Glossary of Intracranial Pressure

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What is the skull?
a closed compartment containing brain.
What is inside skull?
Tissue, brain make up 75% of skull contents.
Blood makes up 12% of volume.
Spinal fluid makes up rest.
What is the Monro-Kellie hypothesis?
if volume added = volume removed, the total volume does not change.
What is ICP?
the pressure exerted by tissue, blood, CSF on the cranial walls.
How is ICP measured?
manometer or transducer
What is normal ICP?
80-180 mm H2O
Sustained pressure above norms is considered
dura distensibility
ability of dura to stretch. The cranial vault limits its distensibility.
Is pressure more of a problem with closed or open head trauma?
Tissue plasticity
ability of brain tissue to be molded or compacted depends on amt. of interstitial fluid.
Can CSF volume be changed?
Yes, body can produce more or less CSF; can displace out of skull.
What substance will decrease production of SCF?
How much of the 135 ml of CSF is in the lateral ventricles?
25-35 ml
What is autoregulation in reference to blood volume and ICP?
the automatic alteration in diameter of the cerebral arteries so that there is a constant blood flow during changes in systemic arterial pressure.
Maintains a constant supply of O2 and glucose to brain and protects from too much fluid.
What are the limits of systemic blood pressure within which autoregulation can operate?
50 to 150 mm HG mean MAP.
What happens when MAP < 50?
vasodilatory response is ineffective so that blood flow (CPP) decreases and signs of ischemia occur.
What happens with MAP > 150?
Vasoconstriction fails so that flow increases to the point that the blood-brain barrier is disrupted and cerebral edema occurs.
What is CPP?
Cerebral perfusion pressure
How is CPP calculated?
MAP=Diastolic + 1/3 pulse pressure
Pulse pressure=diff. between diastolic/systolic
What is normal CPP?
60-90 mm Hg
What happens when CPP<30?
brain death - tissues not perfused.
What factors affect autoregulation?
Pressure changes
Cerebral oxygen tension - PO2 decreases, cerebral vessels dilate.
Metabolic factors: increased O2 and PCO2(most significant -resp. arrest, pneumonia, diabetic coma.
What is the most frequent cause of death with head injuries?
Increased cause of death with head injuries.
What is always a part of increase intracranial pressure?
cerebral edema. sometimes it's a cause, sometimes it's a result.
What is one of the 1st indicators, clinically, of increased ICP?
change in LOC that results from decreased blood flow and low O2 to cerebral cortex and RAS. Everything else is a late sign.
What causes vital sign changes?
Ischemic brainstem.
What is Cushings Triad?
What area of the brain is each associated with?
Elevated BP w/widening pulse-medulla
Bradycardia:full & bounding-pons and medulla
Irregular RR - pons
Is headache a late sign of inc. ICP?
Yes, due to stretching of dura - could be due to underlying problem.
Is vomiting without nausea a late sign of inc. ICP?
yes, often projectile - hypothalamus houses vomiting center.
Are pupillary changes a late sign of inc. ICP?
Yes, pupils react unequally or sluggishly. May have diplopia or blurred vision. EOM - nystagmus
What does an unequal pupil reaction indicate?
An abnormality in the side of brain of the abnormal pupil.
What does fixed, dilated pupil indicate?
Bad sign of possible herniation. Increased pressure pushes brain down and puts pressure on brainstem down to foramen magnum.
Is change in motor or sensory function a late sign of inc. ICP?
What is the major complication of IICP?
Herniation (subtentorial) of cerebellum and brainstem through foramen magnum may cause resp. arrest.
What is the #1 goal of management of IICP?
Support brain function
What is the #2 goal of IICP?
to identify and treat cause.
What is the #1 priority?
Oxygen. Keep PO2 at 100 mm HG or more; keep PCO2 at 25-35 mm HG or more.
Why should vasodilitation be prevented?
It will make ICP go up.
Can diuretics be used to treat IICP?
Yes. Loop or osmotic. Loop-lasix especially good and decreases the production of CSF. Either helps get rid of interstitial and intracellular fluid.
What should you watch when giving diuretics?
K+ and fluid volume
What are glucocorticoids and why can they be used to treat IICP?
antiinflammatories; Want to decrease inflammatory response and edema.
What should be monitored when giving glucocorticoids?
Blood sugar, electrolytes, I&O. Suppress immune system>fever.
Why are barbituates used to treat IICP?
They may decrease metabolic rate of brain cells; helps control seizures
What is used to control seizures caused by IICP?
Can antihypertensives and vasopressors be used to treat IICP?
Yes, depends on what's needed.
Are fluids restricted with IICP? Why or Why not?
