Vizcardo-Galindo Gustavo A, Howe Connor A, Hoiland Ryan L, Carter Howard H, Willie Christopher K, Ainslie Philip N, Tremblay Joshua C
Centre for Heart, Lung & Vascular Health, Faculty of Health and Social Development, University of British Columbia-Okanagan, Kelowna, Canada.
Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, Canada.
High Alt Med Biol. 2023 Mar;24(1):27-36. doi: 10.1089/ham.2022.0107.
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. . 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 (O) 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 O at 3,440 m ( = 7), 4,371 m ( = 7), and 5,050 m ( = 12) using Duplex ultrasound (days 4, 7, and 10 respectively). At 3,440 m, O decreased brachial artery diameter (-5% ± 5%; = 0.04), baseline blood flow (-44% ± 15%; < 0.001), oxygen delivery (-39 ± 16; < 0.001), and peak RH (-8% ± 8%; = 0.02), but not RH normalized for baseline blood flow. Elevated FMD ( = 0.04) with O 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%; = 0.03), but not oxygen delivery, diameter, RH, or FMD occurred with O. These findings suggest that during early trekking at high altitude, O causes vasoconstriction in the upper limb along the arterial tree (conduit and resistance arteries). With incremental high-altitude exposure, O 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.
维兹卡多 - 加林多，古斯塔沃·A.，康纳·A. 豪，瑞安·L. 霍伊兰德，霍华德·H. 卡特，克里斯托弗·K. 威利，菲利普·N. 安斯利，约书亚·C. 特伦布莱。补充氧气对攀登至5050米过程中肱动脉血流动力学和血管功能的影响。《……》24:27 - 36，2023年。——高海拔徒步会改变低地居民的上肢血流动力学并降低肱动脉血管功能。这些变化在缺氧消除后是否可逆尚不清楚。我们研究了补充20分钟氧气（O）对肱动脉血流动力学、反应性充血（RH；微血管功能）和血流介导的舒张（FMD；内皮功能）的影响。参与者（年龄21 - 42岁）在3440米（n = 7）、4371米（n = 7）和5050米（n = 12）处，分别在第4天、第7天和第10天使用双功超声在补充氧气前和补充氧气时进行检查。在3440米处，补充氧气使肱动脉直径减小（-5% ± 5%；P = 0.04）、基线血流量减少（-44% ± 15%；P < 0.001）、氧输送量降低（-39 ± 16；P < 0.001）以及峰值RH降低（-8% ± 8%；P = 0.02），但基线血流量标准化后的RH未受影响。在3440米处补充氧气时FMD升高（P = 0.04）归因于基线直径的减小。在5050米处，补充氧气使肱动脉血流量减少（-17% ± 22%；P = 0.03），但氧输送量、直径、RH或FMD未受影响。这些发现表明，在高海拔早期徒步过程中，补充氧气会导致上肢沿动脉树（传导动脉和阻力动脉）出现血管收缩。随着高海拔暴露程度增加，补充氧气会减少血流量，但不影响氧输送量、RH或FMD，这表明高海拔暴露的持续时间和严重程度对血管功能有不同的影响。
