Ballistics, bombs and burns - Pathophysiology and Management of Blast Injury
D J Read CSC
Royal Darwin Hospital, Darwin, NT
Introduction
Blast injury has traditionally been the domain of the Military Surgeon, but with recent terrorist bombings targeting civilians, any clinician could be called upon to treat this most demanding mechanism of wounding. This talk will cover the basics of pathophysiology and management of blast injury, and give advice on the handling of mass casualties, based on the author’s experience from the two Bali Bombings and Iraq.
To appreciate the enormous wounding potential of blast it is necessary to understand the mechanisms of wounding. It should be empahsised that the mechanisms below result in a complex combination of barometric, blunt, penetrating and thermal injury. These not only frequenly coexist, but also have a propensity to effect multiple parts of the body at once. Blast injury can be classified as follows(1)
Primary Blast Injury: The effect of a pressure wave on air/solid interfaces is responsible for this mode of wounding. Consequently areas of air/solid interfaces are most effected, ie the tympanic membranes will rupture, the lungs will suffer an ARDS type picture and the bowel may rupture, particularly small bowel and especially if submerged.
Secondary blast injury represents he effects of missile injury. This can be part of the explosive device itself (shrapnel) or other material caught in the blast. Both types were evident in the blast of Bali II (2005), the preformed ball bearings representing the prior, the pieces of sand wood and glass from the restaurant the latter. Not all missiles from a blast penetrate – larger fragments eg a fragment of brick from a wall can cause significant blunt injury.
Tertiary blast describes the damage caused by displacement. A massive difference in pressure (blast overpressure) can rip of limbs, or fling a casualty across some distance, once again opening up the possibility of blunt/deceleration injuries.
Fourth Degree injury refers to burns, which includes airway burns.
Fifth degree refers to crush injury, usually from a collapsing building or overturned vehicle.
Inherent in the management of blast injury is the ability to handle mass casualties. Whereas a bullet is designed to wound one, blast will wound many.
At the scene or at the ’casualty clearing area’ accurate triage is imperative, and enormously testing. The Royal Darwin Hospital’s experience of sending senior clinicians forward was successful on both occasions. Some practical aspects include the usefulness of torches, making pens and the use of ketamine.
At the receiving hospital level, a well rehearsed, adaptable disaster plan aids greatly in response. Lessons learnt from the Royal Darwin Hospitals experience in 2002 and 2005 are discussed.
Time of Presentation
Saturday 13 May 2006 - 1330-1500
References
(1) Mellor et al, Chapter 4 - Ballistic and Other Implications of Blast, in “Ballistic Trauma. Clinical Prevalence in Peace and War. J M Ryan et al. 1997 Arnold
