# 21: Kinematics of Trauma.

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21: Kinematics of Trauma

Cognitive Objectives Describe the “three collisions” associated with motor vehicle crashes. Relate how the fundamental principles of physics apply to motor vehicle crashes and other types of accidents. State Newton’s three laws.

Psychomotor Objectives
There are no affective objectives for this chapter. Observe various high-energy injuries and identify potential damage to the patient.

Kinematics of Trauma Injuries are the leading cause of death among children and young adults. Kinematics introduces the basic physical concepts that dictate how injuries occur and affect the human body.

Energy and Trauma Work Force acting over distance Kinetic energy
Energy of moving object Potential energy Product of weight, gravity, and height

Traumatic Injuries Blunt trauma Caused by a force to the body
Injuries do not penetrate soft tissue or organs Penetrating trauma Caused by objects such as knives and bullets Injuries pierce the surface of the body

Mechanism of Injury (MOI)
MOI is the way in which traumatic injuries occur. Different MOIs produce many types of injuries. Isolated to one body system Injuries to many body systems

Vehicular Crashes and MOI
By assessing the crash, the MOI may be determined. By determining the MOI, you may be able to predict the types of injuries that may have happened at the time of impact.

Vehicular Collisions Three types of crashes
Collision of car against another car or object Collision of passenger(s) against interior of car Collision of passenger’s internal organs against the solid structures of the body

Significant MOI Severe deformities to the frontal part of the vehicle
Moderate intrusion from a T-bone accident Severe damage from the rear Collisions in which rotation is involved

Types of Motor Vehicle Collisions
Frontal Lateral Rear-end Rollovers Spins

Frontal Collisions (1 of 2)
Evaluate seat belts and airbags. Remember that supplemental restraint systems cannot prevent all injuries. You should still suspect that serious injuries have occurred.

Frontal Collisions (2 of 2)
Check for contact points. Steering wheels can also cause chest injuries, especially if no airbag is present.

Rear-End Collisions Commonly cause whiplash-type injuries
Unrestrained passengers will be thrust forward into the dashboard. Back seat passengers wearing only lap belts might have a higher incidence of lumbar and thoracic spine injury.

Lateral Collisions Responsible for the highest incidence of deaths.
Lateral whiplash injury is the result. There may be intrusion into the passenger compartment.

Rollover Crashes Injury patterns differ if patients are unrestrained.
The most unpredictable injuries are to unrestrained passengers. Ejection is the most common life-threatening injury.

Spins Vehicle is put into rotational motion.
Vehicle often strikes a fixed object, combining forces of rotation with lateral impact.

Car-Versus-Pedestrian Collisions
Often cause serious injuries to body systems Evaluate MOI to determine: Whether patient was thrown and how far. Whether patient was struck and pulled under car. Presume injury to the spinal cord and maintain immobilization.

Falls Injury potential is related to the height of the fall.
A fall either 15' or three times the person’s height is considered significant. Suspect internal injuries from a significant fall.

Considerations for Falls
The height of the fall The surface struck The part of the body that hit first, followed by the path of energy displacement Always consider syncope or other medical conditions as an underlying cause.

Penetrating Trauma Second largest cause of death in the United States after blunt trauma Penetration can be low-energy, or medium- or high-velocity. The greater the speed of penetration, the greater the injuries.

Low-Energy Penetrating Trauma
Caused accidentally by an object or intentionally with a weapon Injury caused by the sharp edges of the object moving through the body

Medium-Velocity and High-Velocity Penetrating Trauma
Usually caused by bullets Bullets can change shape and ricochet within the body. Pressure waves cause cavitation. If possible, identify weapon caliber and shooting distance.

High-Velocity Penetrating Trauma

Newton’s First Law Objects at rest tend to stay at rest, and objects in motion tend to stay in motion, unless they are acted upon by some force.

Force (F) equals Mass (M) times Acceleration (A)
Newton’s Second Law Force (F) equals Mass (M) times Acceleration (A) F=MA

For every action, there is an equal and opposite reaction.
Newton’s Third Law For every action, there is an equal and opposite reaction.

Injuries to the Head Bruising or tearing of the brain
Bleeding or swelling inside the skull is often life threatening. Some patients may not have signs and symptoms.

Injuries to the Neck Tearing or swelling of trachea can cause life-threatening airway problems. Injury to large blood vessels in the neck may produce swelling that prevents blood flow to the brain. Open wounds to neck vein bleed heavily or allow air to enter the circulatory system.

Injuries to the Chest Broken ribs may interfere with chest’s ability to expand normally. Large vessels may tear, causing massive bleeding.

Pneumothorax Air collecting between lung tissue and chest wall
Compression of lung tissue interferes with oxygen exchange. May also interfere with the functioning of the heart (tension pneumothorax)

Abdominal Injuries Solid organs can tear, lacerate, or fracture, causing serious bleeding and death. Hollow organs can leak digestive fluids. Trauma patients who complain of abdominal pain may have abdominal bleeding.

