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In the past, explosive and blast injuries have occurred during times of organized military conflict or have resulted from non-intentional events, such as industrial accidents. More recently, explosive devices have become a preferred weapon of domestic and foreign terrorists since they are inexpensive to produce, capable of causing large numbers of casualties, and effective at instilling fear in large populations.1 Consequently, blast injuries are being observed in non-combat locations during peace time as evidenced in the Alfred P. Murrah Federal Building in Oklahoma City in 1995, the United States Embassy in Lagos, Nigeria, Africa in 1998, and the 9/11 attacks on the WorldTRADE Center and Pentagon in 2001.

Whenever medical personnel are called upon to treat patients with explosive or blast injuries, conditions will obviously be difficult or austere. Thus it is important for the health provider team to approach these situations in an organized fashion, cognizant of the team’s resources as well as the potential for injuries unique to blast situations.

General Treatment Considerations in Explosion and Blast Injuries

In non-war or non-combat situations, for an explosion or blast to occur other than when unanticipated or by surprise is rare. The health care team needs a general plan outlining an approach to these

disasters. (Vol III—EMP1 Community-Wide Collaboration)While the organized implementation of this disaster plan is of great value in any large emergency, some considerations are unique to

implementing the plan during explosion or blast scenarios. These include:

1. What available resources are at your disposal?

o What available resources—including the number of trained medical personnel, support staff, and equipment—can be mobilized in your health care institution?

o What community resources can be mobilized to assist with the care of the disaster victims? How will these be obtained?

o What resources can be obtained from outside the community? How will these facilities be notified of your needs?

o What state or national agencies—such as the State Department of Health, Federal Emergency Management Agency (FEMA), and American Red Cross—need to be contacted? Who will contact these agencies?

2. How will you triage the patients? Large numbers of victims in a disaster situation can overwhelm almost any medical system. The use of an effective triage system helps to assure that limited resources are utilized to do the greatest good for the greatest number of people. One triage method to consider is a modified START Triage System,5 which is based on classifying patients into one of four categories. (See Vol III— EMP9, Triage.) These categories include patients who:

o Need immediate care to survive–Priority 1 (P-1).

o Need care but can have the care delayed–Priority 2 (P-2).

o Do not appear to have any serious injury but need to be held for later evaluation–Priority 3 (P-3).

o Will most likely die no matter how you assist them–Priority 0 (P-0).

3. What special problems may be associated with the blast/explosion? These may include additional, non-visible, risks such as:

o Biological agent contamination o Exposure to inhalation of toxic agents o Nuclear contamination

o Repeat terrorist assault

4. What injuries unique to blast situations may your patient have? Explosions can produce unique patterns of injury seldom seen outside of combat. These injuries can involve multiple organ systems, especially the lungs, ears, bowel (gastrointestinal [GI] tract), and central nervous system (CNS).

5. How do you manage the wide range of routine traumatic injuries inflicted on your patients in addition to all of the injuries unique to blasts?

6. How do you manage the post-traumatic stress disorder (PTSD) in the victims of the blast, their friends and relatives, and treating medical staff?

Classification of Explosives²

One method of classifying non-nuclear explosives is to divide them as either high-order explosives (HE) or low-order explosives (LE). Examples of HE include TNT, ammonium nitrate fuelOIL , dynamite, and nitroglycerine. Examples of LE include gunpowder, pipe bombs, and pure petroleum-based bombs like Molotov cocktail or aircraft used as guided missiles. HE and LE create different injury patterns, primarily because HE produces a supersonic over-pressurization shock wave that causes unique injuries.

The HE shock wave is created at detonation by the rapid chemical decomposition of the explosive material into gas.¹ This gas is created under high pressure and temperature and is transmitted as the blast (or shock) wave. This pressure-pulse is only a few millimeters thick and travels outward from the point of detonation at supersonic speeds. The blast (or shock) wave may have focal over-pressure up to eight times atmospheric pressure. This sudden change in environmental pressure (blast-wave) impacting with the body causes the primary blast injuries unique to HE. The blast injuries are especially evident in the gas-filled structures on the body, including the lung, GI tract, and middle ear.