Yes, restricted to 65%-75% normal (1600-1900 ml/day). Don't want to contribute to edema.
What kind of fluids are used initially with IICP?
isotonic - adjust to blood values.
What complication could occur from fluid restriction?
Blood becomes thicker, clots possible, can cause strokes > monitor.
What about nutrition and IICP?
Serum glucose should remain up and keep up serum albumin -may need feeding tube with protein.
Why do you initially use isontic fluids with IICP?
Don't want to shift fluids into cells. Typically give NS unless specific reason to give something else.
Is surgery an option for IICP?
Yes, as necessary to treat cause or relieve pressure.
Is suctioning appropriate nursing care with IICP?
Yes, but causes IICP, so suction PRN, briefly and hyperventilate before and after to keep oxygen up with 100% O2.
If suctioning is risky why do it?
For airway maintenance. Secretion my occlude.
What position should the bed be in for IICP.
Keep HOB up 30 degrees - increases venous output from brain through juggular.
Should abdominal distention be prevented?
Yes, abd. distention decreases ventilatory volume.
Are sedatives appropriate with IICP when there is an airway concern?
No, they should be avoided because they decrease RR and effort and decrease LOC.
When are sedatives appropriate?
When pts. are aggitated on vent. they may need sedative to decrease O2 demands, lower ICP, and allow vent to work properly.
What IICP nursing care applies to circulation?
whatever it takes to maintain blood flow perfusion to kidneys, liver, brain most important.
Are neuro checks important?
Yes, to evaluate progress/
Is F&E management important?
Yes. Diabetes Insipidus (decr. ADH)- inc. UOP - specific gravity should be low. SIADH (inc. ADH) - retain fluids. Specific gravity should be high.
What about pt. postion and IICP?
HOB 30 degrees. Venous output and helps ventilation.
Avoid flexion - decr. venous return from brain, puts pressure on jugular.
Should pt. be turned?
Yes, q2, carefully since turning can cause IICP.
Is safety an issue with pt. with IICP?
Yes, prevent injury. May try to get out of bed. Try not to use restraints.
What are 3 ways to measure ICP?
epidural sensor
subarachnoid bolt
intraventricular catheter
Epidural sensor
wire that goes through skull, lies between skull and dura mater. Not very invasive, decr. risk of bleeding,infection. Not very accurate.
Subarachnoid belt
Screwed down through meninges into subarachnoid space. Bolt must remain in patient. Sometimes develop fibrin clots at bolt. Fairly accurate, great risk of infection.
Intraventricular catheter
Places direct pressure. More invasive, great risks. Infection rate is higher. Could have cerebral hemorrhage.
Which monitor for measuring ICP is most accurate?
Intraventricular catheter.
What are factors contributing to IICP?
High CO2 content; low O2 content; valsalva maneuver; restricting body positions, coughing-sneezing, emotional upsets, REM sleep, arousal from sleep, medications as antihistamines.
surgery for ICCP is done...
as necessary to treat cause or relieve pressure.
Nursing management of airway for IICP...
Keep hob up to 30 degrees
avoid sedatives
prevent abdominal distention
What special precaustions should be taken when suctioning a pt. with IICP?
keep brief and hyperventilate with 100% O2 before and after to keep O2 up.
Why should the HOB be kept at 30 degrees for a pt. with IICP?
To increase venous output from brain through juggular.
Why is preventing abdominal distention important for someone with IICP?
That decreases ventilatory volume.
Why avoid sedatives?
They decrease RR and effort, as well as, decreases LOC.
Is there an exception to avoiding sedatives?
Yes, patients who are aggitated on ventilator may need these to decrease O2 demands, lower ICP, and allow vent to work properly.
What nursing management of circulation of pt. with IICP should be done?
Whatever it takes to maintain blood flow. Perfussion to kidneys, liver, brain most important.
Why should nurses to neuro checks regularly?
To evaluate treatment
What should be done to manage F&E management?
Watch for Diabetes Insipidus from decreased ADH.
Watch for SIADH from increased ADH.
What are the signs of diabetes insipidus?
Increased UOP. Specific gravity should be low.
What are signs of SIADH?
Retain fluids. UOP decreases, specific gravity will be high.
What nursing management of pt. position should be done?
HOB up 30 degrees. Avoid flexion of neck - decreases venous return from brain - put pressure on juggular.
Turn q2 carefully.
Why should a pt. with IICP be turned carefully?
Turning increases ICP.
What kind of monitoring of ICP can be done?
Epidural sensor
Subarachnoid belt
What is the epidural sensor?
wire that goes thru skull, lies between skull and dura mater.
