Traffic accidents with drowning mechanical asphyxia: a retrospective survey from the autopsic records of the Milan area in over twenty years

Drowning asphyxia correlated to submersion of the vehicles, although globally widespread, is an infrequent manner of death1, characterized by the causal correlation between two events: trauma and asphyxia. Aim of the Authors is to illustrate, through retrospective survey, the incidence of the phenomenon in more than two decades, analyzing damage and impact mechanisms.Out of 22108 autopsies performed at the Institute of Legal Medicine of Milan (1st of January 1993 to 31st of December 2014), the Authors selected all cases of death occurred in traffic accidents with the vehicle fallen into water, dividing them according to different parameters: role of the victim on the vehicle, location of the event, dynamics of the accident, objective injuries and cause of death. For these victims, all the specimens of organs and organic fluids available in the Archives of the Institute of Legal Medicine underwent histopathological and toxicological testing.Cases useful to this research resulted to be 16 (0.07% of all autopsies and 0.38% of the 4153 traffic accidents occurred in the considered period). The “typical victim" is a young male driver of a car rather than a motorcycle, never surviving to the impact. The dynamics of 88% of these accidents consisted in the car running off the road with the subsequent fall in the water, directly adjacent to roads or falling from bridges, while in the remaining two cases regarding motorcycles, both had previously impacted, respectively, with a truck or with a car. Toxicological tests showed a positive BAC in 47% of cases and just one victim resulted positive for antidepressants and caffeine. Histopathological evidences showed significant microscopic findings in the lungs, and the pursuit of diatoms, performed in all cases, corroborated the cause of death, identified in drowning. Only two victims reported traumatic lesions ascribable to the impact of the vehicle, not sufficient to justify the exitus. The Authors presented the autopsic records of a rare and complex manner of death, characterized by a peculiar forensic-pathological profile resulting from the combination of two events: traffic accident and drowning asphyxia. In these cases, a correct diagnosis of the cause of death, quite difficult due to the possible overlap of these two different harmful manners, is identified on basis of non-lethal traumatic evidences and positive diatoms findings, this last procedure considered as a gold-standard in these kind of events.