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Re-engineering Vehicular Trauma Research Using Finite Element Analysis

Stewart Wang
Stewart Wang

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.

35 MPH Frontal Crash

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.

Automatic Collision Notification (ACN)

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
Ori Rotstein
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
Avery Nathens
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
Hugh Scully

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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