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57 Cards in this Set
- Front
- Back
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What are the 3 components that make up the skull?
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brain tissue
blood cerebralspinal fluid |
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What is intracranial pressure?
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a very important way to monitor a pt with possible elevated pressures
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Intracranial pressure is from?
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the pressure exerted by the total volume of the brain tissue, blood, and cerebralspinal fluid-should remain constant.
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What is normal intracranial pressure?
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0-15 mm HG
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What might happen in your brain if you start to have a bleed, or brain tissues get inflammed?
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Brain might decrease the CSF so blood has room to spread or decrease the blood so the brain has room to enlarge
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How much volume is in the brain?
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120 ml of volume
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What is normal intracranial pressure?
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Normal ICP:0-15
Laying flat:7-15 Standing up: below 0 |
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What are the factors that influence ICP?
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Arterial pressure- HTN, clots can cause blockages
Venous pressure: heart failure w/backup of fluids IntraABD and intrathoracic pressure-lifing, straining, coughing, bathroom, exercising Posture Temperature-vasoconstrict or vasodilate |
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How do blood gases affect intracranial pressure?
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Blood gases-
CO2 levels HIGH H are HIGH or if 02 levels are LOW -ALL CAUSE VASODILATION-- Increases blood flow, increase ICP |
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All of these factors effect the brain how?
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We have a limited way of compensating in our brain, but, the degree of the increase in ICP depends on the ability of the brain to accomodate
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The ability for the brain to adapt to slight changes in the skull is called? who does it not apply to?
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Modified Monro-Kellie doctrine
Does not pertain to neonates or ppl with displaced skull fractures |
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Does the total intracranial volume in skull ever change?
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no, it cannnot. If Volume of one of the components increases, then another one is displaced.
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What are the normal compensatory mechniasms of the body to adapt to an increase in intracrainal pressure (limited ability)?
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1. can alter CSF production or absorption
2. can displace excess CSF in spinal subarachnoid space 3. vasoconstriction/dilation 4. distention of dura or compression of brain tissue |
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How does the brain get glucose?
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it uptakes it itself- does not need insulin!
Lack of glucose for 5 minutes results in irreversible brain damage |
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What regulates the brain flow?
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The brain itself b.c it is the most important organ in our body. Blood is shunted away from other organs in the body
Uses 20% oxygen, 25% glucose |
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How much blood in ml passes through 100g of the brain tissue in 1 minute?
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50 ml/min per 100 g of brain tissue (delievers the oxygen)
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What is the equation for cerebral profusion pressure?
and what is the normal value? |
CPP= Mean arterial pressure-intracranial pressure
CPP should be 70-100 ICP should be 0-15 |
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A value of what CPP is death?
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30 and below
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What CPP value is ischmia and neuronal death?
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50
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Explaint the 4 stages of the intracranial pressure graph?
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Stage 1: high compliance
stage 2: decrease in compliance, increase risk for ICP stage 3: any small addition in volume causes a great increase in ICP, loss of autoregulation stage 4:ICP rising to lethal death |
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What are the main factors that affect the cerebral blood flow?
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CO2 O2 Hydrogen ions
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How does CO2 increase actually adffect cerebral blod flood?
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increase in PaCO2 relaxes smooth muscles, dilates cerebral vessels
INCREASES CEREBRAL BLOOD FLOW (think: its wanting 02) |
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How exactly does low 02 concentration/ high levels of H+ ions affect cerebral blood flow?
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Vasodilators- seen in pt with acidosis
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What is an emergency way to decrease hydrogen ions to try and decrease intracrainial pressure?
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you can blow off H ions concentrations and CO2 levels
-used to be a standard in ICU, but now studies show this can lead to focal problems ---in emergency, can be used if its absolutely necessary-- |
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Increased ICP is from?
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Any situation that causes an increase in brain tissue, cerebralspinal fluid, or blood in skull will cause ICP.
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What kind of edema could be a cause of ICP?
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increased cerebral edema (know there are 3 types: vasogenic, cytoxic, interstitial)
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Describe what vasogenic cerebral edema is caused by?
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Capillary permeability-protiens and fluids enter blood brain barrier d/t breakdown in entry. *Most common form of cerrebral edema
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What is cytoxic cerebral edema?
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blood/brain barrier is intact here.
Disruption in cell membranes-causes cerebral edema |
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What is interstitial cerebral edema?
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Diffusion of cerebralspinal fluid in pt with uncontrolled hydrocephalus or systemic water excess
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What are the typical causes of cerebral edema?
