Stroke Flashcards
Stroke: when does it occur?
- when there is ischemia (inadequate blood flow) to a part of the brain that results in the death of brain cells
How much blood does the brain need?
Cerebral blood flow must be maintained at 20% of cardiac output
What happens if blood flow to the brain is totally interrupted?
- neurological metabolism altered in 30 seconds
- metabolism stops in 2 minutes
- cellular death occurs in 5 minutes
Cerebral autoregulation
- changes in diameter of cerebral blood vessels in response to changes in pressure so the pressure in the brain stays constant
- may be impaired following cerebral ischemia
what factors affect blood flow to the brain?
- systemic blood pressure - when BP drops, vessels dilate and individuals faint because the BP dropped and the brain isnt getting adequate blood flow
- cardiac output - is there damage to the heart or has there been? history of CAD, MI, is the heart pumping adequately
- Blood viscosity
- Arrangement of the brain’s arteries
Collateral Circulation
- another way the body manages risk factors
- if main vessel is clogged, there are numerous ways for blood to get to the area of the brain
- cardiac output has to be reduced by 1/3 before there is reduced blood flow to the brain
- outcome of stroke depends on amount of collateral circulation
Non-modifiable risk factors
Age>65
gender - males have more strokes. females die from them more
race - african american
family history - immediate family member had a stroke
Modifiable Risk Factors
- smoking
- obesity
- alcohol
- inactivity
- high cholesterol
- illicit drug use
- oral contraceptives
Contributing Factors
Hypertension
diabetes (4-5x more likely)
heart disease/CAD (anything related to hearts ability to pump)
Atrial Fibrillation
- most important treatable cardiac related risk factor for developing stoke because the blood is not moving effectively, clots are forming in the quivering atria are then pumped into the brain and can cause stroke
Thrombosis
a clot that forms and stays put and blocks off a vessel. starts in one spot and stays in one spot
Embolism
clot that develops somewhere else, travels, and gets stuck. Can travel from the heart, up from somewhere in the body
Hemorrhage
breaking in vessel wall. rupture of atherosclerotic vessels. produces extensive residual functional loss. Most commonly caused by hypertension .
Types of Strokes
- Ischemic Stroke (85% of strokes) TIA Thrombotic - plaque Embolic - Hemorrhagic Stroke - bursting. ischemic effects when there id bleeding into the brain and the tissues that need it are not getting it. increased ICP Intracerebral Subarachnoid
Progression of ischemic stroke
Thrombosis/embolism -> cerebral infarction (loss of blood supply) -> decreased cerebral percusion and increased ICP -> cerebral ischemia (cell death)
Progression of hemorrhagic stroke
hypertension/aneurysm -> cerebral hemorrhage -> decreased cerebral perfusion and increased ICP -> cerebral ischemia
TIA (transient ischemic attack)
- precursor to ischemic stroke - temporary loss of neuro function lasting < 24 hours. often < 15 minutes.
- caused by microemboli
- patients should go to emerge
Who is at risk for TIA?
- everybody who is at risk for ischemic stroke
- people at risk of a clot forming and traveling
Thrombotic Stroke
- 61% of strokes
- occurs when artery providing blood to brain tissue is blocked - intracranial thrombus
- symptoms slow and progressive, may not have changes in LOC in 1st 24 hours
Lacunar stroke
very deep in a very small vessel
- dementia
Embolic (24% of strokes)
- traveling embolus (often from heart)
- symptoms sudden, no chance of developing collateral circulaiton
- prognosis dependson amount and location of brain tissue affected
Who is at risk for an ischemic stroke?
- hypertension
- known cardiovascular disease
- A-fib
- smoking
- drug use
- inactivity
- diabetes
- ask assessment questions
Hemorrhagic Stroke (15%) Intracerebral (10%)
- hypertension is a significant risk factor
- occurs during activity
- sudden onset with progression of symptoms of min-hours because of bleeding
- headache, nausea, vomiting, sudden alteration in LOC, hypertension
- poor prognosis
Subarachnoid hemorrhagic stroke
- intracranial bleeding into CSF space
- often rupture of cerebral aneurysm can also be trauma or cocaine
- headache, nausea and vomiting, sudden alteration in LOC, hypertension
- poor prognosis
Clinical Manifestations: motor function
- impairment of speech, voluntary movement, swallowing, numbness, paralysis, lack of sensation
- Akinesia - trouble with voluntary movement
Clinical Manifestations: Communication
- left hemisphere dominant: language disorders, comprehension of written and spoken words. Depends on where in the brain the stroke is affecting. Slurred speech, or not making sense, stringing words together that do not make sense.
Broca’s aphasia
difficulty expressing thoughts or words
Wernickes aphasia
difficulty understanding spoken or written language
Amnesic aphasia
problems finding correct names for objects or things
Global aphasia:
loss of all expressive or receptive function
Clinical manifestations: Affect
difficulty controlling emotions. May be exaggerated
Clinical manifestations: Intellectual function
impaired memory and judgement. depending on left side - cautious. Right side- impulsive, move quickly
Clinical manifestations: Spatial/perceptual alterations
different deficits. on side is neglected or forgotten. cannot know how it is going to present
Elimination
temporary. incontinence and difficulty releasing urine. often will regain bladder function
clinical manifestations. ischemic vs hemorrhagic
manifestations do not significantly differ. manifestations depend on the location of the stroke in the brain
Stroke occurs on left side =
Stroke occurs on right side =
right sided deficits
left sided deficits
Diagnostics
- done to confirm that is is a stroke. identify the likely cause of the stroke.
