1
Blast injury
Dr Vincent Ioos
Medical ICU
PIMS
2
Introduction
• Area affected: Irak, Israel, Pakistan, Madrid,
9/11, Beirut…
• Main publications: civilian (Israel), military
(Irak)
• Particularities of blast injury
• Management of mass casualty events
3
Classification of explosives (1)
• Explosives are categorized as high-order
explosives (HE) or low-order explosives (LE).
• HE produce a defining supersonic over-
pressurization shock wave. Examples of HE: TNT, C-4,
Semtex, nitroglycerin, dynamite, and ammonium nitrate fuel oil
(ANFO).
• LE create a subsonic explosion and lack HE’s
over-pressurization wave. Examples of LE: pipe bombs,
gunpowder, and most pure petroleum-based bombs such as Molotov cocktails or aircraft improvised as guided missiles.
• HE and LE cause different injury patterns.
4
Classification of explosives (2)
• “Manufactured” implies standard military-issued, mass produced, and quality-tested weapons.
• “Improvised” describes weapons produced in small quantities (IED), or use of a device outsideits intended purpose, such as converting a commercial aircraft into a guided missile.
• Manufactured (military) explosive weapons are exclusively HE-based.
• Terrorists will use whatever is available
• Manufactured and improvised bombs cause markedly different injuries.
5
Particularities of suicide blast
• High-grade explosive material used by theattackers;
• Ability of the attackers to detonate the explosive device in proximity to the victims by concealingthe explosive device and mingling within a crowd;
• Ability of the attacker to precisely time theexplosion at his or her discretion;
• Large load of heavy shrapnel that accompanythe explosive material.
6
7
8
Blast wave
• The HE “blast wave” (over-pressure
component) should be distinguished from
“blast wind” (forced super-heated air flow),
encountered with both HE and LE.
• Expansion of gas creating a shock wave:
supersonic speed 3000 to 8000m/s
• Blast wave rapidly looses pressure and
velocity with distance and time
9
Blast wave (2)
• Brisance: shattering ability of the blast front
• If closed space: overpressure magnified by
reflection off solid structures
• Open space: little primary blast injury because
of rapid decay of the blast wave
10
Enhanced blast weapons
• A primary blast from these devices disseminates the
explosive and then triggers it to cause a secondary
explosion
• Air delivery, guided missiles, handheld weaponry
• Designed to enhance blast wave + thermal effect
• Lower peak pressure but longer sustained time of
blast overpressure
• Greater damage to soft structures and personnel
11
Action of blast wave on the body
• Stress waves:
– Longitudinal pressure forces, supersonic speed
– Spalling effect at air-tissue interfaces
– Severe microvascular damage and tissue disruption
• Shear waves:
– Transversal waves
– Asynchronous movement of tissue
– Possible disruption of attachments
� ear, lungs, colon, gas-filled organs affected with the damage
initiating at the tissue-gas interface
12
13
14
15
Primary blast injury
• Body armor does not protect against the barotraumaof primary blast injury
• Pulmonary barotrauma is the most common critical injury to people close to a blast center, whether civilian or military
• Systemic acute gas embolism from pulmonary disruption is believed to occlude the blood vessels of the brain or spinal cord
• Primary blast injuries are notorious for their delayed onset
16
17
Closed versus open space
(greater primary blast injury)
18
Blast Injuries: Bus Versus Open-Air Bombings-
-A Comparative Study of Injuries in Survivors of
Open-Air Versus Confined-Space Explosions
J Trauma Volume 41(6), December 1996, pp 1030-1035
19
Blast Injuries: Bus Versus Open-Air Bombings-
-A Comparative Study of Injuries in Survivors of
Open-Air Versus Confined-Space Explosions
• An overall increased mortality rate with explosions in confined spaces.
• Immediate survivors of explosions within confined spaces suffer more severe injuries and present to the ED in a less favorable physiologic condition.
• Confined spaces: higher incidence of primary blast injuries, with a predominance of the more severe pulmonary injuries rather than perforation of tympanic membranes.
• Burns sustained by victims of explosions in confined spaces affect a larger BSA.
• No difference in the incidence of significant penetrating trauma, burns, or traumatic amputations between the two settings.
J Trauma Volume 41(6), December 1996, pp 1030-1035
20
Blast lung (1)
• Direct consequence of the HE over-pressurizationwave.
• Most common fatal primary blast injury among initial survivors.
• Signs of blast lung usually present at the time of initial evaluation, but reported as late as 48 hoursafter the explosion.
• Blast lung is characterized by the clinical triad of apnea, bradycardia, and hypotension.
21
Blast lung (2)
• Pulmonary injuries vary from scattered petechae
to confluent hemorrhages
• Blast lung should be suspected for anyone with
dyspnea, cough, hemoptysis, or chest pain
following blast exposure.
• Characteristic “butterfly” pattern on chest X-ray.
A chest Xray is recommended for all exposed
persons
22
23
24
Ear blast injury
• Significant morbidity, but are easily overlooked.
• Dependent on the orientation of the ear to theblast.
• TM perforation is the most common injury to themiddle ear.
• Signs of ear injury are usually present at time of initial evaluation: hearing loss, tinnitus, otalgia, vertigo, bleeding from the external canal, TM rupture, or mucopurulent otorhea.
• All patients exposed to blast should have an otologic assessment and audiometry.
