ALTERED CEREBRAL TISSUE PERFUSION
Upon completion of this class, the student will be able to:
1. Define the Monro-Kellie hypothesis and how it applies to cerebral function;
Kelly-Monroe doctrine: head is rigid. brain 80%, CSF 10%, Blood 10% all taking up
space in the head. If one increases, the others try to get out of the way. We can
compensate to a point, but not really enough. Increased pressure likes to run out the
foramen magnums but that means increased pressure on the brain stem-- BAD!
2. Calculate cerebral perfusion pressure based on MAP and ICP;
CPP is calculated MAP-ICP. Book says we want CPP greater than 70.
3. Describe causes and effects of increased in brain volume, cerebral blood volume,
and intracranial pressure; pg 410
Increased brain volume: causes: any drug that injures the BBB leaks plasma into the
interstitum of the brain tissue. Also ‘space invading’ lesions; tumors, hemorrhage,
hematoma, etc. Edema from trauma, anoxia, surgery, ischemia.
Effect: incr ICP if not enough compensation by Kelly-Monroe, and herniation, in which
the brain is smushed away from the insult leading to further damage.
Increased cerebral blood volume; causes: systemic hypotension, incr metabolic rate
[pain, fever], systemic acidosis [hypercapnia, ischemia], venous outflow obstruction
[neck at an angle, valsalva, PEEP, etc]. Hypoxia is an arteriolar cerebrovascular dilator,
causing IICP (Brasher, 2008.) Direct damage to to the autoregulatory mechanism causes
passive dilation of blood vessels and IICP.
Effect; Cerebral vasodilation and IICP.
Decr cerebral blood flow; systemic hypertension, decr metabolic rate [sedation,
hypothermia, paralysis], systemic alkalosis [hypocapnia, this is why hyperventilating pts
reduces ICP], cerebral edema, low CO, cerebral vasoconstriction.
Incr CSF: incr production, obstructed circulation, or decr absrobtion [hydrocephalus].
Obstruction from infex or trauma. Decr absorption from meningitis or subarachnoid
hemorrhage.
and intracranial pressure; increased causes too much pressure leading to decr CPP,
leading to more ischemia.
4. Describe neurological assessment of the patient with altered LOC;
Our job is to do a neuro assmt every shift. Give the pt the best glasgow scale you can-their best in the shift.
Glasgow: weird scale but its everywhere.
Generally, brain injury is classified as:
* Severe, with GCS ≤ 8 - that is also a generally accepted definition of a coma
* Moderate, GCS 9 - 12
* Minor, GCS ≥ 13.
Best eye response (E)
There are 4 grades starting with the most severe:
1. No eye opening
2. Eye opening in response to pain. (Patient responds to pressure on the patient’s
fingernail bed; if this does not elicit a response, supraorbital and sternal pressure or rub
may be used.)
3. Eye opening to speech. (Not to be confused with an awaking of a sleeping person;
such patients receive a score of 4, not 3.)
4. Eyes opening spontaneously
Best verbal response (V)
There are 5 grades starting with the most severe:
1. No verbal response
2. Incomprehensible sounds. (Moaning but no words.)
3. Inappropriate words. (Random or exclamatory articulated speech, but no
conversational exchange)
4. Confused. (The patient responds to questions coherently but there is some
disorientation and confusion.)
5. Oriented. (Patient responds coherently and appropriately to questions such as the
patient’s name and age, where they are and why, the year, month, etc.)
[edit] Best motor response (M)
There are 6 grades starting with the most severe:
1. No motor response
2. Extension to pain (adduction of arm, internal rotation of shoulder, pronation of
forearm, extension of wrist, decerebrate response)
3. Abnormal flexion to pain (adduction of arm, internal rotation of shoulder, pronation
of forearm, flexion of wrist, decorticate response)
4. Flexion/Withdrawal to pain (flexion of elbow, supination of forearm, flexion of wrist
when supra-orbital pressure applied ; pulls part of body away when nailbed pinched)
5. Localizes to pain. (Purposeful movements towards painful stimuli; e.g., hand crosses
mid-line and gets above clavicle when supra-orbital pressure applied.)
6. Obeys commands. (The patient does simple things as asked.)
Diagnostic tests: angiography, CT, MRI, EEG.
III.
