Blast Injuries Phillip Jacobson, M'D'

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Blast Injuries Phillip Jacobson, M.D.

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Background

• Terrorism vs. Accidental
• Most terrorist acts involve explosive devices
• Large bombs are easy to produce
• gt 50 deaths per year in U.S. from bombs.1
• 1. FBI Data Center Publication NO. 0367 (1999
  data)

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Background

• 1917 Halifax Disaster
• Two ship collision
• Munitions explosion
• Largest in history
• 2,000 dead
• 9,000 injured
• 20,000 homeless
• Wikipedia.org

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Background

• 1947 Texas City, TX Grand Camp ship caught
  fire
• Carried ammonium nitrate
• Smoke 2,000 feet in air
• 1.5 ton anchor 2 miles away
• 150 ft tidal wave
• 600 deaths
• Stevens HW. The Texas City Disaster, 1947,
  Austin, Tx. U of T Press 1947

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Background

• 1983 U.S. Marine Barracks, Beirut
• Largest deliberate explosive detonation
• Ammonium Nitrate
• 4 story bldg collapse
• 234 immediate dead
• 112 survivors
• Frykberg ER. Mil Med, 198711563-566

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Epidemiology

• gt 1200 intentional bombings/yr in U.S.1
• 1992-20022
• 36,100 U.S. bombing incidents
• 5,931 injuries
• 699 deaths
• 1. FBI Bomb Data Center Bulletin 96-11996
• 2. Kapur G. J Trauma, 2005 591436-1444

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EpidemiologyBlast Victims

• Bombing victims tend to be young
• GCS tends to be low
• High ISS scores
• High mortality
• Shamir MY. Curr Opin Crit Care, 2005 11
  580-584

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Epidemiology Bombing Victims vs. Other Trauma

• Higher ISS
• More body regions injured
• More surgeries required (of all types)
• Higher in hospital mortality
• Kluger Y. J Am Coll Surg, 2004199875-879

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EpidemiologyCasualties/Death

• The following influence casualties
• Magnitude of explosion
• Number of people in area
• Building collapse
• Speed of rescue
• Confined space vs. open air
• Medical resource availability

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EpidemiologyImmediate Mortality

• Literature review of 29 terrorist bombings
• Immediate Mortality
• Structural collapse 25
• Confined space 8
• Open air 4
• Arnold J. Ann Emerg Med, 200443263-273

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EpidemiologyHospitalization Rate

• Literature Review of 29 terrorist bombings
• Hospitalization Rate
• Structural collapse 25
• Confined space 36
• Open air 15
• Arnold J. Ann Emerg Med, 200443263-273

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EpidemiologyED Use

• Literature Review of 29 terrorist bombings
• ED Use
• Structural collapse 48
• Confined space 36
• Open air 15
• Arnold J. Ann Emerg Med, 200443263-273

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EpidemiologyImpact of Building Collapse

• Oklahoma City 1995
• Immediate Mortality
• Collapsed 87
• Uncollapsed 5
• Survivors Hospitalized
• Collapsed 82
• Uncollapsed 5
• JAMA 1996276382

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EpidemiologyImpact of Rescue Speed

• Beirut 1983 4 st bldg collapse, 346 cas.
• 234 immediate deaths (68)
• 112 survivors
• Rescue within 4 hours
• 1 death out of 65 survivors
• Rescue between 5 to 9 hours
• 40/47, (86) dead
• Frykberg ER. Ann Surg, 198955134-141

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Blast InjuryWorld Trade Center

• 12,500 tons of force
• 900 tons TNT energy
• 3,000 dead
• 790 survivors
• 511 nonrescuers
• 279 rescuers
• 18 hospitalized
• MMWR Vol 51 Jan11, 2002

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Blast BasicsNature of Explosions

• An explosion is a rapid chemical conversion of a
  solid or liquid into a gas with energy release
• Low Order Explosives
• High Order Explosives

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Blast BasicsNature of Explosions

• Low Order Explosives
• Slow release of energy (propellants)
• Energy release by deflagration. Things go up in
  flames (e.g. gunpowder).
• High Order Explosives
• Quick release of energy (detonation)
• Transformation of physical space around point of
  explosion. Ambient medium is compressed faster
  than thermal motion can disperse individual
  molecules (e.g., TNT, C4, ammonium nitrate).

