Jeffrey Augenstein

AIRBAG PROTECTED CRASH VICTIMS - THE CHALLENGE OF IDENTIFYING OCCULT INJURIES

At the Ryder Trauma Center of the Jackson Memorial Hospital in Miami, Florida, a multidisciplinary, automobile crash investigation team is conducting a detailed medical and engineering study. The focus is on restrained (seatbelts and/or air bag) occupants involved in frontal crashes who have been severely injured. More than 60 such crashes have been included in the study to date. Initial data analysis indicates that restraint systems are working to reduce many of the head and chest injuries which unrestrained occupants suffer. However, internal injuries among air bag-protected occupants may be unrecognized in the field. Also, extremely high severity crashes are presenting trauma management challenges. This paper provides case examples to illustrate types of chest and abdominal injuries associated with air bag cases. To assist in recognizing the extent of injuries to occupants protected by air bags, it is suggested that additional evidence from the crash scene be used in the triage criteria. For the occult chest/abdominal cases in the Jackson study, deformation of the steering wheel was the vehicle characteristic most frequently observed.

FE Modeling of the Orthotropic and Three-Layered Human Thoracic Aorta

The human aorta consists of three layers: intima, media and adventitia from the inner to outer layer. Since aortic rupture of victims in vehicle crashes frequently occurs in the intima and the media, latent aortic injuries are difficult to detect at the crash scene or in the emergency room. It is necessary to develop a multi-layer aorta finite element (FE) model to identify and describe the potential mechanisms of injury in various impact modes. In this paper, a novel three-layer FE aortic model was created to study aortic ruptures under impact loading. The orthotropic material model [1] has been implemented into a user-defined material subroutine in the commercial dynamic finite element software LS-DYNA version 970 [2], which was adopted in the aorta FE model. The Arbitrary-Lagrangian Eulerian (ALE) approach was adopted to simulate the interaction between the fluid (blood) and the structure (aorta). Single element verifications for the user-defined subroutine were performed. The mechanical behaviors of aortic tissues under impact loading were simulated by the aorta FE model. The models successfully predicted the rupture of the layers separately. The results provide a basis for a more in-depth investigation of blunt traumatic aortic rupture (BTAR) in vehicle crashes.Copyright