# Presentation: 028826

## David Burris, MD - Chair, Surgery, USUHS
Howard Champion, MD – 
Ralph DePalma, MD – Director, National Surgery Program, VHA
Jerry L. Mothershead, MD - 
Creighton Wright, MD – Chief of Staff, Cincinnati VAMC

**David Burris, MD - Chair, Surgery, USUHS**
**Howard Champion, MD – **
**Ralph DePalma, MD – Director, National Surgery Program, VHA**
**Jerry L. Mothershead, MD - **
**Creighton Wright, MD – Chief of Staff, Cincinnati VAMC**

**Blasts and explosions: physical, medical, and triage considerations**

**Notes:**
PL 107-287 mandates the development of training programs for civilian response to terrorist attacks and requires collaboration between the Department of Veterans Affairs, Veterans Health Administration, and the Uniformed Services University of the Health Sciences (USUHS).   Although the initial focus was on biological, chemical, and radiation effects, the vast majority of terrorist incidents, over 98%, actually represent explosions.  In addition, mental health consequences of terrorist incidents are recognized as phenomenally important.  This program was developed by assembling a small group with individuals well known for their work on trauma, blast consequences, and military surgery.  

This presentation is based on the work of the group and relied in part on prior presentations and work from Dr Champion and Mothershead.  The blast triage algorithm is based on the knowledge and practices of Drs Burris and Champion and has not been formally validated but represents widespread belief among surgeons with expertise

The Employee Education System supported the development of this program under the activity chaired by Dr Susan Mather, and includes modules on biological, chemical, and radiation incidents and mental health management along with this surgical program.

## GOALS of PROGRAM

**Understand the mechanisms of blasts and blast injuries**
**Types of explosions**
**Understand the medical consequences and syndromes from blast injury**
**Types and classification of injuries**
**Be able to apply a triage algorithm to blast injury**
**Triage algorithm**
**Other treatment considerations**

**Notes:**
The objectives of this program are 

Understand the mechanisms of blasts and blast injuries
Understand the medical consequences and syndromes from blast injur
Be able to apply a triage algorithm to blast injury
Understand some basic approaches and current controversies in the management of blast consequences

## Section 1: Magnitude of the Problem

**Notes:**
Still need pictures of vehicles (suicide bombing, IED consequences?)
Howard Champion: can we use some of yours (slides 5 and 6)?
Bob Smith: how do we do this as all publicly accessible versions are probably copywrited?
Jerry Mothershead: were your photographs, can we use them, or where are they from so that we can get cw?

## Magnitude of the Problem

**Structural Collapse**
**Any manmade structure – buildings, bridges, dams**
**Design flaws (Hyatt Regency Skywalk)**
**External or internal force (natural, terrorist)**
**Vehicle and open space blast**
**Explosions in vehicles or open space as a consequence **
**Mostly terrorist**

**Notes:**
There are two main kinds of events, with slightly different patterns of injury

Structural collapse happens frequently – and to varied structures.  Most often, these failings are a combination of design flaws and some outside precipitating event.  

Vehicle and open space blast may occur through suicide bombings, where the explosion actually occurs within enclosed space, with enhanced blast injuries. The reflection of waves may lead to standing waves and unusual patterns, so that individuals with very severe injuries may stand side – by side with individuals with far less exposure.  Patients must be considered individually during triage, and it is unreasonable to assume some rooms or areas are safer than others just because some patients had no evidence of injury.  Enhanced blast injury

## Explosive Effects

**Blast Pressure Wave**
**Over-pressure**
**Under-pressure**
**Fragment effect**
**Thermal (incendiary) effect**
**Secondary effects**
**Seismic**
**Reflection**

**Notes:**
The effects of an explosive fall into four categories:
Blast effects – either from over-pressurization or under-pressurization
Fragmentation effects (flying objects that can crush or penetrate)
Thermal effects (burns and inhalation injury)
Secondary effects, which can be due to either reverberations through solid structures, referred to as seismic, or from reflection off structures.

QUESTION TO GROUP: What about tertiary/quartern. Effects?  Are these then 5 and 6?

## TYPES OF EXPLOSIVES

**Traditional explosives **
**Point source**
**Enhanced blast devices**
**Initial explosion disseminates explosive materials**
**Secondary explosion triggers explosion over a far greater area**

**Notes:**
Traditional explosives have a well-defined center point.  Newer explosives, so-called  “Enhanced Blast Devices”,  disseminate undetonated explosives over a geographic area and then, in a second step, explode.  This prolongs the time duration and area colored XXX (WHATEVER THAT COLOR IS) in the prior slide and thereby increases the duration of time and the area under the blast pressure curve above 2.2 psi.  

