Exam 3 - Neuro Flashcards
3 essential components of the skull
brain tissue
blood
CSF
factors that influence ICP
arterial pressure
venous pressure
intaabdominal, intrathoracic pressure
posture
temperature
blood gas (CO2 level)
normal ICP is __ to __ mmHg
5-15 mmHg
when is ICP considered elevated
sustained >20 mmHg
cerebral blood flow is what
amount of blood in mL passing through 100 G of brain tissue in 1 minute
what is the average cerebral brain flow
50 mL/100 G of brain tissue
what occurs during auto-regulation of cerebral blood flow
adjusts diameter of blood vessels
ensures consistant CBF
only effective if MAP is 70-150 mmHg
how to calculate cerebral perfusion pressure (CPP)
MAP - ICP = CPP
what is considered a normal CPP
60-100 mmHg
CPP < __ mmH is associated with ischemia and neuronal death
< 50 mmHg
there are __ stages of increased ICP
4
stage 1: increase ICP
total compensation
stage 2: increased ICP
decrease compensation
RISK for increase ICP
stage 3: increased ICP
failing compensation
clinical s/sx of increase ICP (Cushing’s Triad)
stage 4: increased ICP
herniation imminent = death
increase ICP can occur when there’s an increase of any of these 3 components
brain tissue
blood
CSF
what is cerebral edema
increase extravascular fluid in the brain
what are the 3 types of cerebral edema
vasogenic
cytotoxic
interstitial
what is the most common type of cerebral edema
vasogenic
where does vasogenic cerebral edema occur
mainly in white matter
what occurs during vasogenic cerebral edema
fluid leaks from intravascular to extravascular space
what is the cause of cytotoxic cerebral edema
secondary to destructive lesions or trauma to brain tissue
what occurs during cytotoxic cerebral edema
fluid shifts from extracellular to intracellular
what is the cause of interstitial cerebral edema
usually a result of hydrocephalus
how is interstitial cerebral edema treated
ventriculostomy or shunt
what is Cushing’s Triad
increase SBP
decrease HR
decrease RR
**remember CT s/sx are opposite of shock
s/sx of cerebral edema
change in LOC (flat affect, coma)
Cushing’s Triad
diplopia, ptosis
change in body temp
inability to move eye upward
unilateral pupil dilation
vomiting (not preceded by nausea)
HA (often worse in the AM)
decrease motor function
decorticate vs. decerebrate vs. opisthotonic posturing
decort: flexion towards the core
decere: hyperpronation away from the body
opist: hyperflexion of the back
what are com complications of cerebral edema
inadequate cerebral perfusion
cerebral herniation
how to dx cerebral edema
CT**
MRI
PET
EEG
angiography
ICP, brain tissue oxygenation (LICOX catheter)
doppler
ABG
CBC, Coag, CMP
serum osmolality
what is NOT performed to dx cerebral edema
lumbar puncture
what must be assessed on a pt who needs sent for radiographic testing with suspected cerebral edema
airway
what is a normal serum osmolality
280-300
what will serum osmolality be with increased ICP
maintained >325
GSC measures which 3 areas
eye opening response
verbal response
motor response
what are some causes of inaccurate ICP readings
CSF leak
obstruction/kink in cath
bubbles, air in tubing*
incorrect height of drainage system
difference in height of bolt/transducer
what 2 things does LICOX catheter measure
brain oxygenation
temperature
nursing interventions for increased ICP
keep CPP > 70 mmHg
neurological exams
HOB no more than 30 degrees
neutral head positioning
VS (HTN is common; CT is a LATE sign)
GSC
seizure precautions
space activities
assess pt response to family members
what are some things to avoid with increase ICP
coughing
blowing nose
straining for BM
pushing against bedrail/footboard
isometric muscle exercises
serum osmolarity is kept between __ to __
310-325 to draw extracellular fluid into the vascular system
what kind of IVF is preferred for increased ICP
1/2 NS
NS
what kind of IVF should NOT be administered with increased ICP
NO hypertonic (3%)
NO hypotonic (D5W)
decadron and solumedrol are only effective for ___ and ___; it is NOT effective if r/t ___
effective: meningitis, tumors
not: trauma
HTN drug of choice with increased ICP
nicardipine
what must you turn off prior to assessing pupillary response
the room light
what occurs during oculocephalic reflex (dolls eye reflex)
eyes move when the head moves
what occurs during oculovestbular (caloric stimulation) test
cold water injected into ear, eyes should gaze towards that ear
normal: both eyes
asymmetrical: one eye
negative: no eye movement
must know the cranial nerves
must know the cranial nerves
