Ballistics and blast injury

Question 1

What is cavitation?

Answer 1

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

Question 2

True or false: the denser the tissue involved, the greater the cavitation effect.

Answer 2

True

Question 3

What is the reason exit wounds are usually larger than entry wounds?

Answer 3

The cavitation effect.

Question 4

What is fragmentation?

Answer 4

Bone fragments and/or the missile itself fragmenting and spreading through the body in multiple directions.

Question 5

What is the angle of the yaw?

Answer 5

The angle between the missile and its direction of travel, also called the tilt of the missile.

Question 6

True or false: the greater the angle of the yaw, the greater the damage caused by the missile.

Answer 6

True

Question 7

What is ricochet in ballistics trauma?

Answer 7

A deflection from a rib/pelvis/solid organ causing the projectile to travel an entirely different path once it enters the body.

Question 8

True or false: multiple deflections (ricochets) may occur.

Answer 8

True

Question 9

Describe the projectile injury process

Answer 9

• 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

Question 10

In ballistics trauma, a large hole outside generally means…?

Answer 10

Massive internal damage

Question 11

Provide a rationale for wound packing

Answer 11

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.

Question 12

What is the best treatment for a gunshot pt?

Answer 12

Transport.

Question 13

Why can small low velocity objects be dangerous?

Answer 13

Once taken out the wound may close and appear to externally tamponade with internal bleeding, but no visible trauma from the outside.

Question 14

What is an overpressure wave?

Answer 14

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

Question 15

What are the three different types of explosives?

Answer 15

• High order
• Low order
• IED (incendiary/improvised explosive devices)

Question 16

Low order explosives cause injuries characterised by…

Answer 16

Ballistics-type injuries with associated burns

Question 17

What are the four classifications of blast injury?

Answer 17

• Primary
• Secondary
• Tertiary
• Quaternary (miscellaneous)

Question 18

Describe primary blast injury

Answer 18

• Injury caused solely by blast wave

- Direct or reflected over-pressurisation force and blast wind (superheated air)

Question 19

What organs are most commonly involved in primary blast injury?

Answer 19

Gas filled organs

• Tympanic membrane rupture
• Pulmonary tissue damage
• Globe rupture

Question 20

What is the clinical triad of blast lung?

Answer 20

Apnoea, bradycardia, and hypotension

Question 21

Blast lung is a direct consequence of the ____ ____ ____.

Answer 21

HE over-pressurisation wave

Question 22

Blast lung should be suspected for anyone with what symptoms after blast exposure?

Answer 22

Dyspnoea, cough, haemoptysis, or chest pain.

Question 23

Ear injury should be suspected for anyone presenting with what symptoms after blast exposure?

Answer 23

• Hearing loss
• Tinnitus
• Otalgia
• Vertigo
• Bleeding from the external canal
• Tympanic membrane rupture

Question 24

Abdominal injury should be suspected for anyone presenting with what symptoms after blast exposure?

Answer 24

• Abdo pain
• N + V
• Haematemesis
• Rectal pain
• Testicular pain
• Unexplained hypovolaemia
• Any findings suggestive of acute abdomen

Question 25

True or false: primary blast waves can cause concussions or mild TBI without a direct blow to the head.

Answer 25

True

Question 26

Describe secondary blast injury

Answer 26

Injury caused by flying debris and/or shrapnel

Question 27

Describe tertiary blast injury

Answer 27

Individual is thrown by the pressure wave

Question 28

What are some examples of quaternary blast injury?

Answer 28

• Burns
• Toxic dust/gas/radiation exposure
• Asphyxia
• Crush injury
• Exacerbations of pre-existing conditions