1. BLAST INJURIES: the Anesthesia Provider’s Perspective
Linda E. Pelinka, MD, PhD
Medical University of Vienna
and Ludwig Boltzmann Institute
for Experimental & Clinical Traumatology
Vienna, Austria, European Union
TRAUMA

2. Blast Injuries in the US
Texas 1947: Ammonium nitrate explosion
in a ship carrying cargo of hemp, 500 killed
Texas1989: Petroleum plant 23 killed, injured (mainly males aged 25-44) secondary injuries 2 miles away
NYC 1993: WTC terrorist bomb 6 killed, injured
Oklahoma 1995: AP Murrah building
truck bomb, 167 killed (19 children)

3. „The explosion of a terrorist bomb
in the garage of the World Trade Center resulted in 6 deaths...
...but thousands could have been killed, had one tower been toppled into the other as alledgedly intended.“
Wightman JM and Gladish SL:
Explosions and Blast Injuries. Ann Emerg Med, June 2001

4. BASICS what, why and how
CATEGORIES Primary, secondary, tertiary and quarternary injuries, diagnosis and therapy
SPECIFIC ORGAN INJURIES Lung, gut, ear, brain, extremities diagnosis and therapy

5. BASICS what, why and how

6. What is a blast? Release of energy Chemical conversion
of liquid or solid
to gas

7. What causes a blast?
PROPELLANTS: slower energy release DEFLAGRATION (chemical burning) Gunpowder
EXPLOSIVES: instant energy release DETONATION (causes high pressure of about 4 million psi*) High energy blast wave = shock wave TNT Trinitrotoluene Composition C4 Cyclo-trimethylene-trinitramine
*Psi pounds per square inch

8. What is a blast wave ? SHOCK WAVE
Sudden OVERPRESSURE of medium where blast takes place
injury from sudden overpressure and thermal energy,
related to magnitude and duration of blast
Long duration blast wave: nuclear detonation

9. Phases of a Blast 1. Very short phase: increasing pressure
2. Longer phase: decreasing-negative pressure
3. Short phase of slightly positive pressure
Massive movement of air: BLAST WIND

10. BLAST WIND Strong enough to destroy buildings 145 – 800 mph
Pressure differential 5-15 psi (pounds/sq. inch)
Magnified 2-20 fold by corridors, alleys, confined spaces (corners!)
Leading edge: blast front (highly pressurized,
superheated molecules, supersonic speed ft/sec)

11. Mechanisms of primary blast injury
SPALLATION at liquid-gas interfaces (bowel injuries)
IMPLOSION / RE-EXPANSION hollow structures („crushed egg-shell fx“ of mid-face)
IRREVERSIBLE WORK by pressure differential
„Aluminum can concept“: Damage done when stress = tensile strength of compressed tissue
ACCELERATION / DECELERATION
of organs relative to their fixation points

12. with homogenous densities (liver, spleen, tongue, eye)
Less compression
and visible damage
to solid organs
with homogenous densities
(liver, spleen, tongue, eye)

13. CATEGORIES Primary, secondary, tertiary and quarternary injuries, diagnosis and therapy

14. QUATERNARY
BURNS (HOT GAS, SECONDARY FIRE)
INHALATION (DUST, SMOKE)
CRUSH (STRUCURES COLLAPSING)
Three types of blast injuries that we will discuss
PRIMARY
SECONDARY
and TERTIARY

15. Expected injury to unprotected victims, relative distance from a blast in open air
PBI primary blast injury

16. Primary Blast Injury
Cause: direct effect of blast wave on victim (energy transfer)
Injury almost exclusively to
tissues of inhomogenous densities
(hollow, gas containing)
Read slide

17. Secondary Blast Injury
Cause:
propelled debris which hits victim
Treat same as any
other blunt or penetrating injury

18. Tertiary Blast Injury Cause: Victim impaled or
propelled against hard surface
Treatment same as for penetrating or
blunt trauma (fx, crush injuries, amputations)
Beslan, Chechnia
September 3rd, 2004