## Section 2: Blast Injuries

**Primary Blast Injuries**
**Direct effect of blast wave**
**Secondary Blast Injuries**
**Objects strike individual**
**Tertiary Blast Injuries**
**Individual strikes objects**
**Quaternary Blast Injuries**
**Other effects – burns, infections, crush injuries, delayed collapse**

**Notes:**
In general, most survivable injuries suffered by victims of bombings or explosions are those that healthcare providers are used to treating physical trauma, lacerations, abrasions, crush and penetration injuries, and fractures.    Triage and management therefore generally follows standard emergency medicine management practice.

However, there are unique categories of injuries specific to blasts:
Primary blast injuries are due to the direct effect of the blast wave
Secondary blast injuries are due to flying or collapsing objects
Tertiary effects may be seen with high blast waves, when individuals are thrown through the air, impacting other objects of the ground.
Quaternary blast injuries comprise  those immediate or short term effects of complications as a result of the blast.

## INJURY DISTRIBUTION

**Conventional explosive**
**Blunt trauma**
**Penetrating trauma**
**Inhalation injury**
**Thermal injury / Burns**
**Relatively less primary blast injury **
**Enhanced blast devices / vehicles /enclosed spaces**
**Primary blast injury (pressure-related effects) predominate over blunt trauma**

**Notes:**
Because of the different consequences of explosions, the distribution of injuries difffer somewhat.  With conventional; explosives, we see mostly common injuries.  With enhanced blast injuries, we see far more primary blast injury.

## Primary Blast Injuries

**Occurs most frequently in:**
**Middle ear**
**Lungs**
**Large Bowel**
**Results from:**
**Blast wave contact (dynamic pressure changes) at air-water interfaces**
**Blast loading**
**High frequency stress wave**
**Low frequency shear wave**

**Notes:**
Primary blast injuries occur most frequently in air-filled organs, and results from blast wave dynamic pressure changes at air-fluid interfaces.  At this interface, a high frequency stress wave and a lower frequency shear wave are produced.  Depending on the proximity to the blast and the blast characteristics, one or the other of these waves may be the predominant.

## Primary Blast Injuries

**Ear**
**TM ruptures at 1-8 psi dynamic overpressure**
**Temporary neuropraxia of receptor organs**
**Dislodgement of ossicles may occur**
**Lung**
**Pulmonary contusions – multifocal hemorrhages**
**Pulmonary C-fiber receptor injury causes vagal nerve-mediated cardiogenic shock**
**Other injuries:  hemothoraces, pneumothoraces, traumatic emphysema, AV fistuale, pulmonary barotrauma, venous air emboli**

**Notes:**
The tympanic membrane is the soft tissue most frequently affected.  It takes as little as 1psi overpressurization to rupture an eardrum.  This is usually accompanied by a temporary neuropraxia of the receptor organs of the ear, resulting in deafness, tinnitus and vertigo.  With high enough dynamic overpressures, however, ossicles may be disrupted, and the oval or round windows may rupture, resulting in permanent hearing loss.
In the lung, multifocal contusions are usually seen, but in severe exposures, hemothorax, pneumothorax, and other traumatic injuries may occur.  An interesting phenomenon is sometimes seen, that of a bardycardic non-caridogenic pulmonary edema, thought to be due to injury to pulmonary C-fibers.

## Primary Blast Injuries

**Gastrointestinal Tract**
**Primarily in colon**
**Rupture**
**Usually acutely**
**Delayed due to ischemia**
**Tension pneumoperitoneum**
**Solid organ subcapsular petechiae**

**Notes:**
The large intestine is the abdominal organ most frequently affected by primary blast injury.  Rupture of the colon is the norm, but mesenteric ischemia or infarct may result in delayed rupture.  Infarct, ischemia, and hemorrhage into solid organs may occur, but usually require such force that the blast is not survivable.

## Primary Blast Injuries

**Other locations**
**Eye:  hyphema (rare)**
**Face:  implosion of sinuses (unlikely)**
**Brain:  well protected from PBI**
**Mesenteric, retroperitoneal, and scrotal hemorrhage**

**Notes:**
Other locations may be affected as well.  Very rarely, the eye might be damaged.  This usually takes the form of central serous retinopathy, but hyphema has been reported.

Although facial fractures are more commonly due to flying objects, implosion of the sinuses has also been reported.

