Blast injury
Background
- 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
Spalling Effect
Due to blast pressure forces, injuries are to organs with air-fluid interfaces (spalling effect)
- TMs
- Alveoli
- GI tract
Situational Examples
- Military - young healthy soldiers with body armor reducing thoracic/abdominal injuries but significant groin and lower extremity injuries
- Civilian - children to elderly, higher rates of penetrating thoracic/abdominal injury
Injury Classifications
| Blast Type | Injury Cause | Injuries | Example |
|---|---|---|---|
| Primary | Direct effect from shockwave | Sheer and stress forces | TM rupture, Ocular Injury, concussion, blast lung |
| Secondary | Penetrating trauma, amps, lacs | ||
| Tertiary | Blast propels body or large object into body | Crush injury and blunt trauma | Similar to MVC: Fractures, Pneumothorax, Hemopneumothorax |
| Quaternary | Environmental | Burns, Toxins, Weather | |
| Quinary | Bodily absorption of contaminates | Hypermetabolic state |
Effects based on blast pressure[1]
| Potential Injury | Pressure (PSI) | Structural Effects |
| Loss of balance/temporary ear damage | 0.5-3 psi | Glass shatters; facade fails |
| Slight chance of eardrum rupture | 5-6 psi | Cinderblock shatters; steel structures fail; containers collapse; utility poles fail |
| 50% chance of eardrum rupture | 15 psi | Structural failure of typical construction |
| Lung collapse/damage | 30 psi | Reinforced construction failure |
| Fatal injuries | 100 + psi* | Structural failure |
Clinical Features
Pulmonary
- Blast lung is the most common fatal primary blast injury (PBI)
- Pulmonary contusion
- Pneumomediastinum due to alveolar rupture - pneumothorax, subcutaneous emphysema, pneumopericardium, pneumoretroperitoneum, pneumoperitoneum, air embolus
- Thrombosis, DIC, ARDS
HEENT
- TM rupture most common - not a marker of PBI severity or prognosis
- Hemotympanum
- Ossicle injury
- Direct ophthalmic injury, foreign bodies, or ophthalmic artery air embolus
Thoracic
- Cardiovascular collapse (within seconds)
- Hypotension due to impaired reflex that increases SVR
Infectious Disease
- Transmission of disease due to penetrating trauma is rare but possible with HIV, HCV, HBV
Musculoskeletal
Markers of severe blast injury
- > 10% TBSA burn
- Skull, facial fracture
- Penetrating injury to head or thorax
- Traumatic amputations
Differential Diagnosis
Mass casualty incident
- Radiation exposure (disaster)
- Dirty bomb
- Bioterrorism
- Chemical weapons
- Mass shooting
- Natural Disaster (e.g. Hurricane, Earthquake, Tornado, Tsunami, etc)
- Unintentional large-scale incident (e.g. building collapse, train derailment, etc)
- Major pandemic
- Explosions
Evaluation
- CXR - butterfly distribution, bilateral patchy infiltrates
- CT chest
- FAST, comprehensive CT
- 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
- Labs
- Consider carboxyhemoglobin and electrolytes
- Screening UA for significant explosions
- Burn labs (rhabdomyolysis, compartment syndrome, severe burns)
- DIC labs (PT, aPTT, CBC, D-dimer, thrombin time, fibrinogen)
- White phosphorus labs (hypocalcemia, hyperphosphatemia, LFTs)
Management
- pRBCs and FFP in 1:1 ratio with platelets for hemodynamically unstable patients
- TM rupture - initial treatment 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 patient in left decubitus, head down, feet up position
Disposition
- Ambulatory patient with normal TM evaluation at low risk for occult blast injury - discharge with precautions
- All others require admission
See Also
References
- Terrorism Handbook for Operational Responders by Armando Bevalacqua and Richard Stilp (1998) and the Department of the Navy EODB 60 A-1-1-4 (2001) “Table A-1 http://www.fema.gov/pdf/plan/prevent/rms/428/fema428_ch4.pdf
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