Blast injuries

Blast injuryBYBY

DR.SEFEEN SAIF ATTYADR.SEFEEN SAIF ATTYA

Surgery departmentSurgery department

Blast injuryBYBY

DR.SEFEEN SAIF ATTYADR.SEFEEN SAIF ATTYASurgery departmentSurgery department

Blast injury

Blast injury

Terrorism is now a global phenomenon.

Both civilian, as well as military, surgeons will be exposed to patients

injured in explosions.

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

Blast injury Blast injuries in civilian populations occur as a Blast injuries in civilian populations occur as a

result of result of fireworks, fireworks, household explosions, or household explosions, or industrial accidentsindustrial accidents. . Terrorist tactics may take the form of Terrorist tactics may take the form of letter bombs, letter bombs, suitcase bombs, suitcase bombs, vehicle bombs, and vehicle bombs, and suicide bomberssuicide bombers..

Types of Blasts

High order explosive• Explosion is supersonic • Blast contains a over-pressurized wave

A wave where the air is compressed to a point where it can itself be dangerous

Followed by under-pressure as the air pressure drops before returning to normal

Low order explosive• Explosion is not as fast as the speed of sound• No over-pressurization wave

BackgroundBackground

Explosions have the capability to cause Explosions have the capability to cause multisystem, life-threatening injuries in multisystem, life-threatening injuries in single or multiple victims simultaneously.single or multiple victims simultaneously.

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

Penetrating injuries caused by gunshot wounds are most oftenlimited to one or two body regions. Penetrating injuries caused bythe detonation of an explosive device carried by a suicide bomberare widespread and cover a large surface area. Each particle maycause less damage than gunshot wound (GSW), but the multiplicityof particles causes diffuse tissue damage .

Survivors suffer a combination of penetrating wounds of varying severity and location.

The extent and severity of injury will depend on factors such as the explosive power of the device, distance of the victim from site of detonation, quantity and mass of shrapnel, and attack setting.

A mass movement of air from the rapid expansion of gases at the centre of the explosion displaces air at

supersonic speed. This results in injury patterns ranging from traumatic amputation to total body disruption. When a blast pressure wave hits the body, the force of the impact sets up a series of stress waves that are capable of internal injury, particularly at

air–fluid interfaces. Thus, injury to the ear, lungs, heart and, to a lesser extent, the gastrointestinal tract.

Mechanisms of injuryMechanisms of injuryfollowing bombing attacksfollowing bombing attacks

((11))Primary blast injury (PBI) Primary blast injury (PBI) occurs as a direct effect of changes in occurs as a direct effect of changes in atmospheric pressure caused by the blast waveatmospheric pressure caused by the blast wave . .

Injury to gas-containing organs such asInjury to gas-containing organs such asperforation of the middle ear and BLI are most commonperforation of the middle ear and BLI are most common

((22 ) )Secondary blast injurySecondary blast injury is caused by shrapnel and debris that are propelled is caused by shrapnel and debris that are propelled by the blast. Compared to high-velocity firearms, shrapnel travelby the blast. Compared to high-velocity firearms, shrapnel travel at lower velocity (800–1,000 m/sec vs. 300–400 m/sec, respectively)at lower velocity (800–1,000 m/sec vs. 300–400 m/sec, respectively) , ,and thus the energy each particle contains is lower. The damage each particleand thus the energy each particle contains is lower. The damage each particle inflicts depends on its mass, distance from explosive device, and ballistic inflicts depends on its mass, distance from explosive device, and ballistic shapeshape

( ( 33 ) )Tertiary blast injuryTertiary blast injury includes injury from collapsing buildings and from a includes injury from collapsing buildings and from aVictim’s body being displaced by expanding gasses and high winds; trauma Victim’s body being displaced by expanding gasses and high winds; trauma then occurs from impacting objects and displacement of the victimsthen occurs from impacting objects and displacement of the victims

((44 ) )quaternary injuries.quaternary injuries. Burns and associated injuries Burns and associated injuriessuch as inhalation of dust, smoke, and other chemicalssuch as inhalation of dust, smoke, and other chemicals