19. Quaternary Blast Injuries
Miscellaneous collection of other mechanisms
Flash burns
superficial skin burns by heat of explosion
Methemoglobinemia
poisoning by potassium perchlorate (ammo)
Acute septicemic meloidosis
inhalation of contaminated soil
Psychological sequelae

20. Mortality associated with use of weapons in armed conflicts, wartime atrocities, and civilian mass shootings
Coupland, RM and Meddings, DR: BMJ 319, 407–410; 1999.
Explosive munitions account for over 50%
of all wounds sustained in military combat.
The proportion of civilian casualties due to
explosives is increasing as well.

21. Explosive Devices CONVENTIONAL WEAPONS (Grenades, bombs, rockets)
Multiple fragments
Sec. blast injury
Penetrating injury
ANTIPERSONNEL MINES
(developing countries)
Traumatic amputation
Detonated by only 10 lbs pressure
2000 victims every month (children)
ENHANCED-BLAST MUNITIONS
(fuel-air explosives)
Designed to kill by primary blast
War-Artillery, grenades, mortars
Terrorist bombings-bombs
Natural disasters-
Man-made-Fuel explosions
TERRORIST DEVICES
(few to hundreds of pounds of explosives)
Secondary and Tertiary blast injury

22. Terrorist Devices Designed to Disrupt passing vehicles
Displace vehicles
Eject victims
Cause gross disruption
CAR BOMBS
2-6 lbs of commercial explosive
Under car beneath driver´s seat
Traumatic lower limb amputation
Secondary fragments of metal
BARE CHARGES > 20 lbs
Remote detonation (radio, wire)
Primary blast injury
Secondary fragments of metal and debris
War-Artillery, grenades, mortars
Terrorist bombings-bombs
Natural disasters-
Man-made-Fuel explosions
TRUCK BOMBS > 80 lbs
Detonation creates secondary missiles from body of truck
Penetrating injury, gross disruption

23. Velocity of Explosives
Initial velocity 1800m/sec
Rapid deceleration due to aerodynamic drag (irregular projectile shape, no streamlining like bullet through rifle barrel)
Survivors struck at velocity < 600m/sec
Shimmy effect: tumbling within tissue
Additional damage by environmental debris

24. Tolerance to Blast Wave in Air
radius of effect < radius of projectiles
more damage if blast wave reflected
by surfaces
standing worse than prone
enclosed space worse than open
(multiple reflections)
Read

25. Tolerance to Blast Wave in Water
radius of effect > radius of projectiles
water inhibits movement of projectiles
tension wave (cut-off wave) reflected by surface
attenuates water blast wave closer to the surface
augments water blast wave in greater depth
more damage to deeper body regions
Safer floating than treading water
Safer floating on surface than treading water

26. Tolerance to Blast Wave
Repeated blasts
Effects cumulative (particularly airway: loss of cilia, epithelial flattening, stripping, bleeding) sub-threshold blasts can result in injury if following close to previous blast
Effect decreases with distance
Blast wave travels further and
Lethal radius is 3x greater in water (vs air)
The blast wave travels further in water.

27. Stress wave Shear wave Longitudinal (like sound wave) Short duration
High velocity (175 mph)
Stress wave
Microvascular injuries
Also affects hollow structures
May cause limb avulsions
Deformation of body wall
Asynchronous movement
Tearing from attachments
Shear wave
Transverse
Long duration
Low velocity (50 mph)

28. Multiple sequential posttraumatic aneurysms following high-energy injuries
Freiman S et al, J Orthop Trauma 2002
15 year-old boy
Land mine in Lebanon
Multiple long bone fx (external fixation)
Lacerated right ant. tibial artery (grafted)
20 days later: pseudoaneurysm ulnar artery
34 days later: pseudoaneurysm peroneal artery with
a-v fistula (fluoroscopically controlled embolization and placement of stents)

