Lung injury risk assessment during blast exposure

Blast pulmonary trauma are common consequences of modern war and terrorism action. To better protect soldiers from that threat, the injury risk level when protected and unprotected must be assessed. Knowing from the literature that a possible amplification of the blast threat would be provided by some thoracic protective systems, the objective is to propose an original approach to correlate a measurable parameter on a manikin with a pulmonary risk level. Using a manikin whose response is correlated with the proposed tolerance limits should help in the evaluation of thoracic protective system regarding injury outcomes. A database including lung injury data from large mammals have been created, allowing the definition of iso-impulse tolerance limits from no lung injury to severe ones (∼60% of ecchymosis). As the use of this metric is not sufficient to evaluate the performance of protective systems on a manikin, the iso-impulse tolerance limits were associated with the thoracic response of post-mortem swine under blast loading. It was found that the lung injury threshold in terms of incident impulse is 58.3 kPa·ms, corresponding to a chest wall peak of acceleration/velocity/displacement of 7350 m/s², 3.7 m/s and 6.4 mm respectively. Lung injuries are considered as severe (30-60% of ecchymosis) when the incident impulse exceed 232.8 kPa·ms, leading to a chest wall peak of acceleration/velocity/displacement of 79.7 km/s², 14.7 m/s and 30.1 mm respectively. The defined lung tolerance limits are valid for a 50 kg swine (unprotected) exposed side-on to the blast threat and against a wall.