Vizcardo-Galindo, Gustavo A., Connor A. Howe, Ryan L. Hoiland, Howard H. Carter, Christopher K. Willie, Philip N. Ainslie, and Joshua C. Tremblay. Impact of oxygen supplementation on brachial artery hemodynamics and vascular function during ascent to 5,050 m. High Alt Med Biol. 24:27-36, 2023.-High-altitude trekking alters upper limb hemodynamics and reduces brachial artery vascular function in lowlanders. Whether these changes are reversible with the removal of hypoxia is unknown. We investigated the impact of 20 minutes of oxygen supplementation (O2) on brachial artery hemodynamics, reactive hyperemia (RH; microvascular function), and flow-mediated dilation (FMD; endothelial function). Participants (aged 21-42 years) were examined before and with O2 at 3,440 m (n = 7), 4,371 m (n = 7), and 5,050 m (n = 12) using Duplex ultrasound (days 4, 7, and 10 respectively). At 3,440 m, O2 decreased brachial artery diameter (-5% ± 5%; p = 0.04), baseline blood flow (-44% ± 15%; p < 0.001), oxygen delivery (-39 ± 16; p < 0.001), and peak RH (-8% ± 8%; p = 0.02), but not RH normalized for baseline blood flow. Elevated FMD (p = 0.04) with O2 at 3,440 m was attributed to the reduction in baseline diameter. At 5,050 m, a reduction in brachial artery blood flow (-17% ± 22%; p = 0.03), but not oxygen delivery, diameter, RH, or FMD occurred with O2. These findings suggest that during early trekking at high altitude, O2 causes vasoconstriction in the upper limb along the arterial tree (conduit and resistance arteries). With incremental high-altitude exposure, O2 reduces blood flow without compromising oxygen delivery, RH, or FMD, suggesting a differential impact on vascular function modulated by the duration and severity of high-altitude exposure.

中文翻译：

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在上升至 5,050 米过程中补氧对肱动脉血流动力学和血管功能的影响。

Vizcardo-Galindo、Gustavo A.、Connor A. Howe、Ryan L. Hoiland、Howard H. Carter、Christopher K. Willie、Philip N. Ainslie 和 Joshua C. Tremblay。上升至 5,050 米期间补氧对肱动脉血流动力学和血管功能的影响。高 Alt 医学生物学。24:27-36, 2023.-高海拔徒步改变了低地人的上肢血流动力学并降低了肱动脉血管功能。这些变化是否随着缺氧的消除而可逆尚不清楚。我们研究了 20 分钟的氧气补充 (O2) 对肱动脉血流动力学、反应性充血（RH；微血管功能）和血流介导的扩张（FMD；内皮功能）的影响。参与者（21-42 岁）在 3,440 米（n = 7）、4,371 米（n = 7）和 5,050 米（n = 12）之前和使用 O2 时使用双重超声检查（第 4、7 天、和 10 个）。在 3,440 米处，O2 减少了肱动脉直径（-5% ± 5%；p = 0.04）、基线血流量（-44% ± 15%；p < 0.001）、氧气输送（-39 ± 16；p < 0.001）和峰值 RH（-8% ± 8%；p = 0.02），但不是针对基线血流标准化的 RH。O2 在 3,440 m 处升高的 FMD (p = 0.04) 归因于基线直径的减小。在 5,050 米处，肱动脉血流量减少（-17% ± 22%；p = 0.03），但氧气输送、直径、RH 或 FMD 不会因 O2 而发生。这些发现表明，在早期高海拔徒步旅行期间，O2 导致上肢沿动脉树（导管和阻力动脉）的血管收缩。随着高海拔暴露的增加，O2 在不影响氧气输送、RH 或 FMD 的情况下减少血流量，