29. Has a patient been injured by a blast?
Primary Blast Injury
Has a patient been injured by a blast?
When to suspect:
Type of explosion
Medium of blast (air/water)
Number of blasts and time between blasts
Victim’s location & position to blast
Enclosed area or barrier (reflected wave)
Activity after blast (risk of air embolism)
Ruptured tympanic membrane

30. Primary Blast Injury Lung: most common cause of
early morbidity and mortality
Ear: most sensitive part of body
Bowel: most common cause of
delayed morbidity and mortality
Read and stress each point.
Ear is the best predictor of exposure but is a very low morbidity
Respiratory system (severe pulmonary contusions) will be the cause of most common cause of early deaths
GI tract is the most common cause of delayed death due to perforations.

31. SPECIFIC ORGAN INJURIES Lung, gut, ear, brain, extremities diagnosis and therapy

32. Blast Lung Pathophysiology
Ventilation – perfusion mismatch
Increased shunt
Decreased compliance
Increased work of breathing

33. Blast Lung Caused by blast wave against chest wall
– not through oropharynx and trachea
Symptoms
Dyspnoa
(“can you count to 10 in a single breath?”)
Cough (dry-frothy)
Hemoptysis
Retrosternal pain
Signs
Tachypnoea
Cyanosis
Reduced breath sounds
Dull percussion sounds
Coarse crepitations
Subcutaeous emphysema
Retrosernal crunch (pneumo mediastinum)
This is a list of findings after blast injury to the lung.

34. Blast Lung Pathology and Findings
Alveolar septa torn
Hemorrhage
Laceration
Predeliction for
Mediastinum
Costo-phrenic angles
“Rib markings”
Pneumothorax
Pneumomediastinum
Subpleural cysts
Interstitial emphysema
Subcut. emphysema
Alveolo-venous fistulae
Air embolism
Pulmonary edema
Pulmonary contusions
This is a list of findings after blast injury to the lung.

35. Blast Lung APNOEA BRADYCARDIA HYPOTENSION
acute cardiovascular reflex triad
transmitted by the vagal nerve
APNOEA
BRADYCARDIA
HYPOTENSION
RJ Guy, J Trauma 1998

36. Blast Lung Open-air blast in Beirut
0.6% of initial survivors had blast lung.
Confined-space blast in Jerusalem
35% of initial survivors had blast lung.
Frykberg ER et al: The 1983 Beirut Airport terrorist bombing.
Ann Surg 1989

37. Blast Lung Management 1 similar to that of lung contusion
Airway maintanance, C-spine control
Decompression of pneumothorax
Prophylactic chest drains
Breathing spontaneous if possible
High flow oxygen (15 L/min)
Follow standard Airway, Breathing, Circulation plans
Place a chest tube if a pneumothorax is present (or may consider if patient will be air transported)
Treat all with oxygen. If a ventilator is required, use a low volume strategy (keep plateau pressure < 30)

38. Blast Lung Management 2 similar to that of lung contusion
If intubation is unavoidable
Unilateral lung ventilation, high frequency ventilation, Extra-Corporeal Membrane Oxygenation (ECMO)
Low tidal volume (peak pressure <30)
Reversion to spont. breathing ASAP
Beware of AAE (anesthesia, aircraft)
Follow standard Airway, Breathing, Circulation plans
Place a chest tube if a pneumothorax is present (or may consider if patient will be air transported)
Treat all with oxygen. If a ventilator is required, use a low volume strategy (keep plateau pressure < 30)
AAC acute air embolism

39. Localization of massive hemoptysis
90° counter-clockwise
without head rotation
for left lung
Bleeding from
Alternatives:
Univent tube
Double lumen tube
left lung
right lung

40. Blast Injury to the Ear Symptoms
Hearing loss, high-pitched tinnitus common initially, usually improves
Pain temporary, may last for weeks
Dizziness rare, usually post-concussive
Bleeding
Read

41. Blast Injury to the Ear Findings
Outside-in tympanic membrane rupture in 70% of patients
Foreign material in ear
Cholesteatoma by implanted keratinizing squamous cells
Ossicular injury dislocation, fracture, avascular necrosis

