Aviat Space Envir Md
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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.
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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.