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Automatic Crash Notification (ACN) Systems provide rapid notification with accurate location of automobile crashes. Advanced ACN systems also provide additional information on the nature and severity of the crash. To take advantage of this crash information to improve triage, transport, and treatment decisions, the National Highway Traffic Safety Administration developed a predictive algorithm called URGENCY. The purpose of URGENCY is to identify, instantly and automatically, the approximately 250,000 crashed vehicles with serious injuries occurring each year from the 28,000,000 crashed vehicles with minor or no injuries. [ABSTRACT FROM AUTHOR]

Introduction: Despite advances in the surgical therapy of aortic injury (AI) using endovascular prostheses, more than 60% of motor vehicle crash (MVC) induced AIs die at the scene. In 80 cases of MVC AI, both change in velocity on impact (Delta V) and impact energy (IE) were correlated with autopsy or surgical findings. Of the 34 AIs due to lateral impact MVCs (LMVC), 91% had an aortic isthmus laceration. Computer simulation is used to study the cause of LMVC AI., Methods: To delineate AI mechanism, 10 real life LMVCs (8 left, 2 right) were simulated using a computer-based finite element numerical model. Each began with the initial vehicle impact with another vehicle or fixed object, followed by the vehicle's compartment structures' impact with the patient's chest wall, causing a rise in intra-aortic pressure and the resulting location and pattern of aortic wall stresses and strains. In the real LMVCs, the Delta V ranged from 27.5 to 62 kph with impact energies of from 46,051 to 313,502 joules. In both real-life and the model, the main cause of the chest wall impact was intrusion of the car's B-pillar. Dynamic simulations delineate increased stress and strains at the aortic Isthmus. In some LMVCs, the B-pillar intrusion was also seen to impact the head in the AI cases., Results: In the simulations, aortic pressure rose from 100 mm Hg precrash to as high as 1,322 mm Hg. Both the maximum aortic longitudinal tensile strain and the von Mises Stress were proportional to the maximum force impacted on the chest wall. Aortic isthmus maximum stresses ranged from 1.1 Mega Pascal (MPa) to 3.2 MPa, with longitudinal tensile strains ranging from 8.2% to 48.5%. The simulation dynamics demonstrated that the proximal pressurized turgid aorta initially moves toward the LMVC impact. As a result, the ascending aorta and aortic arch (proximal ascending aorta) rotate about the fulcrum of the great vessels, so that this aortic unit, acting as the long-arm of an Archimedes lever system, exerts the maximum stress and strain at the aortic isthmus or short-arm, where the real-life aortic rupture occurs., Conclusion: Simulation supports the lever hypothesis that the force on the short-arm aortic isthmus is proportionally greater than at the long-arm proximal aorta. Simulation also suggests improved vehicle construction techniques, which increase the strength and resistance to deformation of the B-pillar and vehicle side structure plus a B-pillar airbag will limit the intrusion forces causing LMVC AIs and reduce the incidence of associated head injuries.

Objectives: Can aortic isthmus disruption occurring in a lateral motor vehicle crash (LMVC) be explained by the Archimedes Lever Hypothesis, where the intrathoracic aorta, super-pressurized by the thoracic impact force, functions as a rigid lever system? The long arm of this lever system is the proximal aorta-aortic arch, the short arm is the aortic isthmus fixed distally at the descending aorta, and the fulcrum is at the great vessels, especially the left subclavian artery., Methods: The theory was tested by a simulation technique using a computer-based finite element numerical model system. This simulation model included the dynamics of the crashed vehicles, the direction of force impact, and the structure of the thorax and intrathoracic viscera, including the entire intrathoracic aorta. The specific patient whose data were entered into the model was chosen from a study of 34 LMCV aortic injuries (AIs). The model was constrained by patient and vehicle data from this surviving case., Results: Three sequential lateral thoracic levels impacted by the vehicle side structures were selected. At each level, the maximum mean intra-aortic pressure was 50 to 100 ms after impact, the structure dynamics of the actual crash and the resultant vehicle deformation were simulated; only when the lateral impact was induced in a transverse plane including the first 4 ribs at the level of the aortic arch/isthmus system, with intra-aortic pressures from 200 to 500 mm Hg, were AI-compatible stresses and deformations in the aortic wall achieved at the isthmus., Conclusions: In LMVC AI, the simulation suggests that the aorta functions as an Archimedes Lever System in which the magnified force mediated by the long lever arm produces sufficient strain on the short lever arm to rupture the aorta at the isthmus.

Objective: To examine the effect of change in velocity (DeltaV) and energy dissipation (IE) on impact, above and below the test levels for Federal MVC Safety Standards, on the incidence of spine fractures (SF), spinal cord injury (SCI)), SF mortality and the associated injury patterns in Frontal (F) and Lateral (L) MVCs. Comparison of 214 patients with SF or SCI with 938 patients who did not have SF or SCI., Methods: 1152 MVC adult drivers or front-seat passengers (701 F & 451 L) evaluated at 10 Level I CIREN study Trauma Centers together with vehicle and crash scene engineering reconstruction. Patient seat belt (SB) and/or airbag (AB) use correlated with clinical, or autopsy findings., Results: The relationship between DeltaV and IE rose exponentially as DeltaV increased. Of the 1152 patients, all with AIS> or =3 injuries, there were 214 patients with spine fractures of AIS > or =2. In FMVCs there were more SF patients with Cervical SF than in LMVCs (68F versus 64 L) and more Thoracic (35F versus 21L) and Lumbar (39F versus 16L) SF. However, the incidence of spinal cord injury was greatest in the Cervical SF (33%), compared with the Thoracic SF (18%), or Lumbar SF (2%). Most important, in FMVCs 49% of SF, 47% of SCI and 71% of the SF deaths (p < 0.05) occurred at > mean of 47.4 kph. In contrast, in LMVCs 51% of SF, 52% of SCI and 67% of the SF deaths occurred at DeltaV > mean of 35.3 kph. However, 80% of all deaths in SCI occurred in Cervical SF cases, in these 74% also had a brain injury. In contrast, the deaths in Thoracic SF were due to combinations of brain (45%), thorax (95%) or associated pelvic fracture injuries (50%). Airbag (AB), or Seat belt (SB) restraints appeared to protect FMVC SF patients from SCI at lower DeltaV, but 84% of Cervical SCI patients at DeltaV > 47 kph had AB protection and in a few cases the AB appeared responsible for the SCI. In contrast, 82% of Lumbar SF patients had SB, but in FMVCs where jackknifing due to backloading occurred, improper SB positioning may have contributed to the SF., Conclusions: The implication for SCI in both front seat drivers and passengers in either FMVC or LMVC crashes above their respective DeltaV means is that improved spine fracture protection is necessary at higher DeltaV levels. More effective safety systems to prevent Cervical SCIs should be developed using two-level frontal and side AB & SB+pretensioner devices, which protect against SF at DeltaV both at and 1SD above the FMVC (47 & 72 kph = 30 & 45 mph) and LMVC (35 & 54 kph =22 & 34 mph) means.