Mazurek H, Willim G, Marchal F, Haluszka J, Tomalak W
Rabka Division, National Research Institute for Tuberculosis and Lung Diseases, Rabka, Poland.
Pediatr Pulmonol. 2000 Jul;30(1):47-55. doi: 10.1002/1099-0496(200007)30:1<47::aid-ppul8>3.0.co;2-w.
The upper airway wall motion represents a serious problem when measuring the input impedance of the respiratory system (Zrs) by the forced oscillation technique, particularly in young children. To minimize this error, it has been proposed to vary transrespiratory pressure around the head rather than directly at the mouth, using the head generator technique (HGT). The aim of this study was to collect normative data in preschool children in whom the technique may prove most useful. Zrs was measured using HGT and 4-32-Hz pseudorandom noise input in 127 healthy children. Age ranged from 2. 8 to 7.4 years and height (H) from 0.89 to 1.29 m. The fast Fourier transforms of pressure and flow allowed us to calculate respiratory system resistance (Rrs(f)) and reactance (Xrs(f)) at each frequency (f). Resonant frequency (fn), respiratory system inertance (Irs), and compliance (Crs) were derived from the Xrs(f) data. The technique was accepted by more than 95% of the children. A coherence function </=0.95 required us to reject Zrs values in the lower frequency spectrum. These missing data did not allow reliable estimation of fn, Irs, and Crs in 44% of children. Regression equations of Zrs on growth parameters were obtained. H was the only significant predictive variable. The decrease of Rrs with growth was best described by a multiplicative model [e.g., ln (Rrs(20)) = 2. 5301 - 2.3837. ln (H)]. The slope of the regression lines of Xrs on H was dependent on f: positive between 4 and 16 Hz, negative at high frequency (e.g., 32 Hz), and nonsignificant in the intermediate range (e.g., 20 Hz). Irs and fn decreased significantly and Crs increased as H increased. The current study provides reference values for input impedance of the respiratory system in preschool children with upper airway artifacts minimized. HGT should be particularly helpful at or around 20 Hz, where the signal to noise ratio is larger than at lower frequencies but where upper airway artifacts may significantly corrupt measurements with the standard generator.
当通过强迫振荡技术测量呼吸系统输入阻抗（Zrs）时，上气道壁运动是一个严重问题，在幼儿中尤为如此。为了将此误差降至最低，有人提出采用头部发生器技术（HGT），在头部周围而非直接在口腔处改变跨呼吸压力。本研究的目的是收集该技术可能最有用的学龄前儿童的规范数据。使用HGT和4 - 32 Hz伪随机噪声输入对127名健康儿童测量Zrs。年龄范围为2.8至7.4岁，身高（H）为0.89至1.29 m。压力和流量的快速傅里叶变换使我们能够计算每个频率（f）下的呼吸系统阻力（Rrs(f)）和电抗（Xrs(f)）。共振频率（fn）、呼吸系统惯性（Irs）和顺应性（Crs）由Xrs(f)数据得出。超过95%的儿童接受了该技术。相干函数≤0.95要求我们舍弃低频谱中的Zrs值。这些缺失数据使44%的儿童无法可靠估计fn、Irs和Crs。获得了Zrs与生长参数的回归方程。身高（H）是唯一显著的预测变量。Rrs随生长的降低最好用乘法模型描述[例如，ln(Rrs(20)) = 2.5301 - 2.3837·ln(H)]。Xrs关于H的回归线斜率取决于频率：在4至16 Hz之间为正，在高频（如32 Hz）时为负，在中间范围（如20 Hz）时不显著。随着H增加，Irs和fn显著降低，Crs增加。本研究提供了上气道伪影最小化的学龄前儿童呼吸系统输入阻抗的参考值。HGT在20 Hz左右尤其有用，此时信噪比高于低频，但上气道伪影可能会严重干扰标准发生器的测量。
