Target Audience

This activity is intended for physicians and nurses caring for victims of blast injuries.

Goal

The goal of this activity is to review the potential injuries associated with an explosion.

Learning Objectives

Upon completion of this activity, participants will be able to:

  1. Identify the most common injuries associated with an explosion.
  2. Describe the injuries that are most likely to result in early mortality.
  3. Review blast injury management recommendations.

Blast Injuries: A Review

Introduction

The July 7, 2005, bombing attacks on London's transit system are some of the latest in a series of terrorist-related bombings that have become a worldwide epidemic.[1] Recent mass terrorist bombing incidents include the March 11, 2004, attacks in Madrid, Spain. Ten bombs were hidden in back packs that exploded on commuter trains, killing 191 and wounding 1900.[2] The 1998 simultaneous car bombings in the US embassies in Dares Salaam, Tanzania, and Nairobi, Kenya, resulted in hundreds of deaths and thousands of injuries.[3] In Israel, there were 19,948 terrorist incidents reported between September 2000 and December 2003, of which most were suicide bombings.[4] For the year 2004, bombings of a US facility or interest represented 37% of global terrorist events, while American deaths counted for 1% of total deaths from terrorism.[2] These numbers are expected to increase for the year 2005. Most deaths and injuries related to terrorist attacks of any type occurred in the Near East, Southwest Asia, and Europe/Eurasia, with India, Iraq, the West Bank, and Gaza accounting for the largest numbers.[2]

The United States is not immune to these types of attacks. Recent domestic terrorist bombing events include the first World Trade Center bombing in February 1993, which killed 6 and injured 1000;[3] the Oklahoma City bombing at the Alfred P. Murrah Federal building, where 168 died and 8000 were injured;[5] and the Atlanta Olympic Park bombing in July 1996, where 1 woman died and more than 100 were injured.[6]

Eric Robert Rudolph recently pleaded guilty to the Atlanta bombing as well as the January 1997 bombing of a Sandy Springs, Georgia, family planning clinic; a bombing at the Other Side Lounge in Atlanta, Georgia, in February 1997 that injured 5; and the January 1998 bombing of a Birmingham, Alabama, family planning clinic that killed 1 and injured 1.[6] Rudolph is not alone. There have been 169 arsons and/or abortion clinic bombings since 1982.[7]

Most clinicians have considered caring for victims of explosions and bombings a remote possibility unless the provider was a member of the military or an overseas aid group.[8] That is no longer the case. Bombings are the most common cause of casualties in terrorist incidents. In 93 terrorist attacks reported between 1991 and 2000 that produced more than 30 casualties, 88% involved bombings.[9] These sudden mass casualty situations impose a massive burden on emergency, trauma, and critical care systems. The purpose of this article is to review blast injuries including types, pathophysiology, and management recommendations.



Terrorism

What is terrorism? Terrorism is defined by the United Nations and terrorism expert A. P. Schmid as "an anxiety-inspiring method of repeated violent action, employed by (semi-) clandestine individual, group or state actors, for idiosyncratic, criminal or political reasons, whereby -- in contrast to assassination -- the direct targets of violence are not the main targets. The immediate human victims of violence are generally chosen randomly (targets of opportunity) or selectively (representative or symbolic targets) from a target population, and serve as message generators. Threat- and violence-based communication processes between terrorist (organization), (imperiled) victims, and main targets are used to manipulate the main target (audience[s]), turning it into a target of terror, a target of demands, or a target of attention, depending on whether intimidation, coercion, or propaganda is primarily sought."[10] Terrorism occurs from ideological, racial, or international conflicts during and despite ongoing military conflicts.[1] Whether or not it works is debatable, but terrorism will remain a problem for the foreseeable future.[11]

While terrorist bombings may seem to be a problem that developed in the 1990s, in reality these types of bombings have occurred for some time. In 1886, a bomb exploded in Haymarket Square in Chicago during a labor rally, killing 12.[12] Suicide bombings first became a widely known tactic in World War II when Japanese pilots attacked Pearl Harbor. In the 1980s, this type of bombing became highly favored by terrorist groups in Southwest Asia and Sri Lanka. Since 2001, suicide bombings have been the most frequent and destructive in Iraq and Israel.[13]

Suicide bombers may wear a belt or vest they trigger themselves. Truck and car bombs are also used because these vehicles can carry explosives in large amounts without attracting suspicion. One compact sedan can hold up to 500 pounds of explosives, have a lethal blast range of 100 feet, and a falling glass hazard of 1250 feet (Table 1).[14] One of the deadliest car bombings occurred in Bali, Indonesia, in October 2002. A total of 202 people were killed and 209 injured when a bomb in a mini-bus exploded outside a nightclub.[15] Bombs are relatively inexpensive, easy to make with instructions readily available on the Internet, and can produce large numbers of casualties from a single incident.[1,4,16]

Table 1. Bureau of Alcohol, Tobacco, and Firearms Explosive Standards

Improvised explosive devices (IEDs)/booby traps. Global security.org Web site. Available at: http://www.globalsecurity.org/military/intro/images/vbied-standards-chart.jpg. Accessed October 14, 2005.