Mutisystem Trauma Patient
A patient whose injuries involve more than one body system

Review A 20-year-old man has major open facial injuries after his vehicle struck a tree head-on. Which of the following findings within the car would MOST likely explain his injury pattern? A. Deployed airbag B. Bent steering wheel C. Nonintact windshield D. Crushed instrument panel

Review Answer: C Rationale: The mechanism of injury and condition of the vehicle’s interior suggest likely areas of injury. Head and neck injuries are likely to result when the head and face impact the windshield.

Review A 20-year-old man has major open facial injuries after his vehicle struck a tree head-on. Which of the following findings within the car would MOST likely explain his injury pattern? Deployed airbag Rationale: This typically results in abrasions of the face, head, and arms. B. Bent steering wheel Rationale: This typically indicates the presence of chest injuries. C. Nonintact windshield Rationale: Correct answer D. Crushed instrument panel Rationale: This typically indicates the presence of leg and hip injuries.

Review 2. Which of the following would MOST likely result from the third collision in the “three-collision” effect that occurs during a high-speed, frontal impact, motor vehicle crash? A. Extensive damage to the automobile B. Flail chest and lower extremity fractures C. Massive external trauma with severe bleeding D. Aortic rupture or compression injury to the brain

Review Answer: D Rationale: During the third collision, the body's internal organs collide with the inside of the body. These injuries are usually not as obvious, but are often the most life-threatening. Injuries that may result from this include internal injuries of the brain (compression injuries) and aortic tears, resulting in massive internal bleeding.

Review 2. Which of the following would MOST likely result from the third collision in the “three-collision” effect that occurs during a high-speed, frontal impact, motor vehicle crash? Extensive damage to the automobile Rationale: This would occur in the first collision. B. Flail chest and lower extremity fractures Rationale: This would occur in the second collision. C. Massive external trauma with severe bleeding D. Aortic rupture or compression injury to the brain Rationale: Correct answer

Review 3. Death from a rollover motor vehicle crash is MOST often secondary to: A. crushing injuries. B. airbag related trauma. C. multiple collisions to the interior of the car. D. ejection of the patient from the motor vehicle.

Review Answer: D Rationale: Rollover crashes are the most unpredictable with regard to injuries sustained by the patient. An unrestrained passenger may have struck multiple points within the vehicle. However, the most life-threatening event in a rollover is ejection or partial ejection of the patient from the vehicle. Death is 25 times more likely if a person is ejected from the vehicle.

Review 3. Death from a rollover motor vehicle crash is MOST often secondary to: crushing injuries. Rationale: These injuries occur during ejection or partial ejection. B. airbag related trauma. Rationale: Airbags significantly reduce the risk of death in motor vehicle crashes. C. multiple collisions to the interior of the car. Rationale: This makes the prediction of injury patterns difficult, but is not the most common life-threatening event in a rollover. D. ejection of the patient from the motor vehicle. Rationale: Correct answer

Review 4. A young male experienced severe blunt chest trauma when his passenger car struck another vehicle head-on. During your inspection of the interior of his vehicle, you would MOST likely find: A. deployed airbags. B. steering wheel deformity. C. starring of the windshield. D. a crushed instrument panel.

Review Answer: B Rationale: Blunt chest injuries during a motor-vehicle crash typically occur when the chest impacts the steering wheel. Therefore, your inspection of the vehicle’s interior will most likely reveal a deformed steering wheel.

Review 4. A young male experienced severe blunt chest trauma when his passenger car struck another vehicle head-on. During your inspection of the interior of his vehicle, you would MOST likely find: deployed airbags. Rationale: Typically, this will cause abrasions to the face, head, and arms. B. steering wheel deformity. Rationale: Correct answer C. starring of the windshield. Rationale: Typically, this indicates the presence of head, face, and neck injuries. D. a crushed instrument panel. Rationale: Typically, this indicates the presence of leg and hip injuries.

Review 5. Kinetic energy is a calculation of: A. weight and size.
B. weight and speed. C. mass and weight. D. speed and force.

Review Answer: B Rationale: Kinetic energy is a calculation of mass (weight) and velocity (speed). Energy cannot be destroyed, only converted.

Review 5. Kinetic energy is a calculation of: weight and size.
Rationale: Weight is part of the formula, but size would also mean weight. B. weight and speed. Rationale: Correct answer C. mass and weight. Rationale: Mass and weight are the same. D. speed and force. Rationale: Force is the product of mass times acceleration, all part of Newton’s Second Law.

Review 6. Whiplash injuries are MOST common following _________ impacts. A. rear-end B. rollover C. frontal D. lateral

Review Answer: A Rationale: Whiplash injuries of the neck are a common occurrence following rear-end collisions. As the vehicle is suddenly thrust forward, the occupant’s head is thrust backward. Properly positioned headrests can minimize the severity of whiplash injuries.

