Little Kids in Big Crashes
The Bio-mechanics of
Kids in Car Crashes
Lisa Schwing, RN
Trauma Program Manager
Dayton Children’s
Very Little Research
• There has been very little research
on the forces a crash has on a
child’s body.
• Most research has occurred on
scaled down models of the adult
body.
Kids are not little adults
• Because children are smaller than
adults, traumatic forces in children
usually affect a larger region of the
body. Multisystem injuries are
more common among pediatric
patients.
• High incidence of pulmonary
contusion, liver and spleen injuries.
• Compact - organs are more tightly
packaged.
• Most often, less fat, less muscular,
therefore less protection.
Speed vs Velocity
• Kenetic Energy = ½ mass X velocity 2
E=½ MV 2
• When mass is doubled, so is the energy.
• When velocity is doubled, energy is quadrupled.
• Bottom line – speed kills!
Children have big bobble heads
• In comparison to body
size, the child’s head is
larger in size and weight.
• A child’s neck ligaments
are weaker.
Child Thrown from a Vehicle During a Crash
• Any child that goes airborne up to the age of
10 will land on their head.
The Child’s Skull is Thinner
• Predisposing the
skull to fractures
that are often
accompanied by
epidural or subdural
bleeding. Head
injury is the number
one cause of death
in children involved
in car crashes.
Epidural or subdural bleeding on the Brain
Can be fatal
• An epidural bleed
is usually the
result of a torn
artery (the middle
meningeal artery)
in the brain that
bleeds under
pressure.
A Child’s Ribs are Made of Cartilage.
• Ribs of a child are
horizontal and have
little calcium.
• Fractures are difficult
to identify, but underlying
organs are easily injured.
• Adult ribs are at an
angle, are calcified
and hard and
provide better
protection in a crash.
Chest radiograph taken 6
days after injury reveals
multiple healing fractures at
costovertebral junction and
lateral ribs bilaterally.
Lungs are Smaller and Respiratory Rates Higher
• The lungs have
disproportionately smaller
inside surfaces for
oxygen exchange
compared to an adult.
Depleted oxygen and
fatal chemical changes in
the blood occur very
quickly in children without
adequate oxygen.
What we do know
• Abdominal Muscles are less
developed.
“Baby Buda belly”
• Think potential for
multisystem injuries.
Motor Vehicle Crashes –
Put Children at Risk for Abdominal Injuries
High velocity crashes cause extreme energy transfer to the body. The combination
of tightly packaged abdominal organs and in some cases ill fitting safety restraints
put a child at increased risk for abdominal injuries.
Excessive Energy Transfers to a Small Area
Chance fracture
Flexion injury around the lap belt.
Airbag injuries to children
Back to the math
• E=½ MV 2
5 kg baby
50 mph
921 pound force/foot
Zero chance you
will hold this child
in a 50 mph crash.
Chest and Abdominal injuries
• Chest and Abdominal Injuries are the second leading cause
of death in pediatric trauma associated with car crashes.
• Because the physical exam is
often not reliable and the
history may be incomplete,
missed injuries can lead to
increased morbidity and
mortality.
FAST Exam in Children
• Negative predictability
fairly reliable
• Positive predictability
about 56% and
uncertain due to modest
sensitivity.
• Varying study results
Ruptured Spleen
Goal – Children keep their spleens.
•The 2 children requiring
splenectomies due to trauma
done at DC in the last 12
years were both in MVC’s
and both inappropriately
restrained.
(3yo in booster and 6 yo in
seatbelt ) Both had ruptures
with massive bleeding.
Both had multisystem
injuries with ISS >40. Both
recovered completely.
Blunt Abdominal Injuries – Hollow Organs
• Hollow organ injuries usually require
urgent surgical intervention.
• Esophageal and stomach
• Bowel
• Bladder
Skeletal Differences
• Children have
incomplete bone
calcification.
Children’s bones
are still growing.
Injuries to
growth plates
can arrest bone
growth.
Penetrating vs. Blunt Abdominal Trauma
• Penetrating trauma accounts for < 4% of all
injuries seen at Dayton Children’s.
• Blunt trauma is common.
• While falls are the most
common cause of injury,
severe injuries related to
blunt force trauma are
usually associated with
motor vehicle crashes (not accidents) or children hit by a
car while riding a bike or walking.
Percent of Injury Types at
Dayton Children's
80
70
60
50
Burns
40
Penetrating Injuries
Blunt Injuries
30
20
10
0
1
How bad was the crash? – “Delta v”
• Consider the crashworthiness of
the vehicle, the passenger
characteristics, and restraint
usage.
• Factor in the speed change of
the vehicle as a result of the
crash – known as the Delta v.
• This is the measure of the severity of the impact.
• However, mechanism is not always a factor in the severity of
the injury and at Dayton Children’s was found to be a poor
indicator for predicting injuries.
Disbursing the energy in a crash
• When the energy transfer is isolated to one line or one
spot, the impact to that line or spot is greater.
• Take the energy and spread it out across a larger
surface and the energy transfer to any one spot is .
• A helmet absorbs the energy, spreads it out and
protects the head much like seatbelts protect the
body.
Seatbelt stats
• Children 4-8 years old restrained in seatbelts are 3 times
more likely to be admitted for injuries from a motor vehicle
crash than children from birth-4 years. They are too big for
car seats and too little for seatbelts. Ohio legislators passed a
law October 7, 2009 requiring booster seats for all children 4
to <8 years-of-age and shorter than 4’9”.
No
Perfect
What is wrong here?
• The neck
• The lap belt / buckle
• The position of the legs
What’s wrong here
• The lap belt
• The shoulder
harness
• The 5 point restraint
buckle
• Transfer of crash
energy to a single
area
What’s wrong here?
• Too small/young
for seatbelts.
• Shoulder strap
across abdomen.
• No neck
protection.
What’s wrong here?
• Nothing
Seat Belt Injury = Tier II Trauma Activation
Though seat belts
contribute to a number
of predictable injury
patterns, proper use of
seat belts is statistically
the single best
prevention for motor
vehicle crash fatalities.
• Note the lack of
shoulder strap
markings.
What’s wrong here?
• Lucky baby involved in
a roll over crash.
5-Point Restraints Spread the Crash Impact
Seatbelt Sign
Dayton Children’s admitted 65 children with positive seatbelt signs in
the last 2 years.
The most common injuries
associated with seat belt sign:
deaths
spleen lacerations
liver laceration
renal lacerations
perforated bowel
intracranial bleeds
concussion
skull fracture
lumbar fracture
femur fracture
humerus fracture
pelvis fractures
pulmonary contusions
rib fractures
clavicular fracture
facial injuries
0
11
1
4
1
3
8
2
1
5
3
4
4
3
3
3
Seat Belt sign with
associated lumbar
compression fracture
There is No Substitute for Good Judgment
Kids can Survive Most Car Crashes if
Properly Restrained
Summary
• Researchers are striving to develop accurate ways to
predict a child’s injuries in a motor vehicle crash.
• Kids are not little adults.
• Prevention is key.
• Thank you for all you do!