Blast Injuries

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Blast Injuries

• Amy Kaji, MD, MPH
• November 16, 2005
• Acute Care College
• Medical Student Seminar

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Iraq Car Bombings Current Events
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Historically in US

• Few US bombings have caused mass casualties
• First World Trade Center Attack, February 1993
• Oklahoma City Bombing April 19, 1995
• Fuel and fertilizer used to create a bomb
• 518 injuries and 168 deaths
• Atlanta Olympic Park Bombing, July 27, 1996
• World Trade Center and Pentagon
• September 11th, 2001
• Explosive Device Attacks at Abortion Clinics

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Oklahoma City April 19, 1995
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New York City September 11, 2001
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Classification of Explosives

• High Order (HE) Explosive
• Produce a high pressure shock wave
• Examples include TNT, C-4, Semtex, dynamite
• Low Order (LE) Explosive
• Produce a subsonic explosion
• Examples include pipe bombs, molotov cocktails
• Manufactured Explosive
• Standard military-issued quality-tested weapon
• Improvised Explosive Device (IED)
• Use a device outside its intended purpose
• Commercial jet as a guided missile
• Loaded with metallic objects to inflict
  penetrating injury

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Atlanta, Georgia July 27, 1996
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Bag with Bomb
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Types of Blast Injuries

• Primary
• Due to direct effect of pressure
• Secondary
• Due to effect of projectiles from explosion
• Tertiary
• Due to structural collapse and from persons being
  thrown from the blast wind
• Quaternary
• Burns, inhalation injury, exacerbations of
  chronic disease

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Primary Blast Injury

• Unique to high explosives
• Due to impact of over-pressurization wave with
  body surfaces
• Most commonly involve air-filled organs and
  air-fluid interfaces
• Middle ear
• Lungs
• Gastrointestinal tract
• Types of injuries
• Blast lung
• Tympanic Membrane (TM) rupture
• Abdominal hemorrhage and perforation
• Globe rupture
• Traumatic brain injury (TBI) without physical
  signs of head injury

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TM Injury

• TM - structure most frequently injured by blast
• TM rupture
• Ossicle dislocation
• Disruption of oval or round window
• Symptoms may include hearing loss, tinnitus,
  vertigo, bleeding from external canal,
  mucopurulent otorrhea
• Otologic exam and audiometry for all
• TM rupture is sensitive marker, but absence does
  not exclude other organ injury

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TM Rupture
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Blast Lung

• Lung 2nd most susceptible organ to blast injury
  
• Most common fatal primary blast injury among
  initial survivors
• Pulmonary barotrauma includes
• Pulmonary contusions
• Systemic air embolism
• Free radical associated injuries
• Thrombosis
• Lipoxygenation
• Disseminated Intravascular Coagulation (DIC)

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Blast Lung

• Clinical triad of apnea, bradycardia, and
  hypotension
• Signs usually at initial presentation but may
  manifest as late as 48 hours after explosion
• Should be suspected if dyspnea, cough,
  hemoptysis, or chest pain
• Radiographic findings
• Bihilar butterfly pattern
• Pneumothorax or hemothorax
• Pneumomediastinum and subcutaneous emphysema
• Prophylactic chest tube before general anesthesia
  and air transport if blast lung suspected

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Blast Lung
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Blast Abdominal Injury

• Colon visceral organ most frequently affected
• Mesenteric ischemia from gas embolism may cause
  delayed rupture of large or small intestine
• Intestinal barotrauma more common with underwater
  air blast
• Solid organ injury less likely
• Signs and symptoms
• Abdominal pain, nausea, vomiting, hematemesis
• Rectal pain and tenesmus
• Testicular pain
• Unexplained hypovolemia

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Blast Abdominal Injury
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Other Primary Blast Injuries

• Eye
• Globe rupture, serous retinitis, hyphema, lid
  laceration, traumatic cataracts, injury to optic
  nerve
• Signs and symptoms include eye pain, foreign body
  sensation, blurred vision, decreased vision,
  drainage
• Brain
• TBI due to barotrauma of gas embolism
• Signs and symptoms include headache, fatigue,
  poor concentration, lethargy, anxiety, and
  insomnia

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Globe Rupture
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Secondary Blast Injury

• Due to flying debris and bomb fragments
• Penetrating ballistic or blunt injuries
• Leading cause of death in military and civilian
  terrorist attacks except in cases of major
  building collapse
• Wounds can be grossly contaminated
• Consider delayed primary closure and tetanus
  vaccinations

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Tertiary Blast Injuries

• Due to persons being thrown into fixed objects by
  wind of explosions
• Also due to structural collapse and fragmentation
  of building and vehicles
• Structural collapse may cause extensive blunt
  trauma
• Crush syndrome
• Damage to muscles and subsequent release of
  myoglobin, urates, potassium, and phosphates
• Oliguric renal failure
• Compartment syndrome
• Edematous muscle in an inelastic sheath promotes
  local ischemia, further swelling, increased
  compartment pressures, decreased tissue
  perfusion, and further ischemia

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Crush and Compartment Syndrome
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Potential Intra-operative and Post-resuscitation
Complications

• Surgeons, Anesthesiologists, and Critical Care
  Specialists will need to be aware of potential
  intraoperative and post-resuscitation
  complications
• Occult pneumothorax
• Occult compartment syndrome
• Hyperkalemia
• Crush syndrome
• Rhabdomyolysis

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Quaternary Blast Injuries

• Explosion related injuries or illnesses not due
  to primary, secondary, or tertiary injuries
• Exacerbations of preexisting conditions, such as
  asthma, COPD, CAD, HTN, DM, etc.
• Burns (chemical and thermal)
• White Phosphorous (WP) from munitions causes
  extensive burns, hypocalcemia and
  hyperphosphatemia
• Toxic inhalation
• Radiation exposure
• Asphyxiation (carbon monoxide and cyanide)