Review 6. Whiplash injuries are MOST common following _________ impacts. rear-end Rationale: Correct answer B. Rollover Rationale: This typically causes life-threatening injuries. C. Frontal Rationale: This typically causes chest, head, abdominal, and extremity injuries. D. Lateral Rationale: You should suspect lateral chest and abdominal injuries on the side of impact, as well as pelvic injuries.

A. a person’s head is thrust laterally during a T-bone crash. B. the face strikes the windshield, hyperextending the neck. C. a person falls from a significant height and lands feet first. D. a vehicle abruptly stops, but the occupant continues to move.

Review Answer: C Rationale: Axial loading occurs when the spinal column is compressed. Common mechanisms of injury that cause axial loading including falling from a significant height and landing feet first; diving into shallow water and striking the top of the head on the floor of the pool; or during a rollover crash, when the top of the occupant’s head impacts the roof.

a person’s head is thrust laterally during a T-bone crash. Rationale: This may cause a whiplash, but not a compression injury. B. the face strikes the windshield, hyperextending the neck. Rationale: Hyperextension will not produce a compression injury. C. a person falls from a significant height and lands feet first. Rationale: Correct answer D. a vehicle abruptly stops, but the occupant continues to move. Rationale: Decelerating forces can produce shearing, avulsing, and/or the rupture of organs.

Review 8. A 40-year-old man was standing near a building when it exploded. He has multiple injuries, including a depressed skull fracture, severe burns, and an impaled object in his abdomen. His head injury MOST likely occurred during the ___________ phase of the explosion. A. blast B. primary C. secondary D. tertiary

Review Answer: D Rationale: Blast injuries are associated with three phases: the primary (blast) phase, the secondary phase, and the tertiary phase. During the primary (blast) phase, ruptured eardrums and hollow organ rupture are common. During the secondary phase, impaled objects and shrapnel injuries are common. The tertiary phase occurs when the victim is thrown into a solid object, resulting in blunt trauma to virtually any part of the body.

Review (1 of 2) 8. A 40-year-old man was standing near a building when it exploded. He has multiple injuries, including a depressed skull fracture, severe burns, and an impaled object in his abdomen. His head injury MOST likely occurred during the ___________ phase of the explosion. blast Rationale: This is not nomenclature used in describing one of the three phases of an explosion. B. primary Rationale: This causes injury to the eardrums, lungs, and hollow organs.

Review (2 of 2) 8. A 40-year-old man was standing near a building when it exploded. He has multiple injuries, including a depressed skull fracture, severe burns, and an impaled object in his abdomen. His head injury MOST likely occurred during the ___________ phase of the explosion. C. secondary Rationale: The common injuries in this phase are caused by flying debris. D. tertiary Rationale: Correct answer

Review 9. When assessing a stab wound, it is important for the EMT-B to remember that: A. stabbings to an extremity are rarely associated with an exit wound. B. the majority of the internal trauma will be near the path of the knife. C. most stabbings are unintentional and cause less severe internal injury. D. more internal damage may be present than the external wound suggests.

Review Answer: D Rationale: With low-velocity penetrations, injuries are caused by sharp edges of the object moving through the body and are therefore close to the object's path. Weapons such as knives, however, may have been deliberately moved around internally, causing more internal damage than the external wound suggests.

Review (1 of 2) 9. When assessing a stab wound, it is important for the EMT-B to remember that: stabbings to an extremity are rarely associated with an exit wound. Rationale: The question did not state that the wound was to an extremity. B. the majority of the internal trauma will be near the path of the knife. Rationale: This is true, but EMS providers must have a high index of suspicion for extended injuries due to movement.

Review (2 of 2) 9. When assessing a stab wound, it is important for the EMT-B to remember that: C. most stabbings are unintentional and cause less severe internal injury. Rationale: Any stabbing that penetrates an individual’s skin must be considered severe until ruled out by a hospital physician. D. more internal damage may be present than the external wound suggests. Rationale: Correct answer

Review 10. An unrestrained driver collided with a bridge pillar. Upon inspection of the interior of his vehicle, you note that the lower dashboard is crushed. During your assessment of the patient, you will MOST likely encounter: A. trauma to the pelvis. B. blunt abdominal trauma. C. a severe closed head injury. D. penetrating thoracic trauma.

Review Answer: A Rationale: Impact points are often obvious from a quick inspection of the vehicle’s interior. During a frontal collision, the unrestrained occupant’s knees often impact the lower dashboard. With this type of impact, energy is transferred from the knees, to the femurs, and then to the pelvis or hip.

Review 10. An unrestrained driver collided with a bridge pillar. Upon inspection of the interior of his vehicle, you note that the lower dashboard is crushed. During your assessment of the patient, you will MOST likely encounter: trauma to the pelvis. Rationale: Correct answer B. blunt abdominal trauma. Rationale: This is usually a result of striking the steering wheel. C. a severe closed head injury. Rationale: This is usually the result of striking the windshield. D. penetrating thoracic trauma. Rationale: This is usually caused by flying debris, collision with parts of the vehicle, or other movable objects.