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Acclimatization
Published in Andrew M. Luks, Philip N. Ainslie, Justin S. Lawley, Robert C. Roach, Tatum S. Simonson, Ward, Milledge and West's High Altitude Medicine and Physiology, 2021
Andrew M. Luks, Philip N. Ainslie, Justin S. Lawley, Robert C. Roach, Tatum S. Simonson
Although medications are often used to facilitate acclimatization and decrease the risk of acute altitude illness (Chapters 20 and 22), they cannot provide the same protection against AMS, HACE, or HAPE or improve cognitive and physical performance to the same extent as allowing adequate time for acclimatization and the protective physiological responses. There has been increasing interest among mountaineers and other high altitude travelers in strategies that can be employed ahead of the planned high altitude excursion to accelerate the process of acclimatization. While the most reliable method would be to live 24 hours a day for several weeks in a hypobaric chamber (Houston and Riley 1947; Houston et al. 1987; Richalet 2010), such a strategy is infeasible for the overwhelming majority of people traveling to high altitude, and other less time-intensive strategies are necessary.
Sub-atmospheric decompression illness
Published in Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol, Handbook of Aviation and Space Medicine, 2019
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol
Sub-atmospheric decompression illness (DCI) results from hypobaric decompression to ambient pressures less than 1 atm. May occur during ascent to altitude in aircraft, use of extra-vehicular activity spacesuit, or decompression in hypobaric chamber.
Exercise at altitude
Published in Robert B. Schoene, H. Thomas Robertson, Making Sense of Exercise Testing, 2018
Robert B. Schoene, H. Thomas Robertson
Many studies at extreme altitudes, including both field and hypobaric chamber studies to the equivalent of the summit of Mt Everest, have shown a predictable decrease in maximum oxygen consumption. For instance, the max after prolonged exposure to very high altitudes (∼>6000 m) was 20% of what it was at sea level—some work (one L O2/min vs. 5 L O2/min), but not a lot and certainly not sustainable.
Central Corneal Thickness of Healthy Lowlanders at High Altitude: A Systematic Review and Meta-Analysis
Published in Current Eye Research, 2018
Hsin-Ming Liu, Chyi-Huey Bai, Cher-Ming Liou, Hung-Yi Chiou, Chiehfeng Chen
Our study has several limitations. First, trials conducted at both altitude and simulated altitude were included. Although hypobaric chambers might not necessarily reflect geographical conditions on a mountain, the test for subgroup differences between hypobaric chambers and real altitude in our study showed no statistical significance. Second, 100% oxygen masks were provided to participants of the two trials conducted in the hypobaric chamber. The reason for not giving the same oxygen level at high elevations was because of the chamber safety rules for avoiding decompression sickness, and as the mask covered only the nose and mouth, oxygen was not directly administered to the cornea. Third, CCT changes due to high-elevation exposure were not continuously investigated, and this was mainly because only a minority of included trials reported serial CCT measurements. Thus, further studies with daily measurements of CCT at high altitude and a close follow-up of CCT after descent to lower elevations are required to achieve a comprehensive understanding of cornea edema formation and recovery.
Compound Danshen Dripping Pill inhibits high altitude-induced hypoxic damage by suppressing oxidative stress and inflammatory responses
Published in Pharmaceutical Biology, 2021
Yunhui Hu, Jia Sun, Tongxing Wang, Hairong Wang, Chunlai Zhao, Wenjia Wang, Kaijing Yan, Xijun Yan, He Sun
In order to investigate the function of CDDP in tissue damage caused by hypobaric hypoxia, we used a hypobaric chamber to simulate high altitude low pressure. Exposure to hypobaric hypoxia for 24 h induced pulmonary edoema and vacuoles, which were alleviated by CDDP or ACTZ (Figure 3(A)). ACTZ is a drug approved by US Food and Drug Administration for AMS and used in our study as a reference control. Although no obvious damage could be observed in H & E staining of heart tissue (Figure 3(B)), expression of N-terminal pro-brain natriuretic peptide (NT-proBNP), an important marker indicating injured myocardium (Hall 2004), increased in the rats exposed to hypobaric hypoxia. However, CDDP administration, but not ACTZ, attenuated its increase significantly (Figure 3(C)).
Comparative study of the effect of bilastine and cetirizine on cognitive functions at ground level and at an altitude of 4,000 m simulated in hypobaric chamber: a randomized, double-blind, placebo-controlled, cross-over study
Published in Expert Opinion on Drug Safety, 2018
Ákos Reményi, Andor Grósz, Sándor András Szabó, Zsolt Tótka, Dávid Molnár, Frigyes Helfferich
In our study, due to the points above, we were not satisfied with low altitude testing and with the sole application of the hypoxia condition. The hypobaric chamber was, therefore, an indispensable means of testing, without endangering the health of the volunteers, but with the testing criteria satisfied with 4,000 m maximum simulated altitude.