Editing Hydrostatic shock (section)

==Inferences from blast pressure wave observations==
[[Image:hydrostatic.jpg|400px|right|thumb|Ballistic pressure waves believed to be the mechanism of hydrostatic shock that were measured with a high speed pressure transducer for the specified loads.]]
A shock wave can be created when fluid is rapidly displaced by an explosive or projectile. Tissue behaves similarly enough to water that a sonic pressure wave can be created by a bullet impact, generating pressures in excess of {{convert|1500|psi|abbr=on}}.<ref name="fn_(10)">{{cite journal |last1=Harvey |first1=E. N. |last2=Korr |first2=I. M. |last3=Oster |first3=G. |title=Secondary Damage in wounding due to pressure changes accompanying the passage of high velocity missiles |journal=Surgery |volume=21 |issue=2 |pages=218–239 |year=1947 |pmid=20284789 |display-authors=etal}}</ref>

Duncan MacPherson, a former member of the International Wound Ballistics Association and author of the book, ''Bullet Penetration'', claimed that shock waves cannot result from bullet impacts with tissue.<ref name="fn_(51)"/> In contrast, Brad Sturtevant, a leading researcher in shock wave physics at [[Caltech]] for many decades, found that shock waves can result from handgun bullet impacts in tissue.<ref name="fn_(141)">{{cite journal |last=Sturtevant |first=B. |title=Shock Wave Effects in Biomechanics |journal=Sādhanā |volume=23 |issue= 5–6|pages=579–596 |year=1998 |doi=10.1007/bf02744581|s2cid=120104102 |url=https://authors.library.caltech.edu/104621/1/Sturtevant1998_Article_ShockWaveEffectsInBiomechanics.pdf }}</ref> Other sources indicate that ballistic impacts can create shock waves in tissue.<ref name="fn_(19)"/><ref name="fn_(142)">{{cite journal |last1=Roberts |first1=J. C. |last2=Ward |first2=E. E. |last3=Merkle |first3=A. C. |last4=O’Conner |first4=J. V. |title=Assessing Behind Armor Blunt Trauma in Accordance With the National Institute of Justice Standard for Personal Body Armor Protection Using Finite Element Modeling |volume=62 |issue=5 |pages=1127–1133 |year=2007 |pmid= 17495712|doi=10.1097/01.ta.0000231779.99416.ee |journal=J Trauma}}</ref><ref name="fn_(143)">{{cite journal |last1=Roberts |first1=J. C. |last2=O’Conner |first2=J. V. |last3=Ward |first3=E. E. |title=Modeling the Effect of Nonpenetrating Ballistic Impact as a Means of Detecting Behind-Armor Blunt Trauma |journal=Journal of Trauma |volume=58 |issue=6 |pages=1241–1251 |year=2005 |doi= 10.1097/01.ta.0000169805.81214.dc|pmid=15995477 }}</ref>

Blast and ballistic pressure waves have physical similarities. Prior to wave reflection, they both are characterized by a steep wave front followed by a nearly exponential decay at close distances. They have similarities in how they cause neural effects in the brain. In tissue, both types of pressure waves have similar magnitudes, duration, and frequency characteristics. Both have been shown to cause damage in the hippocampus.<ref name="fn_(21)"/><ref name="fn_(150)">{{cite journal |last1=Cernak |first1=I. |last2=Wang |first2=Z. |last3=Jiang |first3=J. |last4=Bian |first4=X. |last5=Savic |first5=J. |title=Ultrastructural and Functional Characteristics of Blast Injury-Induced Neurotrauma |journal=Journal of Trauma |volume=50 |issue=4 |pages=695–706 |year=2001 |doi= 10.1097/00005373-200104000-00017|pmid=11303167 }}</ref><ref name="fn_(151)">{{cite journal |last1=Cernak |first1=I. |last2=Wang |first2=Z. |last3=Jiang |first3=J. |last4=Bian |first4=X. |last5=Savic |first5=J. |title=Cognitive deficits following blast injury induced neurotrauma |journal=Brain Injury |volume=15 |issue=7 |pages=593–612 |year=2001 |doi=10.1080/02699050119009 |s2cid=219187276 }}</ref> It has been hypothesized that both reach the brain from the thoracic cavity via major blood vessels.

For example, [[Ibolja Cernak]], a leading researcher in blast wave injury at the [[Applied Physics Laboratory]] at [[Johns Hopkins University]], hypothesized, "alterations in brain function following blast exposure are induced by kinetic energy transfer of blast overpressure via great blood vessels in abdomen and thorax to the central nervous system."<ref name="fn_(152)">{{cite journal |last=Cernak |first=I. |title=Blast (Explosion)-Induced Neurotrauma: A Myth Becomes Reality |journal=Restorative Neurology and Neuroscience |volume=23 |pages=139–140 |year=2005 }}</ref> This hypothesis is supported by observations of neural effects in the brain from localized blast exposure focused on the lungs in experiments in animals.<ref name="fn_(150)"/>