As the blast front travels from the explosion, it decreases in pressure until the blast-wave is reduced into an acoustic wave.¹This creates a blast-wind, which can propel objects and people considerable distances, resulting in additional damage to life and objects.

Basic Categories of Blast Injuries²

1. Primary blast injuries²—result from the impact of the blast-wave with the body. The effects are most evident in gas-filled structures on the body where the over-pressurized blast-wave causes rapid compression and expansion of the gas-filled structures resulting in tissue damage, hemorrhage, or organ rupture. (See below for further information about specific organ damage.)

2. Secondary blast injuries²—are due to objects (including bomb fragments and flying debris) becoming energized by the blast, resulting in their acting as projectiles. These flying object-projectiles can affect any part of the body with either penetrating or blunt trauma.

3. Tertiary blast injuries²—result from individuals being thrown by the blast-wind or injuries caused by the collapse of structures due to an explosion. Any part of the body can be affected. Common injuries include fractures, amputations, and/or brain injuries.

4. Quaternary (miscellaneous) blast injuries²—This group includes the other explosion-related injuries, illnesses, or diseases not due to one of the three mechanisms just listed. These include burns and the exacerbation or complications of existing conditions such as asthma; chronic obstructive pulmonary disease (COPD); breathing problems from dust, smoke, or toxic fumes;

and the patient’s development of angina, hyperglycemia, etc.

Specific Blast Injuries

1. Primary Blast Injuries to the Lung (Blast-Lung)²—Blast-lung is a direct consequence of an HE over-pressurized shock wave impacting the body. The signs and symptoms of blast-lung are usually present at the time of initial presentation to the health care facility but may not become

evident for up to 48 hours after the victim is exposed to the explosion. The characteristic clinical triad of severe blast-lung is apnea, bradycardia, and hypotension; but all patients who complain of dyspnea, cough, hemoptysis, or chest pain after an explosion exposure should be evaluated for blast-lung. Lung pathology ranges from simple scattered pulmonary petechiae to confluent lung hemorrhages resulting in severe hypoxia and respiratory failure. Primary blast-lung is the most common cause of death in patients who initially survive an explosion. Management of patients suspected of having blast-lung includes obtaining a routine chest x-ray. The characteristic x-ray finding of significant blast-lung is a butterfly pattern due to pulmonary hemorrhage, but this pattern may not be apparent at the time of initial evaluation. Patients with severe blast-lung may require intubation and respiratory support. Prophylactic chest tubes are recommended for patients suffering from an explosion-generated blast-lung who need general anesthesia or air transport to prevent the patient from developing a post-blast tension pneumothorax during surgery or flight.

2. Ear Injury from Blast² Ear injuries are a common result of explosion exposure, especially in the ear oriented toward the blast. While a perforated TM is the most common manifestation of a blast-ear injury, not infrequently there are no significant early complaints or physical findings at the time of initial evaluation. Ear signs and/or symptoms such as hearing loss, tinnitus, otalgia, vertigo, bleeding from the ear canal, or otorrhea should raise the provider’s suspicion of ear injury. All patients exposed to a blast should have an otological evaluation and audiogram after the more serious injuries have been treated.

3. Abdominal Injuries from Blast (Blast-Abdomen)² Gas-containing structures of the GI tract are especially vulnerable to the primary blast effects of a blast-wave. Injuries include:

o Immediate or late bowel perforation

o Hemorrhage—ranging from small petechiae to large hematomas o Mesenteric shear injuries

o Solid-organ lacerations o Testicular rupture

Symptoms that may suggest a blast injury to the abdomen in a blast victim include:

o Abdominal pain o Evidence for an “acute abdomen”

Clinical findings of a blast-abdomen may be delayed from hours to days.