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Blast BasicsNature of Explosions Other Concerns

• Dual Explosions Terrorists will often detonate
  a second explosion after rescue workers and
  onlookers gather to maximize casualties
• Conventional Bomb as Dispersal Device
  Terrorists may use a conventional weapon to
  disperse WMDs, such as chemical, biological or
  nuclear (dirty bomb) agents

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Mechanism of Injury

• 1 Blast Overpressure Injury
• Caused by pressure blast waves
• 2 Flying Objects
• Leading cause of death
• 3 People flying through air
• 4 Miscellaneous (burns, chemical, inhalation,
  structural collapse)
• Structural collapse causes the highest rate of
  death

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Primary Blast InjuryClinical Manifestations

• Mostly occurs in gas-containing organs.
• (e.g. middle ear, lungs, bowel)
• Tissue compresses slower than air causing stress
  forces and tissue damage
• Less common than other types of injury
• Often delayed onset
• Life threatening

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Primary Blast InjuryTympanic Membrane

• gt 5psi above atm. pressure to rupture TM
• Temporary neurapraxia, deafness, tinnitus,
  vertigo
• De Palma RG, NEJM, 20053521135-1142

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Primary Blast InjuryTympanic Membrane

• Most common 1 blast injury
• In severe blasts structural damage can occur to
  the organ of Corti causing long-term or permanent
  hearing loss
• With absence of TM injury, its unlikely to have
  other 1 blast injuries
• Garth RJN. Scientific Foundations of
  Trauma, 1997225-235

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Primary Blast InjuryPulmonary Injury

• 2nd most common form of PBI
• Requires about 15 psi
• frequency in closed spaces
• Most common life threatening type of PBI

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Primary Blast InjuryPulmonary Injury

• Contusion
• Hemorrhage
• Laceration
• Hemothorax
• Arterial air embolus
• DIC
• ARDS

• Alveolar Rupture
• Pulm Int emphysema
• Subq emphysema
• Pneumomediastinum
• Pneumothorax
• Pneumopericardium
• Pneumopritoneum

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Pulmonary InjuryClinical Manifestations

• Nonspecific
• Tachypnea, cyanosis, chest pain, dyspnea,
  pharyngeal petechiae
• Pulmonary Contusion
• Rales, b.s., dullnes, hemoptysis
• Pulmonary Barotrauma
• b.s., resonance, subq crepitus, trach
  deviation, CV collapse

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Percent Lung Weight / Body Weight
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Primary Blast InjuryPulmonary Injury

• Arterial Air Embolism
• Most common cause of rapid death after initial
  survival
• Often occurs after initiation of positive
  pressure breathing
• Ho Am-H. Anesthesiology, 199990564-575

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Primary Blast InjuryPulmonary Injury

• Arterial Air Embolism clinical manifestations
• EKG ST, T wave changes
• Focal neurological deficits
• Mottling of skin
• Air in retinal vessels
• Demarcated tongue blanching

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Primary Blast InjuryVagal Effect

• Hypotension, bradycardia, nl SVR
• Occurs through afferent C fibers in lungs
• Can last 1-2 hrs
• Blunted with vagotomy in animal studies
• Gur R. J Trauma, 1998 45(6)983-987
• Irwin R. J Trauma, 199743(4)650-655

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Primary Blast InjuryGI Injury

• Ruptures
• Could occur several days after blast from
  stretching, ischemia (mesenteric infarcts) and
  weakening of bowel wall1
• Hemorrhage
• Range from petechiae to large hematomas2
• 1. Paran. J Trauma, 199640472-475
• 2. Sharpnack DD. In Bellamy RA.
  Conventional Warfare Ballistic Blast and
  Burn Injuries, 1991271-294

