Chapter 30. Blast and gunshot injuries
Injuries to blast and gunshot are becoming increasingly common in modern Western society.
Basic rules for blast and bomb incidents
• Do not become a casualty yourself. Do not approach the scene until it has been declared safe – risks of secondary explosions, fire and building collapse are high
• Do not disturb or remove objects found in the environment – they may have forensic or other non-medical implications
• Do not disturb obviously dead victims or move body parts
• If there are multiple victims, triage will be necessary so that those most in need are identified, assessed and resuscitated first. This will normally be coordinated by an ambulance incident officer (in liaison with a medical incident officer)
• Care for multiple victims involves teamwork and it may be necessary to summon medical teams to the site – particularly if entrapment of victims is a feature.
Basic rules for gunshot incidents
• Do not become a casualty yourself. Do not approach the scene until it has been declared safe by the police, preferably by a firearms unit
• The management of the gunshot victim follows exactly the same <C>ABC system as any other trauma patient.
Physical effects of an explosion
A front of high pressure or shock wave is formed which travels through the surrounding environment with a velocity greater than the speed of sound in air.
Behind the shock front is an area of turbulence defined as the dynamic pressure or blast wind.
The magnitude of an explosion is determined to a large degree by the type and quantity of explosive used as well as the environment – whether the explosion occurs in an open space or is confined inside a building.
Other features are the flash from the explosion, the risk of fires developing and the collapse of buildings.
Mechanisms of bomb injury
• Blast shock wave
• Blast wind
• Fragmentation
• Crush
• Burn
• Psychological.
Biological effects of blast
Primary effects
Primary effects result from exposure of the body to the overpressure associated with the shock wave. The most notable effects are in areas of the body where there are air-fluid interfaces:
Ear
The tympanic membrane or eardrum is very susceptible and injury is common but unpredictable. The ear must be correctly aligned to the shock wave for injury to occur.
Abdomen
Injuries range from mild contusion of bowel wall to areas of perforation with faecal spillage and subsequent peritonitis.
Lung
The most significant clinical primary effect is contusion injury to the lungs, which may progress in some cases to ‘blast lung’. The problem results from widespread pulmonary bruising with haemorrhage into the alveolar spaces.
Clinical features of blast lung
• Breathlessness
• Acute respiratory distress
• Use of accessory muscles of respiration
• Pneumothorax
• Haemothorax
• Haemoptysis (rare)
• Sudden death (rare).
Secondary effects
The most common serious clinical problems facing paramedics after an explosion are the penetrating and non-penetrating injuries caused by fragments. These may arise from the casing of the exploding device (primary), or from the environment, such as pieces of glass, masonry and wood propelled by the blast wind (secondary).
Size, shape, type of material, velocity and terminal effectiveness vary enormously. Widespread contamination by foreign bodies and mixed bacterial species is common to all.
Primary fragments – components of the explosive munition or improvised explosive device
Secondary fragments – energised environmental fragments including body parts.
Tertiary effects
Tertiary effects result from gross displacement of the body by the blast wind. The clinical consequences include traumatic amputation and even complete body disintegration.
Injury may also be caused by a body being thrown onto a hard or irregular surface. Finally, tertiary injury may result from building collapse caused by the blast winds.
Burn injury
Burns are common and may be caused by flash, flame or both. Flash burns occur at the moment of detonation and particularly affect exposed parts such as face, arms and legs.
Flame burn occurs if the surrounding environment ignites.
Psychological injury
Over 40% of those involved in incidents such as terrorist explosions may expect to suffer some form of psychological distress in the aftermath period. For the majority of trained personnel, the outlook is very good, particularly if their efforts were successful in reducing morbidity and mortality. Debriefing and stress counselling may be helpful and is now mandatory for many emergency personnel after exposure to a stressful incident such as a bomb explosion.
Wound ballistics and mechanisms of injury
Wounding missiles, irrespective of type, cause injury by penetrating the body and transferring energy to the tissue. Therefore the wounding capacity of a particular missile wound may be defined by:
• The degree of penetration into the body and the structures directly penetrated
• The capacity of the missile to cause injury to structures surrounding and remote from the missile track.
Wounding missiles
Bullets
• Police handguns (many varieties)
• Military handguns
• Military assault rifles (5.56 mm, 7.62 mm)
• Hunting rifles (many varieties)
• Machine guns.
Fragments
Primary
• Natural (fragments from bomb casing, shells and mortars)
• Preformed (claymore mine, etched wire from hand grenades)
• Flechettes (individual darts preloaded into a carrying munition).
Secondary
• Masonry
• Glass
• Wood
• Metal.
Intrinsic
Body parts.
Gunshot injuries
In the UK, gunshot wounds are mainly caused by handguns and shotguns. Although patients are now being seen with wounds caused by bullets from military assault rifles and other military automatic weapons, these are still, fortunately, rare.
Handguns
If there is no event history, a gunshot wound may be missed.
In general, bullet wound entry and exit wounds give very little information on the patient’s condition. Assume serious injury in all cases and arrange rapid transfer to hospital.
Bullets may travel an erratic and unpredictable path and may enter several body cavities. A careful primary survey should detect evidence of intrathoracic or abdominal penetration, which is a particularly ominous feature.
Shotguns
Shotguns have a smooth bore and are designed to fire multiple pellets or shot; some fire large, solid lead or plastic slugs. Pellet size varies from large buckshot to small birdshot.
Wound severity varies enormously and depends on range, body region and size of shot. In general, wounds tend to be extensive, with heavy foreign body contamination, which may include the wadding from the shotgun cartridge.
Military weapons
Assault rifles and automatic weapons are now readily available to criminals and terrorists. It would be sensible to presume anyone wounded by bullets from military weapons to have serious injury until proved otherwise.
For further information, see Ch. 30 in Emergency Care: A Textbook for Paramedics.