4. Central Nervous System Injuries from a Blast² Brain injury from a blast can occur without a direct blow to the head. The primary blast (shock) wave can cause varying central nervous system (CNS) damage from a mild concussion (often referred to as mild traumatic brain injury [MTBI]—see below) to severe brain injuries. Blast CNS injuries may include:

o Concussion

o Closed or open brain injury o Stroke syndrome

o Spinal cord injury

o Air-embolism induced CNS injury

MTBI³ refers to a syndrome caused by a seemingly mild brain injury or concussion that usually presents with minimal or non-observable symptoms but which may have significant long-term sequelae. Long-term signs and symptoms of patients experiencing MTBI may include³:

• Cognitive changes: manifested as attention difficulties, memory problems, difficulty with concentration and orientation.

• Physical complaints: headaches, dizziness, insomnia, fatigue, nausea, blurred vision, or ataxia.

• Behavior changes: including irritability, depression, anxiety, sleep disturbance, emotional lability, loss of initiative, and relationship problems.

A diagnosis of MTBI may be difficult to make since the symptoms are non- specific and are similar to many other medical conditions including PTSD. Consider MTBI in patients with the above symptoms and a history of head trauma or blast exposure, especially if they have amnesia of the event, had loss of consciousness for < 30 minutes, and had a GCS score > 13.

5. Eye Injuries from Blast² As many as 10% of all blast survivors have a significant eye injury. The most common eye injuries are globe perforations from high-velocity projectiles, foreign bodies on the cornea or in the globe, air emboli, or orbital rim fractures. For a patient to have minimal initial discomfort and not present for care of the eye injury for days, weeks, or even months after the event is not unusual.

Symptoms that may suggest eye injury include:

• Eye pain

• Eye irritation

• Foreign body sensation

• Altered vision

• Findings that suggest an eye injury include:

• Periorbital swelling or contusions

• Decreased visual acuity

6. Musculoskeletal and Other Soft Tissue Injuries from Blasts¹ Musculoskeletal injuries from blasts result from the combination of forces generated by a blast. The abrupt rise in atmospheric pressure created by the passing blast-wave causes many fractures and contributes to limb avulsion. The mechanism of explosive blast amputation is frequently the combination of the coaxial forces of the blast-wave inducing the fracture followed by limb avulsion through the fracture site by the dynamic forces of the blast-wind acting on the whole limb. Blast-induced lower limb amputations are most common at the level of the tibial tuberosity, while the upper limb amputations tend to be more distal in the limb. Other soft tissue injury is also common. The debris and casing fragments energized by the blast are propelled with a tumbling and shimmy effect that increases the amount of tissue damage upon impact with a victim. In addition, the debris is very contaminated with environmental bacteria resulting in extensive wound contamination.

7. Other Special Considerations During Evaluation of Blast Victims¹

o Fragments, energized by a blast, do not travel in straight lines after they enter the body.

o Small entry wounds can be associated with extensive internal injury.

o Entry wounds in the buttocks, thighs, or perineum can be associated with intra-abdominal injuries.

o Health care providers need to maintain a high degree of suspicion that a compartment syndrome may develop in injured extremities.

o An entry wound in the groin or the development of a hematoma elsewhere may mean that a major vascular injury has occurred.

Special Considerations in the Care of Patients Manifesting Blast Injuries

The initial approach to patients who have experienced injuries from an explosion or blast follows the CALS Universal Approach for Critical Patient Care with coordination of the team’s efforts to be as efficient and effective as possible. Some special treatment considerations include:

• The potential risk that the victim may have been contaminated with a biological, chemical, or nuclear agent.

• The unique syndromes associated with blast exposure including the development of blast-lung or blast-abdomen.

• When the number of victims is large compared to the number of providers, how to triage patients to maximize the good performed by the treatment team.

• Blast wounds are contaminated with bacteria and debris and are associated with a high risk of infection.¹ Meticulous wound care is essential, including the removal of non-metallic foreign material, excision of non-viable tissue, and irrigation of wounds with copious amounts of solution (isotonic if possible) to help remove bacteria and foreign material.

• Prophylactic antibiotics should be considered.¹

1. Gas gangrene, by anaerobic Clostridium species, is a major threat with blast injuries.

Penicillin IV helps reduce the risk. Alternative antibiotics include erythromycin, chloramphenicol, or a cephalosporin.