Mechanism of primary blast injury

The size of the explosive charge determines the velocity of the blast wave and the duration of overpressure. Detonation of a 50 lb charge of TNT creates an overpressure 100–150 psi. Primary blast injury (PBI) mostly occurs in gas-containing organs such as the lungs, middle ear, and bowel. The three mechanisms which cause tissue damage are termed implosion, spalling, and implosion, spalling, and acceleration–decelerationacceleration–deceleration

implosion occurs as the shock wave travels through an organ containing pockets of gas The pockets of gas are initially compressed by the surrounding fluid.

As the shock wave passes, these pockets of gas expand rapidly, resulting in an internal explosion .

Spalling occurs at the interface between media of different densities when the shock Wave passes from a high density to a lower density substance.

In the lungs these pressure differentials tear the alveolar walls and disrupt the alveolar/capillary interface .

The result is the formation of giant emphysematous spaces filled with blood .

acceleration and deceleration injury occurs as a blast wave accelerates tissues of different densities at different rates causing soft tissue destruction

Acceleration caused by the blast wave of an organ with elastic fixation such as bowel mesentery and rapid deceleration caused by the anatomic fixation can result in organ damage .

Expected injuriesfollowing bombing attacks

Victims of terrorist explosions are more severely injured than victims of other types of trauma

The need for abdominal, vascular, and neurosurgical procedures is higher / The extent of injuries is also more severe and more complex compared with victims of

other forms of trauma .

Effects of the blast and heat waves, and multiple penetrating injuries, are common among victims and

are the hallmark of such attacks .

CategoryCategoryCharacteristicsCharacteristicsBody Part AffectedBody Part AffectedTypes of InjuriesTypes of Injuries

PrimaryPrimaryResults from the impact Results from the impact of the over-of the over-pressurization wave with pressurization wave with body surfaces. body surfaces.

Gas filled structures Gas filled structures lungs, GI tract, and lungs, GI tract, and middle ear.middle ear.Blast lung injuryBlast lung injury

TM ruptureTM rupture and middle and middle ear damage ear damage Abdominal hemorrhage Abdominal hemorrhage and perforation and perforation Concussion Concussion (TBI)(TBI)

SecondarySecondaryResults from flying Results from flying debris and bomb debris and bomb fragments. fragments.

Any body part may Any body part may be affected.be affected.

Penetrating blunt Penetrating blunt injuries injuries Eye penetrationEye penetration

TertiaryTertiaryResults from individuals Results from individuals being thrown by the being thrown by the blast wind.blast wind.


Fracture and traumatic Fracture and traumatic amputation amputation Closed and open brain Closed and open brain injuryinjury

Quaternary Quaternary All explosion-related All explosion-related injuries, illnesses, or injuries, illnesses, or diseases not due to diseases not due to primary, secondary, or primary, secondary, or tertiary mechanisms. tertiary mechanisms.


Burns Burns Crush injuriesCrush injuriesClosed and open brain Closed and open brain injuryinjurybreathing problems breathing problems from dust, smoke, or from dust, smoke, or toxic fumestoxic fumes

Overview of Explosive-Related InjuriesSystemSystemInjury or ConditionInjury or Condition

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

Eye, Orbit, FaceEye, Orbit, FacePerforated globe, foreign body, fracturesPerforated globe, foreign body, fractures

RespiratoryRespiratoryBlast lung, hemothorax, pneumothorax, pulmonary Blast lung, hemothorax, pneumothorax, pulmonary contusion and hemorrhage, A-V fistulas (source of air contusion and hemorrhage, A-V fistulas (source of air embolism), embolism),

DigestiveDigestiveBowel perforation, hemorrhage, ruptured liver or spleen,, Bowel perforation, hemorrhage, ruptured liver or spleen,, mesenteric ischemia from air embolismmesenteric ischemia from air embolism

