VISCOELASTIC NON-UNIFORM VENTILATION

拟议的研究涉及基本呼吸的两个方面 生理、不均匀通风和组织粘度，并显示 两者之间的关系。通风最近被证明是 在相隔1厘米或更小的区域，差异显著， 显然是因为机械系统中固有的不一致性 薄壁组织的属性。在俯卧的狗，小规模的区域 通风量与平均值相差约20%，这 通风不均匀极大地影响了 V/Q分布。组织阻力已被证明是主要的 犬正常呼吸时的肺阻力成分 频率，而是组织底层的耗散机制 对小潮气量的抵抗力尚未确定。 这项拟议的研究结合了体内动态测量 通风与工程建模与分析。实验性的 方法是通过双平面透视跟踪植入到 狗肺的实质。这种方法能够测量体积 体积为1厘米~3量级的实体单元的游程 时间分辨率为30毫秒。初步数据，通过 实质标记技术，显示了小区域的通风 在一个波瓣内不同的相位和区域的幅度 通风与频率有关。这些是粘弹性的指标 机械装置。因此，通过建模和分析，这些数据不是 只提供有关通风不均匀的直接信息，它们还 为了解组织粘弹性机制提供了一个窗口。 将测量正弦肺容量的区域通气量 在广泛的频率范围内振荡，并对肺活量 呼气流速范围很大的动作。机型 总结了区域通风的统计特征和区域通风的特征 将区域通风与气体混合的其他措施和组织联系起来 将会产生抵抗力。数据和模型将用于测试 关于耗散机制的假设，即存在两个 机构，表面张力平衡与较大范围的较长 时间常数和较短时间的肺泡压力松弛 常量。 这项研究最初的重点是了解正常的生理学， 但这也为扩展研究奠定了基础。 病理情况。通风不均匀是 几乎所有的肺部疾病，包括哮喘和肺气肿。之后 对正常肺的研究已经完成，这些方法将应用于 接触过乙酰甲胆碱的狗。

The proposed research addresses two aspects of basic respiratory physiology, nonuniform ventilation and tissue viscosity, and shows the relation between the two. Ventilation has recently been shown to be significantly different in regions that are separated by 1cm or less, apparently because of intrinsic nonuniformities in the mechanical properties of the parenchyma. In the prone dog, small-scale regional ventilation varies by approximately 20% from the mean, and this nonuniformity of ventilation contributes significantly to the width of the V/Q distribution. Tissue resistance has been shown to be the major component of pulmonary resistance in dogs at normal breathing frequencies, but the dissipative mechanisms that underlie tissue resistance for small tidal volumes have not been identified. The proposed research combines in vivo measurements of dynamic ventilation with engineering modeling and analysis. The experimental method is the tracking, by biplane fluoroscopy, of markers implanted in the parenchyma of dog lungs. This method is capable of measuring volume excursions of parenchymal units with volumes of the order of 1 cm3 with a time resolution of 30 ms. Preliminary data, obtained with the parenchymal marker technique, show that the ventilation of small regions within a lobe differ in phase and that the amplitude of regional ventilation is frequency dependent. These are indicators of viscoelastic mechanisms. Therefore, by means of modeling and analysis, these data not only provide direct information about nonuniform ventilation, they also provide a window into tissue viscoelasticity mechanisms. Regional ventilation will be measured for sinusoidal lung volume oscillations over a wide range of frequencies, and for vital capacity maneuvers with a wide range of expiratory flow rates. Models that summarize the statistical properties of regional ventilation and that relate regional ventilation to other measures of gas mixing and to tissue resistance will be developed. The data and modeling will be used to test hypotheses about dissipative mechanisms, namely that there are two mechanisms, surface tension equilibration with a broad range of longer time constants, and alveolar pressure relaxation with a shorter time constant. The initial focus of the research is on understanding normal physiology, but this also lays the groundwork for extension to the study of pathological conditions. Nonuniform ventilation is a hallmark of virtually all pulmonary diseases, including asthma and emphysema. After the study of normal lungs is complete, the methods will be applied to dogs that have been exposed to methacholine.