The problem of police-related cardiac arrest.

The term "positional asphyxia" was originally used to describe the situation in which the upper airways becomes compromised by sharp angulation of the head or neck, or where the chest wall is splinted and the diaphragm is prevented from moving because of an unusual position of the body. The term was redefined in the early 1980s to describe sudden death during physical restraint of an individual who is in a prone position. A large percent of reported victims were overweight males. Most were in early middle age and manifesting psychotic behavior at the time of death. Most were reported to have unremarkable autopsies, save for the finding, in many cases, of cocaine or methamphetamine (more recently synthetic cannabinoids and cathinones as well). As no cause of death was apparent (other than non-specific signs such as pulmonary edema), it became common practice to attribute death to force exerted on the decedent's back. When experimental studies with human volunteers disproved this notion, the term "restraint asphyxia" was substituted for positional asphyxia, but with nearly the exact same meaning. No experimental study has ever determined the actual amount of force necessary to cause asphyxia by force applied to the back (although the range of required static force is known), nor the duration for which it must be applied. This review discusses the epidemiology and the evidence for and against the theory of "restraint/positional" asphyxia. It also considers alternative theories of causation, including the findings of studies suggesting that cardiac channelopathies/cardiomyopathies may explain many cases of ARD.