Explosions and Explosive Devices

Explosions are caused by a rapid chemical conversion of a solid or liquid into a gas with resultant energy release.[8] Explosives are either high or low order.

High-order explosives are designed to detonate quickly, generate heat and loud noise, fill the space with high pressure gases in 1/1000th second, and produce a supersonic overpressurization shock wave that expands from the point of detonation outward in a pressure pulse. This "blast wave" (positive wave) moves in all directions, exerting pressures of up to 700 tons. Shock waves possess the quality of brisance (shattering effect).[8,17,18] The displaced air then compresses and forms a vacuum returning to the point of detonation (negative wave) (Figure 1).[17,19] High-order explosives include TNT, C-4, Semtex, nitroglycerin, dynamite, and ammonium nitrate fuel oil.[8,17,18]

Figure 1. The blast overpressure wave.[1]

Low-order explosives produce a subsonic explosion without the overpressurization wave. Energy is released relatively slowly and burns by a process of deflagration. Low-order explosives include pipe bombs, gunpowder, Molotov cocktails, and pure petroleum-based bombs.[8,17,18] A list of substances considered explosives is available at the Bureau of Alcohol, Tobacco, Firearms and Explosives Web site.[20]

Explosives have several effects: the blast pressure wave as described above; the fragmentation effect; the blast wind; the incendiary thermal effect; secondary blast pressure effects; and ground and water shocks for explosions that occur under ground or water.

Fragmentation effect occurs from projectiles included in the container, projectiles produced from the destruction of the container, and from objects surrounding the detonator and target. These projectiles can travel up to 2700 feet per second.[17]

The blast wind is created by the motion of air molecules responding to pressure differentials generated by the blast. These winds may be as high as those seen in hurricanes but are not sustained.[8,17]

The incendiary thermal effect is different for high- and low-order explosives. High-order explosives produce higher temperatures for shorter periods of time, usually resulting in a fireball at the time of detonation. Low-order explosives have a longer thermal effect and can cause secondary fires.[17]

Secondary blast pressure effects are caused by the blast wave's reflection off surfaces prolonging and magnifying the effect, particularly in enclosed spaces. Greater energy transfer to the body occurs. Underground and underwater explosions propagate the shock waves further and with more force than air.[17,21]

Bombs are weapons and defined as any container filled with explosive material whose explosion is triggered by a clock or other timing device. Terrorist bombs, also known as improvised explosive devices (IEDs), are usually custom made, may use any number of designs or explosives, and are of 2 types: conventional, which are filled with chemical explosives, or dispersives, which are filled with chemicals and/or other projectiles such as nails, steel pellets, screws, and nuts designed to disperse (Figure 2). Nuclear devices, which rely on nuclear fission or fusion, have not been seen to date in terrorist attacks, though the possibility exists and remains a concern.[4,22]

Figure 2. Examples of improvised explosive devices (IEDs).



Mechanisms of Injury and Injury Patterns in Explosions

Explosions produce specific injury patterns and the potential to cause life-threatening multisystem or multidimensional injuries. These patterns are a result of the composition and type of bomb, the delivery method, the distance between the victim and the blast, whether the blast occurred in a closed or open space, and any surrounding environmental barriers or hazards. There are 4 types of blast injury: primary, secondary, tertiary, and quaternary.[1,4,8,18]

Primary blast injury is a direct result of the overpressurization wave's impact on the body. These injuries occur mainly to the gas-filled organs -- the auditory, pulmonary, and gastrointestinal systems. Injuries result from spalling, implosion, inertia, and the extreme pressure differentials at the body surfaces causing a stress wave that reproduces in the underlying tissues. Spalling occurs when the shock wave travels from one medium to one of lesser density, such as from tissue fluid to air, resulting in waves in the first medium that lead to macroscopic and microscopic tears at the interface of the 2 mediums.[1,8,18,23]

Secondary blast injuries result from flying debris and bomb fragments -- the fragmentation effect -- leading to penetrating ballistic or blunt force injuries.[1,4,8,18,23]

Tertiary blast injuries occur as a result of individuals being thrown by the blast wind. Victims may tumble along the ground or be thrown through the air and strike other objects with resultant blunt or penetrating trauma.[1,4,8,18,23]

Quaternary blast injuries are defined as any explosion-related injury or illness not due to any of the above such as burns and inhalational injuries. Temperatures from the explosive gases can reach 3000 degrees centigrade. Victims close to the detonation can sustain third-degree burns that can be fatal. Quaternary injuries can also include exacerbation of underlying chronic conditions (Table 2).[1,4,8,18,23]

Table 2. Mechanisms of Blast Injury

Category

Characteristics

Body Part Affected

Types of Injuries

Primary

Due to high-order explosives. Impact of overpressurization wave on body surfaces.

Gas filled organs: Lungs, Abdomen, Ear

Blast lung injury; Tympanic membrane rupture and middle injury; Abdominal hemorrhage and perforation; Concussion

Secondary

High- and low-order explosives. Due to flying debris, bomb fragments, other projectiles.

Any body part

Penetrating ballistic injuries; Blunt injuries; Ocular penetration

Tertiary

High-order explosions. Due to individuals being thrown by blast winds.

