Impact of Oxygen Supplementation on Brachial Artery Hemodynamics and Vascular Function During Ascent to 5,050 m

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 (O 2 ) 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 2 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, O 2 decreased brachial artery diameter (−5% ± 5%; p = 0.04), baseline blood flow (−44% ± 15%; p