Explosion injury

Explosion injury

• An explosion is a phenomenon resulting from sudden release of energy which is then dissipated by a blast wave, by translocation of objects, or by the generation of heat. Injuries in explosion occur due to four factors 

1) Blast or shock wave

•  When an explosion occurs, the explosive material produces a large volume of gas and releases a large amount of energy.
•  It produces a ‘shock wave’ which spread concentrically from the site of explosion. 
• The injuries depend on the enviornment in which blast occurs :-

Air blast (most common) :

Explosion occurs in air. 

There is barotrauma to air filled hollow organs.

• Tympanic membrane (ear drum) is most sensitive and most commonly injured. 
• Lung is the second organ to be injured and is the most commonly injured hollow organ and most common cause of life threatening injury. 
• Other parts injured are middle ear, cochlea, eyes, bowels, mesentery, omentum and brain. Homogenous solid organs like liver and muscles are usually not affected.
• Under water blast (explosion under water): 
• Gastrointestinal tract is injured most commonly.
• Lungs are also injured.

Solid blast :

• Explosive is detonated near a rigid/solid structure and wave of energy spreads through it. 
• If people are in contact with that rigid structure, injuries take place.
• The injuries are mostly skeletal; fracture of legs and vertebral column are more common.
• GIT damage is more common than lung.

2) Flame or hot gases

•  Burns or burning of body may occur.

3) Flying missiles (debris)

•  Flying pieces of explosive debris may be driven through air against the skin causing bruises, abrasions, lacerations, and ragged perforations.

4) Anoxia

• Various gases liberated during explosion may cause anoxia, e.g. carbon monoxide, nitrous oxide, nitric oxide, HCN and SO,

CLASSIFICATION OF BLAST INJURIES

Primary injuries

• Caused by blast overpressure waves, or shock waves
• Person is close to exploding ammunition, such as a land mine.
• Gas filled structures are most susceptible as air is easily compressible than water
• Blast lung (pulmonary barotrauma)
• Abdominal haemorrhage and perforation
• TM rupture and middle ear damage
• Globe (eye) rupture
• Concussion
• Gastrointestinal injuries may present after a delay of hours or even days. 
• Absence ofexternal injuries; thus internal injuries are frequently unrecognized andtheir severity underestimated.

Secondary injuries

• Caused by fragmentation and other objects propelled by the explosion.
• Results from flying debris, broken glass, loose pieces and bomb fragmentsany body part can be affected.
• Penetratingtrauma with visible bleeding.

Tertiary injuries

• Displacement of air by the explosion creates a blast wind that can throw victims against solid objects. 
• Injuries resulting from this typeof traumatic impact are referred to as tertiary blastinjuries.
• May present as some combination of blunt and penetrating trauma, including bone fractures and coup contre-coup injuries.
• Young children, because they weigh less thanadults, are at particular risk of tertiary injury.

Quaternary injuries or other miscellaneous named injuries,

• All explosion-related injuries, illnesses or diseases not due to primary, secondary, ortertiary mechanisms.
• Burns (flash, partial, and full thickness)
• Crush injuries
• Closed and open brain injury
• Asthma, COPD, or other breathing problems from dust, smoke, or toxic fumes
• Angina Hyperglycemia
• Hypertension Traumatic amputations quickly result in death, and are thus rare in survivors,and are often accompanied by significant other injuries.
• Psychiatric injury