To examine the effect of change in velocity (MV) and energy dissipation (IE) on impact, above and below the test levels for federal motor vehicle crash (MVC) safety standards, on the incidence of aortic injury (AI) and its mortality and associated injury patterns in frontal (F) and lateral (L) MVCs. Comparison of 80 AI and 796 non-AI patients of AIS = 3.
Eight hundred seventy-six MVC adult drivers or front-seat passengers (552 F and 324 L) evaluated by 10 Level I CIREN study Trauma Centers together with vehicle and crash scene engineering reconstruction. Patient seatbelt and/or airbag use correlated with clinical or autopsy findings.
In AI, 63% of cases were dead at the scene and only 16% survived to leave hospital. The relation between IE dissipated in the MVC and the ΔV on impact was exponen-tial as ΔV increased, but the rise in IE for a given ΔV was greater in LMVC than in FMVC (p < 0.05). A more rapid rise in IE/ΔV occurred above the mean ΔV of 48 ± 19.7 kph (30 mph) in FMVC and above the mean ΔV of 36 ± 16.2 kph (23 mph) in LMVC. As ΔV increased above these means, 65% of 46 FMVC aortic injuries (AIs) and 64% of 34 LMVC AIs occurred. In AI patients there was evidence of focusing of the point of IE impact on the upper chest with a higher incidence of rib1–4 fractures than in non-AI (p < 0.01) and more brain, heart, lung and spleen injuries (p < 0.01) consequent to lower seatbelt use (p < 0.01), but LMVC also had more pelvic fx (p < 0.05). Airbags + seatbelts in FMVC and seatbelts in LMVC reduced mortality (p < 0.05) Comparison of AI incidence in three successive 4-year vehicle model year periods showed a progressive decrease as new safety devices were introduced (p < 0.05).
The implications for AI of the focused IE at the upper chest suggest a probable mechanism for MVC AI with the pressurized aortic arch acting as the long arm of a lever system with the fulcrum at the subclavian artery, producing maximum torsional strain at the short arm of the isthmus where 75% of the AIs occurred. AI mortality is also influenced by the associated injuries. To develop more effective safety systems to prevent AI, MVC safety testing with airbags and seatbelts should be carried out at ΔVs of 1 SD above means for FMVC and LMVC.
From the Department of Cell Biology and Molecular Medicine and the Department of Surgery (J.H.S., J.A.S., S.Q.S.), New Jersey Medical School: UMDNJ, Newark, New Jersey; Principal Investigator (J.H.S.), New Jersey CIREN Center.
Submitted for publication March 23, 2004.
Accepted for publication July 23, 2004.
This study was supported by the Crash Injury Research Engineering Network program of the National Highway Traffic Safety Administration, Department of Transportation (contract: DTNH22–00-H-27202).
In addition to the New Jersey CIREN Center, data included in this study were collected by nine other CIREN Center PIs: Lehman Injury Research Center, University of Miami School of Medicine, Miami, FL (J.S. Augenstein, MD, and K.E, Digges, PhD); National Study Center for Trauma and EMS, University of Maryland, Baltimore, MD (P.C. Dischinger, PhD, A.R. Burgess, MD, and J. O’Connor, MD); San Diego County Trauma System & Scripps Memorial Hospital & University of California San Diego Medical Center, San Diego, CA (A.B. Eastman, MD, D.B. Hoyt, MD, and G. Cooper); Children’s National Medical Center, Washington, DC (M. Eichelberger, MD); Fairfax Hospital–Honda Inova Center, Falls Church,ΔVA (S.M. Fakhry, MD, and D.D. Watts, PhD); Froedtert Hospital & Medical College of Wisconsin, Milwaukee, WI (T.A. Gennarelli, MD); Harborview Injury Prevention & Research Center, University of Washington, Seattle, WA (D. Grossman, MD, C. Mock, MD, and F. Rivara, MD); Mercedes-Benz Center, University of Alabama Health System, Birmingham, AL (L.W. Rue III, MD); and University of Michigan Health System & University of Michigan Transportation Research Institute, Ann Arbor, MI (S.C. Wang, MD, and L. Schneider, PhD).
The following members of the New Jersey Regional Medical Examiner’s Office participated in the collection and interpretation of the NJMS CIREN Center’s autopsy data: J. Krolikowski, MD, L. Perez, MD, F. Presswalla, MD, P. Pierre-Louis, MD, W. Williams, MD, L. Zaretski, MD, K. Hutchins, MD, J. Shaikh, MD, G. Natarajan, MD, Z. Hua, MD, T. Blumenfeld, MD, and L. Gonzalez.
None of the authors have any financial or other interest relating to products, companies or organizations mentioned in this manuscript. The opinions expressed here-in represent those of the authors and do not necessarily reflect the official opinion of the sponsoring agency.
Address for reprints: John H. Siegel, MD, New Jersey Medical School: UMDNJ, 30 Bergen Street ADMC 1402, Newark, NJ 07107-1709; email: firstname.lastname@example.org.