An Analysis of Traumatic Rupture of the Aorta in Side Impact Sled Tests 2005-01-0304

Traumatic rupture of the aorta (TRA) is a leading cause of death in high velocity blunt trauma, particularly motor vehicle accidents. However, little is understood about the mechanisms of TRA and thus, the opportunities to prevent TRA in the motor vehicle environment are compromised. The objective of this study was to determine the relationship between impact response and TRA through analyses of data from cadaver tests that successfully produced TRA in lateral impacts.

Seventeen Heidelberg-style side impact sled tests were conducted using unembalmed human cadavers. Three sled speeds were used: 6.7, 9.0, and 10.5 m/s. Three barrier configurations were used: rigid flat wall, rigid wall with a 152-mm offset toward the pelvis, and a flat wall with padding of varying stiffness. Multiple load and acceleration measurements were made on the barrier and cadaver. Potential injury parameters were evaluated and their relative predictive abilities were examined.

Five of the seventeen tests resulted in AIS 4 or 5 TRA. Most were partial circumferential tears in the periisthmic region. All tears resulted from tests involving the rigid barrier or stiff padding. Tests involving softer padding did not result in TRA. Based on logistic regression analysis Average Spine Acceleration (T12-y direction), peak lateral acceleration of the eighth rib on the unstruck side and VCmax had correlation to the presence of TRA. Predictive ability was improved by including T12-z or upper sternum-x acceleration. The latter finding suggests that traction on the aortic arch through anterior displacement of the sternum or vertical displacement of the spine can increase the risk of aortic injury. The inclusion of age provided modest improvement.