NEUROLOGICAL ASSESSMENT
A. Level of consciousness: the most sensitive indicator of neurological function
1.
etiologies: Vowel and TIPPS:
A .. Acidosis (a body-chemistry imbalance) .. Alcohol intoxication
E .. Epilepsy (seizures ... "convulsions")
I .. Infection (especially when accompanied by fever)
O .. Overdose (of "medications," or "drugs," or alcohol)
U .. Uremia (a body-chemistry disorder)
T .. Trauma (to the head) ... Tumor (of the brain)
I .. "Insulin" (states of low or high blood sugar in diabetics or non-diabetics)
P .. Poisoning ...
P…Psychosis (sudden onset)
S .. "Stroke" (TIA or CVA)
2.
a.
b.
c.
arousal: use GCS
Assessed if RAS & brainstem intact
GCS: less than what number means coma state? 7
What stimulation led to what neuro function?
3.
a.
b.
content: higher level; your pt needs to be able to answer questions for this
orientation times 3?
Degree of cognitive function is related to location and size of lesion
B.
Pupillary and ocuomotor reactions
1.
pupils:
Check pupils on our pts. PERRLA: pupils equal round reactive and accomodating (check
this by bringing finger into their center, their pupils should constrict.)
a.
b.
provide info about location of lesions (CN III)
assess for what?
2.
oculomotor: assess CN III, IV, VI, VIII
a.
oculovestibular (caloric): Oculomotor/Ice water caloric: this is only to r/o brain
death. Assesses brain stem function. Docs do it. You put ice water in a basin, put it in the
ears. It stimulates the cranial nerves and makes you barf like crazy. If you put it in the R
ear, your R eye should nystagmus toward the stimulation.
b.
oculocephalic (doll’s eyes) Doll eyes: if you move the head to one side, the eyes
should not follow the direction of the head if brain ok.
Apnea Study: give 100% O2 on vent. Take them off the vent, you watch them for 5
mins. Watch for breathing, HR, and O2sat. The incr in Co2 should make the brain stem
start breathing if not brain dead. This has to be done w/ a neurologist.
C.
1.
Movement
what moves in response to what stimulus?
2.
posturing: decorticate, decerebrate: Posturing: not good! Decerebrate is worse
than decorticate. Spontaneous posturing is REALLY BAD. You want it in response to
stimulation of some sort.
3.
flaccid: Total flaccidity is really bad.
D. Vital Signs: a late sign of brain trouble.
1.
respiratory pattern: Cheyne-Stokes vs apnea
2.
Cushing’s Triad Vitals: Cushings Triad: means pressure on brain stem: increasing
SBP and lowering DBP, low HR
3.
temperature
E.
Cranial Nerve Reflexes: protective, reflect brain stem function
1.
corneal reflex (blink)
2.
gag reflex
3.
cough reflex
4.
swallow reflex
Swallow [5 or 6 different nerves].
5. Discuss collaborative management of patients with altered CPP and
oxygenation;
COLLABORATIVE MANAGEMENT
A. Optimize CPP
1. Want MAP > 90; CPP >70
2.
temperature control: manage infex and antipyretics, cooling blankets and fans
used.
2.5: MANAGE PAIN to decr metabolic/activity/ be fucking humane
3. venous return: HOB up to 30 degrees, laxitives to reduce valsalva, keep neck
straight, not too much PEEP
B. Optimize oxygenation
1.
mechanical ventilation: yes please, b/c pt can’t manage it, also might
hyperventilate w/ stimulation
2.
hyperventilation prn: blows off CO2 hypocapnia is a cerbral vasoconstrictor and
rapidly decreases ICP!
C.
1.
Pharmacologic Therapy
osmotic diuresis: mannitol sucks water off the brain and lowers ICP
2.
sedation/paralytics: keep ICP low by keeping activity/metabolic rate low/null
a.
Pt report with neuromuscular blocking agents (2006, AJCC)
b.
Sedation IV: what drugs are effective
Pain mgmt with opiates. Propofol for sedation. Vec for paralysis but always add a
sedative to it. Propofol is hypotensive in high doses.
D. Safe Environment
1.
monitor stimuli: how? Keep noise and lights and stimuli down, group noxious
activity with long rest periods in between.
2.
family involvement: how?
C.
1.
2.
