Re-engineering Vehicular Trauma Research Using Finite Element Analysis
Stewart Wang
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Ann Arbor trauma surgeon and
molecular immunologist Stewart
Wang is following the roads specified
in the "roadmap of research"
of the US National Institutes of
Health. The roadmap specifies
"new techniques, multi-disciplinary
teams, and translational research
to re-engineer the clinical research
enterprise". After demonstrating by a poll that 95% of
us drove our cars to University Rounds, Stewart took us
through the alarming statistics of vehicular trauma. 1.2
million people are killed and 50 million are seriously
injured each year on the roads of the world.
In his arresting
illustrative case,
an SUV carrying a
mother and three
children T-boned
a sedan driven by
a young man who
crossed the median
and died at the
scene. The right
side of his vehicle
impacted the front
of the SUV. The
mother sustained
minor injuries. All
three children had
non-fatal atlantooccipital
dissociations
demonstrable
on CT scans. There were two lap belt injuries to the
pelvis and intestine of the children who had slipped out
of their annoying shoulder straps, and one skull fracture
secondary to the lack of a booster chair in a six-year-old.
Stewart described the crash injury research network
that is conducting highly effective translational research in
collaboration with engineers from the auto industry and
scientists in the trauma program. Among their findings:
- People with a BMI greater than 28 have less severe abdominal injuries, but more severe
lower extremity injuries
- Blunt trauma is much more challenging diagnostically than penetrating trauma
- Trauma centres, often comprising 100 trained personnel, have substantially better
outcomes than other hospitals
- The incidence of thoracic injuries increases with age. Bone mineralization and rib
cross-sectional shape changes unfavourably with age so that the fragile elderly are much more vulnerable to
rib fractures and their pulmonary complications.
- Automatic Collision Notification (ACN) systems triggered by deployed airbags have
been developed to call
response centres and emergency fire and rescue teams to begin the time-critical management of trauma care. The
system utilizes a
GPS locator to give precise information on the whereabouts of the accident (not "somewhere north of exit 29"). ACN
can preload information on drivers, (eg. on coumadin, insulin, etc.) to alert emergency medical technicians and
the trauma
centre, upgrading the information component that is critical to improved outcomes.
Illustrating the greater challenge that blunt injury presents
compared to penetrating trauma, Stewart projected his list of potential injuries for frontal impact. The list is
quite different for side and back impact. When angle of
impact is known from the ACN at the time of the accident,
the diagnostic evaluation of victims is streamlined.
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Using finite element
analysis,
Stewart and his
colleagues can
vary the "Crash
Test Dummy"
morphology in
computer analyses
to improve
the design of
automobiles and
safety devices.
These manipulations
of the
"morphome "
allow conversion
of the data
on vulnerability
into useful
devices. The translation time is much shorter when the
analyses at trauma conference are conducted in the presence
of automobile engineers who return to their plants
to develop solutions.
Stewart spent his sabbatical at the Japanese Automobile
Research Institute studying the difference between crash
test dummies and cadavers. The familiar crash test dummies
that we see in automobile advertisements were designed in
the 1960s based on three dozen cadavers. The model is
matched to the 50th percentile of age and weight of these
cadavers. Clearly at least three of the accident victims in
our illustrative case did not conform to these dimensions.
The children were age 3, 6 and 7. Stewart's research on the
finite element model allows scientists to tune the model
electronically to fit those who are younger, older, heavier,
etc. Actual crash test dummy tests cost approximately one
million dollars each to instrument, demolish and analyze.
His analysis can be more granular, including variation in
body composition which is influenced by co-morbidities
like diabetes. These morphomes can help, not just vehicular
trauma, but in reducing risk in elective surgery and chemotherapy.
"Biofidelic human body finite element models are
the key to this new branch of science."
In the discussion
period Marv
Tile brought
out the value of
Stewart's technique
for analyzing
soft tissue
injuries.
Ori Rotstein
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Another
surgeon brought
out the safety
advantages of
London taxis,
particularly their
rear-facing seats.
Stewart commented
that the
same positioning
is used by
NASA for its
space personnel,
and Swedes keep children facing backwards until age 4.
He is impressed by how much more rapidly crash science
is now moving from the bench to
the bedside.
Avery Nathens
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Instead of the usual
10-15 years remembered from his
molecular immunology days, information
moves very quickly via the
engineers, so he and his colleagues
are "accelerating
the translation
of medical
discovery to improve health" in
accord with the NIH road map. He
complimented Ori Rotstein and
Avery Nathens: "Though I have
been a visiting professor in many
institutions, I have never experienced
so well-conducted a visiting professorship."
M.M.
Contributions from Formula One Racing
Hugh Scully
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Cardiac surgeon Hugh Scully
suggested linking Stewart
Wang's research more tightly
to the highly successful work
improving the safety of Formula
One auto racing. "In the early
years of Formula One, many
drivers and some spectators were
killed. One in seven drivers died
in the 1960s. The introduction
of seatbelts, then helmets,
improved fuel cells and barriers resulted in a decade
by decade reduction in injury. Foot and ankle injuries
were reduced by moving them behind the front axle
and strengthening the nose cone. The Head and Neck
Injury Project of our group in Indianapolis led to the
HANS system now mandatory in championship racing.
The head is now relatively fixed to the body so that the
moments of force to flex, extend or twist the neck are
no longer as severe a danger despite the weight of the
helmet. The cockpit has been strengthened and headsurround
padding has been added to protect from penetration.
Rapid intervention vehicles with well-trained
paramedics and doctors are immediately dispatched.
Every physician and paramedic at Formula One events is
fully trained in Advanced Life Support. Accident analysis
has been improved to the level of investigation of
airline accidents. The improvements in brakes, fuel cells,
tire technology, and the protective surrounding of drivers
have resulted in a reduction of the death rate to one
per 368 severe accidents, despite increases in speed. The
Formula One research program has brought advances
in protection through cooperation with NASA, the US
Airforce, the airlines and autosports industry. Many of
the benefits of these advances have become part of the
protection of drivers and passengers in conventional
automobiles." Translation of lessons learned in both the
autoracing and the conventional automobile industry
will be accelerated by the cross-fertilization of these
highly productive trauma research programs.
M.M.
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