Fractal nature of regional ventilation distribution
Fractal nature of regional ventilation distribution
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DOI：
10.1152/jappl.2000.88.5.1551
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发表时间：
2000-05-01
影响因子：
3.3
通讯作者：
Glenny, RW
中科院分区：
文献类型：
--
作者：
Altemeier, WA;McKinney, S;Glenny, RW
肺灌注的高分辨率测量揭示了分形分布的实质性空间异质性。这一观察结果导致了这样的假设，即血管树是局部血流的主要决定因素。最近使用气溶胶沉积的研究显示了与灌注密切相关的类似通气异质性。我们假设通气具有类似于血流的分形特征。我们在6只麻醉的机械通气猪中以俯卧和仰卧姿势测量了雾化和注射荧光微球的局部通气和灌注。相邻的区域被聚集成越来越大的组。计算每个簇大小的变异系数以确定分形维数。在最小肺片上，局部通气和灌注高度相关，通气和灌注异质性之间无显著差异。平均而言，通气的分形维数在俯卧位为1.16，在仰卧位为1.09。通气具有类似于灌注的分形特性。通过密切相关性，尽管通气和灌注异质性，有效的气体交换被保留。一个可能的解释是支气管和血管结构的相似几何结构。
High-resolution measurements of pulmonary perfusion reveal substantial spatial heterogeneity that is fractally distributed. This observation led to the hypothesis that the vascular tree is the principal determinant of regional blood flow. Recent studies using aerosol deposition show similar ventilation heterogeneity that is closely correlated with perfusion. We hypothesize that ventilation has fractal characteristics similar to blood flow We measured regional ventilation and perfusion with aerosolized and injected fluorescent microspheres in six anesthetized, mechanically ventilated pigs in both prone and supine postures. Adjacent regions were clustered into progressively larger groups. Coefficients of variation were calculated for each cluster size to determine fractal dimensions. At the smallest size lung piece, local ventilation and perfusion are highly correlated, with no significant difference between ventilation and perfusion heterogeneity. On average, the fractal dimension of ventilation is 1.16 in the prone posture and 1.09 in the supine posture. Ventilation has fractal properties similar to perfusion. Efficient gas exchange is preserved, despite ventilation and perfusion heterogeneity, through close correlation. One potential explanation is the similar geometry of bronchial and vascular structures.