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Primary Blast InjuryGI Injury

• Colon is most common site of hemorrhage and
  perforation
• Tension peritoneum
• Mesenteric retroperitoneal and scrotal
  hemorrhages are possible
• Solid organs generally spared

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Primary Blast InjuryEye and Face Injury

• Rupture of globe
• Serous retinitis
• Hyphema
• Implosions of maxillary sinus
• Crushed egg shell fracture of midface

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Secondary and Tertiary Blast Injury

• Secondary Blast Injury (flying objects)
• Fragments can be part of weapon or other object
• Leading cause of death in blast injury
• Blunt or penetrating trauma
• Tertiary Blast Injury (people flying through air
  and striking other objects)
• Usually very close to explosion source
• Common in Oklahoma City ped. victims

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Blast Injury2 Injuries
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Quaternary Blast Injury

• Crush Injury
• Burns
• Toxic exposure
• Carbon monoxide
• Cyanide
• Chemical
• Radiation

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Quaternary Blast InjuryCrush Injury

• Crush Syndrome Mechanism
• Involvement of Muscle Mass
• Prolonged compression
• Compromised local circulation
• Crush Syndrome Manifestations
• Rhabdomyolysis
• CPK, K, BUN, Creatinine, Uric Acid,
  
• Phosphorus, Ca, Metabolic acidosis
  

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Quaternary Blast InjuryCrush Injury

• Clinical Manifestations
• Renal Failure
• Cardiac arrhythmias
• Compartment syndrome
• DIC
• ARDS
• Shock
• Gonzalez D, Crit Care Med 200533Suppl.S34-
  S41

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Blast Injury ManagementTriage

• 4 accepted categories
• 1. Casualties requiring immediate treatment
  (e.g. hypotension, airway compromise)
• 2. Injuries requiring tx, but delay acceptable
  (e.g. open fx, soft tissue wounds)
• 3. Minimal injuries requiring no tx
  (walking wounded)
• 4. Expectant. Injuries so severe that it
  would not be possible to provide care without
  jeopardizing other salvageable victims

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Blast Injury ManagementTriage

• Multiple Casualty Event
• When number of casualties at one time strain
  hospital or facility resources
• Disaster/Mass Casualty
• When casualty burden exceeds capabilities of
  onsite medical resources
• ACSCOTT Optima Resources 1999

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Blast Injury ManagementTriage

• Overtriage The proportion of survivors assigned
  to immediate care, hospitalization or evacuation
  who are not critically injured.
• Undertriage The proportion of patients who are
  critically injured not assigned to immediate
  care, hospitalization or evacuation.
• Am Coll Surg. Committee on Trauma 1998

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Blast Injury ManagementTriage

• Multiple Casualties Overtriage of 50 is
  necessary to have undertriage of 0.1
• Disasters or Mass Casualties Excessive
  overtriage can cause more overall deaths.2
• 1. Am Coll Surg. Committee on Trauma 1998
• 2. Frykberg E. J Trauma, 200253201-212

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Blast Injury ManagementTriage
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Blast Injury ManagementTriage

• Upside-Down Triage Less severely injured arrive
  at the hospital before most severely injured.

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Blast Injury Management

• Airway
• Breathing
• Circulation
• Disability
• Decontamination
• Exposure

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Blast Injury Management

• Event Details
• Strength of blast
• Closed vs. open space
• Structural collapse
• Rupture of TMs

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Blast Injury ManagementAirway

• For altered mental status
• Secure airway
• Minimize positive pressure ventilation
• Facial or laryngeal injury
• Same as nonblast trauma
• Massive hemoptysis
• Mainstem intubation and ventilation, or
• Double lumen ET tube
• Wrightman JM. Ann Emerg Med, 200137664-678

