Blood flow redistribution and ventilation-perfusion mismatch during embolic pulmonary arterial occlusion.
Blood flow redistribution and ventilation-perfusion mismatch during embolic pulmonary arterial occlusion.
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DOI：
10.4103/2045-8932.87302
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发表时间：
2011-07-01
影响因子：
2.6
通讯作者：
Tawhai, M H
中科院分区：
文献类型：
--
作者：
Burrowes, K S;Clark, A R;Tawhai, M H
急性肺栓塞导致肺内血液重新分布，损害通气/灌注匹配和气体交换，并可通过增加肺血管阻力（PVR）升高肺动脉压（PAP）。一个基于解剖学的多尺度人体肺循环模型被用来模拟阻塞前和阻塞后的流量，研究在栓塞的存在下的血流再分布，并评估灌注血管床的减少是否足以将PAP增加到高血压水平，或者是否需要其他血管收缩机制。包括从空气到血液的氧转移模型，以评估血管闭塞对氧交换的影响。引入5、7和10 mm半径的栓塞以闭塞越来越多的血管系统。计算动脉闭塞后的血流再分布，预测PAP、PVR、血流再分布和微循环血流动力学。由于大的血流储备能力（通过毛细血管募集和扩张），在PAP达到指示高血压的临床显著水平之前，约55%的血管被闭塞。相反，模型预测表明，即使相对较低的闭塞水平也可能导致局部缺氧。流量优先重新分配到重力非依赖性区域，无论闭塞位置如何，因为该区域毛细血管募集的潜力更大。红细胞通过时间低于氧饱和度的最短时间（
Acute pulmonary embolism causes redistribution of blood in the lung, which impairs ventilation/perfusion matching and gas exchange and can elevate pulmonary arterial pressure (PAP) by increasing pulmonary vascular resistance (PVR). An anatomically-based multi-scale model of the human pulmonary circulation was used to simulate pre- and post-occlusion flow, to study blood flow redistribution in the presence of an embolus, and to evaluate whether reduction in perfused vascular bed is sufficient to increase PAP to hypertensive levels, or whether other vasoconstrictive mechanisms are necessary. A model of oxygen transfer from air to blood was included to assess the impact of vascular occlusion on oxygen exchange. Emboli of 5, 7, and 10 mm radius were introduced to occlude increasing proportions of the vasculature. Blood flow redistribution was calculated after arterial occlusion, giving predictions of PAP, PVR, flow redistribution, and micro-circulatory flow dynamics. Because of the large flow reserve capacity (via both capillary recruitment and distension), approximately 55% of the vasculature was occluded before PAP reached clinically significant levels indicative of hypertension. In contrast, model predictions showed that even relatively low levels of occlusion could cause localized oxygen deficit. Flow preferentially redistributed to gravitationally non-dependent regions regardless of occlusion location, due to the greater potential for capillary recruitment in this region. Red blood cell transit times decreased below the minimum time for oxygen saturation (