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Madrid, Spain March 11, 2004
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General Considerations

• Information about distance from and type of
  explosion predict injury severity and type
• Confined space vs. open space
• Increased number of penetrating and primary blast
  injuries if closed space
• Intensity of explosion pressure wave declines
  with cubed root of distance away from explosive
• Standing at 3m has 9x greater pressure than if at
  6m
• Blast wave reflected by solid surfaces
• Person next to a wall may sustain a greater
  primary blast injury

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General Considerations

• Half of all initial casualties seek medical care
  over first hour
• Expect upside down triage
• Most severely injured arrive after less injured
  who bypass EMS and self-transport to closest
  hospitals
• Secondary devices
• Initial explosion attracts law enforcement and
  rescue personnel who will be injured by second
  explosion

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London, England July 7, 2005
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General Management

• Focus on two exams
• Otoscopic exam
• If ruptured TM, chest radiography and eight hour
  observation recommended
• Primary blast injury notorious for delayed
  presentation
• If nonruptured TM and no other symptoms, may
  conditionally exclude other serious primary blast
  injuries
• Pulse oximetry
• Decreased oxygen saturation signals early blast
  lung even before symptoms

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Treatment of Blast Lung

• High inspiratory pressures increase risk of air
  embolism and pneumothorax
• Ventilation should use limited inspiratory
  pressures
• Permissive hypercapnia
• High frequency ventilation may be of value

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Pneumothorax
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Treatment of TM rupture

• Generally expectant management
• Most resolve spontaneously
• Avoid irrigating or probing the auditory canal
• Avoid swimming
• Refer to ENT if no healing or complications occur
• Complications include ossicle disruption,
  cholesteatoma, perilymphatic fistula, and
  permanent hearing loss (1/3)
• Steroids may be helpful in sensorineural hearing
  loss

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Treatment for Acute Gas Embolism (AGE)

• Recompression with 100 oxygen
• Left lateral recumbent position
• Hyperbaric oxygen (HBO) is definitive
• Transfer may be necessary
• Aspirin may be helpful in AGE
• May reduce inflammation-mediated injury in
  pulmonary barotrauma
• Weigh bleeding risk in acute trauma setting

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AGE
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Treatment of Eye Injuries

• 28 of blast survivors sustain eye injuries
• Objects penetrating eye (or any other body part)
  should not be removed in an emergency setting
• Cover affected eye with a paper cup that will not
  exert pressure on the globe
• Remove object in operating room under controlled
  conditions
• Refer patient to ophthalmology for definitive
  treatment

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Treatment of Burns

• Cover burns to minimize heat and fluid loss
• WP burns require special management
• Copious lavage and removal or particles and
  debris
• Rinse with 1 copper sulfate solution
• Combines with phosphorous particles and impedes
  further combustion
• Cardiac monitor
• Hypokalemia and hyperphsophatemia common
• Use moistened face masks to protect from
  phosphorous pentoxide gas exposure
• Avoid use of flammable anesthetic agents and
  excessive oxygen

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WP Smoke Hand Grenade
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WP Burn Victim
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Special Populations

• Pediatric trauma due to terrorism vs. pediatric
  trauma due to non-terrorism related events
• Increased use of Intensive Care Unit (ICU)
  resources
• Higher injury severity scores (ISS)
• Longer hospital stays
• Pregnancy
• Direct injury to fetus is uncommon
• Fetus protected by amniotic fluid
• Fetal attachment to placenta is tenuous
• Risk for placental abruption
• If blast in second or third trimester admit to
  labor and delivery for fetal monitoring

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Guidelines for Disposition

• Limited data prevent establishing optimal
  duration of observation
• Low risk and may be discharged with strict
  precautions after four hours of observation
• Persons exposed to open-space explosions with no
  apparent significant injury, normal vital signs
  and unremarkable lung and abdominal examination
• Moderate risk and should be observed for longer
  periods of time for delayed complications
• Persons exposed to closed-space explosion or
  in-water explosions
• Persons with TM rupture

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Guidelines for Admission

• High risk patients who require admission
• Significant burns
• Suspected air embolism
• Radiation
• WP contamination
• Abnormal vital signs
• Abnormal lung examination findings
• Clinical or radiographic evidence of pulmonary
  contusion or pneumothorax
• Abdominal pain or vomiting
• Penetrating injuries to the thorax, abdomen,
  neck, or cranial cavity

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Selected References

• Arnold JL, Halperin P, Tsai MC, Smithline H. Mass
  casualty terrorist bombings a comparison of
  outcomes by bombing type. Ann Emerg Med
  200443263-73.
• DePalma RG, Burris DG, Champion HR, Hodgson MJ.
  Blast Injuries. N Engl J Med 2005 3521335-42.
• Hogan DE, Waeckerle JF, Dire DJ, Lillebridge ST.
  Emergency department impact of the Oklahoma City
  terrorist bombing. Ann Emerg Med 1999 34160-7.
• Karmy-Jones R, Kissinger D, et. al. Bombing
  related injuries. Mil Med 1994159536-9.
• Lavanos E. Blast Injuries. (Accessed September
  21, 2005, at http//www.emedicine.com/emerg/topic6
  3.htm.).
• Wightman JM, Gladish SL. Explosions and blast
  injuries a primer for clinicians. Atlanta
  Centers for Disease Control and Prevention.
  (Accessed September 21, 2005, at
  http//www.cdc.gov/masstrauma/preparedness/primer.
  pdf.)