21: Kinematics of Trauma
Cognitive Objectives
1. Describe the “three collisions” associated with
motor vehicle crashes.
2. Relate how the fundamental principles of
physics apply to motor vehicle crashes and
other types of accidents.
3. State Newton’s three laws.
Psychomotor Objectives
•
There are no affective objectives for this chapter.
4. 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 highvelocity.
• 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.
Newton’s Second Law
Force (F) equals Mass (M) times Acceleration (A)
F=MA
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 lifethreatening 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
1. 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
1. 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
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 highspeed, frontal impact, motor vehicle crash?
A. 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
Rationale: This would occur in the second collision.
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:
A. 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:
A. 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:
A. 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.
A. 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.
Review
7. Axial loading injuries occur when:
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.
Review
7. Axial loading injuries occur when:
A. 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.
A. 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:
A. 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:
A. 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.