Behind Armor Blunt Trauma Viscous Criteria for Liver Injuries: A Preliminary Study

Abstract The current standardized measure for behind armor blunt trauma (BABT) applications relies on a single parameter (deflection) in Roma Plastilina No. 1 clay and is applied to the entire thoracoabdominal region; however, it is known that the organs inside the thoracoabdominal complex differ in anatomy, function, and injury. The objective of this study was to develop a preliminary set of injury criteria for an improved delineation of liver injury. Using a custom indenter that replicated the backface deformation of hard body armor, BABT impacts were delivered to the liver region of swine. The swine were physiologically monitored for 6 h, euthanized, and necropsied. Injury risk curves (IRCs) were developed using survival analysis, and the viscous criterion was used as the candidate metric. The log-normal distribution best described the biomechanical results. The magnitudes of the viscous criterion at 10%, 25%, and 50% risk levels were 1.5, 1.9, and 2.7 m/s, respectively. The estimated IRC and 95% confidence interval bounds are given in the body of the paper. Additional studies are needed to classify liver injury criteria and develop human IRCs using American Association of Surgery for Trauma (AAST) Injury Scoring Scale and/or another grading method(s).