CirculatoryCirculatoryCardiac contusion, myocardial infarction from air embolism, Cardiac contusion, myocardial infarction from air embolism, shock,, peripheral vascular injury, shock,, peripheral vascular injury,

CNS InjuryCNS InjuryConcussion, closed and open brain injury, spinal cord Concussion, closed and open brain injury, spinal cord injury, injury,

Renal InjuryRenal InjuryRenal contusion, laceration, acute renal failure due to Renal contusion, laceration, acute renal failure due to hypotension, and hypovolemiahypotension, and hypovolemia

Extremity InjuryExtremity InjuryTraumatic amputation, fractures, crush injuries, Traumatic amputation, fractures, crush injuries,

Blast lung injury

• Damage to the delicate alveolar structures can occur fromexposure to the peak overpressure associated with theinitial blast wave and result in alveolar haemorrhages,

oedema and an exudative response manifested as bilateralpulmonary infiltrates on chest X-ray )CXR( – ‘blast lung.’

•This condition is a marker of poor outcome and is an earlycause of death in patients exposed to ‘contained’ explosionsinitiated in a building or semi-closed structure such as abus.

Pathophysiology of BLI

The abrupt movement of the chest wall caused by blast waves does not allow Propagation of pressure waves through the lung results in alveolar wall injury and disruption of the alveolar/capillary interface

The combination of injury to airway epithelium and the creation of giant

emphysema expose the patient to air penetration into the pleura and mediastinum.

Additionally, lung parenchyma is sheared away from the vascular tree by acceleration–deceleration forces, resulting in the development of alveolar–venous fistulas. Air is then forced into pulmonary veins which can lead to air embolism . Signs of AE include air in the retinal vessels, arrhythmias, blindness, chest

pain, and neurological deficits.

AE to the brain or heart may be the most common cause of rapid death solely caused by BLI in immediate survivors and often occurs at initiation of positive pressure ventilation (PPV)

BLI is caused by the effects of the blast wave on the lung parenchyma and has the highest morbidity and mortality

Pulmonary barotrauma is the most common critical injury to victims close to the blast center, and 45% of

fatalities of bomb explosions suffer from BLI

In 17% of deaths lung injury is the sole finding

One half of victims exposed to overpressures of 50–100 psi will manifest pulmonary injury.

Exposure to overpressures greater than 200 psi is universally fatal

Symptoms and signs of BLI

cough, dyspnea, chest pain, hypoxia, tachycardia, apnea, wheezing,

and hemodynamic instability

Diagnosis of blast lung injury

pulmonary contusions ( bilateral and diffuse )

(more severe than in open spaces.)

Considerable blast loads cause ecchymoses, usually in parallel bands which correspond to intercostal spaces

higher energy blast waves cause hemopneumothoraces, traumatic emphysema,

and alveolovenous fistulas.

Chest X-ray of a victim of

bombing attack showing typical

bilateral patchy infiltrates in a butterfly distribution.

Clinical examination can be misleading as a tool for identifying patients with BLI. Indeed, several victims of

terrorist attacks walked into the ER by themselves, only to quickly deteriorate within minutes .

Respiratory rate can aid in diagnosing BLI and victims of bomb explosions with a mean initial respiratory rate of 25 breaths/minutes were significantly more likely to require mechanical ventilation

Chest radiographs are used to determine the presence and severity of BLI and to monitor its progression

Frequent findings include lung contusions, pneumothoraces, pneumo-mediastinum, and subcutaneous emphysema

Treatment of BLI

management of BLI is challenging because of the combination of hemodynamic shock, severe lung injury

and barotrauma, each of which may require contradictory therapies.

Adequate analgesia and aggressive chest physiotherapy are fundamental elements of therapy. All victims with suspected BLI should be given high-flow oxygen.

Diuretics may be used in the setting

of hydrostatic fluid overload as evidenced by elevated pulmonary capillary wedge pressures in hemodynamically stable patients

In victims suffering from BLI the presence of pneumothoraces and hemothoraces should be

aggressively diagnosed and treated in order not to further compromise lung function.

