Template:TBI pathophysiology

Revision as of 14:30, 23 November 2017 by Rossdonaldson1 (talk | contribs) (Cerebral Blood Flow and Autoregulation)
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TBI Pathophysiology

Primary injury

Secondary injury

Brain swelling causes increased ICP which compresses the tissue causing ischemia with direct compression of the vasculature causing brain tissue herniation and brain death

  • Leads to expansion of the original injury (predominantly metabolic insult)
    • Calcium and sodium shifts
    • Mitochondrial damage
    • Production of free radicals
  • Ultimately leads to damage to axonal integrity and axonal transport
    • Enzyme activity leads to apoptosis
  • Microscopic structural injury is often unidentifiable on CT or MRI

Cerebral Blood Flow and Autoregulation

  • vasoconstriction
    • HTN, Hypocarbia, alkalosis
  • No good way to measure cerebral blood flow
    • Use CPP as surrogate
      • CPP is amount of pressure needed to perfuse the brain
      • CPP=MAP-ICP
        • When ICP elevates, CPP decreases
        • Normal ICP
          • 15 in adults
          • <10 to 15 in children
          • 1.5 to 6.0 in infants
  • Autoregulation allows the body to control the cerebral blood flow
    • Autoregulatory mechanism is damaged in most TBI patients