Any body part

Fracture and traumatic amputation; Closed and open brain injury

Quaternary

Any explosion-related injury, illness, or disease not due to primary, secondary, or tertiary mechanisms. Includes exacerbations/complications of pre-existing illnesses.

Any body part

Burns (flash, partial, and full thickness); Crush injuries; Closed and open brain injury; Asthma, chronic obstructive pulmonary disease, smoke inhalation, or respiratory illnesses related to dust, fumes, toxic smoke

Mechanisms of blast injury. CDC Web site. Available at: http://www.bt.cdc.gov/masstrauma/explosions.asp. Accessed October 17, 2005.

A quinary blast injury has been proposed and is felt to be due to toxic materials absorbed by the body from the blast resulting in hemodynamic problems. In an abstract, Sorkin and colleagues noted that 4 patients admitted to the intensive care unit (ICU) after a bombing exhibited hyperpyrexia, sweating, a low central venous pressure (2-5 cm H20), and positive fluid balance not correlated to any other injury.[24,25]

Explosions in closed spaces or that result in structural collapse have higher mortality and injury rates. Arnold and colleagues, in an epidemiologic review of terrorist bombings that produced 30 or more casualties, found that 1 out of 4 victims died immediately in structural collapse, 1 of 12 in confined space bombings, and 1 in 25 in open air bombings. Bus bombings in the Israeli experience resulted in the highest mortality rate.[1,9,21]

The authors also found a triphasic distribution of mortality in the 3 types of bombings; a high immediate mortality rate, a low early emergency department, and a late (inhospital) mortality rate.[9] Kluger found causes of death in bombings were: complete disruption of bodies 14%, multiple injuries 39%, head and chest injuries 21%, head injuries 12%, and chest injuries 11%. Hidden injuries such as air emboli and cardiac dysrhythmias may account for fatalities in which no other cause for death is found.[1]

Injuries varied as well. Structural collapse victims sustained more inhalational and crush injuries (secondary, quaternary injuries) and fewer primary blast injuries. Confined space bombings resulted in more primary and quaternary blast injuries, while open air bombings led to higher rates of ballistic soft tissue injuries or more secondary blast injuries (Table 3).[9]

Table 3. Bombing Characteristics and Impact on Hospitals

Bombing Characteristic

Implication

Anticipated Impact

Numbers of Injured Seeking Emergency Care

Injury Frequency

Injury Severity

Blast site close to hospital

Increased number of injured survivors arrive outside EMS. Decreased EMS transport time.

Increased

Increased primary blast injuries, traumatic amputations, and minor injuries

Variable -- more minor and more severe

Vehicle used as delivery system

Increased explosive magnitude. Possible structural collapse. Increased immediate fatalities close to detonation point or inside collapse.

Increased. May produce hundreds or thousands of injured.

Variable

Increased

Pre-explosion or precollapse evacuation

Increased distance between device and potential victims. Decreased risk.

Decreased

Decreased primary blast injury, traumatic amputations, flash burns

Decreased

Open air setting

Blast energy dissipated; increased area involved. Decreased structural collapse and immediate fatalities.

Increased. May produce up to 200 injuries.

Increased secondary blast injuries

Decreased -- more minor injuries

Confined space setting

Blast energy magnified; decreased area involved. Increased immediate fatalities, number exposed to blast effects; higher in smaller spaces

Decreased. Produces < 100 injuries

Increased primary blast injuries, amputations, burns

Markedly increased

Structural collapse/structural fire

Increased magnitude and higher in taller buildings. Collateral damage beyond structure. Increased number of fatalities. Increased victims inside exposed to smoke and fire; increased evacuation time.

Variable. Decreased numbers inside; increased numbers outside structural collapse. May produce hundreds or thousands of injured. With fire, increased numbers inside

Increased inhalation, crush injuries. In fire, increased burns, inhalation injuries; increased in high rise fires

Increased in collapse; Variable in fire

EMS = emergency medical services.
Adapted from: Halpern P, Ming-Che T, Arnold J, Stok E, Ersoy G. Mass-casualty, terrorist bombings: implications for emergency department and hospital emergency response (part II). Prehosp Disast Med. 2003;18:235-241.

Terrorist bombings result in high injury scores among other findings. Kluger, in an analysis of data from the Israel Center for Disease Control, found that bombing casualties had higher injury severity scores (ISS > 16, 30% vs 10% for other trauma), increased immediate mortality (as high as 29% for closed space bombings), greater inhospital mortality rate (6.2% vs 3% for other trauma), more frequent need for surgical intervention -- particularly orthopedic, longer hospital stays, greater use of intensive care, and younger age groups.[24] Peleg found similar numbers, with 30% having ISS scores > 16, 53% requiring surgical procedures, 23% requiring an ICU stay, and 20% having a hospital length of stay greater than 14 days as compared with victims of other causes of trauma such as car accidents or gunshot wounds.[26] Thus, bombing victims have higher hospital resource utilization than victims of other trauma (Table 4).[23,27]

Table 4. Type of Explosion and Injury Severity (%)

 

Open Space

Enclosed Space

Bus

Mortality

2.8

15.8

20.8

ISS > 15

6.8

11.0

11.0

Multiple injury

4.7

11.1

7.8

Surgery required

13.5

17.6

14.9

ICU required

5.3

13.0

11.3

ISS = injury severity score; ICU = intensive care unit.
Kluger Y. Bomb explosions in acts of terrorism-detonation, wound ballistics, triage and medical concerns. Isr Med Assoc J. 2003;5:235-240.