The degree of injury to lung parenchyma is often such that it is necessary to insert several chest

tubes in order to adequately drain the pleural cavity and allow proper ventilation and

oxygenation

What Happens to the Brain

Studies on rats have revealed that even when the head is protected, blast injuries causes significant neural damage• Damage was particularly severe in the hippocampus of

rats It was hypothesized that the hippocampus was more

susceptible to injury due to its sensitivity to oxygen deprivation

Rats showed signs of cognitive impairments and stress reactions following the injuries

• The blast wave or any penetrating injury may interfere with blood flow in the brain, depriving the brain of needed oxygen.

Research used to focus primarily on damage to gas filled organs (e.g. lungs or intestines), as these were believed to be the organs most significantly affected by blast exposure• The brain was previously believed to be largely

protected by blasts due to the skull• It has now been determined that the brain is just as

susceptible to blast injury as other organs

In fact, TBI has been identified as one of the more frequent injuries during the current conflicts, and accounts for a greater proportion of injuries than in any previous conflict

PhysicalPhysical Headaches Headaches Dizziness Dizziness Insomnia Insomnia Fatigue Fatigue Uneven gait Uneven gait Nausea Nausea Blurred Vision Blurred Vision CognitiveCognitive Attention difficulties Attention difficulties Concentration problems Concentration problems Memory problems Memory problems Orientation problems Orientation problems

Signs and Symptoms of a Traumatic Brain Injury )TBI(Signs and Symptoms of a Traumatic Brain Injury )TBI(

Behavioral Irritability Depression Anxiety Sleep disturbances Problems with emotional control Loss of initiative Problems related to employment, marriage, relationships, and home or school management

Blast AbdomenBlast Abdomen Delayed onset > 8-36 hoursDelayed onset > 8-36 hours – – a. Intestinal intra-wall hemorrhagesa. Intestinal intra-wall hemorrhages b. Shearing of local mesenteric vesselsb. Shearing of local mesenteric vessels c. Sub-capsular and retroperitoneal hematomas,c. Sub-capsular and retroperitoneal hematomas, d. Rupture of liver and spleen, and testicular ruptured. Rupture of liver and spleen, and testicular rupture

SymptomsSymptoms –abdominal pain, nausea, vomiting, –abdominal pain, nausea, vomiting,hematemesis (rare), rectal or testicular pain and hematemesis (rare), rectal or testicular pain and

tenesmustenesmus

SignsSigns – abdominal tenderness, rebound, guarding, absent – abdominal tenderness, rebound, guarding, absent bowel sounds, signs of hypovolemiabowel sounds, signs of hypovolemia

4. 4. Management Management – Resect small bowel contusions > 15 mm,– Resect small bowel contusions > 15 mm,and large bowel contusions > 20 mmand large bowel contusions > 20 mm

what is the pattern of intra-abdominal injury ?

Missiles generated by an explosion travel at a lower velocity compared with GSW

(300–400 m/sec vs. 800–1,000 m/sec, respectively). The damage inflicted will depend on velocity, mass, and distance from the explosion center Victims of terrorist explosions sustain multiple entry sites The pattern of intra-abdominal injury following terrorist explosions is similar to the pattern of injury caused by GSW Injury is most often to the large and small bowel and in nearly a fifth of cases there is injury to more than one segment of bowel. Organs which are partially sheltered by bony structures, such as the liver, spleen, and kidney, are relatively more protected from injury

Abdominal wall of a victim of bombing attack. Notemultiple shrapnel entry sites (black arrows) and penetrating injury to the smallbowel (white arrows).

laparotomies

The approach to intra-abdominal injury following terrorist explosions should be similar to injury caused by other mechanisms of trauma.

The rate of injury to hollow viscera is high and patients need to be carefully evaluated for such injury.

Imaging modalities such as focused abdominal sonography for trauma (FAST) followed by computerized tomography should be utilized extensively to diagnose intra-abdominal injury

Diagnostic peritoneal lavage can be performed to rule outinjury to hollow viscera for victims undergoing other surgicalprocedures. Due to the possibility of delayed presentation ofabdominal injury, catheters can be left in situ for up to 72 h forcontinued abdominal monitoring.