- CT is the primary diagnostic test used after a stroke
Studies for diagnosing stroke
- CTA
- MRI/MRA
- Cerebral or carotid angiography
- Digital subtraction angiography
- transcranial doppler ultrasonography
- lumbar puncture
- lab work
- cardiac assessment
Lab work
- rule out cardiovascular causes:
- troponin
- CKMB
- INR
- PTT
- CBC
- WBC
- hemoglobin
- Electrolytes
- BG
- Hemoglobin A1c
- lipid profile
- Renal and hepatic studies
Why might we want to assess the heart when considering a stroke?
because of the cardiovascular risk. is there CAD is there any other cardio condition we need to know about
Collaborative Care: Prevention
- management of high risk: diabetes hypertension smoking high serum lipids cardiac dysfunction
Drug Therapy
- antiplatelet drugs - for patients who have had a TIA
- Aspirin
- Statins
Surgical Therapy - for pts with hx of TIA
- carotid endarterectomy
- transluminal angioplasty
- stenting
- extracranial - intracranial bypass
F.A.S.T
F - face drooping
A - can you raise both arms
S - speech difficulty
T - time to call 911
Signs and Symptoms (WTHDV - what the heck darth vader)
weakness - sudden loss of strength or sudden numbness in the face, arm, or kg, even if temporary
- trouble speaking - sudden difficulty speaking or understanding or sudden confusion, even if temporary
- vision problems - sudden trouble with vision, even if temporary
- headache - sudden severe and unusual headache
- Dizziness - sudden loss of balance, especially with any of the above signs
CVA (cerebral vascular accident) also known as stroke
- not enough blood supply to brain
- result in blood cell damage. and brain cell damage
- damage occurs within 5 min
- 3rd leading cause of death in Canada
Blood supply to brain
- vertebral artery (20%) and internal carotid artery (80%)
- vertebral artery -> basilar artery -> circle of willis
Why circle of Willis
- if one part is blocked the other part will supply blood
Circle of Willies
- anterior cerebral artery
- middle cerebral artery
- posterior cerebral artery (back part of brain)
- all connect to basilar artery
- anterior communicating artery and posterior communicating artery (arteries that communicate in-between)
CVA can cause:
- increased ICP
- decrease in cerebral perfusion
- cushings triad
Cushings Triad
- systolic BP increases, pulse decreases, respirations will decrease
- opposite of shock
why increase ICP decrease cerebral perfusion?
- cerebral BP tells us how well the heart is pumping blood to the brain.
- if there is increased ICP, there is resistance from the brain and the heart will be less successful in sending blood to the brain
How much pressure is required to get enough blood to brain?
- CPP (cerebral perfusion pressure)
- MAP - ICP = CPP
- MAP is mean arterial pressure - we know how much BP is needed to pump blood to the brain and ICP is how much resistance the blood is meeting so subtracting ICP from MAP will give you the CPP
Normal CPP
60-100 mmHg
Dysarthria
motor control of vocalization is disabled
Right Side damage
spatial deficit, memory, rash decisions
Left sided damage
speech, language deficit memory, cautious
Blood Work
- troponin
- electrolytes
- INR
- PTT
- A1c
- BG check
- lipid profile
Further Cardiac Assessment
- ECG
- Cardiac marker
- Echocardiogram
- Chest x-ray
How do we prevent stroke?
- life-style changes
- pharmacological (prevent blood clot & cholesterol)
antiplatelet (aspirin, apixaban, xerlto, dabigatran)
anticholesterol: statin - surgical
Intervention (GOALS)
- preserving life
- preventing further disability.
ABCs assessment
Airway
Breathing
Circulation
Interventions for Ischemic stroke
- hypertension:
(response to maintain cerebral perfusion - need to maintain BP < 180) - fluid electrolyte balance
(adequate hydration. fluid restriction 1.5-2L/day. no hypotonic fluid because it will worsen cerebral edema. - meds to use: TPA - clot buster. Aspirin -> monitor very closely for bleeding
Hemorrhagic Stroke
- keep BP < 160
- close monitoring for those on blood thinner
- medication treatment (nimodipine - calcium channel blocker. relaxes blood vessels
- surgical intervention can be considered (clipping & coiling)
Interventions for Cerebral Edema (complication of CVA)
- keep head midline and HOB > 30 degrees
- Monnitol IV (diuretic) helps to remove some fluid
Intervention for Bleeding (complication for CVA)
- frequently check BP
Intervention for Hyperthermia (complication of CVA)
- people start to have high fever
- brain lesion on thermal center
- make sure temp is within normal range because increased temp increases brain metabolism
- antipyretic
Intervention for Seizure (complication of CVA)
- seizure precaution
- phenytoin
Intervention for Aspiration (complication of CVA)
NPO for 24-48 hr
Intervention for Increased ICP (complication of CVA)
- elevating HOB by 30 degrees
- providing oxygen
- promoting rest and reducing stimulation
- avoiding postures that restrict venous return
- avoiding valsalva maneuver -> used to lower HR which is not what we want
Interventions for Acute Ischemic Stroke
- meds (TPA - clot buster)
Meds for Increased ICP
- antiseizure
- BP meds
- anipyretics and muscle relaxants
- corticosteroids
- IV fluids
- Hyperosmotic agent
Possible Nursing Diagnosis
- risk for injury related to neurological deficits
- risk for altered nutrition and dehydration
- risk for contracture related to flaccid paralysis or spasticity
- Risk for impaired skin integrity
- Risk for corneal abrasion
Rehabilitation
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