Asphyxia (from Greek a-, “without” and  (sphygmos), “pulse, heartbeat”) is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs.
Carbon monoxide inhalation, such as from a car exhaust: carbon monoxide has a higher affinity than oxygen to the hemoglobin in the blood’s red blood corpuscles, bonding with it tenaciously, and, in the process, displacing oxygen and preventing the blood from transporting it around the body,
Contact with certain chemicals, including pulmonary agents (such as phosgene) and blood agents (such as hydrogen cyanide),
Self-induced hypocapnia by hyperventilation, as in shallow water or deep water blackout and the choking game,
A seizure which stops breathing activity,
Sleep apnea,
Drug overdose,
Ondine’s curse, central alveolar hypoventilation syndrome, or primary alveolar hypoventilation, a disorder of the autonomic nervous system in which a patient must consciously breathe; although it is often said that persons with this disease will die if they fall asleep, this is not usually the case,
Acute respiratory distress syndrome,
Exposure to extreme low pressure or vacuum,
Breathing an industrial atmosphere lacking oxygen (e.g. welding gases, or in containers purged with nitrogen).

Effective when asphyxia is due to choking or a foreign body obstructing the airways. It is useful for individuals who experience difficulty breathing and nausea due to respiratory congestion.
Symptoms: Difficulty in breathing with nausea, choking sensation, and vomiting.