Blast injury

Background

Primary blast injury (PBI, blast overpressure); Secondary (projectile injury); Tertiary (victim propelled due to superheated air); Quaternary (all other injuries - burns, asphyxia, radiation, toxins)
Injuries to organs with air-fluid interfaces (spalling effect)
- TMs
- Alveoli
- GI tract
Military - young healthy soldiers with body armor reducing thoracic/abdominal injuries
Civilian - children to elderly, higher rates of penetrating thoracic/abdominal injury
Primary blast wave increased in closed space - detonation in corner has potential to increase blast yield to 8x
Recent enhanced-blast weapons (EBW) disperses gas before explosion - larger blast wave with lower pressure amplitude that diffuses around corners

Penetrating and blunt injuries, burns, amputations
Markers of severe blast injury
- > 10% TBSA burn
- Skull, facial fx
- Penetrating injury to head or thorax
- Traumatic amputations
Primary blast injuries most likely to cause pulmonary, acoustic/head, thoracic trauma
- Pulmonary is most common fatal PBI
  - Pulmonary contusion
  - Pneumomediastinum due to alveolar rupture - PTX, subQ emphysema, pneumopericardium, pneumoretroperitoneum, pneumoperitoneum, air embolus
  - Thrombosis, DIC, ARDS
- Acoustic/head
  - TM rupture most common - not a marker of PBI severity or prognosis
  - Hemotympanum
  - Ossicle injury
  - Direct ophthalmic injury, FBs, or ophthalmic artery air embolus
- Thoracic - immediate effects
  - CV collapse (within seconds)
  - Decreased BP due to impaired reflex that increases SVR
Transmission of disease due to penetrating trauma is rare but possible with HIV, HCV, HBV

CXR, CT chest
Repeat clinical abdominal exams looking for peritonitis - X-rays, US, CT insensitive except in perforation
Initial CT head may not be enough - may require MRI for DAI

pRBCs and FFP in 1:1 ratio with platelets for hemodynamically unstable pts
TM rupture - initial Tx supportive and enough for 75% with spontaneous healing; operative repair may be necessary for others
Operative exploration for peritonitis
Air embolus (rare) - isolate air in apex of LV by placing pt in left decubitus, head down, feet up position

Pennardt A, Lavonas EJ, Danzl D, Talavera F, Levy DB, Halamka JD. Blast Injuries. eMedicine Medscape Review. Last updated Apr 21, 2014. http://emedicine.medscape.com/article/822587-overview#showall
Yeh DD, Schecter WP. Primary blast injuries - An updated concise review. World J Surg (2012). 36:966-972.
Ritenour AE, Baskin TW. Primary blast injury: Update on diagnosis and treatment. Crit Care Med 2008; 36[Suppl.]:S311-S317.

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