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2011-06-05 14:18:12
Map High Energy Blast

MAP Final - High Energy Blast
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  1. shock heating mechanism of blast
    • -cause by passage of shock front (initial disturbance of air) through the air
    • shock front heats the air to 1000s of degrees
    • -primary cause of burn injuries from blast, not fireball, which is actually the coolest part of the explosion
  2. impluse
    • -main parameter that correlates to damage done by the blast
    • -pressure/time
    • -you can graph the pressure and see it spike, decay and then go slightly negative, area under the curve is the impulse
    • -**better predictor of injury than peak pressure**
  3. blast signature
    • -positive and negative phase of pressure
    • -signature is graph showing impulse
    • -most blast signatures are complex, not "free field", due to reflections of waves off surfaces
  4. reflected blast pressure
    • -reflected pressure is greater than incident pressure, greater than the "predicted" blast pressure, because you add reflected to normal
    • -the biologically relevant pressure
  5. Categories of Blast Injury
    • primary: cause by direct blast energy
    • secondary: projectiles from the blast
    • tertiary: from being propelled by blast and hitting something
    • quaternary: other- inhalation, burns

    *all happen together
  6. Bowel and Blast injury
    • most susceptible
    • -edema, hemorrhage, laceration and ruptuer
    • -progress to perforation
  7. Solid Organs and Blast Injury
    • liver and kidney
    • -more resistant than gas containing organs
    • -lacerations and fractures
  8. Lungs and Blast Injury
    • -leading cause of death
    • -gas exacerbates injury ( like bowel)
    • -cause by barotrauma, compression then decompression, putting alveoli under tension, either rupturing them or damaging membranes, causing fluid leakage --eduma and hemorrhage
  9. Heart and Blast Injury
    • -air emboli leading to infarcts
    • -bruising can occur
    • -myoelectric disruption
  10. Identifying Blast Lung Injury
    • -respiratory difficulty
    • -one side worse then the other
    • -crackles
    • -decrease oxygen sat
    • -see fluid in lungs on radiograph
  11. Head and Blast Injury
    • Ear: not lethal, but low threshold of injury
    • Eye: a secondary blast problem
    • Brain/CNS: more sensitive than previously thought, skull is not rigid, blast wave coupling a concern
  12. Transient Neurotrauma Effects
    • -apnea, bradycardia, hypotension
    • - can be fatal if left alone**
  13. Acute Neurotrauma Effects
    • -edema, pial hemorrhage, increased ICP
    • "blast brain"
  14. Chronic Neurotrauma Effects
    -degenerative cascade leading to injured/dead axons, neurons, astrocytes
  15. Near-Term Post Blast Systemic Physiology
    • Traid of Vagally Mediated Transient Symptoms:
    • 1. HR drop
    • 2. O2 sat drop
    • 3. respiratory rate drop

    --then the values recover