Asphyxia

Asphyxia (from Greek a-, "without" and sexuxis, "pulse, heartbeat") is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs most sensitive to hypoxia first, such as the brain, hence resulting in cerebral hypoxia. Asphyxia is usually characterized by air hunger but this is not always the case; the urge to breathe is triggered by rising carbon dioxide levels in the blood rather than diminishing oxygen levels. Sometimes there is not enough carbon dioxide to cause air hunger, and victims become hypoxic without knowing it. In any case, the absence of effective remedial action will very rapidly lead to unconsciousness, brain damage and death. The time to death is dependent on the particular mechanism of asphyxia.

Asphyxia is used to maim or kill in capital punishment, suicide, torture, and warfare. It is also used non-fatally in martial arts, combat sports, BDSM and during sex as erotic asphyxia. Because the need to breathe is triggered by the level of carbon dioxide in the blood, some victims may not experience an urgent need to breathe and may remain unaware of the onset of hypoxia.