Effects of mild hypoxia on the restoration in cerebral blood flow during temporal decreases in blood pressure and dynamic cerebral autoregulation.

我们进行了这项研究，估计在血压短暂下降期间脑血流的恢复率，以验证我们的假设，即急性暴露于轻度缺氧时，动态脑自动调节受到损害。低氧状态下，股袖放气恢复CBF血流速度的百分比显著降低，传递函数相干性和甚低频增益显著增加。这些结果共同提供了一个一致的发现，即轻度缺氧损害了动态的大脑自我调节，表明在轻度缺氧期间，直立姿势晕厥的风险很高。

We conducted this study estimating the restoration rate in cerebral blood flow during temporal decreases in blood pressure, to test our hypothesis that dynamic cerebral autoregulation is impaired during acute exposure to mild hypoxia. The percentage restoration in CBF velocity by thigh cuff deflation decreased significantly during hypoxia Moreover, transfer function coherence and gain in the very-low-frequency range increased significantly. These results provide together a consistent finding that mild hypoxia impairs dynamic cerebral autoregulation, suggesting high risk of syncope at upright posture during mild hypoxia.