Evidence-based practice
ICP is lower and CPP higher for a 30 degree HOB elevation
febrile state increases LOS
6. Describe the pathophysiology of stroke, including risk factors and clinical
symptoms;
Stroke [thrombus, emboli, or hemorrhage--the emboli travels from somewhere else].
Only 20% of strokes are hemorrhage. HTN the usual culprit for stroke. Ichemia: fixable,
infarction: permanent. Either cause swelling in the brain. “CVA is disruption of brain
blood flow.”
The middle cerebral artery is the most common site of stroke, the tissues start hurting and
swelling. Penumbra: area around dead cells that is ichemic and reversible.
Dysphagia and hemipariasis are most common SE's of stroke
Risks:
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HTN
Hyperlipidemia
DM
Atherosclerosis
Cocaine
A fib
TOB
OC’s birth control pills
Fat
Hypercoagulability
Cerebral aneurysm
Ateriovenous malformation
S&S:
L hemisphere: trouble reading, writing, speaking, R side
immobility/weak/numb/blindness, frustration
R hemisphere: bliss, enlightenment, disorientation, poor judgement, left side weakness,
numb, blind. See you tube:
http://www.ted.com/index.php/talks/jill_bolte_taylor_s_powerful_stroke_of_insight.html
Remember these stroke symptoms "FAST"
F: FACE
# Uneven smile
# Facial droop/numbness
# Vision disturbance
A: ARM & LEG
# Weakness
# Numbness
# Difficulty walking
S: SPEECH
# Slurred
# Inappropriate words
# Mute
T: TIME
# Time is critical
# CALL 911
7. Discuss priority nursing interventions for the patient with an acute brain attack.
Stroke protocols have changed a lot in the last 10 years, w/ TPA and reducing tissue
death. TPA does work w/in 12 hours of MI, 3 hrs of CVA. Protocol goals for MI or
stroke: repurfuse, and fast! TPA has a 1/10 chance of causing bleeding and killing
strokers, Docs are scared to give TPA, AHA and NIH are telling us to get over it.
Criteria is black and white: need to ensure stroke was w/in last 3 hrs, get a CT and r/o
hemorrhagic stroke.
Assess: airway, LOC, GCS, motor, visual, speech function
Dx: ineffective tissue perf, impaired mobility, risk for injury.
RN intervention
 Maintain airway
 Watch for changes in LOC
 HOB to 30 for ICP, neck straight
 Seizure precautions
 Low stim enviro
 TPA: not for hemorrhage, r/o hemorrhage w/ STAT CT or MRI. LP to find blood
in CSF if subarachnoid hemorrhage suspect but not shown in CT. 12-lead to
assess cardiac fxn. Admin w/in 3 hrs, RN’s must assess BP and LOC frequently
[like VS when hanging blood]. Stop TPA if severe n/v, hypertension or h/a.
Delay placement of NG tubes, F/C, art lines. Anticoagulants in the acute phase
ain’t useful and are contraindicated w/ TPA. Anticonvulsants are helpful in the
first 24 hrs post-CVA b/c this is the riskiest seizure period. Balloon angiography
and stenting are used for occlusion in the brain.
 Anticoags: heparin, coumadin
Case Scenarios
1. Your patient is a 68 yo male who is admitted to the ED after developing sudden
loss of speech and left hemiparesis while watching TV at home. What neuro
assessment is indicated stat? Describe his altered cerebral tissue perfusion in terms
of cause and management.
2. You are caring for an 88 yo who was discovered lying at the bottom of the stairs
in her home for 6 hours. She responds to painful stimuli with moaning, moves her
right extreme spon and weakly. VS BP 168/90, HR 124, RR 12. What neuro
assessment is indicated? What collaborative management is indicated?
3. Your patient is a 28 yo victim of a gang-related fight in Santa Rosa. He has
decreaed LOC, becomes agitated with stimulatin, and is on the ventilator. What
sedation is indicated and why? If paralytics are used, what nursing responsibilities
are a priority?
I.
PHYSIOLOGY OF CEREBRAL TISSUE PERFUSION
A.
Arterial circulation: why are arteries at risk to rupture?
B.
Venous circulation: why is gravity important?
C.
Cerebral oxygenation: no reserve!!
1.
autoregulation: what is it?
2.
hyperemia: when does it occur?
