Aviat Space Envir Md
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Aviat Space Envir Md · Jun 2001
The effect of exposure to 35,000 ft on incidence of altitude decompression sickness.
Exposure to 35,000 ft without preoxygenation (breathing 100% oxygen prior to decompression) can result in severe decompression sickness (DCS). Exercise while decompressed increases the incidence and severity of symptoms. Clarification of the level of activity vs. time to symptom onset is needed to refine recommendations for current operations requiring 35,000-ft exposures. Currently, the U.S. Air Force limits these operations to 30 min following 75 min of preoxygenation. The objective of this study was to determine the effect of exercise intensity on DCS incidence and severity at 35,000 ft. ⋯ The results showed that current guidelines for 35,000-ft exposures keep DCS risk below 10% at rest. Exercise, even at mild levels, greatly increases the incidence and rate of onset of DCS.
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Aviat Space Envir Md · Jun 2001
A potential role for free radical-mediated skeletal muscle soreness in the pathophysiology of acute mountain sickness.
It has been suggested that free radicals may be implicated in the pathophysiology of acute mountain sickness (AMS) due to their ability to initiate and propagate cell membrane damage (3). Therefore, the present study was designed to: a) investigate the effects of an expedition to high altitude on metabolic indices of free radical-mediated oxidative stress and assess subsequent implications for skeletal/cardiac muscle damage; and b) determine whether these parameters were different in subjects who developed AMS after gradual ascent to 5100 m (base camp, BC) compared with those who remained healthy. ⋯ Localized free radical-mediated vascular damage of the blood-brain barrier in addition to systemic tissue damage causing overt skeletal muscle soreness may have contributed to the pathophysiology of AMS, the latter through its indirect effects on other non-specific constitutional symptoms such as fatigue and insomnia causing a deterioration in physical performance.