General Management

Bombings result in multiple trauma victims arriving to the hospital in a short period of time. Existing emergency department (ED) and ICU patients should be evaluated to determine who can be moved to free up beds for bombing victims. Effective triage is crucial. Victims should be triaged such that those individuals with a good potential for survival receive immediate medical attention, while those with lesser injuries receive delayed care. Those with a poor prognosis for survival should receive minimal care. Patients should be divided into urgent and nonurgent and receive care in terms of an initial phase of resuscitation while victims continue to arrive to the hospital and a definitive phase when the number of victims arriving has stopped and optimal care can be delivered.[23,28]

Injuries associated with early mortality in order are:

  • Multiple trauma;
  • Head trauma;
  • Thoracic injury; and
  • Abdominal injury.[27]

All management follows Advanced Trauma Life Support Guidelines and begins with attention to the ABCs of trauma care -- airway, breathing, and circulation. Adequate airway protection with attention to ventilatory support and hemodynamics is critical. Once the victim is stabilized, as much history as possible should be obtained. Important historical information includes distance from the explosion; whether open, closed, or semiconfined space; and whether the victim had on body armor, as body armor increases the severity of primary blast injury.[29]

A thorough physical exam should be performed with the patient completely exposed. Examination should focus on evidence for a significant blast exposure such as ruptured tympanic membranes (TM), hypopharyngeal petechia or ecchymoses, retinal artery air embolism, or subcutaneous emphysema.[29]

Suggested laboratory studies include a complete blood count (CBC), serum electrolytes, and type and cross match for blood.[28]



Pulmonary Injuries

Primary blast lung injury (BLI) has the highest morbidity and mortality of the primary blast injuries. In one study of 828 victims of explosions, 17% of fatalities had blast lung injury as the sole finding.[30] In another study of hospitalized terror victims in Israel from September 2000 to December 2001, chest trauma accounted for 31% of injuries and 9.4% of deaths.[26] Arnold and colleagues found that BLI occurred in 42% of victims in confined space bombings vs 10% of those involving structural collapse and 7% of open air bombings.[9] Fifty percent of victims will suffer some pulmonary damage with overpressures of 50-100 psi, and overpressures greater than 200 psi are fatal.[23]

Ho proposed that the high-pressure wave travels through the border between air, alveoli, and blood vessels, causing ruptured blood vessels and alveolar septae leading to blood in the septae and air in the blood vessels.[19] This leads to alveolar hemorrhages, perivascular and peribronchial disruptions, and alveolar pulmonary venous fistulas, which may cause systemic air embolism. Some lung injuries present as simple tension pneumothoraces, and evidence for pneumothorax needs to be sought and treated aggressively. Additional findings may include pulmonary interstitial emphysema, pneumomediastinum, and subcutaneous emphysema.[1,4,23,29]

The degree of hemorrhage determines the degree of respiratory insufficiency. Wegner and Jamieson found that patients with 28% or greater evidence of pulmonary contusion or laceration required mechanical ventilation.[31] Hemoptysis and barotrauma are common signs. Rib fractures and chest wall injuries are not. Symptoms include cough, dyspnea, and chest pain. Signs include hypopharyngeal petechia, hypoxia, cyanosis, apnea, wheezing, decreased breath sounds, and hemodynamic insufficiency (Table 5).[1,4,23,29,32]

Table 5. Clinical Signs and Symptoms of Primary Blast Lung Injury

Clinical Entity

Symptoms

Exam Findings

Nonspecific findings
(common to PBI)

Chest pain

Cyanosis

Dyspnea

Tachypnea

Parenchymal lung injury
(contusion)

Hemoptysis

Rales

Decreased breath sounds

Dullness to percussion

Pulmonary barotrauma
(pneumothorax, pneumomediastinum)

Hemodynamic instability

Decreased breath sounds

Retrosternal crunch

Subcutaneous crepitus

Tracheal deviation or mediastinal shift

Pulmonary laceration
(hemopneumothorax)

Hemoptysis

Decreased breath sounds

Hemodynamic instability

Retrosternal crunch

Subcutaneous crepitus

Tracheal deviation or mediastinal shift

Dullness to percussion

PBI = primary blast injury.
Reprinted from Toxicology, 121, Argyros G., Management of primary blast injury, 105-115, Copyright 1997, with permission from Elsevier.

