The Effectiveness of Different Personal Protective Ensembles in Preventing Blast Injury to the Thorax

Abstract : It is well established from numerous documented cases of bomb blasts that under certain conditions (determined by the amount and proximity of explosive), the transmitted shock wave and associated overpressure generated by the detonation of an explosive device, can cause critical and fatal injuries to the thorax, e.g., "blast lung". As such injuries tend to be internal and thus difficult to detect, there has been considerable debate in recent years on the significance of the blast overpressure injury in the context of demining/mine clearance, compared with other more visible injuries, such as, amputation of extremities, fragmentation wounds, blindness, etc. A wide range of personal protective ensembles are currently deployed in the field, incorporating disparate stackings of materials over the thoracic region. The purpose of this study is to quantitatively assess the relative effectiveness of different laminations for blast overpressure protection to the deminer's chest. The range of test candidates included variations of ballistic flak vests, or aprons comprised entirely of soft ballistic materials with different numbers of layers, as well as the recently developed and field tested HDE Demining Ensembles by Med-Eng Systems Inc., in both their Basic and Enhanced forms. The HDE Ensembles consist of a hybrid combination of blast-energy absorbing components mixed with soft and rigid ballistic materials, while the Enhanced HDE uses an extra layer of high density rigid ballistic material overtop the Basic layout. A "chest simulator", instrumented to measure transmitted blast overpressure, as well as Hybrid II mannequins with pressure sensors and accelerometers mounted inside the chest, were both used as test surrogates to evaluate the effectiveness of different systems.