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brain surgery
Meningitis, encephalitis Mass lesions hemorrhages head injuries vasular accident toxic or metabolic conditions-uremia, hepatic encephalopathy arsenia/lead intoxication |
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Explain how the body tries to fix its self but really is working against itself to fix cerebral edema?
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Insult-swelling-pushing on blood vessels. Brain tells body to vasodilate and bring 02 in so brain doesnt get ischmic---more edema---more ICP
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What is the earliest signs of increased intracranial pressure (may or may not be seen? ?
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Vision Blurred
HA projectile vomiting, no nausea |
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What #1 sign would absolutely tell us pt is having increased intracranial pressure?
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Change in level of conciousness
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What kind of vital signs would we see in a pt with increased intracranial pressure?
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Cushing's triad-
Hypertension (high systolic with widening pulse pressure -High high systolic, diastolic is not going really high) Bradycardia Irregular respirtations |
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Why do you see the Cushings triad in ICP pt?
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ICP--pt has decreased CPP-activated sypathetic nerve system--vasoconstriction--increased contractability of heart, increased cardiac out--HTN. Increased BP picked up by barorecptors in carotid arteries-stimulates vagal (flight response)- bradycardia. Pressure on brain stem affects respiratory centers-build up of CO2.
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What are the occular signs in pt with increase ICP?
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pupil dilation and changes in reactivity
Unilateral at first depeneding on what side of brain affected, then bilateral |
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If pt becomes acutely unconcious, you better suspect
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an increase in INTRACRANIAL PRESSURE
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Dilated pupils can indicate?
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pressure on crainial nerves. Pinpoint pupils can be pons damage or on drugs
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What does the more serious postuing look like in a pt with loss of motor function experiencing increase in ICP, called decerabrate posturing?
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Extensor -upper and lower limbs extended following a stimulus.
Indicates brain damage below nucleus. VERY BAD |
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What is the decorticate posturate position in coma pt?
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"mummy like" position- not as serious. Upper limbs flexed over body, lower limbs extended
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What is the glascow coma scale used for? and what 3 areas do you numerically assess?
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assess how pt is doing neuro wise:
eye opening verbal response motor response |
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How does the scale work?
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the higher the number, the better off you are
best is 15/15 |
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3-5 glascow scale number means?
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probably fatal
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If your number is 8 or below,
How is none? What does 3 mean? |
trouble!
0=none, worst than deceribrate 3 means no respone in pupils, verbal, or motor funtion. (1=none) BAD |
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What diagnostic tests might pt need if suspect ICP?
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MRI
CT Angiography-leaks EEG-brain is firing O2 measure measuring ICP |
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What is the nursing care assciated with increase intracranial pressure?
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Neuro check with glascow scale 1-2 hours, fluid/electrolyte assessment, grips, pupils
MAINTAIN AIRWAY |
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What is an exact way to monitor the pt with ICP's respiratory/02 function?
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Pa02-maintain 100 mmHG or more
ABG analysis guides 02 therapy Mechanical ventillator? |
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What body postion should be maintained in ICP pt?
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HOB up 30 degrees, if not contraindicated
Turn to prevent ulcers |
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GI wise, what must you watch for?
Can pt cough? |
Constipation and bladder distention
NO COUGHING These all increase ICP d/t straining |
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Spread out nursing activity, why?
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less stimulation on pt brain, less stress, can decrease pressure or put less on it
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What is the gold standard for measuring intracranial pressure?
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VENTRICLES
*** all methods open the pts brain to outside world, huge risk of infection. |
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What other places we can measure intracranial pressure?
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subarachnoid space
epidural space brain parenchymal tissue |
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What kind of pts would we monitor ICP this closely?
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Admitted with Glasgow Coma scale of 8 orl less
those with abnormal CT scans or MRI |
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What is one of the benefits of monitoring intracrainial pressure so invasively?
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you can intermittenly remove fluid as well
-document as output |
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What is the drug therapy for ICP pts?
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Mannitol-Osmoti diuretic
Corticosteriods- for swelling, watch for hypoglycemia, infections, GI bleed Barbiturates- decrease metabolic rate and needs of brain antiseizure meds-Dilantin-prevents seizure, preventing expenditure by body |
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How should we use the hyperventillation therapy in pt with ICP?
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Breif periods may be used for cerebral HTN
-contricts blood vessels , decreasing cerebral blood floow, decreasing ICP Only do every so often |
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For ICP pt, what kind of states will they be in (2)?
Increased need for what electrolyte? What is the key IV fluid for this pt? |
Hypermetabolic and hypercatabolic state
Increase need for glucose Keep pt normovolemic IV .9% NaCl |
