BMJ  2005;331:119-120 (16 July), doi:10.1136/bmj.331.7509.119 (published 11 July 2005)

Editorial

Blast injury in enclosed spaces

All doctors should know the basic management of patients injured by explosive blast

The bomb attacks on the transport network in London on 7 July 2005 have illustrated the lethality of explosions in confined urban spaces. Such indiscriminate attacks could occur again in the near future. The management of casualties injured by blasts is mainly the preserve of the military doctor, but the bombing of a bus outside BMA House graphically illustrates that any doctor may be called on to manage patients injured in explosions.

While all casualties injured in explosions should be managed initially according to the advanced trauma life support (ATLS) guidelines, starting with airway, breathing, and circulation,¹ general doctors should also be aware of the specific features of blast injury. Detailed advice and clinical guidance for the non-specialist on managing casualties injured by blasts is freely available online from the Centers for Disease Control and Prevention in the United States.²

Injuries caused by explosive blast were classified by Zuckerman during the second world war according to the physical effects on the body caused by the released energy.³ Primary injuries result from the interaction of the blast shock wave with the body and affect the areas where air and tissue meet, including the ear, lung, and the gut. Secondary injuries result from the collision of energised fragments with the body. Tertiary injuries result from displacement of the whole body or body parts by the blast energy, and include traumatic amputations. In addition, tissues are burned by the hot gases from detonation and from inhalation of smoke and debris in aerosol form.

Immediate clinical manifestations of acute lung injury include pneumothorax, pulmonary oedema, and air embolism. Delayed effects over the next 24-48 hours create a picture similar to acute respiratory distress syndrome, with hypoxia and diffuse infiltrates in the lung, and high mortality.⁴ Traumatic amputation of a limb, as a marker of severe multisystem injury, also has high mortality.⁵ Tympanic perforation is common in the survivors of blasts at close proximity, but damage to the eardrum without obvious signs of other injuries does not seem, on the basis of one observational study, to be associated with more serious morbidity such as lung damage.⁶

Simple blast waves in an open space create a rapid rise in air pressure usually lasting less than 10 milliseconds. In enclosed environments the reflection of blast waves from walls and other surfaces creates complex waves of longer duration. This allows greater transfer of energy to the body, increasing the risk of primary blast injuries such as tympanic perforation and blast lung⁷ and increasing displacement of the body wall, which may cause a shearing effect on larger organs, especially abdominal viscera.⁸

In two explosions in the open air in Israel, mortality among casualties who required treatment in hospital was 8% (15 deaths among 204 casualties), whereas after two blasts in the enclosed space of a bus 49% of patients (46 deaths out of 93) eventually died.⁹ In addition, the severity of injuries among the survivors was higher in the bus bombing as graded by the injury severity score (mean score 4 after a blast in the open air compared with 18 after a bus bombing, with a greater proportion of the casualties from the bus having primary blast injuries: 34% in the open air compared with 78% on the bus). Similar observations were made among casualties when the Irish Republican Army (IRA) bombed pubs in the United Kingdom in the 1970s.¹⁰

The bombings on 7 July in London caused a large number of casualties (around 700), but most injured people were discharged from hospital soon after assessment and treatment. Many were injured by non-penetrating fragments, which can be managed without surgery.¹¹ In an uncontrolled incident, vast numbers of "walking wounded" can lead to a "reverse triage effect" where patients with minor injuries present to hospitals before the serious casualties arrive, swamping emergency services to the detriment of the severely wounded.² That this phenomenon did not occur on 7 July testifies to the outstanding integrated response by the pre-hospital services in controlling actions at the scenes of the incidents and in triaging patients appropriately.

Lewisham University Hospital, London SE13 6LH
(eddie.chaloner{at}btopenworld.com)

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Competing interests: EC organises educational courses relating to aspects of war injuries and terrorism and has received payment for these from Mark Allen Healthcare Ltd.

References

1. Mannion SJ, Chaloner EJ. Principles of war surgery. BMJ 2005;330: 1498-500.[Free Full Text]
2. Centers for Disease Control and Prevention. Explosions and blast injuries: a primer for clinicians. May 2003. www.bt.cdc.gov/masstrauma/explosions.asp (accessed 11 Jul 2005).
3. Zuckerman S. Experimental study of blast injuries to the lungs. Lancet 1940;ii: 219-24.
4. Maynard RL, Coppel DL, Lowry KG. Blast injury of the lung. In: Cooper GJ, Dudley HAF, Gann DS, Little RA, Maynard RL, eds. Scientific foundations of trauma. Oxford: Butterworth Heinemann, 1997: 214-24.
5. Hull JB. Traumatic amputation by explosive blast: pattern of injury in survivors. Br J Surg 1992;79: 1303-6.[Medline]
6. Leibovici D, Gofrit ON, Shapira SC. Eardrum perforation in explosion survivors: is it a marker of pulmonary blast injury? Ann Emerg Med 1999;34: 168-72.[CrossRef][Medline]
7. Cooper GJ. Protection of the lung from blast overpressure by thoracic stress wave decouplers. J Trauma 1996;40: S105-10.[Medline]
8. Cooper GJ, Taylor DEM. Biophysics of impact injury to the chest and abdomen. J R Army Med Corps 1989;135: 58-67.[Medline]
9. Leibovici D, Gofrit ON, Stein M, Shapira SC, Noga Y, Heruti RJ, et al. Blast injuries: bus versus open-air bombings—a comparative study of injuries in survivors of open-air versus confined-space explosions. J Trauma 1996;41: 1030-5.[ISI][Medline]
10. Cooper GJ, Maynard RL, Cross NL, Hill JF. Casualties from terrorist bombings. J Trauma 1983;23: 955-67.[Medline]
11. Bowyer HW. Management of small fragment wounds in modern warfare: a return to Hunterian principles? Ann R Coll Surg Engl 1997;79: 175-82.[Medline]

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