2. In severely contaminated blast injuries, Pseudomonas aeruginosa may be a problem.

Consider giving an aminoglycoside IV or a different drug effective against Pseudomonas.

3. Open fractures need coverage against gram-positive organisms. A penicillinase-resistant penicillin or a cephalosporin IV is appropriate.

4. Tetanus is a high risk. Give the patient tetanus prophylaxis and consider the need for anti-tetanus immunoglobulin.

• Post-Traumatic Stress Disorder⁴ – The development of PTSD is a risk following any traumatic event associated with a sense of horror or helplessness, the development of serious injury, or the threat of serious injury or death. It may manifest not only in survivors who have directly

experienced the traumatic event but also in the relatives and/or close friends of the victims as well as in rescue workers. Frequently, symptoms associated with the PTSD do not become apparent for weeks or months following a traumatic event. The symptoms characteristic of PTSD are similar to those observed with patients suffering with the late sequelae of MTBI and include:

1. Cognitive effects – such as poor concentration, memory loss, shortened attention span, or indecisiveness.

2. Emotional manifestations – including depression, numbness, feeling of being overwhelmed, or volatile emotions.

3. Physical complaints – of nausea, dizziness, rapid heart rate, headache, tremors, or undefined pain.

4. Behavior changes –including irritability, excessive silence, suspicion, argumentum, or withdrawn.

The care of patients with injuries as a result of a blast or explosion exemplifies the critical need for the provider team to have a preplanned approach to major disasters. This includes having a well developed disaster plan utilizing all of the available resources as efficiently as possible; a triage system designed to fit your facility; the proper basic equipment to handle critical, life-threatening, emergencies; and a system

built to maximize the cooperation of the health care team. With proper planning, major disasters can be managed to the benefit of the great majority of the victims with a minimum of risk to the provider team.

https://calsprogram.org/manual/volume3/Section13/19-EMP18Expl&BlastInjuries13.html

Introduction:

An explosion is a process where any substance or device capable of creating a sudden gas expansion, releasing potential energy and thus creating a pressure wave.

Compression of the air in front of the pressure wave, which heats and accelerates air molecules, leads to sudden increase in atmospheric pressure and temperature

transmitted to the surrounding environment as a radially propagating shock wave, known as the

„Blast wave. [1]

Injuries directly inflicted by this sudden increase in air pressure after an explosion are referred to as „primary blast injuries, and mainly affect primary gas containing structures (lungs, middle ears and gastrointestinal tract). [1-3]

A minimum pressure of about 700 kPa (100 lbs/sq inch) is necessary for severe tissue damage in humans. [4

Secondary blast injuries result from blast-energised bomb fragments and other displaced objects causing penetrating trauma.

Tertiary blast injuries occur when the body is accelerated away from the blast wave at first and is then abruptly decelerated on rigid objects resulting in blunt force trauma. [1]

Quaternary injuries (Miscellaneous blast related injuries) encompass injuries caused by collisions, falling masonry, buildings, beams, etc.

[5] Explosive force is highly directional. The parts of the body directly exposed to the explosive force only are injured. An explosion at ground level mainly injures legs and feet.

When a person is in front of a bomb when it blows up, the face, chest, forearms, hands, inner thighs and legs below knees are injured, but the back of the body, the lower legs and face escape. If a person is bending down over the bomb, the face, chest, legs and hands are severely damaged. [4]

Orthopaedic trauma resulting from an

explosion is manifested as a primary, secondary, tertiary or quaternary (miscellaneous) blast injury in isolation or in combination.

Although uncommon in survivors, the direct effects of changes in atmospheric pressure caused by the blast wave (primary blast injury) can fracture bones and it is probably responsible for limb avulsions in victims exposed to stress waves of sufficiently high intensity

http://medind.nic.in/jal/t15/i1/jalt15i1p85.pdf

79) After an incised wound, new collagen fibrils are seen along with growing epithelium. The age of the wound is

a) 4-5 days b) About 1 week c) 12-24 hours d) 24 -72 hours A

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