Chest x-ray will show a "butterfly pattern," a result of pulmonary infiltrates and contusions. Lung damage can occur over time, so clinicians need to be vigilant with repeated examinations and arterial blood gases. Further deterioration will produce complete whitening similar to adult respiratory distress syndrome (ARDS). Additional testing may include computed tomography (CT) scan of the lungs.[1,23]

Specific treatment for BLI includes supplemental high-flow oxygen for hypoxemia, including masks and endotracheal intubation if required. Difficulty in ventilation may require limited peak inspiratory pressures (< 40 cm H20), volume-controlled ventilation, permissive hypercapnia, and other innovative ventilatory techniques. Chest tubes should be inserted for pneumothoraces.[4,23,29]

Pizov and colleagues followed 15 patients who sustained BLI as a result of a bus bombing. Patients were divided into mild, moderate, and severe BLI (Table 6). Of the 15 patients, 11 survived, and 3 of the 4 patients with severe BLI died. ARDS developed in all patients with severe BLI and in 33% of those with moderate BLI. Patients with mild BLI had no positive pressure ventilation (PPV) and no positive end-expiratory pressure (PEEP). Those with moderate BLI had PPV and PEEP, though judicious use of PPV is recommended and pressures kept as low as possible to avoid further alveolar damage and systemic air embolism. Innovative therapies along with PPV and PEEP used on patients with severe BLI included independent lung ventilation, use of nitric oxide, and high-frequency jet ventilation with PPV.[30] Permissive hypercapnia may not be possible in victims with concomitant head injuries. Extracorporeal membrane oxygenation has been attempted with mortality varying by severity of lung injury (0% in mild cases; 66% in severe).[4]

Table 6. BLI Severity Score

 

Severe BLI

Moderate BLI

Mild BLI

Pa02/FI02

< 60

60-200

> 200

Chest x-ray

Massive bilateral lung infiltrates

Bilateral or unilateral lung infiltrates

Localized lung infiltrates

Bronchopleural fistula

Yes

Yes/No

No

BLI = blast lung injury.
Pizov R, Oppenheim-Eden A, Matot I, et al. Blast lung injury from an explosion on a civilian bus. Chest. 1999;115:165-172.

Blast lung needs to be differentiated from lacerated lung as early in the clinical course as possible, as the former is treated with careful ventilation and the latter may only respond to surgical intervention.[1,23]

ARDS can develop 24-48 hours after the injury and is seen in those victims with combined injuries of blast exposure, inhalational injury, significant soft tissue injury, multiple long bone fractures, and those requiring massive transfusions.[29]

Air emboli can develop in any patient with significant pulmonary injury and may be the cause of immediate death in BLI. Symptoms include sudden blindness, focal neurologic deficit, chest pain, or sudden loss of consciousness. Physical findings may include air in retinal vessels on fundoscopy, focal neurologic deficits on exam, mottled skin, and cardiac arrhythmias on EKG. Treatment includes supplemental oxygen and positioning in the left lateral decubitus position with head down. Definitive care is treatment in a hyperbaric chamber.[29]



Gastrointestinal (GI) Injuries

Primary blast injury to the GI tract involves the gas-containing organs far more than the solid organs; however, with high overpressures, solid organs can be affected as well. Injuries such as lacerations, hemorrhage, and contusions to liver, spleen, and kidney are the result of deceleration.[1,33]

Hollow viscous injuries include hemorrhage, petechia, and circumferential rings of hemorrhage. Transmural lesions can lead to bowel perforation, hemoperitoneum, peritonitis, and sepsis. Perforations are not common (0.1% to 1.2%) but may develop up to 24-48 hours later; however, delays of up to 14 days have been reported.[4,23,33]

Paran and colleagues reported on 3 patients who developed terminal ileum perforations requiring surgical resection. One patient was operated on immediately for signs of peritonitis on admission while the other 2 developed symptoms 24 hours later. Whether the perforations were due to an evolving injury or missed initially is unclear, but patients with blast injury should have serial abdominal examinations.[34]

Symptoms of GI involvement include abdominal pain, nausea, vomiting, diarrhea, and tenesmus, rectal, or testicular pain. Physical findings may be absent or diminished bowel sounds, bright red blood per rectum, guarding, rebound tenderness, and unexplained hypovolemia. Any patient with abdominal findings should have surgical intervention.[18,29]

In the Israeli experience, diagnostic peritoneal lavage (DPL) is useful for patients with abdominal wall perforations by projectiles or in the unconscious or intubated patient.[1] Otherwise, ultrasound and abdominal CT scans may be used. CT may reveal extraluminal gas, hemoperitoneum, solid organ injury or disruption, or bowel wall hematomas with large fluid collections. However, CT has poor sensitivity in identifying hollow viscous injury; if symptoms persist, a DPL should be performed. For victims who are hemodynamically unstable despite a negative DPL, surgical intervention may be required as DPL can miss retroperitoneal injury, mesenteric hematomas, and subcapsular solid organ injuries.[1]



Neurologic Injuries

Neurologic injuries may present as "dead on the scene" events. Subarachnoid and subdural hemorrhages are most often found in fatalities, and severe head injury is the chief cause of mortality in blast victims. Head injuries accounted for 29% of injuries in the Madrid bombings and 80 of the victims of the Oklahoma City bombing. Eight had severe brain injuries and 72 had mild to moderate head injuries, with 46% having concussions and 35% with closed head injuries.[1,8,35,36]