The brain is characteristically not affected by primary blast injury due to its bony protection.  Loss of consciousness or coup/countra-coup injury are the result of secondary or tertiary injuries.

## Secondary/Tertiary Blast Injuries

**Fragments**

**Notes:**
Further from the blast center, secondary injuries predominate.  These may be the result of large flying objects, such as cinder blocks, but are more frequently the result of smaller particles or fragments. Fragmented piece of material travel a very high speeds.  Fragment injuries may be minimal, or extensive.  Fragments may also produce other hazards through severing electrical lines, rupturing tanks or gas lines, and further weakening structures.

Tertiary injuries are due to the victim being thrown as the result of the blast.

## Quaternary Blast Injuries

**(also Thermal/Incendiary Bombs)**
**Thermal effects seen as a consequence of burns either during the explosion or from associated fires**
**Nuclear explosives**

**Notes:**
An incendiary bomb contains inflammable matter. Incendiary bombs were a major weapon in attacks on cities in World War II, causing widespread destruction. To hinder firefighters, delayed-action high-explosive bombs were usually dropped with them. In the Vietnam War, US forces used napalm in incendiary bombs. Napalm consists of powdered aluminum soap or similar compounds used to gelatinize oil or gasoline. Incendiary bombs have been found as booby traps in clandestine drug labs, and have been used by terrorists, especially in South America.

Nuclear detonations produce significant primary thermal effects.  Other explosives tend to not cause primary fires, due to oxygen consumption during the explosion.  Incendiary bombs will produce primary fires.

## Inhalation Injuries

**Most common in enclosed spaces**
**Common inhalants**
**Smoke**
**Oxides of Nitrogen**
**Phosgene**
**Carbon Monoxide**
**Cyanide**
**Heavy metal fumes**

**Notes:**
Inhalation injuries are common in structural collapses.  Some of the more common inhalants are shown.  Others, such as propane or natural gas, displace oxygen, but nonetheless pose secondary explosion or fire hazards.

## Crush Syndrome

**A condition resulting from damage to the renal tubules in kidneys following severe injury to muscle tissue in crushing accidents. **

**Edema**
**Oliguria**
**CK > 25,000**

**Notes:**
Crush syndrome and the related compartment syndrome are seen frequently in structural collapses.

Crush syndrome is a metabolic derangement resulting from damage to muscle tissues.  The release myoglobin further exacerbates this problem by blocking renal tubules.  In addition ot oliguric renal failure, the impaired renal function results in accumulation of K+ released during muscle damage.  The degree of elevation of creatinine has been correlated with the severity of renal failure, with 25,000 appearing to be the break point, although many of these patients also suffer some degree of pre-renal azotemia as well.

## Compartment Syndrome

**Perfusion pressure < tissue pressure in a closed anatomic space. **
**Left untreated:**
**Tissue necrosis**
**Functional impairment**
**Renal failure**
**Death**
**Sites:  hand, forearm, upper arm, abdomen, buttock, and entire lower extremity. **

**Notes:**
Hand in hand with crush injury is the phenomenon called compartment syndrome.  Compartment syndrome occurs when damaged muscle within an inelastic sheath becomes edematous.  This in turn promotes local ischemia, which then continues the vicious cycle of selling, increased compartment pressures, decreased perfusion and further ischemia.  Left untreated, compartment syndrome will result in local tissue death, and may be a harbinger of crush syndrome.  Common sites include the extremities, abdomen and buttock.

## Compartment Syndrome

**69% associated with fracture**
**1****st**** signs: pain on passive movement and swelling**
**Diagnosis:  5 Ps**
**Pain, paresthesia, pallor, poikilothermia, pulselessness **
**Treatment:**
**Elevation**
**Fasciotomy**
**Mannitol?**
**HBO?**

**Notes:**
Compartment syndrome can occur without a crush injury, and indeed, in the majority of cases, compartment syndrome is superimposed on a fracture.

Although the 5 Ps of diagnosis are classically listed, these are relatively unreliable early indicators, except pain and paresthesia.

The conservative treatment for compartment syndrome is elevation of the affected limb with continuous compartment pressure and mean arterial pressures, since it is the difference in these pressures that will best indicate the presence of compartment syndrome.  Emergency fasciotomy may be required.

## Entrapment: Survival Modifier

**http://www.ukfssart.org.uk/structural_collapse.htm**

**Notes:**
The epidemiology of crush injuries in structural collapses was well studied after an earthquake in Japan in 1995.  Over 5% of those admitted to area hospitals suffered some form of crush injury, the majority of the lower extremities.  Overall mortality amongst these victims was 13%, although those with multiple areas crushed, especially the torso, faired much worse as a group. 

