Blast Injuries

Safwat Abd El Kader

MD, FRCS, FICS

Professor of Surgery

Cairo University

Cairo - Egypt

Background Explosions have the capability to cause

multisystem, life-threatening injuries in single or multiple victims simultaneously.

These types of events present complex triage, diagnostic, and management challenges for the health care provider.

Explosions can produce classic injury patterns from blunt and penetrating mechanisms to several organ systems, but they can also result in unique injury patterns to specific organs including the lungs and the central nervous system CNS.

Understanding these crucial differences is critical to managing these situations.

Background cont. The extent and pattern of injuries produced by an

explosion are a direct result of several factors including the amount and composition of the explosive material (eg, the presence of shrapnel or loose material that can be propelled, radiological or biological contamination).

The surrounding environment (eg, the presence of intervening protective barriers).

The distance between the victim and the blast. The delivery method if a bomb is involved. Any other environmental hazards. No two events are identical, and the spectrum and

extent of injuries produced varies widely.

Background cont.

In many parts of the world, undetonated military incendiary devices such as land mines and hand grenades contaminate the sites of abandoned battlefields.

Such devices cause significant numbers of civilian casualties years and even decades after local hostilities cease.

During wartime, injuries arising from explosions frequently outnumber those from gunshots with many innocent civilians becoming victims.

Background cont. Much of the challenge facing

the care providers is the potential for the sudden creation of large numbers of patients who require extensive medical resources.

This scenario can overwhelm local and hospital resources. Emergency physicians must remain attentive to the possibility and consequences of blast injuries.

Background cont.

Once notified of a possible bombing or explosion, hospital-based physicians should consider immediately activating hospital disaster and contingency plans, including preparations to care for anywhere from a handful to hundreds of victims.

Explosive Weights for Potential Improvised Explosive Device (IED) Packages

Threat Type Size Weight

Pipes 2" x 12"4" x 12"8" x 24"

6 lbs.20 lbs.120 lbs. (Uncommon)

Bottles 2 Liter2 Gallon5 Gallon

10 lbs.30 lbs.70 lbs. (Uncommon)

Boxes Shoe BoxBriefcase1 Cubic Foot ContainerSuitcase

30 lbs.50 lbs.100 lbs. (Uncommon)225 lbs. (Uncommon)

 

Pathophysiology Blast injuries traditionally are divided into 4

categories: primary, secondary, tertiary, and miscellaneous also called quaternary injuries.

A patient may be injured by more than one of these mechanisms.

A primary blast injury is caused solely by the direct effect of blast overpressure on tissue. Air is easily compressible, unlike water. As a result, a primary blast injury almost always affects air-filled structures such as the lung, ear, and gastrointestinal (GI) tract.

Pathophysiology

A secondary blast injury is caused by flying objects that strike people.

A tertiary blast injury is a feature of high-energy explosions. This type of injury occurs when people fly through the air and strike other objects.

Miscellaneous quaternary blast related injuries encompass all other injuries caused by explosions.

DePalma, R. G. et al. N Engl J Med 2005;352:1335-1342

Mechanisms of Blast InjuryCategory Characteristics Body Part Affected Types of Injuries

Primary Unique to HE, results from the impact of the over-pressurization wave with body surfaces. 

Gas filled structures are most susceptible - lungs, GI tract, and middle ear.

Blast lung (pulmonary barotrauma) TM rupture and middle ear damage Abdominal hemorrhage and perforation - Globe (eye) rupture- Concussion (TBI without physical signs of head injury) 

Secondary Results from flying debris and bomb fragments. 

Any body part may be affected.

Penetrating ballistic (fragmentation) or blunt injuries Eye penetration (can be occult)

Tertiary Results from individuals being thrown by the blast wind.

Any body part may be affected.

Fracture and traumatic amputation  Closed and open brain injury

Quaternary  All explosion-related injuries, illnesses, or diseases not due to primary, secondary, or tertiary mechanisms.  Includes exacerbation or complications of existing conditions.

Any body part may be affected.

Burns (flash, partial, and full thickness) Crush injuriesClosed and open brain injuryAsthma, COPD, or other breathing problems from dust, smoke, or toxic fumesAnginaHyperglycemia, hypertension

Mortality/Morbidity Mortality rates vary widely

between incidents. An analysis of 29 large bombing events between 1966 and 2002 showed 8,364 casualties, including 903 immediate deaths and 7,461 immediately surviving injured.

Immediate death/injury rates were higher for bombings involving structural collapse (25%) than for confined space (8%) and open air detonations (4%).

Mortality/Morbidity Unique patterns of injury are found in

all bombing types. Injury is caused both by direct blast overpressure (primary blast injury) and by a variety of associated factors.

Enclosed-space explosions, including those occurring in busses, and in-water explosions produce more primary blast injury.

Explosions leading to structure collapse produce more orthopedic injuries.

Land mine injuries are associated with a high risk of below- and above-the-knee amputations.

Mortality/Morbidity Presence of tympanic

membrane (TM) rupture indicates that a high-pressure wave (at least 40 kilopascal [kPa], 6 psi) was present and may correlate with more dangerous organ injury.

Theoretically, at an overpressure of 100 kPa (15 psi), the threshold for lung injury, TM routinely ruptures.

CLINICAL History: If possible, determine

what material caused the explosion. High-order explosives

(HEs) Low-order explosives

(LEs)

CLINICAL

If possible, determine the patient's location relative to the center of the explosion.

Because explosions often cause multiple casualties, anticipate activating the hospital or regional disaster plan.

