A car passenger involved in an accident can be triaged based on the type of impact, extent of vehicular damage and estimated velocity change involved. The change in speed that a vehicle undergoes during the crash shows the strongest correlation with the severity of injury. The authors are from the Washington Hospital Center in Washington, DC.
Types of impacts for front seat passengers
(1) direct frontal: damage extending more than 2/3 of frontal width of car
(2) offset frontal: damage extending less than 2/3 of frontal width of car
(3) side, with passenger on side struck
(4) side, with passenger on side opposite the side struck
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Parameters Predicting >= 10% Probability of Patient with Injuries ISS >= 16
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Type of Impact
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Estimated Change in Speed
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Crush Distance
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direct frontal
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>= 20 mph
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>= 20 inches
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offset frontal
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>= 22 mph
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>= 28 inches
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side impact
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>= 15 mph
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>= 15 inches
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Equations were derived to predict the probability of injury with ISS >= 16. These are shown in Figures 1 to 4 on pages 648-649.
percent of front seat occupants with ISS >= 16 following direct frontal collision =
= 0.0262 * ((velocity change in mph) ^ 2.0035)
percent of front seat occupants with ISS >= 16 following offset frontal collision =
= 0.0024 * ((velocity change in mph) ^ 2.6941)
percent of front seat occupants with ISS >= 16 following side impact on same side =
= 0.0028 * ((velocity change in mph) ^ 2.7567)
percent of front seat occupants with ISS >= 16 following side impact to opposite side =
= 0.0840 * ((velocity change in mph) ^ 1.9097)
If the equations are solved for percent ISS = 10 (percent), then the data in the table above is obtained.
Different variables decreasing the risk to the passenger (associated with an increased threshold velocity for serious injury):
(1) Using a seatbelt (increased the threshold velocity for serious injury by about 5 mph).
(2) If unrestrained: being the driver.
(3) In side impacts: being on the side opposite to the impact.
Limitations:
• Cars designed to absorb the energy of the impact (crumple zones, reinforced doors, etc.) would probably require a higher velocity change and greater damage to produce the same degree of passenger injury.
• I am unsure how prevalent airbags were in the vehicles studied.
• The data did not appear to include backseat passengers or accidents with rollover.
