Asphyxia: a rare cause of death for motor vehicle crash occupants.

Motor vehicle related trauma is one of the leading causes of traumatic death. Although most of these deaths are because of severe blunt force trauma, there are people without severe injury who die of asphyxia related to the motor vehicle collision. There were 37 deaths because of motor vehicle related asphyxia in San Diego County during 1995-2004. Almost half (48.6%) of these deaths were because of compression asphyxia, 29.7% were positional asphyxia deaths, and 16.2% died of a combination of compression and positional asphyxia. We were unable to classify the mechanism of asphyxia for the remaining 5.4% of asphyxia deaths. Almost all occupants dying from asphyxia were involved in rollover crashes and may have been incapacitated by obesity, drug or alcohol intoxication, or blunt force trauma. Compression asphyxia deaths occurred both from vehicle crush with intrusion into the passenger compartment and from ejection of the occupant and subsequent crushing by the vehicle. Positional asphyxia occurred in positions interfering with normal respiration, including inversion. None of the occupants had injury severe enough to result in death at the scene if they had not first died of asphyxia. This study suggests classifying the mechanism of asphyxia for these fatalities may be a challenge to forensic pathologists who seldom see these rare deaths.