Mortality increases dramatically during the first couple of days.  Those who survive longer times usually have minimal injuries, and fatalities are due to environmental stressors, dehydration, or infections.  Whereas in trauma we normally consider the golden hour most critical, for entrapped victims, rescuers often refer to the golden day.

## Treatment PrioritiesSame as for all trauma patients

**Airway –Ensure patent airway and Oxygen**
**Tracheal intubation, surgical airway**
**Breathing-Treat pneumo/hemothorax**
**Circulation- Stop Bleeding, restore perfusion**
**Control obvious external hemorrhage**
**Seek and treat internal hemorrhage**
**Controlled, careful use of fluids**
**Seek occult injuries**
**US, DPL, Rare role for CT**

**Notes:**
The treatment priorities for all injured patients are the same.  After the initial, obvious life threatening injures are identified and treated, the less obvious must be sought.  Blast overpressure can lead to pulmonary, and hollow viscous injuries with delayed presentation.  Eye and neurologic injures can also occur from blast.  Entrapment and crush may lead to compartment syndromes, and delayed life-threatening tissue ischemia.

## TREATMENT PRIORITIESOn-site considerations

**Impalement**
**Penetration by flying objects and fragments**
**Don’t remove**
**Cover and, if possible, stabilize *****in situ *****to prevent worsening damage**
**Burns – cover (relatively clean materials) **
**To prevent further gross contamination**
**To prevent heat loss**
**Transportation / fractures**
**Consider splinting long-bone fractures**

**Notes:**
After initial ABCs, and control of massive bleeding, in preparation for transport, three issues should be addressed, management of impalement, burns, and long bone fractures.  

Blasts and explosions may lead to impalement.  Impaled objects should not be removed except in hospital unless it is absolutely necessary to transport patients.   Removal may worsen injury and lead to bleeding, major contamination, and death.  Often objects can be cut or shorted in the field.  But removal should be avoided wherever possible.  

Second, burns should be covered before transport for two reasons.  There is substantial heat loss after loss of epidermal integrity and fluid seepage.  The larger the burn, the more heat is lost.  In addition, covering may prevent further contamination.  Obviously, such coverings should be relatively clean.   

Finally, transportation of fractures in long bones may be difficult without some temporary splinting.  In addition, such splinting may prevent further neurovascular compromise  and bleeding.

## Diagnosis History

**Description of incident**
**Building, vehicle, outdoors, type of device**
**Difficulty breathing**
**Loss of hearing**
**Entrapment **
**Pain and swelling of extremities**
**Time from injury**
**Trajectory of penetrating fragments**

**Notes:**
Beyond the usual trauma history, some items should be emphasized.  Blasts inside of structures may lead to reflected and augmented blast waves in unusual patterns.  A non-injured survivor may be next to a casualty sustaining massive blast injury.  Early respiratory distress may be a manifestation of blast lung injury.  A ruptured TM is a marker for blast injury.  Prolonged confinement in one position, or extremities trapped under rubble may show crush injury and compartment syndrome.  Small fragment wounds in the torso from a oblique trajectory may be superficial while those impacting perpendicular to the body may have penetrated body cavities creating major organ injury or internal hemorrhage.

## DiagnosisPhysical examination

**Frothy sputum**
**Early pulmonary edema from primary blast injury grim prognosis, may be triage marker**
**Tympanic Membrane**
**Marker for blast overpressure**
**Fragment wounds**
**small external wounds may mask significant internal damage**
**Signs of internal bleeding**

**Notes:**
The important findings, worth remembering, are
Frothy, pink sputum represent pulmonary injury.  The earlier it happens, the worse the prognosis

A ruptured tympanic membrane means there was more than 1 psi.  In the absence of a ruptured tm, there is no risk for hollow viscous injury

Small wounds may result from penetration, I.e., fragments.  If you can reconstruct the physical lay-out, you may be able to identify the incoming direction  and what organ is at risk 

Signs of internal bleeding are important as you must then be cautious with fluid resuscitation

## Treatment Considerations

**Usual surgical approaches for trauma**
**Observation for pulmonary blast injury**
**TM rupture a marker**
**Follow O2 Sat for 6-8 hours**
**Pulmonary blast injury**
**Limit fluids**
**Ventilator support with limited inspiratory pressure and PEEP.**

**Notes:**
So, standard emergency clinical management of injuries: ABC, etc

Observation for blast injury requires a portable otoscope  and an O2 saturation meter.  

