Blast Injuries: An Overview

All information on this page has been synthesized from the Blast Injury Information Fact Sheets developed by The TIIDE Partnership and CDC, under the leadership of American Trauma Society (www.amtrauma.org/page/BlastInjuries).¹

Introduction

Blast injuries, while often associated with mass casualty incidents in settings such as warfare or terrorism, are also prevalent in industrial accidents and other scenarios outside of combat zones. Such injuries can be complex, combining mechanical trauma with exposure to toxic substances. In this article we will cover solely mechanical blast injuries, outlining the four categories of injury and providing blast-specific clinical pearls to add general trauma management guidelines. This will be a quick hit article that should get you ready for both the boards and in the scenario of a mechanical blast patient presentation.

Categories of Blast Injury

Editors note: Who cares what we call these injuries? You should – and the people who will be communicating to you, and if you are in a place where you will be transferring a patient, those who you will be communicating with, will need you to be specific. We get it – the later you are in residency the easier it is to realize that these patients should be assessed like all your trauma patients. If nothing else, this breakdown of blast injuries provides us a framework that we can use to make sure we don’t miss things (such as looking in the patient’s ears for tympanic membrane rupture – when was the last time you really spent time in a patient’s ears during your trauma secondary exam?), and is an easily testable topic (and easy points) for the boards.

Primary

• Mechanism: increased air pressure from blast impacts body surface.
• Common Injuries: preferential damage to air-filled structures due to shearing forces from rapid compression and re-expansion.
  • Tympanic membrane rupture
  • Pulmonary contusion
  • Colon perforation and/or hemorrhage 

Secondary

• Mechanism: fragments launched by blast striking body surface. 
• Common injuries: primarily penetrating injuries, but also can cause blunt trauma.
  • Amputation
  • Penetrating eye injury
  • Laceration

Tertiary

• Mechanism: victim physically displaced by blast wind and striking surrounding objects.
• Common Injuries: primarily blunt force, however can cause penetrating wounds depending on surface struck.
  • Fracture
  • Traumatic Brain Injury (TBI)
  • Internal hemorrhage 

Quaternary

• Mechanism: all injuries that fall outside of the defined prior three categories. 
• Common Injuries
  • Burns
  • Toxic exposure
  • Crush injury 
  • Psychological 

System Based Pearls 

Head

Brain and cervical spine

• TBI can occur without loss of consciousness (LOC)
• The three most common injuries:
  • Diffuse axonal injury (DAI) from shearing forces
  • Cerebral contusion from coup counter coup forces
  • Subdural (SDH) from shearing of bridging veins
• Pediatric patients have proportionally larger heads, leading to increased rates of high spinal injury, assume cervical injury until proven otherwise, and place patients in a cervical spine collar²

Eye

• The eye is tough and resistant to primary pressure injury, with the most common presentation is bilateral penetrating injury
• Significant damage can be present with minimal symptoms and normal vision, using fluorescein stain and checking for Seidel sign³ will help rule out globe rupture
  • If you confirm globe rupture – give antibiotics, tetanus prophylaxis, and consult your ophthalmologist (they may want specific imaging)

Ear

• Isolated TM rupture is not a marker for more widespread primary blast injuries
• It is common to have temporary hearing threshold changes lasting hours to weeks
• Untreated ear injuries, though not life threatening, can have serious long term sequelae, provide ENT referral if symptomatic
• Treat TM perforation and external canal lacerations with antibiotic eardrops and local wound care – you may need ENT consultation for patients with disruption of the auricular cartilage

Lung/Chest

• Anyone with the mechanism to deliver a skull fracture, penetrating injury to torso or head, or burns >10% TBSA are high risk for concurrent traumatic lung injury
• Air emboli are higher on differential due to compressive shear forces on lung allowing air entry to arterial circulation
• Pediatric patients are at elevated risk of severe thoracic injuries in the absence of rib fracture as well as more rapid progression to tension pneumothorax due to increased rib and mediastinal compliance
• Mechanical ventilation and positive pressure have increased risk alveolar rupture and air embolism in these patients, if you need to intubate – use lung protective settings (ARDS settings – 6-8 cc/kg for tidal volume, appropriate PEEP)
• Judiciously administer IV fluids in those with lung injury due to elevated risk of pulmonary edema
• Consider toxins such as CO, cyanide, and methemoglobinemia in patients with refractory hypoxemia and respiratory distress
• Pulmonary blast injury acutely manifests on imaging as “batwing” appearance. If it doesn’t rapidly clear, admit patient for monitoring⁴

