Design and conduct of %26apos;Xtreme Alps%26apos;: A double-blind, randomised controlled study of the effects of dietary nitrate supplementation on acclimatisation to high altitude

作者：Martin Daniel S^*; Gilbert Kawai Edward T; Meale Paula M; Fernandez Bernadette O; Cobb Alexandra; Khosravi Maryam; Mitchell Kay; Grocott Michael P W; Levett Denny Z H; Mythen Michael G; Feelisch Martin

来源：Contemporary Clinical Trials, 2013, 36(2): 450-459.

DOI：10.1016/j.cct.2013.09.002

• High altitude
• Critical care
• Hypoxia
• Hypoxaemia
• Nitric oxide
• Exercise
• Microcirculation

The study of healthy human volunteers ascending to high altitude provides a robust model of the complex physiological interplay that emulates human adaptation to hypoxaemia in clinical conditions. Nitric oxide (NO) metabolism may play an important role in both adaptation to high altitude and response to hypoxaemia during critical illness at sea level. Circulating nitrate and nitrite concentrations can be augmented by dietary supplementation and this is associated with improved exercise performance and mitochondria( efficiency. We hypothesised that the administration of a dietary substance (beetroot juice) rich in nitrate would improve oxygen efficiency during exercise at high altitude by enhancing tissue microcirculatory blood flow and oxygenation. Furthermore, nitrate supplementation would lead to measurable increases in NO bioactivity throughout the body. %26lt;br%26gt;This methodological manuscript describes the design and conduct of the %26apos;Xtreme Alps%26apos; expedition, a double-blind randomised controlled trial investigating the effects of dietary nitrate supplementation on acclimatisation to hypobaric hypoxia at high altitude in healthy human volunteers. The primary outcome measure was the change in oxygen efficiency during exercise at high altitude between participants allocated to receive nitrate supplementation and those receiving a placebo. A number of secondary measures were recorded, including exercise capacity, peripheral and microcirculatory blood flow and tissue oxygenation. %26lt;br%26gt;Results from this study will further elucidate the role of NO in adaption to hypoxaemia and guide clinical trials in critically ill patients. Improved understanding of hypoxaemia in critical illness may provide new therapeutic avenues for interventions that will improve survival in critically ill patients.

• 出版日期2013-11