Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung.
Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung.
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DOI：
10.1097/ccm.0000000000002234
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发表时间：
2017-04
影响因子：
8.8
通讯作者：
Bayat S
中科院分区：
文献类型：
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作者：
Broche L;Perchiazzi G;Porra L;Tannoia A;Pellegrini M;Derosa S;Sindaco A;Batista Borges J;Degrugilliers L;Larsson A;Hedenstierna G;Wexler AS;Bravin A;Verbanck S;Smith BJ;Bates JH;Bayat S
正压通气使肺暴露于机械应力，这可能加重损伤。这种病理过程的确切机制仍然难以捉摸。描述短时间范围内腺泡长度尺度的募集/去募集（R/D），并使用计算模型检验相邻肺单位之间的机械相互依赖性决定R/D的空间和时间分布的假设。实验在压力控制模式（PCV）通气的麻醉家兔中进行。肺连续成像在约1.5分钟的时间间隔，在每个呼气末正压（PEEP）为12，9，6，3和0厘米水柱之前和之后的伤害。通过减去后续图像来分析R/D的范围和空间分布。在一个现实的肺结构中，我们实现了一个机械模型，其中每个单元都有单独的压力和打开和关闭的速度。根据连续时间点的通气量比较，计算去招募和招募肺分数（Fderecruited，Frecruited）。在所有测试的PEEP水平下，尽管PCV稳定，但在短时间内相邻肺泡发生替代R/D。计算模型再现这种行为，只有当相邻的腺泡之间的实质相互依赖占。当包括机械相互依赖性时，模拟接近地模拟了Fderecruited和Frecruited的实验幅度，而排除机械相互依赖性时，在PEEP ≥ 3 cmH2O时，Frecruited值为零。这些发现进一步深入了解了损伤肺的微观行为，并提供了一种测试保护性通气策略的方法，以防止R/D和随后的肺损伤。
Positive pressure ventilation exposes the lung to mechanical stresses that can exacerbate injury. The exact mechanism of this pathological process remains elusive. Describe Recruitment/Derecruitment (R/D) at acinar length scales over short time frames and test the hypothesis that mechanical interdependence between neighboring lung units determines the spatial and temporal distributions of R/D, using a computational model. Experiments were performed in anaesthetized rabbits ventilated in Pressure Controlled mode (PCV). The lung was consecutively imaged at ~1.5 min intervals, at each Positive End-Expiratory Pressure (PEEP) of 12, 9, 6, 3 and 0 cmH2O before and after injury. The extent and spatial distribution of R/D was analyzed by subtracting subsequent images. In a realistic lung structure we implemented a mechanistic model in which each unit has individual pressures and speeds of opening and closing. Derecruited and Recruited lung fractions (Fderecruited, Frecruited) were computed based on the comparison of the aerated volumes at successive time points. Alternative R/D occurred in neighboring alveoli over short time scales in all tested PEEP levels and despite stable PCV. The computational model reproduced this behavior only when parenchymal interdependence between neighboring acini was accounted for. Simulations closely mimicked the experimental magnitude of Fderecruited and Frecruited when mechanical interdependence was included, while its exclusion gave Frecruited values of zero at PEEP ≥ 3 cmH2O. These findings give further insight into the microscopic behavior of the injured lung and provide a means of testing protective-ventilation strategies to prevent R/D and subsequent lung damage.