Intracranial Pressure
Terms
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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
- abnormal
- 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?
- Closed
- 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?
- diuretics
- 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?
-
CPP=MAP - ICP
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?
- Yes
- 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?
- Dilantin
- 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...
-
Suctioning
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
Coughing-sneezing
Emotional upsets
REM sleep
Arousal from sleep
Medications as antihistamines - Types of head injuries?
-
Scalp lacerations
Fractures - 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?
-
Comminuted
Depressed
Compound
Linear - 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
-
Infection
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?
- NO
- 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)
-Meningioma
-Metastatic tumors
-vascular tumors - Glioma
- 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
- Meningioma
- 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.
IICP
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.
Chemotherapy
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?
-
Meningitis
Encephalitis
Brain Abscess - Meningitis
- 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
Photophobia
Fever
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
Clear
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=
-
Petechiae
DIC
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