42. Blast Injury to the Ear: The London Bridge Incident
Walsh RM et al, J Accident & Emergency Med 1995
12 patients required treatment for ear injuries
3 of these patients had perforated ear drums with persistent loss of hearing
9 patients had short term loss of hearing and tinnitus (4 hrs - 4 wks)
None had balance problems

43. Treatment of Blast Injury to the Ear
85% of peforations heal spontaneously
Surgery (grafting) for large perforations (>80% of surface area)
No need for immediate surgery (<1yr)
No need for prophylactic antibiotics
Long term review for cholesteatoma

44. Blast Injury to the Bowel
Combined intra-abdominal stress
and shear waves:
Hematoma & tear of the mesentery & bowel
Immediate rupture of the bowel
Stretching, ischemia, transmural weakening
Late transmural necrosis – late rupture – septic MOF
Detection may be difficult (silent for days, delayed rupture)
Read

45. Blast Injury to the Bowel
Examination
Delayed diagnostic peritoneal lavage
probably most sensitive
CT and ultrasound unreliable
Treatment
Abdominal exploration and repair
Beware of risk of air embolism in patient under general anesthesia

46. Blast Injury to the Bowel
Signs and symptoms
Nausea and vomiting
Hematemesis (rare)
Rectal pain
Testicular pain
Abdominal tenderness, guarding
Absent bowel sounds
Hypovolemia
Signs and symptoms
Nausea and vomiting
Hematemesis (rare)
Rectal pain
Testicular pain
Abdominal tenderness, guarding
Absent bowel sounds
Hypovolemia

47. Blast–induced neurotrauma: A myth becomes reality.
Cernak I, Presented at the 7th International Neurotrauma Symposium. Medimond International Proceedings, Bologna, Italy, 2004.
In the past, research has focused on blast
injuries to gas-containing organs (lung, ear,
gastrointestinal tract), perhaps because the
brain was believed to be protected by the skull.

48. Traumatic brain injury in the war zone.
Okie, S. N. Engl. J. Med. 352, 2043–2047; 2005.
More recent research indicates that TBI is a
common consequence of blast injury. TBI
accounts for a larger proportion of casualties
among soldiers surviving wounds sustained
in combat in Iraq and Afghanistan than in
previous conflicts.

49. Cernak I et al. J Trauma 50, 695–706; 2001.
Ultrastructural and functional characteristics of blast injury-induced neurotrauma.
Cernak I et al. J Trauma 50, 695–706; 2001.
Reactive gliosis and neuronal swelling and
cytoplasmic vacuolation were observed in the
hippocampus of rats subjected to thoracic blast
injury even if the head was protected.

50. Cernak I et al. Brain Inj. 15, 593–612; 2001.
Cognitive deficits following blast injury-induced neurotrauma: possible involvement of nitric oxide.
Cernak I et al. Brain Inj. 15, 593–612; 2001.
Cognitive impairment and oxidative
stress also were observed after blast
injury in rats.

51. Blast-Induced Brain Injury and Posttraumatic Hypotension and Hypoxemia
Dewitt DS and Prough DS. J Neurotrauma 2008
Hemorrhage accounted for approximately 50% of
combat deaths, and the lungs are one of the primary
organs damaged by blast overpressure. Thus, it is
likely that blast-induced lung injury and/or
hemorrhage leads to hypotensive and hypoxemic
secondary brain injury in a significant number of
combatants exposed to blast overpressure injury.

52. Blast-Induced Brain Injury and Posttraumatic Hypotension and Hypoxemia
Dewitt DS and Prough DS. J Neurotrauma 2008
Unfortunately, the paucity of reproducible animal
models of blast injury has limited research on the
pathophysiology of blast injury and many important
features have not been investigated: Cerebral blood
flow, cerebral vascular reactivity to blast-induced
brain injury, effects of hemorrhagic or hypoxemic
posttraumatic insults on the blast-injured CNS.