25
26
Blast abdominal injury
• Gas-containing sections of the GI tract mostvulnerable to primary blast effect.
• Bowel perforation, hemorrhage (ranging fromsmall petechiae to large hematomas), mesenteric shear injuries, solid organlacerations, and testicular rupture.
• abdominal pain, nausea, vomiting, hematemesis, rectal pain, tenesmus, testicularpain, unexplained hypovolemia, or anyfindings suggestive of an acute abdomen.
• Clinical findings may be absent until the onset of complications.
27
Blast brain injury
• Primary blast waves can cause concussions or mild traumatic
brain injury (MTBI) without a direct blow to the head.
• Primary blast injury can also result in cranial fractures around
air-filled sinuses and focal neurologic deficits as a result of air
embolism
• Consider the proximity of the victim to the blast particularly
when given complaints of headache, fatigue, poor
concentration, lethargy, depression, anxiety, insomnia, or other
constitutional symptoms.
• the signs and symptoms of postconcussion syndrome overlap
with those of PTSD
28
In the field (1)
• Scoop and run approach
• Needle thoracostomy or endotracheal
intubation, early use of tourniquet may be life
saving
• Victims with amputated body parts and no sign
of movement + those with no pulse and fixed
dilated pupils are considered dead: no further
effort
29
In the field (2)
• Objects that are impaling a person should be
removed or manipulated only in an operating
room.
• To facilitate the transport of impaled patients,
the objects can be cut or shortened.
• Transporting patients with long-bone fractures
requires temporary splinting to manage pain
and also to avert further soft-tissue damage
30
31
Injury Severity Score / AIS
• Abbreviated injury scale: categorize the injuries of victims of motor vehicle collisions.
• Severity from 1 (least severe) to 5 (survival uncertain) within six body regions: head/neck, face, chest, abdominal/pelvic contents, extremities, and skin/general. Nonsurvivable conditions are assigned an AIS of 6.
• The AIS does not accurately measure the effects of multiple injuries. It is used in coding injuries for other scoring systems or for outcome analysis systems
• Injury Severity Score — The ISS is calculated from the AIS for the three most severely injured regions :
ISS = (AIS1) squared + (AIS2) squared + (AIS3) squared
32
ISS / other scoring system
• ISS limited by:
– its inability to adjust for the cumulative effect of coexisting injuries in one region (eg, subdural hematoma and intraparenchymal hemorrhage),
– the lack of a direct linear relationship between increasing score and severity,
– the lack of consideration of preexisting conditions that may affect trauma outcomes.
– ISS is a valid predictor of mortality, length of stay in the hospital or intensive care unit, and cost of trauma care.
• RTS (systolic BP, respiratory rate, GCS)
• TRISS (ISS +RTS)
• START: Simple Triage and Rapid Treatment
• …
33
Damage control surgery
• Surgical concept: « the best operation for a patient is
one, definite procedure »
• Multiple trauma patients die from coagulopathy,
hypothermia, meabolic acidosis
• DCS: control of haemorrhage, prevention of
contamination and protection from further injury
• ICU: warming, correction of acidosis and
coagulopathy…
• Staged procedure (definitie surgical procedure)
34
White phosphorus burns (1)
• Copious lavage of the area, removing identifiable particles (which should be placed in water to prevent further combustion), and covering the area with saline-soaked gauze to prevent further combustion.
• Use of a Wood lamp in a darkened resuscitation suite or operating room may help identify WP particles in the wound.
• Rinse the contaminated burn with copper sulfate solution 1%, remove WP particles, and then use copious saline lavage to rinse off the copper sulfate.
• Copper sulfate combines with phosphorous particles to create a blue-black cupric phosphide coating. This impedes further WP combustion and makes particles easier to find.
35
White phosphorus burns (2)
• Never apply copper sulfate as a dressing. Excess copper sulfate absorption can cause intravascular hemolysis and renal failure.
• WP injury can lead to hypokalemia and hyperphosphatemiawith ECG changes, cardiac arrhythmias, and death. Place the patient on a cardiac monitor and closely track serum calcium levels. Intravenous (IV) calcium may be required.
• Moistened face masks and good ventilation help protect patients and medical personnel from the pulmonary effects of phosphorous pentoxide gas.
• Naturally, avoid the use of flammable anesthetic agents and excessive oxygen around WP
36
Administration of multiple-casualty
event
• Analysis of blast incidents indicates that "upside-down" triage is common; less injured patients typically arrive at the hospital, via ambulance or private vehicle, before the most severely injured victims
• First, peri-incident intensive care management (‘forward deployment’) and
• second, maintaining a ‘chain of command’ with efficient triage
• Patient identification, tracking and documentation
37
In the ER
• Senior most trauma surgeon take the lead and
should define prorities for access to OT
• Avoid heroic procedures compromising
delivery of efficient care to the salvageable
victims
• Risk of undertriage, so repeated assessment
should be performed
38
39
Control and coordination:
Accordion approach
40
41
Challenges
• Many hours and sometimes days are requiredfor the situation to stabilize and eventuallynormalize
• Treating teams are physically and emotionallyexhausted from the continuous workload, especially when repeat attacks occur withindays;
• Repeated reassessment by the treating teams and SIC to ascertain that all patients receiveoptimal care is fundamental.
• In these circumstances, a strong personalcommitment by the treating teams and SIC ispivotal to success.