Pulmonary perfusion in supine and prone positions: an electron-beam computed tomography study
Pulmonary perfusion in supine and prone positions: an electron-beam computed tomography study
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DOI：
10.1152/jappl.2001.90.4.1342
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发表时间：
2001-04-01
影响因子：
3.3
通讯作者：
Evans, TW
中科院分区：
文献类型：
--
作者：
Jones, AT;Hansell, DM;Evans, TW
急性呼吸窘迫综合征的特征是通气灌注比的改变。现有的局部肺灌注研究技术难以应用于危重病人。采用电子束计算机断层扫描技术研究了俯卧位对6名健康受试者局部肺灌注的影响。在完全吸气时，依次在仰卧位、俯卧位和（原始）仰卧位获得对比增强切片。沿非依赖轴向依赖轴放置感兴趣的区域并计算相对灌注。当对肺实质重新分布进行校正时，在仰卧位和俯卧位均存在肺灌注的重力梯度。在仰卧位和俯卧位之间的灌注分布没有差异，但使用较小区域的数据分析显示肺解剖邻近区域之间的灌注具有明显的异质性。俯卧位肺实质分布较均匀。据估计，重力对仰卧位22-34%的灌注异质性和俯卧位27-41%的灌注异质性负有责任。这些数据支持这样的假设，即重力以外的因素在决定人体肺灌注分布方面可能至少同样重要。如果采用取样组织体积较大的技术，则可能无法检测到非重力因素的影响。
Acute respiratory distress syndrome is characterized by alterations in the ventilation-perfusion ratio. Present techniques for studying regional pulmonary perfusion are difficult to apply in the critically ill. Electron-beam computed tomography was used to study the effects of prone positioning on regional pulmonary perfusion in six healthy subjects. Contrast-enhanced sections were obtained sequentially in the supine, prone, and (original) supine positions at full inspiration. Regions of interest were placed along the nondependent to dependent axis and relative perfusion calculated. When corrected for the redistribution of lung parenchyma, a gravitational gradient of pulmonary perfusion existed in both supine and prone positions. The distribution of perfusion between the supine or prone positions did not differ, but data analysis using smaller regions of interest demonstrated marked heterogeneity of perfusion between anatomically adjacent regions of lung. The distribution of lung parenchyma was more uniform in the prone position. Gravity was estimated to be responsible for 22-34% of perfusion heterogeneity in the supine and 27-41% in the prone positions. These data support the hypothesis that factors other than gravity may be at least as important in determining the distribution of pulmonary perfusion in humans. The influence of nongravitational factors may not be detectable if techniques that sample large tissue volumes are employed.