II.
INTRACRANIAL PRESSURE
A.
Brain volume
1.
blood-brain barrier
2.
permeable to: what?
3.
what could increase it?
B.
Cerebral Blood Volume
1.
conditions that increase flow:
2.
conditions that decrease flow:
C.
Cerebrospinal Fluid
1.
where is it?
2.
how much is it?
3.
CSF displaced most easily and quickly into external jugular vein
D.
Intracranial Pressure
1.
def: pressure exerted by CSF within the ventricles of the brain
2.
value: 0-15 mmHg
3.
normal fluctuation
E.
Cerebral perfusion pressure: depends on cerebral blood flow and intracranial
pressure
1.
normal 80-100 mm Hg
2.
need what value to ensure adequate cerebral oxygenation?
3.
MAP-ICP
F.
Decreased Intracranial Adaptive Capacity
1.
increase in brain volume due to?
2.
increase in cerebral blood volume due to?
3.
increase in CSF due to?
III.
NEUROLOGICAL ASSESSMENT
A.
Level of consciousness: the most sensitive indicator of neurological function
1.
etiologies: Vowel and TIPPS
2.
arousal:
a.
RAS & brainstem intact?
b.
GCS: less than what number means coma state?
c.
What stimulation led to what neuro function?
3.
content: higher level;
a.
orientation times 3?
b.
Degree of cognitive function is related to location and size of lesion
B.
Pupillary and ocuomotor reactions
1.
pupils:
a.
provide info about location of lesions (CN III)
b.
assess for what?
2.
oculomotor: assess CN III, IV, VI, VIII
a.
oculovestibular (caloric)
b.
oculocephalic (doll’s eyes)
C.
Movement
1.
what moves in response to what stimulus?
2.
posturing: decorticate, decerebrate
3.
flaccid
D.
Vital Signs
1.
respiratory pattern: Cheyne-Stokes vs apnea
2.
Cushing’s Triad
3.
temperature
E.
Cranial Nerve Reflexes: protective, reflect brain stem function
1.
corneal reflex (blink)
2.
gag reflex
3.
cough reflex
4.
swallow reflex
IV.
ICP MONITORING
A.
Types:
1.
intraventricular monitoring: gold standard
a.
diagnostic
b.
therapeutic: how?
2. subarachnoid bolt
2.
intraparenchymal device
B.
Waveforms
1.
nursing responsibilities
2.
pattern/trends
3.
troubleshooting system integrity
C.
Evidence-based practice
1.
ICP is lower and CPP higher for a 30 degree HOB elevation
2.
febrile state increases LOS
V.
DIAGNOSTIC PROCEDURES
A.
MRI
B.
CT
C.
EEG
D.
Angiography
VI.
COLLABORATIVE MANAGEMENT
A.
Optimize CPP
1.
MAP > 90; CPP >70
2.
temperature control
3.
venous return
B.
Optimize oxygenation
1.
mechanical ventilation
2.
hyperventilation prn
C.
Pharmacologic Therapy
1.
osmotic diuresis
2.
sedation/paralytics
a.
Pt report with neuromuscular blocking agents (2006, AJCC)
b.
Sedation IV: what drugs are effective?
D.
Safe Environment
1.
monitor stimuli: how?
2.
family involvement: how?
C.
Evidence-based practice
1.
ICP is lower and CPP higher for a 30 degree HOB elevation
2.
febrile state increases LOS
VII.
ALTERED CEREBRAL PERFUSION: ACUTE BRAIN ATTACK
A.
Pathophysiology: atherosclerosis; penumbra
B.
Classifications
1.
TIAs
2.
hemorrhagic: what causes and who is at risk?
3.
ischemic: what causes and who is at risk?
C.
Risk factors: know these!
D.
Assessment and Diagnosis
1.
vascular territory compromised
a.
carotid ischemia: what sx?
b.
Vertebrobasilar ischemia: what sx?
2.
hemiplegia
3.
dysphagia
4.
A,B,Cs
5.
Nursing Diagnoses: list 3 priority ones
E.
Management
1.
rtPA within 3 hours if not hemorrhagic cause [local recombinant tissue
plasminogen activator]
2.
surgery Carotid TEA
3.
early ambulation and rehab
4.
nutritional needs
5.
safety
6.
family support
7.
prevention!