Aviat Space Envir Md
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Aviat Space Envir Md · Feb 2009
Review Comparative StudyCivil aviation rules on crew flight time, flight duty, and rest: comparison of 10 ICAO member states.
Members of the International Civil Aviation Organization (ICAO) use various criteria to control flight crew scheduling and rest periods with the intention of reducing fatigue and thus improving airline safety. Comparison of these rules across nations may allow future harmonization of the criteria. ⋯ Although the 10 states in this study have common aims and premises for regulating crew duty, their regulations diverge with respect to details, using different tools in an effort to prevent the occurrence of excessive fatigue in aircrew members.
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Aviat Space Envir Md · Dec 2008
Predive sauna and venous gas bubbles upon decompression from 400 kPa.
This study investigated the influence of a far infrared-ray dry sauna-induced heat exposure before a simulated dive on bubble formation, and examined the concomitant adjustments in hemodynamic parameters. ⋯ A single predive sauna session significantly decreases circulating bubbles after a chamber dive. This may reduce the risk of decompression sickness. Sweat dehydration, HSP, and the NO pathway could be involved in this protective effect.
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Aviat Space Envir Md · Nov 2008
Two hypoxia sensor genes and their association with symptoms of acute mountain sickness in Sherpas.
Hypoxia-inducible factor (HIF) and von Hippel-Lindau tumor suppressor protein (VHL) are hypoxia sensors that control cellular responses to hypoxia. Although many Sherpas live at high altitudes for their entire lives, some of them manifest symptoms of acute mountain sickness (AMS) during mountaineering at extremely high altitudes. We hypothesize that the two hypoxia sensor genes might associate with the occurrence of AMS symptoms in Sherpas at extremely high altitude. ⋯ These genetic variants of HIF1A and VHL are not associated with AMS symptoms that occur in Sherpas at extremely high altitudes. It seems unlikely that HIF1A and VHL are associated with hypoxic sensing sensitivity in Sherpas.
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Aviat Space Envir Md · Oct 2008
Civilian helicopter accidents into water: analysis of 46 cases, 1979-2006.
When a helicopter crashes or ditches into water the crew and passengers must often make an escape from underwater and a number of the occupants do not survive. This paper examined fatality rates, human factors problems with escape, and causes of death in Canadian civilian registered helicopter accidents in water (1979-2006). ⋯ Survival rates for Canadian registered helicopter accidents into water (78%) show little change from previously reported worldwide data. Lack of warning time, rapid sinking, and inversion were the significant factors in the survival rate. The practical implication is that crew and passengers involved in planned flights over water must wear all the life support equipment on strap-in and not have it stowed on the back of the seat or in the cabin.
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The adverse effects of hypoxic hypoxia include acute mountain sickness (AMS), high altitude pulmonary edema, and high altitude cerebral edema. It has long been assumed that those manifestations are directly related to reduction in the inspired partial pressure of oxygen (P(I)O2). This assumption underlies the equivalent air altitude (EAA) model, which holds that combinations of barometric pressure (P(B)) and inspired fraction of O2 (F(I)O2) that produce the same P(I)O2 will result in identical physiological responses. ⋯ These data provide evidence for an independent effect of P(B) on hypoxia and AMS, and thereby invalidate EAA as an ideal model of isohypoxia. Refinement of the EAA model is needed, in particular for applications to high altitude where supplemental O2 is inadequate to prevent hypoxic hypoxia. Adjustment through probabilistic statistical modeling to match the current limited experimental observations is one approach to a better isohypoxic model.