Transcript Medical Aspects of Blast Injuries Matthew D. Sztajnkrycer, MD, PhD Assistant Professor of Emergency Medicine Mayo Clinic [email protected] Amado Alejandro Báez MD Msc [email protected].

Medical Aspects of
Blast Injuries
Matthew D. Sztajnkrycer, MD, PhD
Assistant Professor of Emergency Medicine
Mayo Clinic
[email protected]
Amado Alejandro Báez MD Msc
[email protected]
Learning Objectives
 Discuss
the epidemiology of
blast injuries.
 Describe the physics of blast
injuries.
 Describe special scenarios in the
management of blast injuries.
Performance Objectives
 At
the end of the course the
student should be able to:
 Discuss
the prehospital and
hospital management of blast
injuries.
Why Blast Injuries?
 Deaths
from terrorist acts:
–Oklahoma City
168
–World Trade Center
2,801
–Madrid train bombings 202
–Tokyo sarin attack
12
–American Anthrax
5
Physics of Blast Injuries
 Blast
(shock) wave
–Pressure transmitted radially
from source into surrounding
medium.
–3 components:
–Positive phase
–Negative phase
–Mass movement of wind (blast
wind)
 Defining
characteristic of
conventional explosive is the
variation in ambient pressure
over time.
 During the positive phase, wave
causes rapid increase in ambient
air pressure
(blast overpressure).
 Biological
effects of a
conventional blast depend
primarily on:
–Peak overpressure
–Duration of positive phase
Blast Injury
 Blast
waves cause injury because
of rapid external loading on the
body and organs.
 May cause internal injury in aircontaining organs without any
external signs of trauma.
Middle ear
 Lung
 GI tract

Categories of Blast Injury
 Primary
 Secondary
 Tertiary
 Combined
Primary Blast Injury
 Direct
concussive effect of the
pressure wave on the victim.
–Shear effects at the air-tissue
interface.
 More likely to occur in after
detonation in an enclosed space.
Primary Blast Injury
 Organ
most sensitive to the
primary blast effect is the ear.
 Transient hearing loss generally
resolves in first few hours after a
blast.
 Up to 30% of victims may have
permanent hearing loss.
 Essentially all severely injured
patients have TM perforations.
Primary Blast Injury
No patient with isolated TM
perforation developed signs of
pulmonary or GI blast injury.
Eardrum Perforation in Explosion Survivors:
Is It a Marker of Pulmonary Blast Injury?
Leibovici D, Gofrit ON, and Shapira SC.
Ann Emerg Med 1999;34: 168 - 172.
Primary Blast Injury
 Injury
to lung is cause of greatest
morbidity and mortality.
 Most obvious and consistent sign
of pulmonary blast injury is
hemorrhage.
 Classically, patients develop
rapid respiratory deterioration
with need for ventilatory support.
Primary Blast Injury
 Other
pulmonary injuries
include:
–Pneumothorax
–Hemothorax
–Pneumomediastinum
–Subcutaneous emphysema
–Air emboli
Air Emboli
 Result
from traumatic alveolarvenous fistulae.
 Responsible for most of the early
mortality.
 More severe the pulmonary
hemorrhage, the greater the
likelihood of significant embolism.
Primary Blast Injury
 Gastrointestinal
blast injury most
commonly results in tissue tearing
and hemorrhage.
 GI blast injury more commonly occurs
after blast wave propagation in water.
 GI hemorrhage and perforation is
most common in the lower small
intestine or cecum, where gas
accumulates.
 Secondary
blast injury:
Results from propelled objects
striking victim.
– May be penetrating or blunt.
 Tertiary
blast injury: Results
from victim being propelled
against structure by the blast
wave or blast winds.
 Combined
blast injury:
Occurs when primary blast
injury occurs in the setting of:
–Secondary or tertiary blast injury
–Burns
–Inhalational or toxic exposure
–Radiation
Prehospital Management
 Extrication
and life support are the
primary management priorities.
 In circumstances of building
collapse, trend towards high
mortality (90%).
 Extent of blast injury cannot be
reliably assessed by typical rapid
triage examination.

Dogma: As a result, high overtriage rates are “mandated”.
History
 What
type of explosive and how
much?
 Where was victim located with
respect to the blast?
 What did the victim do after the
blast?
 Were fire/fumes present to cause
inhalational injury?
 What was orientation of head and
torso to the blast?
Hospital Management
 Airway
and ventilation
management.
– Supplemental Oxygen
– PEEP/CPAP - watch for air emboli.
– Positive pressure ventilation and
general anesthesia has been reported
to increase mortality in blast injury.
– Surgery should be postponed 24 - 48
hours whenever possible.
 Consider
abdominal films in all
patients with significant blast
injury.
 CT Scan Abdomen/Pelvis for
patients with appropriate
signs and symptoms.
 Hearing in both ears should be
tested at bedside.
 Wound
Management:
–Tetanus status.
–Local exploration.
–Delayed primary closure.
–IV followed by oral
antibiotics for all but the
most trivial wounds.
Special Scenarios Homicide Bombings
 Referred
to as the “walking
smart bomb.”
 Device typically consists of 10 30 lbs of explosive.
 May also contain:
– Nails, bolts, ball bearings, or other
secondary blast elements.
– Hazardous chemicals and pesticides.
 Bombers
may have HIV, HepB.
Recognition: Stay ALERT
 A: Alone
and nervous
 L: Loose and/or bulky clothing
 E: Exposed wires (possibly
through sleeve)
 R: Rigid mid-section (explosive
device or other weapon)
 T: Tightened hands (may hold
detonation device)
Radiation Dispersal Device (RDD)
 Conventional
explosive used to
disseminate radionuclide.
–“Dirty bomb”
–Nuclear explosion does not
occur.
–Greatest radiation threat from
device occurs prior to explosion.
Radiation Management
 Radiation
deaths are delayed.
 Management of conventional
injuries and acute life threats
takes precedence over
radiation exposure.
–Treat injury first, then
decontaminate.
Situational Awareness Secondary Device
 Emerging
trend in terrorist
bombings.
 First described in Northern Ireland.
 First used in the U.S. in 1997 in
Georgia at abortion clinic bombings.
 A first device or dummy device lures
first responders to the scene, where
a secondary device detonates at a
time to maximize responder
casualties.
Summary
 Blast
injuries remain a
significant terrorist threat.
 Principal organs affected are
the ear, lung, and intestine.
 Stay ALERT to the threat of
homicide bombers.