News Release

Civilian doctors, not just those in combat settings, urgently need training on blast injuries

Peer-Reviewed Publication

The Lancet_DELETED

The increasing incidence of terrorist attacks means that doctors in civilian settings, as well as those in combat operations, need training on blast injuries. The issues surrounding these frequently devastating injuries are discussed in a Seminar published Online First and in an upcoming edition of the Lancet, written by Dr Stephen Wolf, Department of Emergency Medicine, Denver Health Medical Center, Denver, CO, USA, and colleagues.

Blast injuries are physically and psychologically devastating. Although explosions can result from industrial or recreational accidents, terrorist acts that cause injury in military and civilian settings are taking place at an increasing rate. Conservative estimates show that these events have risen four-fold from 1999 to 2006 worldwide, and injuries related to these acts have increased eight-fold. Historically, specialist doctors in combat settings have been those given training to deal with blast injuries—but the current threat of terrorism means that these injuries can occur in just about any location, civilian or combat. The authors say: "Every physician involved with emergency care needs to understand the unique injury patterns and management of people injured by an explosion."

Explosions result from the almost instantaneous conversion of a solid or liquid into a gas after detonation of an explosive material. The blast wave displaces the surrounding air (or water) and can generate winds of several hundred km/h. These winds propel objects or people, thus causing injury. As water is non-compressible, a blast-wave in water has a greater potential for injury as the wave can spread rapidly with little dissipation. Distance from an explosion determines a person's exposure to the 'peak overpressure' or maximum pressure of the blast wave. Even being just a few metres away from an explosion can greatly increase a person's chances of survival, depending on the explosive used. Standing next to a wall can make a person experience enhanced blast pressure as the blast wave reflects back; being in enclosed spaces such as buses or trains also causes increased injury as the explosive forces are contained and reflected. Thus enclosed-space explosions result in higher rates of injury and mortality. The Seminar details the types of explosive that can cause blast injuries.

Blast injuries are divided into five categories. Primary blast injuries (PBIs) take place when the blast overpressure reaches the person and transmitted forces exert their effect on the body, causing direct tissue damage. Areas of air-tissue interface are particularly vulnerable, meaning the lungs, gastrointestinal system, and hearing systems of people are most at risk. Various forces work in PBIs, including implosion and shearing forces. Secondary blast injuries (SBIs) are created by debris that is physically displaced by the blast overpressure, so can cause injuries similar to stab wounds, and physical assaults. Some bombs contain nails, ball bearings or other items designed to cause maximum damage through SBIs. Debris can be sent hundreds of metres, whereas the blast overpressure which causes PBIs is usually confined to tens of metres. Thus, SBIs are more common than PBIs. Tertiary blast injuries (TBIs) are caused when a person is physically moved by the blast, and sustains blunt trauma injuries such as head injuries, fractures and other trauma. Quaternary and quinary blast injuries are the last category, and refer to injuries caused directly by the explosion but are not classified as PBIs, SBIs, or TBIs. Examples include burns, radiation, and poisoning.

The authors look at the specifics of PBIs, and say that 17—47% of patients who die from explosions have evidence of PBI in the lungs. The forces involved disrupt the alveolar structure of the lung and the capillary walls, and can cause pooling of blood and fluids with the tissue of the lungs. Special mention is given to arterial air embolism, a situation when air enters the arterial system causing tissues not to receive adequate blood supply. Chest radiographs should be taken where lung injury is suspected. The authors discuss a number of treatment strategies, including the importance of careful fluid resuscitation and management of ventilatory status.

In the gastrointestinal system, blast injuries can cause damage to the bowel wall and cause spontaneous or delayed rupture or disrupt the blood supply to the intestines. Patients with haemorrhagic shock from intestinal injury should undergo careful volume resuscitation, being mindful of the patients pulmonary status, until emergency surgery can be performed.

Depending on the explosion's setting, between 2% and 32% of all people injured, and up to 94% of those with primary blast injuries will have ruptured tympanic membranes in their ears. Tinnitus is common in affected patients, and vertigo can also occur. Small membrane ruptures can spontaneously heal, but those that involve more than 5% of the surface area may need surgery depending on the degree of rupture (in 17—89% of cases). The authors also discuss damage to the central nervous system, and also to the musculoskeletal system. Injuries to the musculoskeletal system from PBIs, SBIs, and TBIs comprise around 54% of all combat injuries—largely due to improvised explosive devices. Such injuries can lead to compartment syndromes, where fractures, burns, and tissue damage can elevate pressures in a limb or 'compartment', leading to further tissue injury, blockage of blood vessels, and tissue death.

The authors conclude: "Worldwide, a paradigm shift has taken place in modern-day conflict. The rise in urban warfare tactics by terrorist and paramilitary groups means that local health systems must be prepared to manage devastating explosion-related injuries. Acute care providers (physicians, nurses, and ancillary staff from emergency medicine, surgery, orthopaedics, and anaesthesiology), who are most likely to be the first receivers of injured people, have an urgent responsibility to know and understand the diagnostic and management issues unique to blast injuries."

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Dr Stephen Wolf, Department of Emergency Medicine, Denver Health Medical Center, Denver, CO, USA T) +1 303 436 8842 stephen.wolf@dhha.org

For full Seminar, see: http://press.thelancet.com/blast.pdf


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