Automobile collisions are triple events which succeed each other at millisecond intervals after the primary impact of the car with some object. The second collision (the deceleration of the vehicle's occupants against the vehicle's interior) and the third (the deceleration of the internal body organs and movable column of blood within the cardiovascular system) can produce bodily injury, especially because of hydraulic loading, due to compression of the cardiovascular system and/or the third collision's water- hammer effect. Non-penetrating cardiac trauma is difficult to diagnose because the victim may have none or only a few signs for symptoms suggesting a cardiovascular disorder; other bodily injury may mask it. The predominant symptom is chest pain; there may also be shortness of breath, weakness, restlessness, and cyanosis. Although some of these may be evident upon first examination, they frequently develop within 28-48 hours after injury. Knowledge of the accident's circumstances from an engineering viewpoint can be helpful. Careful examination of the driver for several days following a moderate-speed impact in a frontal or left-side collision is indicated, particularly if the chest contracted some structure. Forces from many other directions may also lead to cardiovascular injuries. Blood studies may be confirmatory. Depending upon the symptoms and physical findings, x rays of the chest, ribs and sternum must be taken. At least five daily ekg's should be obtained. New restraint systems for car occupants and the energy-absorbing steering column are promising advances in automotive safety. Six representative case histories are presented.
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