CSF, ICpressure and cerebral blood flow Flashcards
what is monroe-kellie doctrine
skull is closed compartment with fixed volume - change in volume = change in pressure
what is content of skull (3)
- brain
- blood
- CSF
where is CSF made
choroid plexu
what is total CSF col
120ml
what is CSF flow
lateral vent>3rd vent>cerebral aqueduct>4th vent.>subarachnoid space>absorbed by arachnoid villi
where is CSF
30ml in vents, the rest in subarachnoid space
what is normal ICP
9-12mmH2O
what can change ICP
changes in volume of intracranial vault - mass effect, fluid leak
what are 2 stages of high ICP
- organ dysfunction (smonolence, confusion)
2. organ failure (loss of cons., coma, death)
how much of blood does brain get
15% of body
what is normal brain perfusion
50-55 ml/min/100g
what are 2 problem levels
ischemia when under 18-20
cell death under 8-10
what is formula for CBF
CBF = Cerebral perfusion pressue/CVR
what is CPP formula
MAP-ICP
3 causes of intracranial hypertension
- obstructed CSF flow or absorbtion
- increased intracranial contents (tumor or hemmorage)
- generalized brain edema (trauma, hepatic encephalopathy)
2 types of hydrocephalus
- non-communicating (block)
2. communicating (poor abs., or rarely too much production)
3 causes of immediate morbidity or mortality in subarachnoid hemm
- rupture associated trauma
- acute hydroceph
- repeat hemmoracg
what is ventriculoperitoneal shunt
valve that drains the fluids into the peritoneum
what is aqueductal stenosis
non-communicatin hydroceph
3 ways to decrease ICP
- lower CSF vol
- lower CBV
- releive mass effect
how to decrease CSF (3)
- external diversion
- lower production - acetezolamide - carbonic anydrase inhib
- decrease brain ISF - mannitol
4 ways to decrease CBV
- normalize pCO2 and O2
- max venous outflow (vertical)
- decrease pCOS - hypervent
- increase CPP – paradoxically can lower ICP
2 ways to lower mass effect
- expand space
2. remve tumor
