Blast injuries

Explosives, IED’s and Blast Injuries

Dale Carrison, DO, MS, FACEP, FACOEP

Professor/Chairman Emergency Medicine

University Medical Center

University of Nevada School of Medicine

Bombings

First terrorist bombing in Belgium 1585

6,000Kg gunpowder used to destroy a bridge.

> 1,000 fatalities, many with no external evidence of injury.

Bombings

70% of all terrorists incidents are conventional.

10,000 terrorists explosions from 1990-1995.

Goal is to induce panic and apprehension.

Explosion

Rapid chemical conversion of a solid or liquid into a gas with resultant energy release.

Explosives

Propellants (e.g., gunpowder) release energy relatively slowly.

High explosives (e.g., TNT, PETN, C-4) almost instantaneous transformation of the physical space occupied by the original material within a few microseconds. Therefore, under extremely high pressure.

5 Billion Pounds Produced Each Year in U.S.

Explosive matter

Explosives

Chemicals for non-explosive purpose

High explosives(HE) Propellants(LE) Pyrotechnic (LE)

° 1 ° 2

Military-grade

Industrial-grade

Gun

Rocket

Lead azideHg fulminateTetrazene

Singles = TNT; RDX; PETN; Mixes = CB; RDX-based plastics; Torpex

Gelatins; powders; permitted; ANFO; slurries, emulsions

Black powder

Double base; composites; liquid fuels; oxidizers

Flashes, FlaresFume generators

Optical/acoustic signals, fireworks

Fertilizer grade ammonium nitrate Chlorates as weed killers

Gas generating for foam plastics

Organic peroxides as catalysts

NTG and PETN-soln for pharmaceuticals

Salts of nitrated organic acids for pest-control

From Explosives, R. Meyer – 5th Edition

Explosion

Virtual instantaneous increase in pressure can be so abrupt that high-explosive blast waves (blast wind) are also “shock waves.”

Shock waves possess a characteristic called “brisance” (shattering effect).

Explosion

The gas expands with an exponential increase in pressure.

It forms a sphere.The sphere of this compressed air is

called a shock wave, blast pressure head, blast wind, or blast wave.

Leading edge is called the “blast front.”

POLICEPOLICE

EFFECTS OF AN EXPLOSIONEFFECTS OF AN EXPLOSION

Explosion

PROCESS OF DETONATION

Blast Front

Explosion

This wave of compressed air can be measured as overpressure or direct impulse.

The magnitude of the overpressure is proportional to the amount and type of explosive used.

Overpressure

Overpressure is measured in pounds per square inch.

Relative power is calculated by multiplying PSI X duration in milliseconds of the impulse.

Overpressure

Overpressure of 58 – 80psi is 95% lethal.

7 – 8psi can shear brick walls or overturn rail cars.

5psi can rupture tympanic membranes.

0.5 – 1psi can break windows and knock people down.

Shock Wave

The shock wave has 3 components:– Positive phase– Negative phase– Mass air movement.

POLICEPOLICE

Dynamite Dynamite

Positive PhasePositive Phase

Negative PhaseNegative PhaseAfter an ExplosionAfter an Explosion

EFFECTS OF AN EXPLOSION

Shock Wave

Positive phase.– Velocity and duration of the blast head.

Dependant upon:– Size/type of the explosive– Surrounding media– Distance from the detonation.

Shock Wave

Closed spaces magnify the effects of the direct impulse.

“Shock Wave” “bounces” off hard surfaces and is referred to as a “Reflected Impulse.”

Shock Wave

Shock waves all create similar rates of rise in pressures at the blast front.

The magnitude of this “positive-phase impulse” becomes the important property in the generation of the Primary Blast Injury (PBI).

Shock Wave

Negative phase.– Partial vacuum is created near the

epicenter after outward movement of air– Consumption of oxygen by the burning

process.

Shock Wave

The “reflected impulse” may combine with the “direct impulse” and increase injuries at a greater distance from the blast site than expected.