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Blast Injury ManagementBreathing

• Open pneumothorax
• Seal chest wall and thoracostomy
• Pulmonary contusion
• 100 O2
• Minimize positive pressure
• Consider unilateral lung vent

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Blast Injury ManagementBreathing

• Persistent pneumothorax
• Additional thoracostomy
• Unilateral ventilation
• High frequency ventilation
• Wrightman JM. Ann Emerg Med, 200137664-678

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Blast Injury ManagementCirculation

• Tension Pneumothorax
• Needle thoracentesis and tube thoracostomy
• Massive Hemothorax
• Tube thoracostomy and autotransfusion
• Hypovolemic Shock
• Frequent small fluid boluses
• Avoid hypervolemia
• Transfuse blood for hemorrhage
• Consider spinal shock

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Blast Injury ManagementCirculation

• Suspected arterial air embolus
• 100 O2
• Left lateral recumbent position
• Minimize positive pressure or unilateral lung
  ventilation
• Consider hyperbaric O2

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Blast Injury ManagementCirculation

• Vagal reflex BP, HR, nl SVR
• Will resolve spontaneously
• Should respond to atropine (never studied)

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Blast Injury ManagementGeneral

• Open fxs Immobilize and cover with sterile
  dressing and broad spectrum abx
• Long bone fxs Splint and avoid neurovascular
  compromise
• Objects penetrating the eye Cover with paper cup
  or clean object. Do not remove object

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Blast Injury ManagementGeneral

• TM Ruptures
• Will generally heal spontaneously
• Avoid swimming and immersing head in water
• Topical abx for auditory canal debris
• Sensorineural hearing loss may respond to
  steroids

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Blast Injury ManagementGeneral

• For suspected 1 blast injury
• Chest and abdominal films
• Frequent examination of chest and abdomen
• Try and avoid positive pressure ventilation
• If surgery is required and pt. stable, consider
  spinal, local or regional anesthetic techniques

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Blast Injury ManagementGeneral

• Crush Syndrome
• Most likely from structural collapse
• Often delayed
• Brought on by rhabdomyolysis
• Renal failure, DIC, ARDS, shock
• Tx with fluids, alkalinazation, consider osmotic
  diuresis

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Blast Injury ManagementGeneral

• Consider smoke inhalation
• CO poisoning
• Cyanide (from incomplete combustion of plastics)
• Consider hypocalcemia (from white phosphorus
  munitions)
• Tetanus status

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Blast Injury ManagementPediatric Considerations

• High incidence of head trauma
• High incidence of amputations
• High incidence of abdominal and thoracic injuries
  in deceased
• Quintana D. J Ped Surg, 199732307-311

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Blast Injury ManagementPregnancy Considerations

• Fetus well protected by amniotic fluid
• Placental injury more likely
• Klehauer Betke assay
• Fetal maternal hemorrhage
• 2nd to 3rd trimester should be observed in
  LD for fetal monitoring

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Blast Injury Summary

• Conventional blast is most common form of
  terrorism
• Bombing victims have a higher ISS than other
  trauma victims
• Confined spaces and/or structural collapse lead
  to more severe injuries
• Elapsed time before rescue is crucial

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Blast Injury Summary

• Mechanisms of Blast Injury
• 1 Blast wave, injury to gas-filled organs
• 2 Flying objects, leading cause of death
• 3 People flying through air
• 4 Miscellaneous (structural collapse high
  death rate)

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Blast Injury Summary

• Appropriate Triage
• ATLS Management
• Assess TMs, lungs, abdomen for 1 blast injury
• Use fluids and positive pressure ventilation
  carefully

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Blast InjuryEnding Statement

• The panic, chaos, and emotional trauma of such
  disasters can magnify the loss of life and are
  best combatted by prompt and vigorous leadership,
  and a preexisting plan for immediate rescue
  disposition and treatment of casualties.
• Berry FB. Bull Am Coll Surg, 19564160-66