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Selection and Training
Published in David G. Newman, Flying Fast Jets, 2014
For the purposes of demonstrating the effects of hypoxia, most air forces use a hypobaric chamber. These devices consist of a large main chamber in which the students sit (up to 12 aircrew at a time). The atmospheric pressure in this chamber is altered by a series of vacuum pumps to produce the desired altitude. Most chambers can simulate altitudes well above 50,000 feet (up to 100,000 feet in many cases). The chambers are also generally able to produce a rapid or explosive decompression, to simulate loss of cockpit pressure or loss of the canopy, for example. This training allows aircrew to become familiar with the fundamental features of decompression, and what it feels like. It also allows them to practise some of the protective techniques that they must learn, such as positive pressure breathing for aircrew operating at altitudes over 40,000 feet. The rate of ascent and descent of the chamber’s altitude is generally computer-controlled in modern chambers.
Circulating markers of intestinal barrier injury and inflammation following exertion in hypobaric hypoxia
Published in European Journal of Sport Science, 2023
Zachary J. McKenna, Bryanne N. Bellovary, Jeremy B. Ducharme, Michael R. Deyhle, Andrew D. Wells, Zachary J. Fennel, Jonathan W. Specht, Jonathan M. Houck, Trevor J. Mayschak, Christine M. Mermier
Participants were instructed to refrain from alcohol for 24 h, strenuous exercise for 12 h, and caffeine for four hours before the experimental trial. During the experimental trial, participants underwent a six-hour exposure to hypobaric hypoxia simulating an altitude of 4572 m (∼430 Torr). Altitude was simulated using a customized hypobaric chamber at the University of New Mexico. Simulated ascent increased by ≤ 305 m per minute to prevent confounding symptoms related to a rapid simulated ascent (e.g. ear pain, dizziness, lightheadedness). During the first three hours of exposure participants completed two 30-minute bouts of cycling at workload equal to 50% of their normobaric VO2max (Roach et al., 2000). The cycling bouts were separated by at least one hour. Heart rate (Polar H10) and oxygen saturation (SpO2) (Nonin Go2 pulse oximeter) were measured at the end of each bout of exercise and again at the end of the six-hour exposure just prior to descending. Participants were free to read or interact with video screens while seated during the resting periods and were permitted to eat a standardized light snack (380 calories) and drink water ad libitum. Participants were not permitted to sleep during the hypoxic exposure. AMS was assessed using the modified Lake Louise AMS score (Roach et al., 2018). Lake Louise AMS scores were recorded after six hours of hypobaric hypoxic exposure. Classifications of AMS was AMS + for scores greater than or equal to 3 with headache and AMS – for scores less than 3 (Roach et al., 2018).