Abdomen

• Pediatric patients have more pliable ribs and thinner abdominal walls offering less protection to proportionally larger solid abdominal organs
• Remember that the FAST exam is not as sensitive or specific for intra-abdominal injuries in pediatric patients⁵

Extremities

• Assume all wounds contaminated – that means giving tetanus prophylaxis if none given within five years, antibiotics if needed (e.g. an open fracture), perform extensive irrigation of wounds if planning on primary closure
• Lower threshold for surgical intervention in penetrating trauma as small surface footprint can have extensive underlying damage due to irregular shape and increased contamination risk of blast debris (much like finger injection injuries in high-pressure paint applicators)
• Crush injuries can release intracellular contents (much like tumor lysis syndrome – potassium, phosphate, and uric acid) that in large enough concentrations can cause cardiac dysrhythmia and renal failure

Burns

• All burns >15% TBSA get fluids, even a delay of 4 hours to initiation has significant mortality consequences, the CDC still recommends Parkland formula but they acknowledges UOP is the best measure of perfusion status
• Buns count as wounds! Give tetanus prophylaxis if indicated 
• Full thickness burns to thorax and extremities may require escharotomy, especially in patients with concurrent lung injuries as these wounds can restrict thoracic expansion needed to drive adequate ventilation
• Intubate early if you suspect inhalation injury, before mucosal swelling from progressive edema can obscure views and lead to a difficult airway; as always resuscitate before you intubate, and be on the lookout for blast lung as discussed above

Psychiatric

Blast injuries present a multifaceted risk not only in terms of physical trauma but also in terms of significant long-term psychiatric impacts. These mental injuries can persist long after physical wounds have healed and affect EMS and ED providers as well as the blast victims themselves. Psychological effects can present as physical, emotional, cognitive, and behavioral manifestations in both acute and long term timeframes. Integrating mental health support into trauma care and acknowledging the risks to the healthcare team is vital to the longevity of the healthcare system. 

Summary

Blast injuries arise from various scenarios, such as warfare and industrial accidents, leading to complex mechanical trauma. These injuries are categorized into four types: primary, secondary, tertiary, and quaternary, each associated with distinct injury mechanisms and examples. We don’t often see blast injuries, so keep the above pearls in mind for managing different body systems affected by blast injuries. Alongside physical injuries, there is a significant psychological impact on victims and healthcare providers that we should remember to acknowledge and treat as well. In the end, most of us will see blast injuries on the computer screens while we take boards, but keep this article as a reference when you are faced with a real patient scenario.

Cite this post: Kirra Paulus, MD, Arman Hussain, MD. “Blast Injuries: An Overview”. GW EM Blog. 12/11/2024. Available at: https://gwemblog.com/blast-injuries-overview/

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References

1. American Trauma Society. “Blast Injury Information – American Trauma Society.” Amtrauma.org, 2024, www.amtrauma.org/page/BlastInjuries. Accessed 8 Dec. 2024. ↩︎
2. Fox, Sean. “Pediatric Cervical Spine Injury.” Pediatric EM Morsels, 8 Feb. 2019, pedemmorsels.com/pediatric-cervical-spine-injury/. ↩︎
3. iEM Education Project Team. “Siedel Test.” International Emergency Medicine Education Project, International Emergency Medicine Education Project, 22 Feb. 2019, iem-student.org/2019/02/22/siedel-test/. Accessed 8 Dec. 2024. ↩︎
4. Sinnott, J. D., et al. “Blast Lung.” BMJ, vol. 350, no. feb05 5, 5 Feb. 2015, pp. h363–h363, https://doi.org/10.1136/bmj.h363. Accessed 27 Nov. 2020. ↩︎
5. Liang, Tian, et al. “The Utility of the Focused Assessment with Sonography in Trauma Examination in Pediatric Blunt Abdominal Trauma.” Pediatric Emergency Care, Mar. 2019, p. 1, https://doi.org/10.1097/pec.0000000000001755. Accessed 26 Dec. 2019. ↩︎