Template:TBI pathophysiology: Difference between revisions
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===[[TBI]] Pathophysiology=== | ===[[TBI]] Pathophysiology=== | ||
====Primary injury==== | ====Primary injury==== | ||
* | *Contusions | ||
**bruises to brain parenchyma | **bruises to brain parenchyma | ||
*Hematomas | *Hematomas | ||
| Line 35: | Line 17: | ||
====Secondary 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'' | ''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 | *Leads to expansion of the original injury (predominantly metabolic insult) | ||
*Calcium and | **Calcium and sodium shifts | ||
*Mitochondrial damage | **Mitochondrial damage | ||
*Production of free radicals | **Production of free radicals | ||
*Ultimately leads to damage to axonal integrity and axonal transport | *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 | *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 | |||
*Cushing Reflex- more common in children than adults | |||
**Hypertension | |||
**Bradycardia | |||
**Respiratory Irregularity | |||
Revision as of 13:48, 23 November 2017
TBI Pathophysiology
Primary injury
- Contusions
- bruises to brain parenchyma
- Hematomas
- Epidural
- Subdural
- Intraparenchymal
- Intraventricular
- Subarachnoid
- Diffuse Axonal Injury
- Direct Cellular Damage
- neurons
- axons
- tearing and shearing of tissues
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
- Use CPP as surrogate
- Autoregulation allows the body to control the cerebral blood flow
- Autoregulatory mechanism is damaged in most TBI patients
- Cushing Reflex- more common in children than adults
- Hypertension
- Bradycardia
- Respiratory Irregularity