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

Iraq: Car Bombings Current Events

Historically in US… Few US bombings have caused mass casualties 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 Fuel and fertilizer used to create a bomb 518 injuries and 168 deaths 518 injuries and 168 deaths – Atlanta Olympic Park Bombing, July 27, 1996 – World Trade Center and Pentagon September 11 th, 2001 September 11 th, 2001 – Explosive Device Attacks at Abortion Clinics

Oklahoma City April 19, 1995

New York City September 11, 2001 New York City September 11, 2001

Classification of Explosives High Order (HE) Explosive High Order (HE) Explosive – Produce a high pressure shock wave – Examples include TNT, C-4, Semtex, dynamite Low Order (LE) Explosive Low Order (LE) Explosive – Produce a subsonic explosion – Examples include pipe bombs, molotov cocktails Manufactured Explosive Manufactured Explosive – Standard military-issued quality-tested weapon Improvised Explosive Device (IED) 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

Atlanta, Georgia July 27, 1996

Bag with Bomb

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

Primary Blast Injury Unique to high explosives Unique to high explosives Due to impact of over-pressurization wave with body surfaces Due to impact of over-pressurization wave with body surfaces Most commonly involve air-filled organs and air-fluid interfaces Most commonly involve air-filled organs and air-fluid interfaces – Middle ear – Lungs – Gastrointestinal tract Types of injuries 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

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

TM Rupture TM Rupture

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

Blast Lung Clinical triad of apnea, bradycardia, and hypotension Clinical triad of apnea, bradycardia, and hypotension Signs usually at initial presentation but may manifest as late as 48 hours after explosion 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 Should be suspected if dyspnea, cough, hemoptysis, or chest pain Radiographic findings 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 Prophylactic chest tube before general anesthesia and air transport if blast lung suspected

Blast Lung Blast Lung

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

Blast Abdominal Injury

Other Primary Blast Injuries Eye 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 Brain – TBI due to barotrauma of gas embolism – Signs and symptoms include headache, fatigue, poor concentration, lethargy, anxiety, and insomnia

Globe Rupture

Secondary Blast Injury Due to flying debris and bomb fragments Due to flying debris and bomb fragments Penetrating ballistic or blunt injuries 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 Consider delayed primary closure and tetanus vaccinations

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

Crush and Compartment Syndrome

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 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 Crush syndrome Rhabdomyolysis Rhabdomyolysis

Quaternary Blast Injuries Explosion related injuries or illnesses not due to primary, secondary, or tertiary 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 White Phosphorous (WP) from munitions causes extensive burns, hypocalcemia and hyperphosphatemia – Toxic inhalation – Radiation exposure – Asphyxiation (carbon monoxide and cyanide)

Madrid, Spain March 11, 2004 Madrid, Spain March 11, 2004

General Considerations Information about distance from and type of explosion predict injury severity and type 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 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 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 Person next to a wall may sustain a greater primary blast injury

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

London, England July 7, 2005

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

Treatment of Blast Lung High inspiratory pressures increase risk of air embolism and pneumothorax 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

Pneumothorax

Treatment of TM rupture Generally expectant management 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) Complications include ossicle disruption, cholesteatoma, perilymphatic fistula, and permanent hearing loss (1/3) Steroids may be helpful in sensorineural hearing loss Steroids may be helpful in sensorineural hearing loss

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

AGE

Treatment of Eye Injuries 28% of blast survivors sustain 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 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

Treatment of Burns Treatment of Burns Cover burns to minimize heat and fluid loss Cover burns to minimize heat and fluid loss WP burns require special management 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 Combines with phosphorous particles and impedes further combustion – Cardiac monitor Hypokalemia and hyperphsophatemia common Hypokalemia and hyperphsophatemia common – Use moistened face masks to protect from phosphorous pentoxide gas exposure – Avoid use of flammable anesthetic agents and excessive oxygen

WP Smoke Hand Grenade

WP Burn Victim

Special Populations Pediatric trauma due to terrorism vs. pediatric trauma due to non-terrorism related events 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 Pregnancy – Direct injury to fetus is uncommon – Fetus protected by amniotic fluid – Fetal attachment to placenta is tenuous Risk for placental abruption Risk for placental abruption – If blast in second or third trimester admit to labor and delivery for fetal monitoring

Guidelines for Disposition Limited data prevent establishing optimal duration of observation Limited data prevent establishing optimal duration of observation Low risk and may be discharged with strict precautions after four hours 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: 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

Guidelines for Admission High risk patients who require 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

Selected References Arnold JL, Halperin P, Tsai MC, Smithline H. Mass casualty terrorist bombings: a comparison of outcomes by bombing type. Ann Emerg Med 2004;43: Arnold JL, Halperin P, Tsai MC, Smithline H. Mass casualty terrorist bombings: a comparison of outcomes by bombing type. Ann Emerg Med 2004;43: DePalma RG, Burris DG, Champion HR, Hodgson MJ. Blast Injuries. N Engl J Med 2005; 352: DePalma RG, Burris DG, Champion HR, Hodgson MJ. Blast Injuries. N Engl J Med 2005; 352: Hogan DE, Waeckerle JF, Dire DJ, Lillebridge ST. Emergency department impact of the Oklahoma City terrorist bombing. Ann Emerg Med 1999; 34: Hogan DE, Waeckerle JF, Dire DJ, Lillebridge ST. Emergency department impact of the Oklahoma City terrorist bombing. Ann Emerg Med 1999; 34: Karmy-Jones R, Kissinger D, et. al. Bombing related injuries. Mil Med 1994;159: Karmy-Jones R, Kissinger D, et. al. Bombing related injuries. Mil Med 1994;159: Lavanos E. Blast Injuries. (Accessed September 21, 2005, at Lavanos E. Blast Injuries. (Accessed September 21, 2005, at Wightman JM, Gladish SL. Explosions and blast injuries: a primer for clinicians. Atlanta: Centers for Disease Control and Prevention. (Accessed September 21, 2005, at Wightman JM, Gladish SL. Explosions and blast injuries: a primer for clinicians. Atlanta: Centers for Disease Control and Prevention. (Accessed September 21, 2005, at