Blast injuries

blasts human hx about 1000 yrs (china/mbe middle e and euro ind too), 

blast: interplya local, systemic, and cerebral responses, complications from polytrauma common, including blast lung (PBLI), acute kidney injury (AKI) acute lung injury (ALI), or heterotropic ossification (ectopic bone formation in blast amputations- causes pain, delayed healing, reduced limb function).  

Primary: pressure wave- over then under pressurization of air (lung, ear, bwoels, brain), fluid air filled organs, 

secondary - debris- blunt, penetrating

tertiary- being thrown

quaternary- other (inhalation burns)

spallation, implosion, and inertia- like last ball in newtons cradle accelerates blast into less dense tissue- nothing to slow it, too much kinetic energy- so damage from rapid expansion compression gases, and shearing forces from tissues accelerating at dif rates

Analysis of  probability of survival using UK data from Operation BANNER in Northern Ireland in 1969 to 1997 through to Operations TELIC and HERRICK in Iraq and Afghanistan has shown that the mean New Injury Severity Score (NISS) associated with 50% probability of survival has increased from 29 to 43 over the past four decades (184).  In clinical terms this means an injury severity associated with a 50% chance of dying during Op BANNER carried an approximate 70% chance of survival during Iraq or over 90% in Afghanistan. Conversely, injuries during current conflicts in Afghanistan associated with 50% risk of mortality would have been 95% fatal during earlier operations in Northern Ireland (184) Reasons for this include increased medical training and ‘buddy-buddy’ care at the point of wounding with early hemorrhage control, improved body armor, forward deployment of prehospital physicians and surgical teams delivering early damage control resuscitation and surgery, and the rapid retrieval and evacuation of casualties from the battle space (170; 215). armor- survive, but w blast injury

PBLI- primary blast lung injury- non blunt/penetrating acute lung injury within 12 hrs blast exposure

shockwave alveolar rupture intra-parenchymal bleeding and subsequent edema, if close to blast, enclosed space, or irritant smoke exposure, blast damage esp at interface density changes, vagal nerve stim-- brief brady, hypotens, apneic period, mbe fatal air embolism to circ or fistula broncho-pleural, reflefctive surfaces extend and mbe increase blast distance/force, Madrid train bombings 2010 10 devices in train, 250 serious casualties 150 w blast lung, 

ss mbe delayed, resp distress, restlessness, mbe hemoptysis, cyanosis, hypoxemia, imaging abnormal >50%, resp symptoms <50%

imageryL uni or bilat focal opacities, diffuse loss lung translucency, reduced rib expansion, radiological evidence barotrauma (pneumo or hemo thorax, pneumomediastinum, pneumopericardium, surgical or interstitial emphysema,  

tx: lung protective ventilation, blast lung UK mil analysis epiphenomenon in multitrauma pts

Primary Blast Lung Injury: the UK Military Experience

2011 analysis: Blast Injury to the Lung: Epidemiology and Management, University Hospital Birmingham