Mechanisms of Injury and Specific Urological Injuries in Mass Casualty Events

Buildings and bridges collapses, earthquakes, floods, and tsunamis, train collisions and aircraft catastrophes tend to be associated with an inconceivably high number of victims and carry the potential of becoming mass casualty scenarios. However, such extreme situations often carry such a high fatality rate that they do not necessarily respond to the definition of a mass casualty event that can overwhelm the medical facilities available (Caro 1974; Cooper et al. 1983). Unfortunately, mass casualty events in recent history are frequently associated with civilian terrorism and are most often the result of explosions. Shootings rarely result in a large number of injuries to become a mass casualty event and other possible mechanisms, such as chemical or biological attacks, will not be discussed in the present chapter because there are no specific urological aspects of their resultant injuries.

Terrorist-related mass casualty events tend to result in a higher overall injured population and a higher mortality/injured ratio than everyday civilian trauma (Huller and Bazini 1970). The incidence of multiple penetrating injuries and the large number of multisystem and multiorgan injuries are highly associated with this type of injury mechanism. The combined effects of blast, penetrating shrapnel, and improvised projectiles (nails, screws, and bolts), burns, and gunshot wounds in those circumstances make these injuries more complex, with unpredictable damage associated with possible undertriage and unexpected subsequent deterioration.

The mechanism of injury in explosions is divided in three phases: primary blast injury caused by the powerful shock wave that spreads from the site of explosion outward. Lungs and ears (air-containing organs) are most commonly injured at this time, but any tissue can be potentially damaged by the wave passing through the body. Pneumothorax and perforated eardrums are most frequently diagnosed in survivors of primary blast (Walsh et al. 1995). Limb and earlobe amputations have been described in victims situated within a short distance of the explosion site as a result of the primary blast waves. In fatalities, the leading cause of death is believed to be air emboli in the coronary and pulmonary vessels together with severe pulmonary injuries, torn alveoli, and pulmonary bleeding (DePalma et al. 2005; Huller and Bazini 1970; Wightman and Gladish 2001). Urogenital injuries as a direct result of primary blast have not been described in survivors of blast injuries. This is probably because parenchyma and fluid-filled organs are remarkably resistant to this mechanism of injury and the rather well-protected location of the kidneys and ureters.

The secondary injury is produced by debris and projectiles set in motion by the explosion. In the recent terrorist attacks described in the literature, these secondary blasts have significantly augmented morbidity. Relatively small bombs, carried in bags or body belts by suicide bombers have inflicted disproportionately severe secondary blast injuries by being augmented with bolts, nails, and various projectiles. These projectiles behave like high- or low-velocity missiles depending on their shape and the distance of the victim from the explosion site (Almogy et al. 2004; Kluger 2003). Penetrating injuries to the urogenital system, as to any other organ, have been described as a result of these so-called upgraded killing devices (Archbold et al. 1981).

The tertiary injury occurs when the victim displaced by the blast wave hits a fixed object. An acceleration-deceleration mechanism produces severe injuries to parenchymal organs, large blood vessels, and bony structures. Blunt renal, ureteral, and bladder injuries are induced by this mechanism. (Archbold et al. 1981; Kluger 2003).

Patterns and severity of injuries caused by civilian explosions are different when the explosions are in an outdoor, open-air site, or in closed place such as a bus or a room (Almogy et al. 2004; Leibovici et al. 1996). Explosions in confined spaces are extremely devastating because of the amplification of the blast wave by reflections and structural damage with ensuing collapse of walls and concrete.

Renal vascular and parenchymal injuries can lead to significant morbidity and mortality due to severe bleeding and urine leakage. Interestingly, a review of reports of major events involving mass casualties revealed a relatively small number of reportedly major renal injuries in relation to the large number of victims and to the severity of their other injuries. The reported Irish and Balkan (Frykberg and Tepas 1988; Hudolin and Hudolin 2003) experience mentions a 2 % rate of significant urogenital injuries in survivors of terrorist bombings. The overall rate is certainly higher, but these patients probably have significant associated injuries and therefore a high mortality rate. In a report describing the mass casualty event in the Oklahoma City bombing, Mallonee at al. (1996) state that in this terrorist attack that destroyed the Murrah Federal Building in 1995 and injured 759 people (168 of whom died), no specific urogenital injuries were described and urologists were not even among the list of specialists that were called to the operating room. Similarly, in the suicide bombing at the Sbarro pizzeria in Jerusalem in 2001, a suicide bomber detonated himself in a busy restaurant (Almogy et al. 2004), causing 146 casualties and 14 immediate deaths, with no specified urologic injuries.

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