Hypoxia (medical)

Hypoxia is a pathological condition in which the body as a whole (generalised hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. Hypoxia in which there is complete deprivation of oxygen supply is referred to as anoxia.

Hypoxia is distinguished from apoxemia. Apoxemia is an abnormally low partial pressure of oxygen (PO2) in arterial blood . A frequent error is to use the term hypoxemia to mean low oxygen content in arterial blood. It is possible to have a low oxygen content (eg due to anemia) but a high PO2 also incorrect use can lead to confusion.

Generalised hypoxia occurs in healthy people when they ascend to high altitude, where it causes altitude sickness, and the potentially fatal complications of altitude sickness, high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Hypoxia also occurs in healthy individuals when breathing mixtures of gases with a low oxygen content, for example while diving underwater, especially with closed-circuit rebreather systems that control the amount of oxygen in the air breathed in. Altitude training uses mild hypoxia to increase the concentration of red blood cells in the body for increased athletic performance.