Blast waves can cause concussion or mild traumatic brain injury. Neurologic impairment from blast injury was initially attributed to air emboli in the cerebral circulation. However, studies in animals suggest that the overpressure wave is transferred to the central nervous system, causing diffuse axonal injury. Higher levels of blast overpressure can cause skull fractures or coup-counter-coup injuries.[4,33]

Victims may complain of headache, fatigue, poor concentration, lethargy, depression, and insomnia. Symptoms include retrograde amnesia, apathy, and psychomotor agitation, and may be difficult to discern from posttraumatic stress disorder.[4,18,33]

Head injuries are classified according to the Glasgow Coma Scale (GCS; Table 7) as:

  • Mild = GCS 13-15
  • Moderate = GCS 9-12
  • Severe = GCS ≤ 8

Patients with impaired consciousness, neurologic signs, or GCS 13-14 should be referred for urgent CT scan of the head. If abnormal, then neurosurgery should be consulted. Surgery may be required for subdurals, epidurals, or contusions. Patients with GCS 9-12 should have CT scan of the head as well as a CT of C1, 2, and C7; T1 along with AP; and lateral x-rays of the cervical spine to rule out cervical spine injury. Severe traumatic brain injury with GCS ≤ 8 requires neurosurgical management in an ICU.[37,38]

Table 7. Glasgow Coma Scale

 

Response

Score (in points)

Eye opening

Opens on own; blinking at baseline

4

To verbal command

3

To pain

2

Does not open

1

Talking

Alert, oriented

5

Confused, disoriented, but answers questions

4

Inappropriate words

3

Moans, unintelligible words

2

Does not talk

1

Motor response

Obeys commands

6

Purposeful to pain

5

Moves away from pain

4

Flexion movements (decorticate posturing)

3

Extension movements (decerebate posturing)

2

No response

1

Adapted from: Glasgow Coma Scale. CDC Web site. Available at: http://www.bt.cdc.gov/masstrauma/gscale.asp. Accessed October 17, 2005.

Management of severe head injury includes intubation and ventilation, maintenance of appropriate body temperature, judicious oxygen management, continuous arterial pressure monitoring, sedation, pain control, neuromuscular paralysis, and cervical spine control. Arterial pressures should be maintained above 90 and cerebral pressures below 20. Additional treatment includes management of blood sugars, nutrition, seizures, and prevention of thromboembolic events.[37,38]



Auditory Injuries

The ear is most sensitive to blast injuries and the organ most often affected. In the Oklahoma City bombing, 35% of survivors reported auditory injury.[35] The most common finding is rupture of the TM at the pars tensa region.[8,23] In the Madrid bombings, 41% of 243 victims treated at the hospital closest to the bombing site had TM perforation. Arnold found TM perforations in 50% of confined space bombings, 14% of structural collapse, and 8% of open air bombings. However, hearing loss can occur without TM rupture.[9,29,36]

Overpressures of at least 5 psi are required to rupture the TM, but damage to the cochlea and disruption of the ossicles can occur at lower pressures. Blast overpressure tears sensory cells from the basilar membrane, which eventually heals but may heal with scar leading to continued symptoms.[23,39] A ruptured TM suggests other blast injuries may be present, and the patient should be carefully evaluated to exclude these.

Hearing loss may be conductive due to TM rupture, ossicular damage, or serous otitis; or hearing loss may be sensorineural due to damage to the cochlea. It usually resolves in the first few hours of exposure but may be permanent in up to 30% of victims. Other symptoms include otalgia, tinnitus, and vestibular dysfunction with vertigo or bleeding from the external ear canal.[18,29] In one study of 17 survivors of a bus bombing in Israel in 1994, complaints at the time of admission were ear fullness in 88.2%, tinnitus in 88.2%, otalgia in 52.9%, dizziness in 41.2% and ear discharge in 52.9%.[40]

TM perforation is a primary blast injury but does not appear to be an early manifestation of an occult pulmonary blast injury. In another Israeli study of 11 terrorist attacks resulting in 145 fatalities and 647 injuries, 142 had isolated TM perforation, 18 with isolated BLI, 31 with both, and 2 with intestinal blast injury. No patient with isolated TM perforation later developed BLI.[41]

Treatment consists of avoiding additional auditory injury. A 1976 study by Melenik found that soldiers with hearing loss or tinnitus transferred to a noncombat unit had hearing improve by 31% vs 8.7% for those who stayed in the combat unit.[29] An otolaryngologist (ENT) should evaluate all patients with ruptured TM. Debris should be removed by suction under microscope from the external canal. The need for surgery is determined by the ENT. Many auditory injuries resolve or stabilize over the first few months of injury.[23,29]



Orthopedic Injuries

Trauma to the musculoskeletal system in an explosion may be due to primary, secondary, or tertiary mechanism alone or in combination. Blast overpressure and high-velocity blast winds generated by the explosion may fracture bones or cause tumbling of victims leading to traumatic amputations. Projectiles from the explosion can lead to fractures.[1,8,28]

