THE INFLUENCE OF PERSONAL BLAST PROTECTION ON THE DISTRIBUTION AND SEVERITY OF PRIMARY BLAST GUT INJURY

Primary blast injuries have been recognized since World War I when the most significant reported injury was to the lung, The prevalence of i njury to tissues containing air was underlined by the frequency of gut blast injury in underwater explosions mostly reported during World Wa r II, Gut injury is the most likely cause of mortality after the more immediate effects of pulmonary primary blast injury, Effective protect ion has been achieved for lungs exposed to short duration external bla st waves by the placement of stress wave decouplers on to the thoracoa bdominal wall in a pig model, thus modifying the energy coupled into t he body, A combination of two densities of glass-reinforced plastic pl ate and Plastazote foam (GRP/PZ) effectively eliminated pulmonary inju ry in 17 protected animals, compared with the production of severe bla st lung in nine unprotected animals (p < 0.001), Partial pulmonary pro tection was achieved using a plasticized lead and plastazote foam deco upling combination (PbPVC/PZ) in a further group of 10 animals, Peak i ncident overpressures were not significantly different in any group, S mall bowel contusions were highly significantly reduced in the GRP/PZ groups when compared with unprotected animals and with PbPVC protected animals (both p < 0.001); no significant reduction was observed in th e summed colonic contusion size in any protected group. Intestinal per fo rations were also highly significantly reduced in both GRP/PZ group s (p < 0.001), Primary pulmonary blast injury and probably small bowel injury are caused by the propagation of coupled stress waves within t he body, Elimination of these injuries implies prevention of stress wa ve propagation, Because colonic injury was not prevented by the same p rotection, a different mechanism for the injury is suggested: transmis sion and propagation of shear waves, These findings have important imp lications for blast protection and the clinical management of primary blast casualties.