Intracranial pressure (ICP): Difference between revisions
Jump to navigation
Jump to search
| Line 3: | Line 3: | ||
*Brain parenchyma: 1400 ml (80% total, 10% solid, 70% tissue water) | *Brain parenchyma: 1400 ml (80% total, 10% solid, 70% tissue water) | ||
*CBV: 150 ml (10% total) | *CBV: 150 ml (10% total) | ||
*CSF: 150 ml (10% total) <small>(tot. ~1700 ml)</small> | *[[CSF]]: 150 ml (10% total) <small>(tot. ~1700 ml)</small> | ||
== 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 | ||
Revision as of 00:24, 9 August 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)