Physiology-Based Liver Injury Criteria for Behind Armor Blunt Trauma

Area of Science:

• Biomechanical Engineering
• Trauma Research
• Protective Equipment Evaluation

Background:

• Current behind armor blunt trauma (BABT) risk assessment relies on outdated criteria (44 mm), established over 50 years ago.
• Existing BABT criteria do not account for region-specific injury responses and organ tolerances within the thoraco-abdominal region.
• The need for organ-specific tolerance data is critical for accurate Warfighter protection assessment.

Purpose of the Study:

• To develop novel BABT liver injury risk curves using an experimental animal model.
• To establish preliminary liver tolerance criteria for BABT applications.
• To enhance the evaluation of body armor effectiveness for the thoraco-abdominal region.

Main Methods:

• Live swine were subjected to impacts simulating BABT scenarios using a custom-designed indenter system.
• Impacts were precisely targeted at the liver region, followed by a 6-hour monitoring period and necropsy.
• Parametric survival analysis and the viscous criterion metric were employed to develop liver injury risk curves.

Main Results:

• Mean viscous criterion values were determined for mild (2.3 m/s at 10% risk, 4.0 m/s at 50% risk) and moderate (4.0 m/s at 10% risk, 7.1 m/s at 50% risk) liver injuries.
• The developed injury risk curves demonstrated good-to-fair quality at tested injury probability levels.
• The study provides the first BABT liver injury risk curves derived from live swine survival analysis.

Conclusions:

• The developed liver injury risk curves serve as preliminary criteria for BABT applications.
• These findings can significantly improve the assessment of current and future body armor designs.
• Enhanced body armor evaluation will contribute to improved Warfighter safety and medical readiness for liver injuries.