Compressive asphyxia (also called chest compression) is mechanically limiting expansion of the lungs by compressing the torso, hence interfering with breathing. Compressive asphyxia occurs when the chest or abdomen is compressed posteriorly. In accidents, the term traumatic asphyxia or crush asphyxia usually refers to compressive asphyxia resulting from being crushed or pinned under a large weight or force. An example of traumatic asphyxia includes cases where an individual has been using a car-jack to repair a car from below, and is crushed under the weight of the vehicle. Pythons, anacondas, and other constrictor snakes kill through compressive asphyxia. In cases of co-sleeping ("overlay"), the weight of an adult or large child may compress an infant's chest, preventing proper expansion of the chest. Risk factors include large or obese adults, parental fatigue or impairment (sedation by drugs or alcohol) of the cosleeping adult and a small shared sleeping space (for example, both adult and infant sharing a couch).
In fatal crowd disasters, compressive asphyxia from being crushed against the crowd causes the large part of the deaths, rather than blunt trauma from trampling. This is what occurred at the Ibrox disaster in 1971, where 66 Rangers fans died; the 1979 The Who concert disaster where 11 died; the Luzhniki disaster in 1982, when 66 FC Spartak Moscow fans lost their life; and at the Hillsborough disaster in 1989, when 96 Liverpool fans were crushed to death in an overcrowded terrace. In confined spaces, people push and lean against each other; evidence from bent steel railings in several fatal crowd accidents have shown horizontal forces over 4500 N (equivalent to a weight of approximately 450 kg, or 1014 lbs). In cases where people have stacked up on each other forming a human pile, estimations have been made of around 380 kg (838 lbs) of compressive weight in the lowest layer.
The cause of death of the detainees who have been restrained and left prone, for example in police vehicles, and cannot move into safer positions, has been referred to as "positional asphyxia". Restraint asphyxia is death or lost consciousness (to die later in a coma from anoxic brain damage), while being restrained in positions that cause asphyxia by facial compression, neck compression, or chest compression. This mostly occurs during law enforcement or psychiatric restraint situations. It may be that the positional asphyxia deaths of detainees are actually active chest compression deaths caused by the weight of restrainers holding uncooperative detainees down in a prone position during the process of being handcuffed and otherwise secured. Thus, the passive deaths following custody restraint presumed to be due to positional asphyxia after being secured by mechanical restraints may actually be examples of active restraint asphyxia occurring during the process of placing restraints.
Chest compression is also featured in various grappling combat sports, where it is sometimes called wringing. Such techniques are used either to tire the opponent or as complementary or distractive moves in combination with pinning holds, or sometimes even as submission holds. Examples of chest compression include the knee-on-stomach position, or techniques such as leg scissors (also referred to as body scissors and in budō referred to as do-jime, 胴絞, "trunk strangle" or "body triangle") where you wrap the legs around the opponent's midsection and squeeze them together.
Pressing is a form of torture or execution that works through asphyxia.
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