Tomalak W, Peslin R, Duvivier C, Gallina C
Unité 14 de Physiopathologie Respiratoire, Institut National de la Santé et de la Recherche Médicale, Vandoeuvre-les-Nancy, France.
J Appl Physiol (1985). 1993 Dec;75(6):2656-64. doi: 10.1152/jappl.1993.75.6.2656.
The aim of this investigation was to assess the optimal frequency range for analyzing respiratory transfer impedance (Ztr) in terms of tissue and airway mechanical properties using the six-element model of DuBois et al. (J. Appl. Physiol. 8:587-594, 1956). Ztr was measured in nine healthy subjects from 2 to 64 Hz by studying the relationship between airway flow and pseudorandom pressure oscillations applied around the chest. The measurements were performed with and without two mechanical loads placed at the mouth: an added inertance of 1.4 Pa.s2.l-1 and an added resistance of 1.65 hPa.s.l-1. The data were corrected for the shunt effect of upper airway walls. The changes in Ztr induced by the loads were very consistent up to 56 Hz with the T-network topology assumed in DuBois's model; the agreement deteriorated at higher frequencies, presumably due to the difficulty of obtaining a homogeneous pressure field around the chest. The fit of the model to the data also worsened sharply at above 56 Hz. In the 2- to 56-Hz frequency range, similar values of the tissue and airway coefficients were obtained with and without the loads. In that frequency range the confidence intervals of the coefficients were better than 10%. We conclude that DuBois's model is valid from 2 to 56 Hz in healthy subjects and allows accurate partitioning of airways and tissue properties. In addition, we present evidence that the upper airway shunt negligibly influences Ztr data and the derived coefficients provided airway flow is measured with a low-impedance pneumotachograph.
本研究的目的是使用杜波依斯等人（《应用生理学杂志》8:587 - 594, 1956年）的六元件模型，根据组织和气道力学特性评估分析呼吸传递阻抗（Ztr）的最佳频率范围。通过研究气道流量与施加在胸部周围的伪随机压力振荡之间的关系，在9名健康受试者中测量了2至64 Hz范围内的Ztr。测量是在口部放置两个机械负载的情况下和未放置机械负载的情况下进行的：一个增加的惯性为1.4 Pa.s².l⁻¹，一个增加的阻力为1.65 hPa.s.l⁻¹。对数据进行了上呼吸道壁分流效应的校正。在高达56 Hz时，负载引起的Ztr变化与杜波依斯模型中假设的T型网络拓扑非常一致；在更高频率时一致性变差，可能是由于难以在胸部周围获得均匀的压力场。在高于56 Hz时，模型与数据的拟合也急剧恶化。在2至56 Hz频率范围内，无论有无负载，均获得了相似的组织和气道系数值。在该频率范围内，系数的置信区间优于10%。我们得出结论，杜波依斯模型在健康受试者中从2至56 Hz是有效的，并且能够准确划分气道和组织特性。此外，我们提供的证据表明，如果用低阻抗呼吸流速仪测量气道流量，上呼吸道分流对Ztr数据和导出系数的影响可忽略不计。