53. Blast-Induced Brain Injury and Posttraumatic Hypotension and Hypoxemia
Dewitt DS and Prough DS. J Neurotrauma 2008
Reactive oxygen species (ROS) are
produced by TBI. Superoxide radicals
combine with nitric oxide, another ROS
produced by blast injury, to form peroxy-
nitrite, a powerful oxidant that impairs
cerebral vascular responses.

54. SECONDARY BRAIN DAMAGE VICIOUS CYCLE
ICP
CBV CPP
CBF
AUTOREGULATION

55. Functional Impairments
Pseudoanurysms
Intracerebral hemorrhage & vasospasm
Increased BBB permeability edema
Diffuse axonal damage impaired information processing
Regional malperfusion motor/sensory malfunction
Cognitive deficits retro/anterograde amnesia, confusion, indecisiveness
Ropper A. N Engl J Med 2011; 364/22:

56. Surgical Team’s experience in Operation Iraqi Freedom.
Patel TH et al.J Trauma 57, 201–207; 2004.
Improvements in body armor, transport
and battlefield surgical care have all
contributed to increased survival.

57. Musculoskeletal Blast Injury
Most common injury in modern warfare Secondary injury (debris projectiles)
Surgical debridement
Excision of non-viable tissue
Drainage
Delayed closure

58. Chitosan-based hemostatic dressing: experience in current combat.
Wedmore I, Holcomb JB et al. J Trauma 60, 655–658; 2006.
Hemostatic dressings, bandages or pads filled
with substances that promote clotting, have
been very effective in reducing hemorrhage.
bandages containing chitosan, a carbohydrate
Derived from chitin, were 100% successful in
stopping or reducing hemorrhage from external
wounds in Operation Iraqi Freedom.

59. Potentially Fatal Traumatic Amputation
Debris propelled upward along
tissue planes
Compartment
injury
Contamination
Sepsis

60. Blast Wave-induced Fracture
Contaminated with bacteria
High risk of infection
Tetanus prophylaxis ASAP
Antibiotic prophylaxis ASAP
Major threats: Gas gangrene, Pseudomonas

61. Blast Injury and Air Embolism Main cause of immediate and early death Signs and symptoms depend on vascular bed affected
Signs and symptoms
EKG: Arrhythmia, ischemia
Somnolence, headache,
Motor and/or sensory loss
Vertigo, ataxia
Seizures
Facial or tongue blanching
Transient blindness
Read

62. Treatment of Air Embolism
Avoid/treat low vascular pressure
Avoid high airway pressure
Avoid head-down position
Administer oxygen
Hyperbaric oxygen therapy ASAP
e.g. after hemorrhage
e.g. resuscitation with PPV
increases intra-cranial pressure
promotes embolism to coronary vessels
reduces volume of bubbles
improves blood flow to tissues

63. Problems following Blast Injury
Combination: primary, secondary, tertiary, quaternary
Combination of chemical and biological injury
Toxic gas inhalation
Read

64. TAKE HOME MESSAGES

65. AIRWAY Mentally altered Intubation to safeguard airway
Sponteneous breathing if possible
Hemoptysis
Unilateral ventilation of less injured lung

66. BREATHING Lung contusion 100% oxygen, PEEP+PPV if necessary
Unilateral ventilation of better lung avoids barotrauma in compliance mismatch
Pneumothorax
Additional chest drains

67. CIRCULATION Hypovolemic shock Normalize pre-load to avoid AAE
As much fluid as necessary
As little fluid as possible
Cardiogenic shock
Coronary AAE semi/left-lateral decubitus position
hyperbaric oxygen

68. CONSIDER PRIMARY INJURY IN ALL BLAST VICTIMS
LUNG INJURY presents early Exclude before general anesthesia and air transport
ABDOMINAL INJURY presents late May be silent until sepsis is advanced
EAR INJURY is easily overlooked Source of significant morbidity and litigation

69. Blast - induced Air Embolism main cause of early death
Read