Burrowes K S, Clark A R, Wilsher M L, Milne D G, Tawhai M H
Department of Computer Science, University of Oxford, Wolfson Building, Parks Road, Oxford, OX1 3QD, UK,
Ann Biomed Eng. 2014 Aug;42(8):1631-43. doi: 10.1007/s10439-014-1011-y. Epub 2014 Apr 26.
Hypoxic pulmonary vasoconstriction (HPV) is an adaptive response unique to the lung whereby blood flow is diverted away from areas of low alveolar oxygen to improve ventilation-perfusion matching and resultant gas exchange. Some previous experimental studies have suggested that the HPV response to hypoxia is blunted in acute pulmonary embolism (APE), while others have concluded that HPV contributes to elevated pulmonary blood pressures in APE. To understand these contradictory observations, we have used a structure-based computational model of integrated lung function in 10 subjects to study the impact of HPV on pulmonary hemodynamics and gas exchange in the presence of regional arterial occlusion. The integrated model includes an experimentally-derived model for HPV. Its function is validated against measurements of pulmonary vascular resistance in normal subjects at four levels of inspired oxygen. Our results show that the apparently disparate observations of previous studies can be explained within a single model: the model predicts that HPV increases mean pulmonary artery pressure in APE (by 8.2 ± 7.0% in these subjects), and concurrently shows a reduction in response to hypoxia in the subjects who have high levels of occlusion and therefore maximal HPV in normoxia.
低氧性肺血管收缩（HPV）是肺特有的一种适应性反应，通过这种反应，血流从肺泡氧含量低的区域分流，以改善通气-灌注匹配及由此产生的气体交换。先前的一些实验研究表明，急性肺栓塞（APE）时HPV对低氧的反应减弱，而另一些研究则得出结论，HPV导致APE时肺血压升高。为了解这些相互矛盾的观察结果，我们使用了基于结构的10名受试者综合肺功能计算模型，来研究在存在局部动脉闭塞的情况下HPV对肺血流动力学和气体交换的影响。该综合模型包括一个基于实验得出的HPV模型。其功能通过在四种吸氧水平下对正常受试者肺血管阻力的测量进行了验证。我们的结果表明，先前研究中明显不同的观察结果可以在一个单一模型中得到解释：该模型预测，HPV会使APE患者的平均肺动脉压升高（在这些受试者中升高8.2±7.0%），同时显示，在闭塞程度高、因此在常氧状态下HPV最大的受试者中，对低氧的反应降低。
