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A crush injury is caused by prolonged or forceful compression of a body part, such as an arm or leg, resulting in damage to muscle, nerves, blood vessels, bone, and other tissues. While a minor crush injury, such as closing a door on a finger, can sometimes be treated at home, severe crush injuries are medical emergencies that require immediate attention to prevent complications and preserve function in the affected body part. The most common scenarios for severe crush injuries are accidents, such as motor vehicle collisions, and natural disasters, such as earthquakes.
In a crush injury, the normal chemical balance of the muscle cells is disrupted as a result of abnormal compression forces. The direct injury to the muscle damages the structures in the cell membranes that pump calcium and potassium into the cells and sodium out of the cells. The increase in calcium levels inside the muscle cells causes enzymes that are normally found there to become destructive to muscle tissue. This destruction can lead to breakage, or rupture, of the muscle cell membrane and result in cell death.
The rupture of the muscle cell membrane causes substances to leak out of the cell. These substances, which include potassium, calcium, creatinine, and myoglobin, a protein that normally supplies oxygen to muscle cells, can then enter the bloodstream. The release of these chemicals into the body's circulatory system is known as rhabdomyolysis. If left untreated, rhabdomyolysis can lead to kidney failure, shock, and ultimately death. A person with a crush injury who shows signs of damage to other body systems is said to be suffering from crush syndrome.
The prevention of crush syndrome is a primary goal of the treatment of crush injury. Intravenous fluid containing both sodium bicarbonate and mannitol is given to patients to prevent kidney damage and stabilize blood pressure. Surgery may be needed to repair the damage to nerves and bone. To prevent infection, patients may receive antibiotics and a tetanus shot.
Statistics about the incidence of crush injury come mainly from reports from medical workers who have treated people injured in natural disasters, such as earthquakes. Almost three-fourths of crush injuries affect the legs, with about 10% of injuries affecting the arms and just under 10% affecting the trunk. In the United States, information about the treatment of crush injury and crush syndrome is part of the federal Emergency Preparedness and Response system.