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# What is Blunt Trauma?

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• Edited By: Kristen Osborne
2003-2019
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Blunt trauma is the result of an external object impacting the body without penetrating the skin. It is the leading cause of trauma death. The term “blunt trauma” is an umbrella term that encompasses such injuries as concussions, fractures, and compressions. The term itself refers to the way the injury happened, rather than the nature of the injury itself.

Often, the only symptom of this type of injury is mild internal bleeding that may not present symptoms until hours after the accident, which is why first-responders and emergency room personnel tend to be very thorough with imaging and tests even when the patient does not feel injured. If left untreated, a seemingly minor blunt trauma injury could turn serious very quickly.

The leading cause of blunt trauma is automobile accidents, but it can also result from sports injuries, assaults, or explosion. The vast majority are caused by car-to-car crashes where the driver impacts the steering wheel or dashboard. Head and abdominal blunt trauma are the leading causes of trauma-related death, and minor cases can go undiagnosed for lack of external symptoms.

Blunt trauma injuries are rooted in the basic laws of physics, more specifically, those regarding kinetic energy. As Sir Isaac Newton, a 17th century physicist, expostulated, “a body in motion will remain in motion unless operated on by an outside force.” In other words, a car will keep going until something stops it, be it a brake or another car. The force equation states that:

Force = Mass x Acceleration

Multiplying an object’s acceleration by its mass gives the force of impact absorbed by the object stopping it. It also underlines the importance of speed in the severity of the resulting blunt trauma injury. Because the kinetic energy equation is:

Kinetic Energy = (Mass x Velocity2) / 2,

doubling the weight of the moving object doubles the impact, but doubling the speed quadruples the impact.

According to Newton, “the force that sets an object in motion must be absorbed before the object will stop.” In the case of blunt trauma, it is the body that absorbs this force. Absorbing this energy is what causes the cells in the body to compress to the point of crushing, which is called a compression injury. Shear injuries occur when an organ and its attachment mechanism decelerate at different speeds, causing a strain that can lead to detachment. Kidneys and spleens are commonly prone to shear forces. Severe impact can produce so much pressure on an organ that it can literally pop, a condition called an overpressure injury. The lungs and bladder are especially vulnerable to overpressure injuries.

Cars equipped with safety belts, air bags, and crumple zones reduce the risk of blunt trauma injury, and defensive driving reduces the risk of accident. Protective sports gear like helmets, chest pads, and shin guards are also effective in preventing this type of injury, and workers in hazardous professions should follow safety protocol to avoid a chance of injury.