What are the advantages/disadvantages of the epidural sensor?
Not very invasive
Decreased risk of bleeding
Decreased risk of infection
Not very accurate
What is the subarachnoid belt?
It is screwed down through the meninges into subarachnoid space. Bolt must remain.
What are the adv/disadv of subarachnoid belt?
Pt. sometimes gets fibrin clots at bolt.
Great risk of infection.
Fairly accurate.
Intraventricular Catheter..
3rd type of ICP monitor.
Most accurate; more invasive; greater risk of infection; could have cerebral hemorrhage.
What are some factors that contribute to IICP?
High carbon dioxide content
Low oxygen content
Valsalva maneuver
Restricting body positions
Emotional upsets
REM sleep
Arousal from sleep
Medications as antihistamines
Types of head injuries?
Scalp lacerations
what are the facts about scalp lacerations?
there is a lot of bleeding; risk of infection; bleeding can usually be controlled with pressure - usually no significant problems.
What are the different types of fractures?
A comminuted fracture...
crushing injury with breaks in lots of places.
A depressed fracture...
portion of bone pressing down into underlying brain tissue.
A compound fracture...
open communication to the outside.
A linear fracture...
Basilar - Broken bone but no displacement. Simple, usually heels nicely. Problem - can tear blood vessels underneath.
basilar skull fracture...
linear fracture in area of frontal or temporal bones
A basilar skull fracture is associated with CSF leaks because...
because of tearing of the dura
Anerior fossa fracture -
linear fracture that causes periorbital ecchymosis - raccoons eyes. Often get SPF leak from nose.
Middle fossa fracture
Linear fracture that causes mastoid ecchymosis - Battles sign, otorrhea, hemotypanium -CSF leak from the ear.
What are 2 methods of dx CSF leaks.
Halo sign
Glucose strip will be + if CSF.
If pt. is having drainage from the nose what should you do.`
collect it so it doesn't stay there. No nasal suctioning, no NG tube.
Why no NG tube?
An NG tube has a tendency to go up, if there is a tear could go through to brain.
What are some major complications of basilar skull fracture
Hemotoma formation
What is a concussion?
a minor injury in which there is "sudden transient mechanical head injury with disruption of neural activity and change in LOC".
Are there usually long term effects from concussion?
What is a contussion?
A major injury in which there is bruising of brain tissue that may lead to edema, ischemia, necrosis, hemmorrhage.
What are some S/S of contussion?
Altered LOC, possible amnesia, possible neuro dysfunction. Early on can't tell difference between contusion/concussion.
Is it necessary to prevent pt. from going to sleep?
No, it is better to let them go to sleep and wake them up periodically.
What is the coup-contrecoup phenomena?
an injury with 2 types of trauma.
Coup injury:
on side of blow, 2 degree compression. Whipping forward, then backwards, blood vessels get torn.
Contrecoup injury:
on opposite side of coup injury and occurs primarily because of pulling and tearing of tissues and vessels with some compression damage.
What type of injuries which occur with MVA but also with boxers and others?
Acceleration/deceleration when head moves quickly in one direction and then stops abruptly (deceleration).
What is the treatment for any of the head injuries?
Remove boney fragments or depression. Prevent infection with antibiotics and clean dressings. Observe for and treat IICP.
What are the types of hematomas?
Intracerebral hemorrhage
Subarachnoid hemorrhage
Epidural hematoma
Subdural hematoma
Intracerebral hemorrhage:
as with laceration, HTN (stroke). Bleeding into brain tissue itself or can get with high BP - stroke.
Subarachnoid hemorrhage:
ruptured vessels, aneurysms (stroke) - most common cause is ruptured aneurysms of arterial venous anomalities person is born with. Usually in Circle of Willis with bleeding into subarachnoid space.
Epidural hematoma:
a medical emergency with 50% mortality due to herniation. Bleeding above the dura and under the skull. Emergency because tends to be due to arterial rupture with hematomas occuring quickly.
What is a sign of an epidural hematoma?
At MVA - change in LOC, the pt. seems O.K., then on way to emergency room, person deteriorates with quick progression of injury.
What are epidural hematomas most often associated with?
Tears of middle meningeal artery (with linear fracture of temporal bone) and with blunt trauma.
How long does it take for symptoms of an hematoma to show up after an injury?
1-12 hours after trauma.
Subdural Hematoma:
under dura between dura and brain tissue. Usually venous in nature. Blood collects more slowly. No rapid collection rate - have time to treat.
S/S of subdural hematoma:
LOC declines gradually over time
3 kinds of subdural hematomas:
Acute: rapid deterioration with symptoms occuring in less than 48 hours.
