Ballistics and blast injury Flashcards
What is cavitation?
A temporary vacuum cavity and dissipating shock wave formed in the wake of a high velocity projectile as it passes through body tissue causing injury to vessels and organs well outside the missile path
True or false: the denser the tissue involved, the greater the cavitation effect.
True
What is the reason exit wounds are usually larger than entry wounds?
The cavitation effect.
What is fragmentation?
Bone fragments and/or the missile itself fragmenting and spreading through the body in multiple directions.
What is the angle of the yaw?
The angle between the missile and its direction of travel, also called the tilt of the missile.
True or false: the greater the angle of the yaw, the greater the damage caused by the missile.
True
What is ricochet in ballistics trauma?
A deflection from a rib/pelvis/solid organ causing the projectile to travel an entirely different path once it enters the body.
True or false: multiple deflections (ricochets) may occur.
True
Describe the projectile injury process
- Tip impacts tissue
- Tissue pushed forward and to the side
- Pressure or shock wave laterally and perpendicular to bullet path
- Rapid compression crushes and tears tissue
- Cavity forms behind bullet, pulling in debris with suction
- Rapid internal pressure changes tear tissue
- Bullet exits body with vacuum material following
In ballistics trauma, a large hole outside generally means…?
Massive internal damage
Provide a rationale for wound packing
The cavitation effect and subsequent shock wave damages organs and vessels causing haemorrhage. Packing the wound applies internal pressure and the clotting agent added to most wound packing kits helps tamponade the bleed until the pt reaches definitive care.
What is the best treatment for a gunshot pt?
Transport.
Why can small low velocity objects be dangerous?
Once taken out the wound may close and appear to externally tamponade with internal bleeding, but no visible trauma from the outside.
What is an overpressure wave?
Intense pressure and sudden negative pressure of the blast wave and negative pressure wave travel through the body causing significant disruption across differing tissue densities
What are the three different types of explosives?
- High order
- Low order
- IED (incendiary/improvised explosive devices)
Low order explosives cause injuries characterised by…
Ballistics-type injuries with associated burns
What are the four classifications of blast injury?
- Primary
- Secondary
- Tertiary
- Quaternary (miscellaneous)
Describe primary blast injury
- Injury caused solely by blast wave
- Direct or reflected over-pressurisation force and blast wind (superheated air)
What organs are most commonly involved in primary blast injury?
Gas filled organs
- Tympanic membrane rupture
- Pulmonary tissue damage
- Globe rupture
What is the clinical triad of blast lung?
Apnoea, bradycardia, and hypotension
Blast lung is a direct consequence of the ____ ____ ____.
HE over-pressurisation wave
Blast lung should be suspected for anyone with what symptoms after blast exposure?
Dyspnoea, cough, haemoptysis, or chest pain.
Ear injury should be suspected for anyone presenting with what symptoms after blast exposure?
- Hearing loss
- Tinnitus
- Otalgia
- Vertigo
- Bleeding from the external canal
- Tympanic membrane rupture
Abdominal injury should be suspected for anyone presenting with what symptoms after blast exposure?
- Abdo pain
- N + V
- Haematemesis
- Rectal pain
- Testicular pain
- Unexplained hypovolaemia
- Any findings suggestive of acute abdomen
True or false: primary blast waves can cause concussions or mild TBI without a direct blow to the head.
True
Describe secondary blast injury
Injury caused by flying debris and/or shrapnel
Describe tertiary blast injury
Individual is thrown by the pressure wave
What are some examples of quaternary blast injury?
- Burns
- Toxic dust/gas/radiation exposure
- Asphyxia
- Crush injury
- Exacerbations of pre-existing conditions
