Dorrington Keith L, Balanos George M, Talbot Nick P, Robbins Peter A
Department of Physiology, Anatomy & Genetics, Sherrington Bldg., Parks Road, University of Oxford, Oxford, OX1 3PT, UK.
J Appl Physiol (1985). 2010 May;108(5):1084-96. doi: 10.1152/japplphysiol.90963.2008. Epub 2010 Feb 25.
Regional blood flow in the lung is known to be influenced by the alveolar PCO2 and alveolar PO2. For the healthy lung, the extent to which this influence is of functional importance in limiting heterogeneity in alveolar gas composition by matching regional perfusion (q) to regional ventilation (v) remains unclear. To address this issue, the efficiency of regulation (E) was defined as the percent correction to an initial perturbation in regional alveolar gas composition generated by the pulmonary vascular response to the disturbance. This study develops the theory to calculate E from global measurements of vascular reactivity to CO2 and O2 in human volunteers. For O2, these data were available from the literature. For CO2, an experimental component of the present study used Doppler echocardiography to evaluate the magnitude of the global vascular response to hypercapnia and hypocapnia in 12 volunteers over a timescale of approximately 0.5 h. The results suggest a value for E of approximately 60% over a wide range of values for v-to-q ratio (approximately 0.1-10) encompassing those found in normal lung. At low v/q (<0.65), the vascular response to O2 forms the dominant mechanism; however, at higher v/q (>0.65), the response to CO2 dominates. The values for E suggest that the pulmonary vascular responses to both CO2 and O2 play a significant role in ventilation-perfusion matching in the healthy human lung.
已知肺内局部血流受肺泡二氧化碳分压（PCO2）和肺泡氧分压（PO2）的影响。对于健康的肺而言，通过使局部灌注（q）与局部通气（v）相匹配来限制肺泡气体成分异质性时，这种影响在功能上的重要程度尚不清楚。为了解决这个问题，调节效率（E）被定义为对由肺血管对干扰的反应所产生的局部肺泡气体成分初始扰动的校正百分比。本研究建立了一种理论，可根据对人类志愿者血管对二氧化碳和氧气反应性的整体测量来计算E。对于氧气，这些数据可从文献中获取。对于二氧化碳，本研究的实验部分使用多普勒超声心动图在大约0.5小时的时间尺度上评估了12名志愿者对高碳酸血症和低碳酸血症的整体血管反应幅度。结果表明，在v/q比值的广泛取值范围（约0.1 - 10，涵盖正常肺中的取值）内，E值约为60%。在低v/q（<0.65）时，血管对氧气的反应是主要机制；然而，在较高v/q（>0.65）时，对二氧化碳的反应起主导作用。E值表明，肺血管对二氧化碳和氧气的反应在健康人肺的通气 - 灌注匹配中都起着重要作用。