Shock Wave

Shock Wave

Effects are cumulative.Example:

– A blast that causes a 1% mortality when experienced once, causes a 20% mortality when experienced twice, and 100% mortality if experienced three times.

1. Safety Fuse

2. Electric Blasting Cap

3. Dynamite

Primary ExplosiveElectric Wires

Secondary Explosive

EXPLOSIVE DANGEROUS

EXPLOSIVE TRAINELECTRIC BLASTING CAPS

EXPLOSIVE DANGEROUS

1. Shock Tube

2. Non-Electric Blasting Cap

3. Dynamite

Primary Explosive

Secondary Explosive

HMX/Aluminum Powder

EXPLOSIVE TRAIN

Shock Wave

SHOCK TUBE

1. Safety Fuse

2. Non-Electric Blasting Cap

Low Explosive Primary Explosive

(Black Powder)

EXPLOSIVE TRAINTIME/SAFETY FUSE

EXPLOSIVE DANGEROUS Shock Wave

4. ANFO Blasting Agent

3. Booster

Secondary Explosive

Tactical Uses

Det Cord Injury

POLICEPOLICE

INJURIES

Blasting Cap

M-80

I.E.D.M-116 Pipe BombFireworksCO2

Injuries

Primary blast injuries (overpressure) occur in gas-containing organ systems.– Middle ear, – Lungs,– Bowels.

Physical Findings

PBI

New research indicates that most pathophysiologic effects on the body result from the consequences of extreme pressure differentials developed at body surfaces.

PBI

“Blast loading” Force results in rapid acceleration of

the surface, creating a relatively high-frequency “stress wave” propagated into the underlying tissues.

PBI – Tympanic Membrane

Tympanic membrane ruptured from overpressure of 1 – 8 psi.

Less common is dislocation of the joints in the inner ear.

Temporary hearing loss very common. Structural damage to the organ of Corti

can cause permanent hearing loss.

PBI – Tympanic Membrane

Studies show no correlation between ruptured TM and Blast Lung.

TM’s generally heal without complications

PBI - Lung

Pulmonary contusion– Worse on side of approach of blast

waves in open air.– Bilateral and diffuse when victim is

located in confined space.Degree of pulmonary pathology is

proportional to the velocity of chest wall displacement.

Blast Lung

PBI to lung is referred to as blast lung.

Greater incidence in confined spacesMajor cause of death in PBI’sAlveolar membranes tornMinimal to massive hemorrhage with

hemothorax or air emboli

Blast Lung

Diagnosis made clinicallyConfirmed by CXR showing a

butterfly appearance with or without pneumothorax

Similar to Pulmonary Contusion or ARDS

Respiratory distress with hypoxemia greatest in the first 72 hours.

Blast Lung

Treatment similar to Pulmonary Contusion.

Studies have shown no long term effects

Generally normal after 1 year

Degree of Injuries - Pulmonary

PBI - Hypotension

Bradycardia and hypotension without hemorrhage.– Blast loads directly at the chest cause a

unique vagal nerve-mediated form of cardiogenic shock without compensatory vasoconstriction.

– Occurs within seconds and resolves over 1 – 2 hours.

PBI – Arterial Air Embolus (AAE)

Hemopneumothoraces, traumatic emphysema, and alveolovenous fistulas from stress-induced tears of air-tissue interfaces.

Lead directly to bronchopleural fistulas or Arterial Air Embolus (AAE).

PBI - AAE

AAE to the brain or head may be the most common cause of rapid death caused solely by PBI in immediate survivors.

May be precipitated by positive-pressure ventilation (PPV).

Often occurs at the moment of PPV.

PBI - Abdomen

Injuries occur in similar manner and at similar overpressures to the lungs.

Hemorrhages, from petechiae to large hematomas are the dominant form of pathology.

Colon most common site of hemorrhage and/or perforation.

PBI - Abdomen

Tension pneumoperitonem

Mesenteric, retroperitoneal, and scrotal hemorrhages.

Usually no significant compression of solid organs.

