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Assessing the Effects of Crew Exposure to Cabin Altitudes of 8,000 ft to 10,000 ft. A Literature Review and Recommendations
Abstract/OtherAbstract :
Introduction. In an effort to prolong airframe life of E model CCl30 aircraft, cabin pressure has been degraded to 10 PSI from the normal 15.3 PSI. This has resulted in higher cabin altitudes at operational altitudes. Whereas at normal operational altitudes, cabin altitudes used to be in the 1,500 ft range, they are now between 8,000 ft and 10,000 ft. Such cabin altitudes have recently provoked 2 physiologic incidents. Acute Mountains Sickness (AMS) has been reported at altitudes as low as 6,500 ft. This report will review the literature on AMS and will address the issue of risk management for aircrews flying at cabin altitudes between 8,000 ft and 10,000 ft. Review of AMS. Essentially, travelling too quickly to altitudes over 8,000 ft often results in symptoms of AMS with nearly 25% of persons affected at 6,500 ft. Incidence and severity of AMS vary with rate of ascent, altitude attained, time at altitude and original altitude. AMS symptoms can start to appear within 5 to 6 hours of exposure to altitude. If ascent is halted, AMS usually resolves within 1-2 days, but substantial discomfort and inconvenience are commonly encountered. Above 13,000 ft, the life threatening high altitude pulmonary (HAPE) and/or cerebral (HACE) edema occurs in about 5% of those afflicted with AMS. While there are several different theories as to the mechanism on onset of AMS, the exact cause remains unclear. Certainly, the hypoxia and hypercapnia that are brought on by unprotected exposure to altitude result in vasodilatation that in turn increases cerebral blood flow. The blood-brain barrier (BBB) may be altered in hypoxia and may facilitate increase cerebral blood volume as well as intracranial pressure and may explain swollen and edematous brains on autopsy. Craniospinal capacitance (the ability to shunt cerebrospinal fluid from the brain to the spinal canal in response to raised intracranial pressure) may prevent or attenuate AMS symptoms.
Authors :
Paul, Michel, Gray, Gary
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Contributors :
DEFENCE RESEARCH AND DEVELOPMENT TORONTO (CANADA)
Publication Detail :
Publisher :  -     Type :  Text     Format :  text/html    
Date Detail :
2002-08
Subject :
ANATOMY AND PHYSIOLOGY, MEDICINE AND MEDICAL RESEARCH, *STRESS(PHYSIOLOGY), *ALTITUDE SICKNESS, FLIGHT CREWS, CANADA, SIGNS AND SYMPTOMS, MOUNTAINS, HIGH ALTITUDE, HYPOXIA, EXPOSURE(PHYSIOLOGY), TRANSPORT AIRCRAFT, BLOOD CIRCULATION, AIRCRAFT CABINS, CEREBROSPINAL FLUID, HYPERCAPNIA, RISK MANAGEMENT., FOREIGN REPORTS, CC-130 AIRCRAFT, AMS(ACUTE MOUNTAINS SICKNESS)
Coverage :
-
Relation :
-
Source :
DTIC
Copyright Information :
APPROVED FOR PUBLIC RELEASE
Other Details :
Languages :  en    
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