Fatemian Marzieh, Herigstad Mari, Croft Quentin P P, Formenti Federico, Cardenas Rosa, Wheeler Carly, Smith Thomas G, Friedmannova Maria, Dorrington Keith L, Robbins Peter A
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK.
J Physiol. 2016 Mar 1;594(5):1197-213. doi: 10.1113/JP270061. Epub 2015 Jun 5.
Pulmonary ventilation and pulmonary arterial pressure both rise progressively during the first few hours of human acclimatization to hypoxia. These responses are highly variable between individuals, but the origin of this variability is unknown. Here, we sought to determine whether the variabilities between different measures of response to sustained hypoxia were related, which would suggest a common source of variability. Eighty volunteers individually underwent an 8-h isocapnic exposure to hypoxia (end-tidal P(O2)=55 Torr) in a purpose-built chamber. Measurements of ventilation and pulmonary artery systolic pressure (PASP) assessed by Doppler echocardiography were made during the exposure. Before and after the exposure, measurements were made of the ventilatory sensitivities to acute isocapnic hypoxia (G(pO2)) and hyperoxic hypercapnia, the latter divided into peripheral (G(pCO2)) and central (G(cCO2)) components. Substantial acclimatization was observed in both ventilation and PASP, the latter being 40% greater in women than men. No correlation was found between the magnitudes of pulmonary ventilatory and pulmonary vascular responses. For G(pO2), G(pCO2) and G(cC O2), but not the sensitivity of PASP to acute hypoxia, the magnitude of the increase during acclimatization was proportional to the pre-acclimatization value. Additionally, the change in G(pO2) during acclimatization to hypoxia correlated well with most other measures of ventilatory acclimatization. Of the initial measurements prior to sustained hypoxia, only G(pCO2) predicted the subsequent rise in ventilation and change in G(pO2) during acclimatization. We conclude that the magnitudes of the ventilatory and pulmonary vascular responses to sustained hypoxia are predominantly determined by different factors and that the initial G(pCO2) is a modest predictor of ventilatory acclimatization.
在人类适应低氧的最初几个小时内，肺通气和肺动脉压均会逐渐升高。这些反应在个体之间差异很大，但这种变异性的来源尚不清楚。在这里，我们试图确定对持续性低氧反应的不同测量指标之间的变异性是否相关，这将提示存在一个共同的变异来源。80名志愿者在特制的舱室内分别接受了8小时的等碳酸血症性低氧暴露（呼气末P(O2)=55托）。在暴露期间，通过多普勒超声心动图测量通气和肺动脉收缩压（PASP）。在暴露前后，测量对急性等碳酸血症性低氧（G(pO2)）和高氧性高碳酸血症的通气敏感性，后者分为外周（G(pCO2)）和中枢（G(cCO2)）成分。在通气和PASP方面均观察到了显著的适应，后者在女性中比男性高40%。未发现肺通气反应和肺血管反应的幅度之间存在相关性。对于G(pO2)、G(pCO2)和G(cCO2)，但不是PASP对急性低氧的敏感性，适应期间增加的幅度与适应前的值成比例。此外，在适应低氧期间G(pO2)的变化与大多数其他通气适应指标密切相关。在持续性低氧之前的初始测量中，只有G(pCO2)预测了适应期间随后的通气增加和G(pO2)的变化。我们得出结论，对持续性低氧的通气反应和肺血管反应的幅度主要由不同因素决定，并且初始G(pCO2)是通气适应的一个适度预测指标。
