Dec. 2, 2019 Flashcards
How does the cranium of and adult differ form that in an infant? How does this relate to inc INTRACRANIAL PRESSURE (ICP)?
In adults the cranium is fused and fixed together, in an infant the bones are not yet fused. This mean that when there is an inc in ICP the infants cranium is (too an extent) able to expand, whereas the adults is not
What % of the brain is made up of tissues? What % is B/CSF?
Tissue - 80%
B/CSF - 10% each
What is the usually amount of ICP in mmHg?
5 - 15 mmHg
How do you calculate CEREBRAL PERFUSION PRESSURE (CPP)?
MAP - ICP
Usually 60 - 80 mmHg
How do you calculate MAP?
S + (2 x D) / 3
Below what CPP does CEREBRAL ISCHEMIA set in?
A CPP of below 50
What is the MONRO-KELLIE hypothesis?
That small fluctuations in tissue or fluid volume are compensated for by each other to maintain a stable ICP
What are PROLIFERATING LESIONS? What effect do these have on ICP?
Tumor or hemorrhage, these cause volume changes in the cranium which inc ICP
What happens in the 1st compliance for inc ICP?
- Displace CSF: push it into the spinal cord
- Secrete less CSF
- Reabsorb more CSF
What happens in the 2nd compliance?
There will be a dec in perfusion
What is the limitation of the 2nd compliance?
Perfusion can only be dec by a certain amount because if there is too much dec in perf, this will result in CEREBRAL ISCHEMIA
What is the final consequence of inc ICP?
Brain compression and displacement
What are the MNFTs of inc ICP?
Cushing's Triad - Widening pulse pressure (HTN) - Irregular breathing d/t impact on brain stem and respiration center in the brain - Bradytardia
How might l/o Fx result from a hemorrhage in the brain?
When a vessel is bleeding the tissue distal to it will become ISCHEMIC
How might l/o Fx result from a hematoma in the brain?
The hematoma may press on a spot in the brain that is control of a specific Fx, and the compression may result in l/o Fx at both the local, and target site
What tissue is affected in an INTRACEREBRAL hemorrhage/hematoma?
The brain tissue
Where would an EPIDURAL bleed be taking place?
Between the cranium and the DURA MATER
What vessel is usually severed in an EPIDURAL bleed?
The middle meningial A
- Lots of B loss because this is an A
Where does a SUBDURAL bleed take place?
Between the DURA MATER and ARACHNOID MATER
How do the membranes affect HEMATOMAS in a SUBDURAL bleed?
They encapsulate the HEMA
How do RBCs contribute to a SUBDURAL HEMA?
While encapsulated they are lysed, and their contents are released. This incs the concentration of solutes in the HEMA, which incs the OSMOTIC PRESSURE (pull). This will pull more fluid into the HEMA, causing dehydration d/t cellular efflux
What are the risk factors of developing a brain bleed?
- Aging (after the age of 50)
- Degenerative changes
- Higher risk of ANEURYSM (rupture)
- DM
- HTN
A CVA has what effect on B flow?
Acute ISCHEMIA
What is the difference between a focal and global CVA?
Focal - Small vessel affected
Global - Large vessel affected
Ischemia in the brain causes…
…acute neurologic impairment
What is the difference between a red stroke and a white stroke?
Red stroke = HEMORRHAGIC stroke (~20% of CVAs)
White stroke = ISCHEMIC stroke (~80% of CVAs)
What is one major risk factor for having a stroke?
Atherosclerosis
A brief overveiw of the patho for a CVA?
Vessel blockage -> inadeq perf -> hypoxia -> brain cannot metb anaerobically -> infarction w/in mins
What 2 components are essential for aerobic metb?
O2 and glucose
What is a NECROTIC CORE?
The infarcted, permanently dead cells in the brain d/t a CVA. The core is surrounded by perfused (but not optimally perfused) brain cells
What is the PENUMBRA?
The moderately perfused brain cells surrounding the NECROTIC core, still salvageable but will die if left
Brief overview of a HEMORRHAGIC CVA
Severed vessel -> hemorrhage -> brain compression -> hypoxia etc
Complications of a CVA?
- Coma
- Death
