AIRWAY GEOMETRY AND WALL MECHANICAL-PROPERTIES ESTIMATED FROM SUBGLOTTAL INPUT IMPEDANCE IN HUMANS
AIRWAY GEOMETRY AND WALL MECHANICAL-PROPERTIES ESTIMATED FROM SUBGLOTTAL INPUT IMPEDANCE IN HUMANS
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DOI：
10.1152/jappl.1994.77.1.441
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发表时间：
1994-07-01
影响因子：
3.3
通讯作者：
JACKSON, AC
中科院分区：
文献类型：
--
作者：
HABIB, RH;CHALKER, RB;JACKSON, AC
我们测量了插管受试者在功能残气量下16和2,048 Hz之间的输入阻抗。然后使用模型计算相应的声门下阻抗（Z（SG）），其中气管插管由分布参数双端口网络表示。Z（SG）很好地描述了一个模型的基础上Horsfield的非对称气道几何形状在总肺容量（TLC）与非刚性壁。软骨气道壁包括单独的软骨和软组织室，而非软骨气道壁只有软组织室。两个隔室由串联电阻、惯性和顺应性组成，其值从气道尺寸和壁材料特性（粘度、密度和杨氏模量）计算。气道壁厚度通过缩放气道壁面积-直径关系来确定。气道长度和直径分别通过单因子和阶次依赖的S形曲线从Horsfield TLC值缩放。估计的软组织粘度和杨氏模量分别为1.04 +/- 0.21 cmH（2）O.s和593 +/- 319 cmH（2）O。气道长度和气管直径与Horsfield值无统计学差异。与Horsfield TLC值相比，更外周气道的估计直径显著减小（例如，类似于末端气道处的40%），这与当肺从TLC放气到功能性残气量时气道口径的减小一致。这些结果表明，高频Z（SG）声门下气道的几何形状和壁的属性是敏感的，通过使用适当的结构模型，可以估计气道几何形状和气道壁参数。
We measured input impedance between 16 and 2,048 Hz in intubated subjects at functional residual capacity. The corresponding subglottal impedances (Z(SG)) were then computed using a model where the endotracheal tube was represented by a distributed-parameter two-port network. Z(SG) was well described by a model based on Horsfield's asymmetric airway geometry at total lung capacity (TLC) with nonrigid walls. The walls of the cartilaginous airways included separate cartilage and soft tissue compartments, whereas the noncartilaginous airway walls had only a soft tissue compartment. Both compartments consisted of a series resistance, inertance, and compliance, the values of which were computed from airway dimensions and wall material properties (viscosity, density, and Young's modulus). Airway wall thickness was determined by scaling an airway wall area-diameter relationship. Airway lengths and diameters were scaled from the Horsfield TLC values by a single factor and by an order-dependent sigmoidal curve, respectively. The estimated soft tissue viscosity and Young's modulus were 1.04 +/- 0.21 cmH(2)O.s and 593 +/- 319 cmH(2)O, respectively. Airway lengths and tracheal diameters were not statistically different from the Horsfield values. The estimated diameters of the more peripheral airways were significantly reduced compared with the Horsfield TLC values (e.g., similar to 40% at the terminal airway), which is consistent with the reduction in airway caliber when the lung deflates from TLC to functional residual capacity. These results indicate that high-frequency Z(SG) is sensitive to subglottal airway geometry and wall properties and that by use of appropriate structural models one can estimate airway geometry and airway wall parameters.