Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
European Synchrotron Radiation Facility, Grenoble, France.
Sci Rep. 2022 Mar 23;12(1):5056. doi: 10.1038/s41598-022-09052-9.
The magnitude and distribution of strain imposed on the peripheral airspaces by mechanical ventilation at the microscopic level and the consequent deformations are unknown despite their importance for understanding the mechanisms occurring at the onset of ventilator-induced lung injury. Here a 4-Dimensional (3D + time) image acquisition and processing technique is developed to assess pulmonary acinar biomechanics at microscopic resolution. Synchrotron radiation phase contrast CT with an isotropic voxel size of 6 µm is applied in live anesthetized rats under controlled mechanical ventilation. Video animations of regional acinar and vascular strain are acquired in vivo. Maps of strain distribution due to positive-pressure breaths and cardiovascular activity in lung acini and blood vessels are derived based on CT images. Regional strain within the lung peripheral airspaces takes average values of 0.09 ± 0.02. Fitting the expression S = kV, to the changes in peripheral airspace area (S) and volume (V) during a positive pressure breath yields an exponent n = 0.82 ± 0.03, suggesting predominant alveolar expansion rather than ductal expansion or alveolar recruitment. We conclude that this methodology can be used to assess acinar conformational changes during positive pressure breaths in intact peripheral lung airspaces.
尽管了解在呼吸机诱导性肺损伤发生时的机制对于理解在微观水平上机械通气对周围气腔施加的应变幅度和分布以及随之而来的变形非常重要，但目前仍不清楚这些信息。在这里，开发了一种 4 维（3D+时间）图像采集和处理技术，以在微观分辨率下评估肺腺泡生物力学。在受控机械通气下，对麻醉大鼠进行同步辐射相衬 CT 检查，体素大小为 6μm 各向同性。在体内获取区域性腺泡和血管应变的视频动画。基于 CT 图像得出由于正压呼吸和肺腺泡和血管中的心血管活动导致的应变分布图。肺外周气腔的区域应变平均值为 0.09±0.02。将 S=kV 表达式拟合到正压呼吸过程中外周气腔面积（S）和体积（V）的变化中，得到指数 n=0.82±0.03，表明主要是肺泡扩张而不是导管扩张或肺泡复张。我们得出结论，该方法可用于评估完整外周肺气腔在正压呼吸过程中的腺泡构象变化。