Symptoms Acute (0-2 Hours) Sub-Acute (2-48 Hours)

Chronic (>48 Hours)

Constitutional

Dyspnea Malaise Apathy Amnesia

Progressively Worsening Dyspnea

Fever

 

Localized

Pleuritic Chest Pain

Non-productive cough

Cardiac Chest Pain

Abdominal Pain Hematochezia Hematemesis Ear Pain Hearing Loss Vertigo Balance Problems Eye Pain Visual Changes Focal Numbness Paresthesias

New or Progressive Chest Pain

Productive Cough Bilious Emesis New or Progressive

Abdominal Pain Nausea Urge to Defecate Tinnitus

Persistent Hearing Loss

Physical: Examine lungs for

evidence of pulmonary contusion and pneumothorax.

Abdominal injuries from explosions may be occult, and serial examinations are often required.

Physical: Many experts recommend obtaining a chest

radiograph in the presence of isolated tympanic membrane (TM) rupture since this may indicate exposure to significant overpressure.

In a large series of victims of bombings, mostly involving closed spaces, 22% of patients with eardrum perforation had other significant injuries.

Signs Acute (0-2 Hours) Sub-Acute (2-48 Hours)

Inspection

Penetrating trauma Traumatic amputation Seizure activity Respiratory difficulty Hemoptysis Pharyngeal petechiae Tongue blanching Mottling of non-dependent

skin Inadequate chest-wall

expansion Abrasions

Auscultation Asymmetric Breath Sounds Rales Wheezes

Newly Asymmetric Breath Sounds

Palpation

Subcutaneous Emphysema Abdominal Tenderness Spinal deformity or

Tenderness

New or progressive abdominal tenderness

Abdominal rigidity or rebound tenderness

Percussion Asymmetrical Chest Percussion  

Other Altered Mental Status Focal Neurologic Deficit

Fever Delayed Shock

Overview of Explosive-Related InjuriesSystem Injury or Condition

Auditory TM rupture, ossicular disruption, cochlear damage, foreign body 

Eye, Orbit, Face Perforated globe, foreign body, air embolism, fractures

Respiratory Blast lung, hemothorax, pneumothorax, pulmonary contusion and hemorrhage, A-V fistulas (source of air embolism), airway epithelial damage, aspiration pneumonitis, sepsis

Digestive Bowel perforation, hemorrhage, ruptured liver or spleen, sepsis, mesenteric ischemia from air embolism

Circulatory Cardiac contusion, myocardial infarction from air embolism, shock, vasovagal hypotension, peripheral vascular injury, air embolism-induced injury

CNS Injury Concussion, closed and open brain injury, stroke, spinal cord injury, air embolism-induced injury 

Renal Injury Renal contusion, laceration, acute renal failure due to rhabdomyolysis, hypotension, and hypovolemia

Extremity Injury Traumatic amputation, fractures, crush injuries, compartment syndrome, burns, cuts, lacerations, acute arterial occlusion, air embolism-induced injury 

Lung

Hemorrhage: Pulmonary contusion Hemoptysis Hemothorax

Escape of Air: Pneumothorax Pulmonary pseudocyst Arterial gas embolism

(AGE)

“Blast Lung”White Butterfly Sign

Tension Pneumothorax

GI Tract

Hemorrhage: Hematoma leading to

obstruction Upper or lower GI bleeding Hemoperitoneum

Escape of Contents: Mediastinitis Peritonitis

Blast Abdomen1. Delayed onset > 8-36 hours – more

common in submersion a. Intestinal intra-wall

hemorrhages b. Shearing of local mesenteric

vessels c. Sub-capsular and

retroperitoneal hematomas, d. Fracture of liver and spleen, and

testicular rupture2. Symptoms – exposure + abdominal

pain, nausea, vomiting, hematemesis (rare), rectal or

testicular pain and tenesmus3. Signs – abdominal tenderness,

rebound, guarding, absent bowel sounds, signs of hypovolemia4. Management – Resect small bowel

contusions > 15 mm, and large bowel contusions > 20

mm

Neck Injury

Signs and Symptoms of a Traumatic Brain Injury (TBI)

Physical Headaches Dizziness Insomnia Fatigue Uneven gait Nausea Blurred Vision Cognitive Attention difficulties Concentration problems Memory problems Orientation problems

Behavioral Irritability Depression Anxiety Sleep disturbances Problems with

emotional control Loss of initiative Problems related to

employment, marriage, relationships, and home or school management 

Ear

Middle ear: Ruptured tympanic membrane (TM) Temporary conductive hearing loss

Inner ear: Temporary sensory hearing loss Permanent sensory hearing loss

Risk Factors The closer a casualty is to an explosion, the more likely he will receive primary blast injury (PBI) from the effects of blast overpressure alone, particularly if behind cover and shielded from ballistic trauma.

  Personnel in enclosures (buildings, ships, armored vehicles, etc.) are at greater risk, regardless of whether detonation occurred inside or outside the enclosure.

 

Risk Factors:   Personnel treading water are at higher risk for

abdominal than thoracic blast injury from underwater explosion.  

Fully submerged personnel are at equal risk of combined thoracic and abdominal blast injury, as are personnel in open air, but equivalency occurs at three times distance from explosion underwater compared to open air.  

   Body armor increases the risk of

PBI, but decreases the risk of secondary blast injury from fragments, shrapnel, and debris due to its ballistic protection of vital structures.  

Tertiary blast injury occurs when the high-velocity blast wind generated by pressure differentials accelerate personnel to tumble along the ground, strike solid objects , or impale themselves on other objects.  Secondary and tertiary mechanisms result in conventional blunt and penetrating trauma

Rubber bullet Wael Emad 14 years old boy Died 22 October,2000 Palestine Time magazine