Intracranial pressure (ICP): Difference between revisions
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*Normal ICP: <10-15 mmHg, varies w/ age, position, straining, & coughing | *Normal ICP: <10-15 mmHg, varies w/ age, position, straining, & coughing | ||
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== Monro-Kellie doctrine == | == Monro-Kellie doctrine == | ||
* ↑ in vol. of one intracranial compartment → ↑ ICP unless offset by ↓ vol. in another compartment | * ↑ in vol. of one intracranial compartment → ↑ ICP unless offset by ↓ vol. in another compartment | ||
* Brain parenchyma predominantly incompressible fluid, CBV & CSF key in buffering additional intracranial volume by ↑ venous outflow/↓ CBF, displacing/↓ intracranial [[CSF]] | * Brain parenchyma predominantly incompressible fluid, CBV & CSF key in buffering additional intracranial volume by ↑ venous outflow/↓ [[CBF]], displacing/↓ intracranial [[CSF]] | ||
* Infants have extra volume compensation w/ open fontanelle | * Infants have extra volume compensation w/ open fontanelle | ||
* Pathologic processes can easily ↑ ICP by exceeding compensatory capacity due to small size of CBV & CSF compartments | * Pathologic processes can easily ↑ ICP by exceeding compensatory capacity due to small size of CBV & CSF compartments | ||
| Line 23: | Line 23: | ||
*formation of cerebrospinal fluid (If) | *formation of cerebrospinal fluid (If) | ||
*sagittal sinus pressure (PSS) | *sagittal sinus pressure (PSS) | ||
<hr> | |||
= ICP monitoring = | |||
== Purpose of ICP monitoring == | |||
# Early warning | |||
# Goal directed Tx | |||
== Indications (BTF) == | |||
# abnml CT | |||
# GCS <9 | |||
# Hx of TBI | |||
[[Category:Neurophysiology]] | [[Category:Neurophysiology]] | ||
[[Category:Neurotrauma]] | [[Category:Neurotrauma]] | ||
Latest revision as of 05:26, 22 November 2024
- Normal ICP: <10-15 mmHg, varies w/ age, position, straining, & coughing
ICP & intracranial volume
- Brain parenchyma: 1400 ml (80% total, 10% solid, 70% tissue water)
- CBV: 150 ml (10% total)
- CSF: 150 ml (10% total) (tot. ~1700 ml)
Monro-Kellie doctrine
- ↑ in vol. of one intracranial compartment → ↑ ICP unless offset by ↓ vol. in another compartment
- Brain parenchyma predominantly incompressible fluid, CBV & CSF key in buffering additional intracranial volume by ↑ venous outflow/↓ CBF, displacing/↓ intracranial CSF
- Infants have extra volume compensation w/ open fontanelle
- Pathologic processes can easily ↑ ICP by exceeding compensatory capacity due to small size of CBV & CSF compartments
Pressure-Volume curve
- Additional intracranial volume initially accommodated w/ little/no Δ ICP (flat part of curve)
- Once craniospinal buffering capacity exhausted (decompensation point), small ↑ in intracranial vol. → substantial ↑ ICP
Davson equation
ICP = If * Rout - PSS
- resistance to cerebrospinal fluid outflow (Rout)
- formation of cerebrospinal fluid (If)
- sagittal sinus pressure (PSS)
ICP monitoring
Purpose of ICP monitoring
- Early warning
- Goal directed Tx
Indications (BTF)
- abnml CT
- GCS <9
- Hx of TBI