Blast injury

Overview
Blast injuries are inflicted on individuals subjected to the effects of the detonation of high-order explosives, explosives that produce a supersonic over-pressurization shock wave, as well as low order explosives which produce a subsonic explosion with no over-pressurization wave. These injuries are compounded when the explosion takes place in a confined space.

Blast injuries are divided into four classes:
 * Primary: injuries due to high-order explosive over-pressurization shock wave as it moves through the body from solid and liquid sections to gas-filled organs, in particular the lungs, gastro-intestinal tract and middle ear. Solid- and liquid-filled organs are not subject to primary blast injury. These injuries are not necessarily obvious to observers.
 * Secondary: injuries due to bomb fragments and other objects propelled by the explosion. These injuries may affect any part of the body and sometimes result in visible hemorrhage.  At times the propelled object may become embedded in the body, obstructing the loss of blood to the outside. However, there may be extensive loss of blood within the body cavities. Shrapnel wounds may be lethal and therefore many anti-personnel bombs are designed to generate shrapnel and fragments.
 * Tertiary: injuries as a result of the victim becoming a missile and being thrown against other objects. The injuries sustained are then similar to those that are sustained by blunt trauma, including bone fractures and coup/ contre-coup injuries≠.
 * Quaternary: all other injuries not included in the first three classes. These include burns, crushing injuries and respiratory injuries.