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espect to incident waves and the degree of reflected shock waves to which the victim is
exposed.
Primary blast injury. Primary blast injuries (PBI) are injuries caused specifically by
exposure of the body to the blast wave. Pulmonary barotrauma, air embolization, and
intestinal perforation are the unique principal causes of death after a blast. Although most
injuries in an explosion are secondary, tertiary, and miscellaneous (crush, burn,
inhalational), a person close enough to a detonation would be subjected to the effects of
the blast on a microscopic level.
Urban bomb blasts tend to have the following characteristics:
• Most victims sustain minor injuries.
• Most injuries affect the head, neck, and extremities.
• Torso injuries are uncommon yet lethal.
• Primary blast injuries are uncommon because victims tend to die before arriving
at the hospital.
However, because all bomb blast incidents are different, the types of injuries seen are
variable. A blast that occurs in an enclosed space, such as a bus, is associated with more
severe injuries and a higher incidence of primary blast injuries. The number of casualties
would be expected to be less than in an equipotent detonation in open space. Mortality is
also higher when a blast occurs in an enclosed space, because the shock wave is
contained and reaches a higher overpressure and a longer positive phase. However,
containment of the wave does not affect the generation of propelled debris. Therefore,
secondary and tertiary injuries, including amputations from large objects, are the same
whether the blast occurs in an enclosed space or open air.
The spectrum of PBI reflects involvement of the gas-containing organs and the
pathophysiologic effects of these organs on other systems (Table 7.2). As in conventional
trauma, all victims should be managed with careful attention to the airway, breathing, and
circulation; however, in certain patients, complications may arise with respect to positivepressure
ventilation and fluid resuscitation management.
Blast lung injury and air embolization. The anatomic structure of the lung makes it
susceptible to the effects of blast barotrauma. Alveolar spaces are engulfed by delicate
capillaries in a way that maximizes the surface area available for gas exchange.
Pathophysiology. The pathophysiology induced by the blast involves the spalling of
particles across the tissue-gas interface (alveolus) with the generation of micro-tears. This
fills the air space with blood, edema, and tissue particles, impairing gas exchange. The
most common lesion of the airway is the stripped-epithelium lesion, in which the
bronchial epithelium and mucociliary apparatus are stripped from the basal lamina,
resulting in ulcerations of the submucosa and impaired clearing of secretions. Structural
tears occur through interfaces of blood vessels and air spaces, creating direct openings
where air bubbles could escape into the circulation.
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