Organ MC involved in blast injuries (AIPG 2010)
a. Explosion is defined as the sudden release of previously confined energy and is characterised by production of heat, large amount of gas & plenty of noise.
i. Atomic explosions.
ii. Mechanical explosions- due to build-up of pressure e.g. Steam in a steam boiler.
iii. Chemical explosions- Dispersed & Condensed.
b. When an explosion occurs, explosive material is converted into a large volume of gas with release of tremendous amount of energy & pressures upto 1000 tons/sq inch (15,000 atm. pressure) & temperature upto 3000 0C.
c. A person can be injured in many ways by an explosion:-
i. Disruptive effects of blasts- due to victim being in contact or immediate vicinity of the bomb, he may be blown to pieces.
ii. Flame & Radiant heat- temperature of explosive gases can reach upto 3000 0C and the radiated heat can cause "flash burns" (when the person is between a feet of the bomb).
iii. Air blast- An explosion produces a 'shock wave' which spreads concentrically from the site of explosion at about the speed of sound. This wave of very high pressure is followed by a weak wave of negative pressure (below atmospheric pressure), a suction effect which lasts about 5 times as long. The shock wave lasts for milliseconds and a pressure exceeding 100 pounds/sq. inch is necessary to cause serious damage to a body. A shock wave can knock a person down, more objects & demolish buildings (much like an earthquake).
• Lungs- "blast lung".
• Ear- T.M. Rupture + haemorrhage in ear.
• GIT & Others- Sub-peritoneal haemorrhages, laceration of internal organs, intracranial haemorrhage, contusion of brain, aorta & heart, ruptured stomach & bowel. Death may occur from pulmonary air embolism.
• Underwater/Immersion blast- When explosion occurs in the water,
• Solid blast- when the pressure wave forces a solid material against the body. In these GIT damage is more common than lung damage. Sometimes death may occur without any external injury.
iv. Flying missiles- The bomb may drive multiple fragments of bomb or pieces of nearby objects e.g. Gravel, glass, wood, brick, plaster etc. through the air into the skin and cause bruises, abrasions and puncture lacerations (this triad of injuries is diagnostic) all over the skin.
v. Falling masonry- When a building is destroyed by a bomb blast the persons inside may sustain multiple injuries caused by the collapsing masonry. The cause of death is usually traumatic asphyxia.
vi. Poisoning by fumes- If bomb explodes in a confined or closed space, enough CO may be produced to cause death by asphyxia.