Tympanic membrane rupture

The ear is the most sensitive organ to blast injury, and auditory injury has been reported in up to 41% of survivors following

bombing attacks Peak overpressures as low as 5 psi can rupture the tympanic membrane (TM) and overpressures of 15 psi will cause TM rupture in 50% of victims.

Blast overpressure tears sensory cells from the basilar membrane, which eventually heals with scar leading to continued symptoms

Attack setting will determine the frequency of auditory injury and ranges from 8% in open spaces to 50% in confined spaces

Hearing loss may be conductive due to TM rupture, ossicular damage, It may also be

sensorineural due to cochlear damage.

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

Inner ear: Inner ear: Temporary sensory hearing loss Temporary sensory hearing loss Permanent sensory hearing loss Permanent sensory hearing loss

Immediate otoscopic examination for TM rupture should beperformed by an otolaryngologist in all cases. Treatment consistsof removal of debris from the external canal by suction undermicroscope and keeping the ears dry.

Symptoms and signs immediately following the attack included aural fullness (88.2%), tinnitus (88.2%), otalgia (52.9%) ear discharge (52.9%), and dizziness (41.2%).

Normal hearing following TM rupture is uncommon andhearing loss can present as mixed (61.8%), sensorineural (26.5%),or conductive (8.8%). Even at 6-month follow-up some form ofhearing loss can persist in up to 80% of victims

The role of TM rupture as a predictor of primary blast injury is unclear. Several authors advocate the value of routine

otoscopy in triaging victims of terror bombing attacks to identify those suffering from severe PBI in general, and BLI in particular.

Experience does not support such a pivotal role for the otoscopic examination Indeed, more than one third of victims with BLI do not have tympanic membrane rupture at all. TM rupture is possibly associated with BLI in confined spaces such as buses

Blast lung injury Traumatic brain injury Blast abdomen T.M. rupture Burns among survivors

Burns among survivors

High-explosives produce higher temperatures for shorter periods of time, usually resulting in a fireball at the time of detonation.

The intensely hot flames created cause burns of varying degrees and depths, usually to victims in close proximity to the detonation

victims with extensive burns (>30% body surface area) rarely survive However, burns of lesser degrees are quite common among survivors and necessitate adequate fluid resuscitation

as well as local wound treatment. Burns are usually located on exposed body parts,

The essentials of managing burns following terrorist bombingattacks are similar to burns caused by other causes.

Terror-related burn victims also sustain a combination of blast and penetrating injuries. Thus, early excision is

usually delayed until victims are stable enough.

Autologous skin grafting may be delayed even further, depending on the overall status of the patients. Early treatment of partial thickness burn wound consists of mechanical debridement with wet gauzes.

Burns involving small BSA are treated with topical antimicrobial agents, while larger areas are treated with

homografts. Homografts cover the wounds for 10–14 days and provide protection from desiccation and infection.

General management of blast injuries

The structures injured by the primary blast wave, in order of prevalence, are the middle ear, the lungs and the bowel. However, the commonest urgent clinical problem in survivors is penetrating injury caused by blast-energised debris and fragments of the exploding device.

The deafness of blast victims caused by tympanic membrane rupture makes communication difficult and may complicate early assessment.

The management of penetrating wounds differs little from that of missile wounds usually heavily contaminated with dirt, clothing and secondary missiles such as wood, and other materials from the environment. Such contaminants may be driven deeply into adjacent tissue planes opened up by the force of the explosion.

one cannot be sure of complete wound excision and it is imperative that wounds should be left open at the end of the initial operation and delayed primary closure performed.

conclusions

Terror-related blast generated by suicide bombing attacks results

injury, which is a combination of blast, penetrating wounds, and burns. Victims of indoor attacks sustain more BLI and burns. The work-up and management of these victims includes extensive utilization of

imaging modalities and a multi-disciplinary approach.

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Blast injuries