If any indication for blast injury, clinical standard care is necessary

## Treatment Considerations

**Hollow viscus injury**
**Presentation may be delayed for several days**
**Peritoneal signs may be subtle in those with other injuries**
**In MasCal situation, selected patients without other injuries may be discharged with appropriate warnings after observation for pulmonary injury.**

**Notes:**
If a ruptured TM is found, hollow viscous injury is of concern.  Some, like bowel disease, may take several days to appear.  In mass casualty settings, with space constraints, asymptomatic individuals should be sent home with appropriate warnings for observation

## Resuscitation

**Control fluid use to balance tissue perfusion, risk of rebleeding and edema.**
**Accept lower than normal blood pressure until bleeding controlled**
**Normal mentation and radial pulse (MAP 80)**
**Balanced fluid management for renal preservation in crush syndrome with above considerations**

## Crush Syndrome

**Treatment**
**Look for associated injuries**
**Fluids **
**Monitor CVP, UO (100 mL/hour)**
**Alkalinization of urine – pH 6.5-7.4**
**NaHCO****3 ****(1 amp in 1 L of 1⁄2 NS)**
**Diuresis **
**Mannitol (maximum 200 g.day) after normal CVP**

**Notes:**
No single treatment strategy for crush injury exists.  Hydration, with promotion of diuresis may prevent or reduce renal compromise. Others feel that alkalinization of urine to reduce acidosis and to prevent precipitation of myoglobin in the tubules is of benefit.  Some believe that mannitol is of advantage in promoting diuresis and as a free radical scavenger.  If used, adequate fluid status as measured by CVP should be obtained first, as the osmotic diuresis could lead to a dehydrated state, and compound the problem.

## Triage

**Indication**
**When demand outstrips resources (MasCal situation)**
**Goals**
**To identify patients salvageable with resources at hand**
**Quickly sort patients with minimal equipment.  Portal otoscope will be useful**

**Notes:**
Clinicians, all clinicians, should understand the function and goals of triage.  We use triage when demand outstrips our resources, I.e,, mass casualty situations or under-staffing, or many others

The goal is to identify those patients who will benefit from intervention and exclude those who will not

For blast injury, you need a portable otoscope, in addition to usual clinical tools.

## Blast triage: critical elements

**Tympanic membrane rupture **
**A sentinel for the possibility of primary blast injury (pulmonary or visceral)**
**Monitor O****2**** 6-8 hours**
**Location at blast may not predict severity due to reflected pressure waves and other factors**
**Ascertaining type of explosion may guide triage**

**Notes:**
Two critical elements in triage for after blasts and explosions that differ from usual blunt and penetrating trauma are examination of the external ear canal for tympanic membrane integrity and monitoring O2 saturation for early signs of pulmonary edema

TM integrity: the tympanic membrane may rupture at pressures as low as 1 psi, substantially below the 2.2 psi associated with pulmonary injury.  In the absence of a ruptured tympanic membrane, blast victims need no specific follow-up for blast consequences beyond those of blunt and penetrating trauma, inhalation, other visible injuries, and mental health

O2 saturation is an early indicator of pulmonary edema and becomes abnormal generally before onset of recognizable symptoms.  The vast majority have onset in less than eight hours; after eight hours the probability of pulmonary damage is vanishingly small.  If O2 desaturation does occur, prolonged observation after 8 hours is necessary, for at least 36 hours.  If it progresses, patients must receive appropriate care.

Certain blast effects may be random due to reflected pressure waves in different structures and environments.  These may be increased with enhanced explosive devices (fuel air explosives and thermobaric devices).

## +

- No obvious injuries

- Obvious Injuries

**Otoscopic Exam**

- -

- Observe
- O2 Sat 6-8 hours

- -

- Admit

- D/C with
- Abd Warnings

- Release

- -

- Treat Injuries
- as usual

- Injury RX and
- blast observation
- (pulmonary/visceral)

**Triage Algorithm**

**Notes:**
Please note the utility of the portable otoscope to determine the need for blast observation.

## The plan is nothing, planning is everything			-D. Eisenhower

**The planning process helps all involved to understand the options and flexibly adapt to different circumstances**

**Notes:**
In general, please remember, planning is important but the plan you develop is often not very useful.  Identification of the fundamental principles, the ability to apply them, and the presence of a hospital infrastructure is what will make you successful.