Hypoxia

In medicine

The hypoxia consists of a reduction in the oxygen concentration in blood sufficient to bring signs and symptoms of an inadequate oxygenation of fabrics.

The hypoxemy occurs when arterial oxygen is located under the normal value. A not corrected hypoxemy leads to a hypoxia.

(For review: Sharp and Bernaudin, 2004; Richalet and Herry, Medicine of the alpinism and the sport of mountains (ED Masson)

Hypoxia hypobare and hypoxia normobare

The hypoxia of altitude (that of the natural environment) is known as hypobare. It is the pressure decrease of the atmospheric air (less 760mmHg) which leads to the pressure decrease partial of each gas which composes it, of which the Dioxygène. However each gas remains identical in proportion, there are always 20.93% of Dioxygène in the air.

On the contrary, there exists the hypoxia normobare, often used in laboratory to simulate a rise in altitude. This it is not a pressure decrease of the air, but simply a reduction on behalf of the Dioxygène in the air (less than 20.93%), by injecting for example a surplus of Azote to the gas mixture.

In pedology

This term of hypoxia is also used in Pédologie for a ground low in oxygen.

In watery ecology

The hypoxia of fresh water, brackish and marine, often directly caused by the human activities can lead an aquatic environment to the Anoxie (total deprivation of dioxygene) and to the more or less durable phenomenon of dead Zone (disappearance of higher forms of life). Many recent causes of hypoxia add their noxious effects on the ecosystems and health via the increased production of dangerous Toxine S for the man in the mediums low in dioxygene, of which certain likely to be accumulated by fish, shells (Huître S, hull S, mould S.), littoral marine mammals, birds that the Man consumes. The botulinic toxin is an example.

Random links: