Ventilatory, hemodynamic, sympathetic nervous system, and vascular reactivity changes after recurrent nocturnal sustained hypoxia in humans
Ventilatory, hemodynamic, sympathetic nervous system, and vascular reactivity changes after recurrent nocturnal sustained hypoxia in humans
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DOI：
10.1152/ajpheart.00653.2007
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发表时间：
2008-08-01
影响因子：
4.8
通讯作者：
Weiss, J. Woodrow
中科院分区：
文献类型：
--
作者：
Gilmartin, Geoffrey S.;Tamisier, Renaud;Weiss, J. Woodrow
反复和间歇性夜间低氧是几种疾病的特征，包括慢性阻塞性肺疾病、充血性心力衰竭、肥胖-低通气综合征和阻塞性睡眠呼吸暂停。然而，在这些疾病状态下，低氧对心血管发病率和死亡率的影响尚不清楚。为了探讨反复夜间低氧对血流动力学、交感神经活性和血管张力的影响，我们对10名正常志愿者在夜间持续低氧14个晚上(平均血氧饱和度84.2%，9h/晚)前后进行了评估。在暴露期间，受试者表现出对低氧的呼吸习服，表现为静息通气量(动脉二氧化碳分压41.8+/-1.5vs.37.5+/-1.3毫米汞柱，平均+/-SD；P<；0.05)和等量低氧呼吸反应(斜率0.49+/-0.1vs.1.32+/-0.2 L/分钟每下降1%饱和度；P<；0.05)。受试者的平均动脉压(86.7±-6.1比90.5+/-7.6毫米汞柱；P<；0.001)、肌交感神经活动(2 0.8±-2.8次/分钟比28.2+/-3.3次/分钟；P<；0.0 1)和前臂血管阻力(39.6+/-3.5比47.5±-4.8毫米汞柱)显著增加。Ml(-1)(.)100g组织(.)最小；P<；0.05)。急性等量低氧时前臂血流量在暴露后增加，但在选择性臂动脉内输注α-阻滞剂酚妥拉明时，暴露后没有变化。最后，在低氧暴露后，反应性充血减少到前臂缺血15分钟。因此，反复夜间低氧会增加交感神经活性，改变外周血管张力。这些变化可能导致与慢性复发性缺氧相关的临床疾病相关的心脑血管风险增加。
Recurrent and intermittent nocturnal hypoxia is characteristic of several diseases including chronic obstructive pulmonary disease, congestive heart failure, obesity-hypoventilation syndrome, and obstructive sleep apnea. The contribution of hypoxia to cardiovascular morbidity and mortality in these disease states is unclear, however. To investigate the impact of recurrent nocturnal hypoxia on hemodynamics, sympathetic activity, and vascular tone we evaluated 10 normal volunteers before and after 14 nights of nocturnal sustained hypoxia (mean oxygen saturation 84.2%, 9 h/night). Over the exposure, subjects exhibited ventilatory acclimatization to hypoxia as evidenced by an increase in resting ventilation (arterial PCO2 41.8 +/- 1.5 vs. 37.5 +/- 1.3 mmHg, mean +/- SD; P < 0.05) and in the isocapnic hypoxic ventilatory response (slope 0.49 +/- 0.1 vs. 1.32 +/- 0.2 l/min per 1% fall in saturation; P < 0.05). Subjects exhibited a significant increase in mean arterial pressure (86.7 +/- 6.1 vs. 90.5 +/- 7.6 mmHg; P < 0.001), muscle sympathetic nerve activity (20.8 +/- 2.8 vs. 28.2 +/- 3.3 bursts/min; P < 0.01), and forearm vascular resistance (39.6 +/- 3.5 vs. 47.5 +/- 4.8 mmHg (.) ml(-1) (.) 100 g tissue (.) min; P < 0.05). Forearm blood flow during acute isocapnic hypoxia was increased after exposure but during selective brachial intra-arterial vascular infusion of the alpha-blocker phentolamine it was unchanged after exposure. Finally, there was a decrease in reactive hyperemia to 15 min of forearm ischemia after the hypoxic exposure. Recurrent nocturnal hypoxia thus increases sympathetic activity and alters peripheral vascular tone. These changes may contribute to the increased cardiovascular and cerebrovascular risk associated with clinical diseases that are associated with chronic recurrent hypoxia.