Hypoxia names a situation whereby the oxygen availability is not sufficient enough for the body vital functions.
It can be found in several pathological situations such as respiratory or cardiac diseases. The body as a whole or only a body part (tissue hypoxia) are deprivated of the proper oxygen supply. Hypoxia occurs when the oxygen inflow is too weak for the cells. Such a mismatch emerges when the lungs are unable to oxygenate the blood enough, for instance in a chronic obstructive pulmonary disease (COPD) case or a sleep apnea syndrom.
An arterial oxygen quantity reducing (hypoxemia) can also be seen in some physiological situations, such as altitude.
Hypoxia exists under diverse forms :
- continue (the level of hypoxia remains steady on a given time),
- intermittent (hypoxic and re-oxygenation phases sequences)
- chronic (on an extended period)
- normobaric (under see level like atmospheric pressure conditions),
- hypobaric (induced by an atmospheric pressure decrease, such as altitude).
Hypoxia can also generate adaptations and/or maladaptations.
The body can adapt to hypoxemix conditions, for example by increasing ventilation, heart rate and blood flow. By extending the hypoxia exposition time, the body will drive up its hemoglobin production and thus its oxygen blood transport capacity. Hence, the hypoxia exposition can be responsible for a couple of favorable adaptations (some athletes use it as a way of improving their physical performances).
Hypoxia might seem to have good effects on the body, but it can also be responsible for numerous noxious effects on the body. For instance, by inducing vascular abnormalities, inflammation and even cell death. Hypoxia is a key element in numerous pathological situations.