Traumatic amputations have a poor prognosis as victims have usually been exposed to extremely high blast overpressures; however, large projectiles can also cause amputation.[23,28,36] Eleven percent of fatalities in one series had traumatic amputation, and the survival rate was 1% for victims with traumatic amputation.[23]

In the Israeli experience, fractures and lacerations of the upper and lower extremities occurred at 38%. Crush injuries, severe soft tissue injuries, and penetrating injuries of the extremities from projectiles were present as well.[4] From October 2000 to June 2003, 71 suicide bombings with 906 victims were treated in Israel. Twenty-one percent of victims required orthopedic surgery.[24] In the Madrid bombings, shrapnel wounds and fractures constituted 36% and 18% of musculoskeletal trauma, respectively.[36] In the Oklahoma City bombings, 35% of survivors sustained musculoskeletal injuries, with 37% of these victims having multiple fractures.[35]

Victims may have multiple shrapnel sites leading to extensive soft tissue damage and open fractures.[42] Fragments and projectiles may cause more severe soft tissue damage than bullets due to tumbling and the introduction of dirt, clothing, and other environmental debris. Clinicians should be aware that:

  • Fragments may not travel in straight lines;
  • Significant internal injuries may result from small entrance wounds;
  • Intra-abdominal injury should be suspected in any victim with entrance wounds in the thighs, perineum, or buttocks;
  • Any hematoma may indicate a vascular injury; and
  • Compartment syndrome and rhabdomyolysis can be complications of musculoskeletal injuries, especially in the setting of structural collapse and/or prolonged extrication.[18,28]

As a result, a liberal approach to radiography is warranted, as is the consideration of whole body CT scanning for any individual with significant multiple shrapnel wounds.[28,42]

Treatment in the ED and ICU consists of continuous reassessment of vital signs and hemodynamic status. Tetanus prophylaxis and antibiotics are warranted for all individuals. These wounds are at high risk for infection and gas gangrene. Operative treatment is up to the orthopedic surgeon, who may take the patient for primary debridement followed by repeat debridement as warranted and delayed closure of the wounds. Amputation may be required for extremities deemed unsalvageable.[28]



Ocular Injuries

In explosions, most ocular injuries are due to the secondary blast effect from projectiles such as falling glass, shrapnel, added nails, bolts, and other metal along with environmental debris. The blast wave propels these particles out from the area of detonation.[23] Arnold and colleagues found that eye injuries were found in 4% of bombings with structural collapse, 6% of confined space, and 1% of open air bombings. Penetrating eye trauma was 2%, 2%, and 1% for each type, respectively.[9] Eye injuries comprised 16% of injuries in 243 victims in the Madrid bombings.[36]

The ocular surface is only 0.10% of the total body surface area but can account for 2% to 16% of injuries in bombings.[43]

Mines and colleagues conducted a detailed retrospective study of the ocular injuries sustained in the Oklahoma City bombing (Table 8). In the series, most of the injuries were caused by flying glass. Of note is that 36% of the patients who sustained an ocular injury also sustained a head injury. And 50% of those with an open globe injury also had a head injury.[43]

Table 8. Types of Ocular Injuries in the Oklahoma City Bombing

Type of Injury

Number of injuries (%)

Corneal abrasion

25 (21%)

Lid/brow laceration

23 (20%)

Open globe injury

12 (10%)

   Corneal laceration

4 (3%)

   Scleral laceration

4 (3%)

   Unspecified

4 (3%)

Conjunctivitis/irritation

10 (9%)

Ocular contusion

7 (6%)

Hyphema

6 (5%)

Orbital fracture

6 (5%)

Retinal detachment*

5 (4%)

Corneal burn

4 (3%)

Traumatic cataract

3 (3%)

Cranial nerve injury

3 (3%)

Vitreous hemorrhage

3 (3%)

Intraocular foreign body

2 (2%)

Subconjunctival hemorrhage

2 (2%)

Lacrimal system injury

1 (1%)

Optic nerve injury

1 (1%)

Recti transaction

1 (1%)

Scleral abrasion

1 (1%)

Total

115 (100%)

*Four additional patients reported development of retinal detachment that could not be verified or was not related to the bombing
One patient sustained bilateral sixth cranial nerve palsy; another patient developed Bell's palsy
Mines M, Thach A, Mallonee S, Hildebrand L, Shariat, S. Ocular injuries sustained by survivors of the Oklahoma City bombing. Ophthalmology. 2000;107:837-843.

Symptoms are eye pain or irritation, foreign body sensation, change in vision, and periorbital swelling. Management of these injuries includes a careful and thorough examination. An attempt should be made to examine all eye structures including eyelids, globe, cornea, fundus, and surrounding bony orbit. Globe injuries are associated with orbital floor fractures at a rate of 10% to 25%. An accurate visual acuity should be obtained once other injuries have been evaluated and stabilized. Thermal burns usually involve the eyelids. Superficial burns of the eyelids may be treated with irrigation and ophthalmic ointment. Corneal abrasions are treated with topical antibiotics, cycloplegics, and topical nonsteroidal anti-inflammatories. Tetanus immunization should be given.[44]

