Positional asphyxia (also known as postural asphyxia) occurs when someone's position prevents adequate breathing. A small (but significant number) of people die suddenly and without apparent reason during restraint by police officers.
- Positional asphyxia is a potential danger of some physical restraint techniques,
- People may die from positional asphyxia by simply getting themselves into a breathing-restricted position they cannot get out of, either through carelessness or as a consequence of an accident.
Research has suggested that restraining a person face down position is more likely to cause the restriction of breathing than restraining a person face up. Risk factors which may also increase the chance of death include: obesity, prior cardiac or respiratory problems; and the use of illicit drugs such as cocaine. Almost all subjects who have died during restraint have engaged in extreme levels of physical resistance against the restraint for a prolonged period of time. Other issues in the way the subject is restrained can also increase the risk of death, for example kneeling or otherwise placing weight on the subject and particularly any type of restraint hold around the subjects neck.
Confining a person is a straightjacket that is too small for the wearer for long periods of time can cause positional asphyxia. (The arms crossed over the chest can prevent breathing.)