Supine and prone differences in regional lung density and pleural pressure gradients in the human lung with constant shape
Supine and prone differences in regional lung density and pleural pressure gradients in the human lung with constant shape
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DOI：
10.1152/japplphysiol.00324.2009
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发表时间：
2009-09-01
影响因子：
3.3
通讯作者：
Hoffman, Eric A.
中科院分区：
文献类型：
--
作者：
Tawhai, Merryn H.;Nash, Martyn P.;Hoffman, Eric A.
Towai MH，Nash MP，Lin C，Hoffman EA.仰卧位和俯卧位在恒定形状的人肺中区域肺密度和胸膜压力梯度的差异。应用生理学杂志107：912-920,2009。2009年7月9日首次出版；doi：10.1152/japplPhysiol.00324.2009。在健康肺中，俯卧位和仰卧位的组织密度和胸膜压力梯度的差异的解释已经从几项研究中推断为仰卧位时心脏对依赖组织的压缩；然而，这一假设尚未得到直接证实。胸壁和横隔膜的形状变化，以及相对于重力的形状也可能产生差异。本文将探讨这第三种机制的贡献。采用有限元分析方法，对仰卧位和俯卧位左肺在功能剩余容量下的组织密度和静态弹性反冲进行了估算。仰卧位模型的几何形状来自两个受试者的多层螺旋CT成像：一个是正常人(受试者1)，另一个是小气道疾病患者(受试者2)。对于每个受试者，俯卧位模型是仰卧的肺形，重力反转；因此，俯卧位模型不受横隔膜、胸壁或心脏移位的影响。通过对每个受试者仰卧位和仰卧位肺的多排计算机断层扫描区域密度测量以及俯卧位和仰卧位肺的独立研究来验证模型估计。受试者1仰卧位密度梯度的幅度(受试者1为-4.33%/cm，受试者2为-4.96%/cm)几乎是俯卧位肺密度梯度(受试者1为-2.72%/cm，受试者2为-2.51%/cm)的两倍，与狗的测量结果一致。相应的胸膜压力梯度仰卧位为0.54cmH(2)O/cm(受试者1)和0.56cmH(2)O/cm(受试者2)，俯卧位为0.29cmH(2)O/cm(受试者1)和0.27cmH(2)O/cm(受试者2)。在没有“容器”的形状改变或肺对心脏的支持的情况下，预测了较小的俯卧梯度。心脏的影响是限制了肺变形的形状。
Tawhai MH, Nash MP, Lin C, Hoffman EA. Supine and prone differences in regional lung density and pleural pressure gradients in the human lung with constant shape. J Appl Physiol 107: 912-920, 2009. First published July 9, 2009; doi:10.1152/japplphysiol.00324.2009. The explanation for prone and supine differences in tissue density and pleural pressure gradients in the healthy lung has been inferred from several studies as compression of dependent tissue by the heart in the supine posture; however, this hypothesis has not been directly confirmed. Differences could also arise from change in shape of the chest wall and diaphragm, and because of shape with respect to gravity. The contribution of this third mechanism is explored here. Tissue density and static elastic recoil were estimated in the supine and prone left human lung at functional residual capacity using a finite-element analysis. Supine model geometries were derived from multidetector row computed tomography imaging of two subjects: one normal (subject 1), and one with small airway disease (subject 2). For each subject, the prone model was the supine lung shape with gravity reversed; therefore, the prone model was isolated from the influence of displacement of the diaphragm, chest wall, or heart. Model estimates were validated against multidetector row computed tomography measurement of regional density for each subject supine and an independent study of the prone and supine lung. The magnitude of the gradient in density supine (-4.33%/cm for subject 1, and -4.96%/cm for subject 2) was nearly twice as large as for the prone lung (-2.72%/cm for subject 1, and -2.51%/cm for subject 2), consistent with measurements in dogs. The corresponding pleural pressure gradients were 0.54 cmH(2)O/cm (subject 1) and 0.56 cmH(2)O/cm (subject 2) for supine, and 0.29 cmH(2)O/cm (subject 1) and 0.27 cmH(2)O/cm (subject 2) for prone. A smaller prone gradient was predicted without shape change of the "container" or support of the heart by the lung. The influence of the heart was to constrain the shape in which the lung deformed.