Dexter V Reneer, Carolyn A Crowdus, Sarbani Ghoshal, Julie Corkins, Richard D Hisel, Braden T Lusk and James W Geddes
Blast-induced traumatic brain injury (bTBI) has been described as the defining injury of Operations Enduring
Freedom and Iraqi Freedom (OEF/OIF). Although there has been a significant amount of research characterizing
the brain injury produced by blast, greater understanding of the contribution of each component of the shockwave
to the injury is needed. Large animal models of bTBI utilize chemical explosives as their shockwave source while
small animal models predominantly utilize compressed air-driven membrane rupture as their shockwave source. We
previously designed and built a multi-mode shock tube capable of utilizing air-driven membrane rupture or chemical
explosives (oxyhydrogen: A 2:1 mixture of hydrogen and oxygen gasses to produce a shockwave. Compressed airdriven
shockwaves exhibited longer duration positive phases than compressed oxyhydrogen-driven shockwaves of
similar peak overpressure. The longer duration of compressed air-driven shockwaves results in greater energy being
imparted on a test subject than would be impacted by shockwaves of identical peak overpressures from the other
sources. Animals exposed to compressed air-driven shockwaves exhibited more extensive brain surface hematoma
and more blood-brain barrier compromise than did animals exposed to oxyhydrogen-driven shockwaves of even
greater peak overpressure. Taken together, these data suggest that compressed air-driven shockwaves contain more
energy than their chemical explosive-derived counterparts of equal peak overpressure and can result in greater injury
in an experimental animal model. Additionally, these data suggest that exposure to longer duration shockwaves can
result in more severe bTBI. The results of this study are relevant to the design of blast wave mitigation technology
and future clinical intervention