gergely, Gingl Zoltán, Czövek Dorottya, Hantos Zoltán
Department of Pathology, University of Szeged, Szeged, Hungary.
Department of Obstetrics and Gynecology, University of Szeged, Szeged, Hungary.
Front Pediatr. 2022 Apr 4;10:867883. doi: 10.3389/fped.2022.867883. eCollection 2022.
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.
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.
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.
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.
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.
振荡法已被广泛用作儿童和成人呼吸功能的非侵入性标准化测量方法；然而，关于婴儿的相关信息有限。
确定呼吸阻抗（Zrs）在测量过程中的变异性，描述Zrs在呼吸周期内变化的程度和特征，并评估其对新生儿传统振荡法测量的影响。
109名健康新生儿在产后前5天自然睡眠期间参与了本研究。使用了定制的波管振荡测量装置，分别使用8 - 48 Hz伪随机信号和16 Hz正弦信号进行频谱和呼吸周期内振荡测量。将电阻 - 顺应性 - 惯性（R - C - L）模型拟合到从连续30秒记录中获得的平均Zrs频谱。从三段90秒记录中估计呼吸周期内各点（如呼气末、吸气末和最大流量点）的阻力（Rrs）和电抗（Xrs）。所有自然且无伪迹的呼吸均纳入分析。
测量过程中平均R、C和L值的变化分别很大（平均变异系数：10.3%、20.3%和26.6%）；呼吸周期内测量值的波动程度相似（20 - 24%）。呼吸周期内分析还显示，呼吸周期中Rrs和Xrs有较大波动：峰峰值变化分别达到零流量Zrs幅值的93%（范围：32 - 218%）和41%（9 - 212%）。
Zrs的呼吸周期内追踪为呼吸系统动力学的决定因素提供了新的见解，并突出了机械非线性对从传统频谱振荡法获得的平均Zrs数据的偏差影响。
