Mechanical properties of the airway tree: heterogeneous and anisotropic pseudoelastic and viscoelastic tissue responses
Mechanical properties of the airway tree: heterogeneous and anisotropic pseudoelastic and viscoelastic tissue responses
复制标题
DOI：
10.1152/japplphysiol.00090.2018
复制
发表时间：
2018-09-01
影响因子：
3.3
通讯作者：
Levenston, Marc E.
中科院分区：
文献类型：
--
作者：
Eskandari, Mona;Arvayo, Alberto L.;Levenston, Marc E.
尽管肺部疾病是美国的第三大死因，但对呼吸道阻塞和肺部机制的研究仍然很少。缺乏相关数据导致计算肺模型从气管的可用材料数据推断机械特性。此外，尽管呼吸道具有潜在的生理学相关性和作为组织重塑和疾病进展的指标的实用性，但其依赖于时间的粘弹性行为在很大程度上被忽视了。在这里，我们解决了明确的需要，呼吸道特定的材料特征，以提供信息的生物物理研究的支气管树。取5个新鲜猪肺，从三个水平(气管、大支气管和小支气管)和两个方向(轴向和周向)制备标本。单轴拉伸试验显示出明显的非均质性和各向异性。总体而言，线性伪弹性模量轴向显著高于周向(30.5+/-3.1比8.4+/-1.1kPa)，周向样本中小支气管显著高于气管和大支气管(12.5+/-1.9比6.0+/-0.6和6.6+/-0.9kPa)。周向试件在300 S以上的应力松弛百分率高于轴向试件(38.0+/-1.4vs.23.1+/-1.5%)。轴向和周向气管样本的应力松弛百分率(26.4+/-1.6%和42.5+/-1.7%)高于相应的大、小支气管组。这种体外的伪弹性和粘弹性表征揭示了新的各向异性和异质性行为，并使我们能够构建特定于气道的本构关系。我们的结果为呼吸道力学奠定了必要的基础，为未来的研究扩展到围绕肺损伤的临床问题奠定了基础，并进一步直接启用了用于肺部疾病阻塞预测的计算工具。新的和值得注意的了解肺力学是研究疾病进展所必需的。尽管远端呼吸道是疾病表现和闭塞的部位，但气管力学构成了绝大多数体外呼吸道组织特征。此外，粘弹性研究很少，而时间依赖行为可能是组织重塑的潜在生理指标。在这项研究中，报告了支气管树的各向异性和异质性材料属性，解决了对呼吸道特定材料属性的迫切需求。
Airway obstruction and pulmonary mechanics remain understudied despite lung disease being the third cause of death in the United States. Lack of relevant data has led computational pulmonary models to infer mechanical properties from available material data for the trachea. Additionally, the time-dependent, viscoelastic behaviors of airways have been largely overlooked, despite their potential physiological relevance and utility as metrics of tissue remodeling and disease progression. Here, we address the clear need for airway-specific material characterization to inform biophysical studies of the bronchial tree. Specimens from three airway levels (trachea, large bronchi, and small bronchi) and two orientations (axial and circumferential) were prepared from five fresh pig lungs. Uniaxial tensile tests revealed substantial heterogeneity and anisotropy. Overall, the linear pseudoelastic modulus was significantly higher axially than circumferentially (30.5 +/- 3.1 vs. 8.4 +/- 1.1 kPa) and significantly higher among circumferential samples for small bronchi than for the trachea and large bronchi (12.5 +/- 1.9 vs. 6.0 +/- 0.6 and 6.6 +/- 0.9 kPa). Circumferential samples exhibited greater percent stress relaxation over 300 s than their axial counterparts (38.0 +/- 1.4 vs. 23.1 +/- 1.5%). Axial and circumferential trachea samples displayed greater percent stress relaxation (26.4 +/- 1.6 and 42.5 +/- 1.7%) than corresponding large and small bronchi. This ex vivo pseudoelastic and viscoelastic characterization reveals novel anisotropic and heterogeneous behaviors and equips us to construct airway-specific constitutive relations. Our results establish necessary fundamentals for airway mechanics, laying the groundwork for future studies to extend to clinical questions surrounding lung injury, and further directly enables computational tools for lung disease obstruction predictions.NEW & NOTEWORTHY Understanding the mechanics of the lung is necessary for investigating disease progression. Trachea mechanics comprises the vast majority of ex vivo airway tissue characterization despite distal airways being the site of disease manifestation and occlusion. Furthermore, viscoelastic studies are scarce, whereas time-dependent behaviors could be potential physiological metrics of tissue remodeling. In this study, the critical need for airway-specific material properties is addressed, reporting bronchial tree anisotropic and heterogeneous material properties.