Subacute: Slower deterioration with symptoms occuring from 48 hours to 2 weeks after injury.
Chronic: Progressive decline in LOC with symptoms occuring more than 2 weeks after injury - even 1-2 months.
Why does chronic subdural hematoma occur often in older people?
Cerebral atropthy - larger space to fill.
What is the #1 management of head injury?
monitor for and treat IICP
Management of head injury includes:
Assume you have a spinal cord injury until proven otherwise.
Logroll to move; keep head in neutral position. Remember ABCs and monitor progression of hematoma.
What procedures are usually done?
CT Scan to see how big hematoma is.
Craniotomy or drill burr holes.
What complication do these pts with hematomas often develop?
Stress Ulcers, are prone to seizures, meningitis or brain abscess, risk for hypo/hyperthermia (hypothalamus), risk for diabetes insipidus and SIADH.
Intracranial tumors:
most are primary tumors, some are metastatic with primary source from lungs, breast, kidney, GI tract, prostate, uterus.
Common Intracranial tumors:
-Glioma (glioblastoma, astrocytoma)
-Metastatic tumors
-vascular tumors
From glial cells (cells that hold neurons together). Not defined tumors, hard to find edges. Gliomas are usually malignant and aren't good surgical candidates
Benign tumor that arises from meninges - well-encapsulated so can see edges well. Excellent surgical candidates - sometimes getting to them is difficult -curative.
Metastatic Tumors
treatment usually not curative because arises elsewhere.
Vascular Tumors
AV malformation - present at birth, but not apparent until its grown. Area where you have arterioles connected directly to venules - serves no purpose. Can of worms. Often in Circle of Willis near brainstem. Poor surgical candidates because of location.
S/S of intracranial tumors
Focal motor and/or sensory deficits which vary based on location of tumor.
Seizures due to changes in neural activity
Endocrine changes due to effects of pituitary and hypothalamus
H/A - blood irritating to meninges.
Treatment of intracranial tumors
surgery is treatment of choice if it's accessible.
Sometimes combination of the 2
Why does chemotherapy work?
Malignant cells alter the blood brain barrier so chemoagents can get through.
What is goal of nursing care?
#1 is prevention of management of IICP, prevent seizures, infection.
Relieve pain and keep pt. as comfortable as possible.
Cranial Surgery - Craniotomy:
Done to repair bleeders, evacuate hematomas, remove boney fragments or foreign bodies, drain abscesses, remove tumors
What are the primary concerns following a craniotomy?
Prevention of IICP
Safety (seizures)
Prevention of infections
prevention of hazards of immobility
emotional support
What are some inflammatory Conditions of the brain?
Brain Abscess
acute inflammation of meninges involving both brain and spinal cord.
When does meningitis usually occur?
Usually in Fall or Winter because it usually follows something else.
What is the most frequent cause of meningitis?
virus; can be bacterial, parasitic, or fungus.
Who usually gets meningitis?
immunocompromised, long-term steroid use.
What is the most common bacterial cause of meningitis?
haemophilus influenza
Neisseria meningitis
Often results in fulminating disease (rapidly progressing)
6-8 hours death.
Bacterial Meningitis
Mortality highest for this kind. Is a medical emergency due to exudate; 10-20% show fulminating infection with DIC and septicemia and may die within a few hours of onset.
S/S of Bacterial Meningitis
1st - severe H/A (irritation of meninges)
Nuchal rigidity
Rash and seizures
Change in LOC
Kernigs Sign:
With thigh flexed on abdomen cannot extend leg with meningeal irritation; + is abnormal, have meningitis; negative is normal
Brudzinski Sign
Flexing the neck causes flexin of hip and knees with meningeal irritation; + is abnormal, have meningitis, negative is normal.
How do you dx meningitis?
CSF analysis
What characteristics will the CSF have with bacterial meningitis?
Protein elevated
Glucose decreased
Purulent - exudate
WBC elevated
Organisms present
What are the characteristics of CSF with viral meningitis?
protein elevated, but less
Glucose normal, maybe decreased
WBC normal
No organisms
What are complications of Meningitis?
Residual neurological deficits - blindness, deafness, acute cerebral edema - may leave mentally retarded or physically retarded.
Hydrocephalus - when flow is impended.
DIC secondary to bacterial toxins
Friedrickson-Waterhouse Syndrome=
Adrenal hemorrhage
Lose Na+ and water
no inflammatory response
Treatment for meningitis:
Specimen for culture
antibiotic if bacteria suspected
What should be done if cultures come back HIV or Neisseria Men?
Isolation - spreads rapidly in closed environment

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