Evaluation by an ophthalmologist is warranted for any suspected globe injuries, deep corneal foreign bodies or abrasions, orbital fractures, suspected retinal detachments, hyphemas, intraocular foreign bodies, corneal burns, second or third degree eyelid burns, deep lid lacerations, subconjunctival hemorrhage, or any head injury that may involve the orbit or compromise vision.[44]



Miscellaneous Injuries

Thermal Burns

Quaternary injuries such as burns are due to local fires, victims' burning clothing, and proximity to the explosion. The high temperatures from the explosive gases can result in heat lung injury, toxic gas inhalation, and flash burns ranging from first to third degree.[1,23]

Burns were 14%, 45%, and 11% of injuries for structural collapse, confined space, and open air bombings in Arnold's study. In the Oklahoma City bombing, 9 persons suffered thermal burns with 7 hospitalized for burns involving more than 70% of body surface area (BSA).[9,35]

Management consists of assessing the amount of BSA involved in the burn. The most common method is the rule of 9s, where the body is divided by anatomic areas in order to estimate BSA burned. In an adult, the head/neck is 9%, each upper extremity is 9%, the torso is 18% for anterior and posterior, and each lower extremity is 18%. Patients should be categorized by severity of burn into major, moderate, and minor to optimize burn care (Table 9).[45]

Table 9. Burn Categories

Major Burn

Moderate Burn

Minor Burn

Partial thickness burns > 25% BSA in adults

Partial thickness burns 15% to 25% BSA in adults

Partial thickness burns < 15% BSA in adults

Partial thickness burns > 20% BSA in children < age 10 or adults > 50

Partial thickness burns 10% to 20% BSA in children < 10 or adults > 50

Partial thickness burns < 10% BSA in children < 10 or adults > 50

Full thickness burns > 10% BSA

Full thickness burns 2% to 10% BSA

Full thickness burns < 2% BSA

Burns to face, eyes, ears, hands, feet, or perineum that can lead to decreased function or cosmetic impairment

Burns to face, eyes, ears, hands, feet, or perineum that will not lead to decreased function or cosmetic impairment

Burns to face, eyes, ears, hands, feet, or perineum that will not lead to decreased function or cosmetic impairment

Caustic chemical burns

 

 

High voltage electrical burns

 

 

Inhalation injury or other trauma

 

 

Burns in debilitated patients

 

 

Major burns should be treated at a burn center; moderate burns require hospitalization for initial care but not at a burn center; minor burns may be treated as outpatients.

Adapted from: Edlich R, Bailey T, Bill T. Thermal burns. In: Marx J, Hockberger R, Walls R. eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 5th ed. Philadelphia, Pa: Mosby; 2002:802-813.

Burn inhalation may lead to airway edema in 12-24 hours, so patients with suspected airway injury should be intubated. Patients with stridor, sooty tongue, or severe facial swelling are candidates. Fiberoptic bronchoscopy should be considered for victims with inhalation injury to assess the anatomic level of involvement and severity of the injury. Carboxyhemoglobin levels should be obtained, and patients with levels > 10% may require treatment in a hyperbaric chamber.[45]

Moderate to major burns should receive fluid resuscitation through large bore IVs; however, this may need to be balanced against other injuries such as BLI or head trauma. These burns should be transferred to a burn center for definitive care. If transfer is not possible due to other injures, then the burns should be cleansed, the blisters debrided, and covered with topical antibiotic ointments and sterile dressings or sheets. Minor burns may be treated in a similar fashion.[45]

Unusual Infections

Singer describes 2 incidents where human remains shrapnel not only caused injury, but one suicide bomber was hepatitis B positive and the other was HIV positive. Therefore, in suicide bombings, victims in close proximity to the bomber may need to be treated similarly to individuals with blood-borne pathogen exposure.[4]



Summary

Terrorist bombings will continue to be a difficult problem into the foreseeable future. Clinicians should be aware of the types of potential injuries and appropriate management in these mass casualty situations so that definitive care can be provided to victims while utilizing hospital resources effectively.



Additional Resources

Mass Casualties

CDC Emergency Preparedness and Response
http://www.bt.cdc.gov/

Christen H, Maniscalco P, Christian H. Mass Casualty and High-Impact Incidents: An Operations Guide. 1st ed. Saddle River, NJ: Prentice Hall; 2002.

Hogan D, Burstein J, eds. Disaster Medicine. 1st ed. Philadelphia, Pa: Lippincott; 2002.

Johannigman J. Disaster preparedness: It's all about me. Crit Care Med. 2005;33:S22-28.

Moore E, Feliciano D, Mattox K, eds. Trauma. 5th ed. Philadelphia, Pa: McGraw-Hill; 2004.

Bioterrorism

Bioterrorism and Public Health Preparedness Programs
http://www.cdc.gov/programs/bt.htm

Bioterrorism Readiness Plan: A Template for Healthcare Facilities
http://www.cdc.gov/ncidod/hip/Bio/13apr99APIC-CDCBioterrorism.PDF



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Author

Sussan K Sutphen, MD, MEd

Member, American Medical Writers Association, ACPE; Diplomat, ABEM

Disclosure: Sussan K. Sutphen, MD, MEd, has disclosed no significant financial relationships

 

   
 

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