Increased Intracranial Pressure Flashcards
This powerpoint is going to be from the recording from the increased intracranial pressure
First thing is we must understand what is in our head before we start talking about the fluid that will increase the pressure in our head.
The skull has 3 essential components which are ?
Brain tissue
Blood
Cerebrospinal fluid (CSF)
what are some factors that influence increased intracranial pressure ?
arterial pressure
venous pressure
intraabdominal and intrathoracic pressure
posture
temperature
blood gases (co2 levels)
something we need to understand and know is something called the
monro-kellie doctrine
what is this ?
if one of the three component of the skull, so blood, brain tissue or CSF increases, the other two will decrease in order to maintain balance of intracranial pressure
monro-kellie doctrine only works if what?
the skull is closed
what is normal intracranial pressure ?
5-15
when is our concern for intracranial pressure, like at what number ?
more than 20 and its sustained
what are some normal compensatory adaptations your body does in order to help maintain normal intracranial pressure? (3)
think of the 3 components again
changes CSF volume
changes in intracranial blood volume
changes in tissue brain volume
its very important to note that the body ability to compensate is what?
very limited
once our ability to compensate is gone, or if intracranial pressure increases, we are going to do what?
decompensation
we do look at something called cerebral blood flow when the patient is having increase intracranial pressure.
what does cerebral blood flow mean ?
the amount of blood in milliliters passing through 100g of brain tissue in 1 minute
typically what is the normal cerebral blood flow ?
50ml/min per 100g of brain tissue
the brain uses __% of the body oxygen
the brain uses __% of its glucose
20
25
something to add here, its important to note that we keep talking about perfusion and glucose levels, why do think that?
the reason why we keep mentioning about perfusion is because of the fact that when the body is struggling to maintain adequate circulation , the body will shunt oxygen from “unimportant areas.” and focus mainly on the important ones, like the brain and the heart, which is why we see that the brain uses 20% of oxygen
we mentioned before for glucose that a diabetic patient is in more critical care due to hypoglycemia than hyper, and the reason is for the fact that we are using over 25% of our glucose in our brain to function, so when we dont have enough, we have those neuro changes
what is auto regulation ?
this is something the body will do on its own to compensate by the way before we begin to decomp
adjusts diameters of blood vessels to ensure consistent blood flow
auto regulation is only effective when ?
the mean arterial pressure (map) is 70-150mm hg
what does cerebral perfusion pressure mean ?
the amount of pressure needed to ensure blood flow to the brain
what is normal cerebral perfusion pressure ?
60-100
less than 50 cerebral blood flow is associated with what 2 things ?
ischemia
death of neurons
there are 4 stages of increased intrancranial pressure, which are ?
stage 1 : total compensation
stage 2: decrease compensation and risk for increase intracranial pressure
stage 3 : failing to compensate ; clinical manifestations of increase intracranial pressure ( Cushing triad )
stage 4 : herniation imminent -> death
stage 1 its the total compensation, what are the 2 things that are happening ?
accommodation and auto regulation intact
stage 3 is the failing to compensate and clinical manifestations are becoming present for increase intracranial pressure
stage 3 is also known for what other situation ?
Cushing’s triad
what are the 3 factors that affect cerebral blood vessel tone ?
carbon dioxide
oxygen
hydrogren ion concentration
how does carbon dioxide affect cerebral blood vessel tone ?
what happens when its increased
what happens when its decreased
increase co2 causes smooth muscle relaxation, dilation of vessels, improved CBF
- slow deep breaths, slower respiratory rate
- improved blood flow
decreased co2 causes vasoconstriction and decreased CBF
- hyperventilation
- decreased blood flow
how does oxygen affect our cerebral blood vessel tone ?
low levels of oxygen causes dilation, but will cause anaerobic metabolism and lactic acid build up and then cellular death
how does hydrogen ion concentration affect cerebral blood vessel?
results from lactic acid build up, acidosis and vasodilation - auto regulation is lost
usually a result from low oxygen and then goes into metabolic acidosis
then with that lactic acid build up, we have acidosis and vasodilation of the vessels and the ability to compensate is gone pretty much
increased intracranial pressure is life threatening
its caused by an increased in any of the 3 components, which are ?
brain tissue, blood, CSF
cerebral edema
hypercapnia, cerebral acidosis, impaired auto regulation, hypertension
in the powerpoint she uses a good diagram to describe the steps of having increased intracranial pressure
there are 5 steps
what is the 5 steps.
first one to start us off is brain injury
- brain injury
- tissue edema causing increased intracranial pressure
- compression of brain tissue and decreased blood flow
- necrotic tissue and edema
- increased CO2 causing vasodilation and increase intracranial pressure
what are some clinical manifestations that we see in a patient who has cerebral edema ? (2)
think very broad
change in level of consciousness
change in vital signs
how does the patient appear when they have a change in level of consciousness when they have cerebral edema?
flattening of affect -> coma
( no emotion, no facial expression, tone of voice is very flat, avoid eye contact, very bored and uninterested )
- confusion, agitation, combativness
what are some changes in vital signs when we see a patient who has cerebral edema? (2)
Cushing’s triad
change in body temperature
what is Cushing’s triad in cerebral edema Clincal manifestation ?
we do need to know this
5 things apart of this
systolic hypertension with widened pulse pressure, bradycardia with bounding pulses, irregular respirations
Cushing’s triad is a what?
medical emergency
why do we have a change in body temperature when the patient is having cerebral edema?
usually its a what?
the hypothalamus regulates our body temperature, so when we have increased pressure, our hypothalamus can regulate it and will cause us to be unable to maintain a good body temp
hyperthermia ( hot, fever )
patients can have a compression of oculomotor nerve, what do we check for ? (4)
unilateral pupil dilation
( occurs on ipsilateral (same) side as the lesions )
- dilation of the pupil of the side of the injury
sluggish or no response to light
inability to move eye upward
eyelid ptosis (drooping of the eyelid)
clinical manifestations
other cranial nerves
- diplopia, blurred vision, eom changes
central herniations can manifest as ___
uncle herination causes ____
papilledema presents with __
sluggish but equal pupils
dilation of unilateral pupil
( one pupil )
persistent increased in intracranial pressure
( can also be seen with severe hypertension )
patients may also experience decrease in motor function
what is contralateral hemiparesis/hemiplegia ?
a patient may find it very hard to move, typically the opposite side of the lesion
so like I hurt the right side of my brain, so I can’t move anything on my left side of the body
posturing a very important indictor on the severity of the brain injury or overall increased intracranial pressure.
we have 4 types, what are they called ?
decorticating posturing
decerebrate posturing
mixed-decorticate
opisthotonic