Pathology

Injuries - Penetrating

Secondary blast injuries– Injuries from

devices that contain foreign bodies:• Nails• Rivets • Ball bearings• Nuts and bolts,• Etc.

Secondary Missiles

Injuries – Penetrating


Medically, usually no different than other penetrating injuries seen.

Complicated by the PBI’s.

Bone and tissue from suicide bombers may be secondary missiles.– Aids, hepatitis, etc.


Secondary missiles created by container fragments or added missiles can have velocities of up to 1,500m/sec.

Rapid deceleration seconday to poor ballistic properties.

Injuries

Tertiary injuries – Blunt trauma.– Physically thrown through the air and

strike or impale themselves on objects.– Collapsing structures.– Other objects propelled through the air

striking the victim.

Tertiary Injuries

Severe head injury is a leading cause of death in victims of blasts.

Subdural and subarachnoid hemorrhages are the most common findings in fatalities.

Injuries

Thermal injuries Primary or

secondary incendiary. – Inhalation– Dermal

Thermal Burns– Few victims admitted to burn centers– Little skin grafting needed

Thermal BurnsFlash Burns

Large body surface area

Shallow depth

EMS Scene

Contact incident commander to ensure that the area is safe to enter.

Beware of #2 or secondary explosion directed at personnel responding to the first incident.

EMS Scene

Recent studies suggest the PBI victims do poorly when strenuous physical activity follows significant blast loading.– Reduce activity of potential blast-

exposed individuals.– Provide history of activity to ED

personnel receiving patient.

Post Mortem Care - Mass fatality event– Identification & notification– Family Assistance Center needed at scene!

Suicide Bombs Explosives worn on

belt or vest Significant Shrapnel Arms raised to

maximize damage

Suicide Bombers Why Suicide? Prevention is difficult to impossible !

– NO SECURITY SYSTEM IS IMPENETRABLE IF THE BOMBER HAS A SUICIDAL INTENT

Terrorists can change targets at the last minute– Crude guided missile

Suicide Bombers = only 0.6% of all attacks . . .

. . . but 66% of all fatalities!

Suicide Bombers

With explosive device strapped to body they sustain massive injuries.

Frequently lose their heads, secondary to the primary explosion.

Suicide Bombers

They sustain massive bodily injuries because of being at ground zero.

Remains of first terrorist in yard

Remains of third terrorist - (probably blew up with dog)

Suicide Bombers

Devices designed for maximum explosive value and fragmentation.

Suicide Bombers

Easily concealable and maximum secondary missile effect.

Improvised Explosive Device: IED

IED’s

Explosive material Shrapnel Common package

Women’s clinic

Otherside nightclub

Package BombsLight enough to carry easily

Common enough to blend in

Centennial park

POWER SOURCE – 9-V BATTERYS.

Firing switch in comparison

to similar switch

RESIDUE OF SUITCASE SUITCASE FRAME

RIGHT SHOEOF THE BOMBER

RESIDUE OF A LEATHER OBJECT

NYLON CLOTH STRIPS

CARDBOARD GLUED TO BULB HOUSE

BULB HOUSE WHICH HOUSED THE INITIATOR

POWER SOURCE – 9-V BATTERY.

FIRING SWICH.

SIMILAR SWICH.

ELECTRIC WIRES.

RESIDUE OF DETONATOR

SIMILARDETONATOR

RESIDUE OF MOBILE PHONE

COMPERISSON OF PIECES FOUND AT THE SCENEWITH A SIMILAR MOBILE PHONE

GENERAL VIEW – INSIDE OF THE CAR

DRIVER'S SEATFRAME

HEAD SUPPORT

Suicide Bombers Massive Destruction

Suicide Bombers

Car bombing with early detonation.

PSYCHOLOGICAL TRAUMA

Conclusion

Basic Understanding of Explosive and Explosive Devices

Awareness of Explosive Injuries Awareness of Suicide Bombers and

IED’sAwareness of Presence of Evidence

Explosives and Blast Injuries

QUESTIONS

Blast injuries

Technology

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