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Advanced Principles of Anesthesia > Week 2 - Stroke and Cerebrovascular Disease > Flashcards

Week 2 - Stroke and Cerebrovascular Disease Flashcards

1
Q

What is the incidence of stroke?

A

1 cause of long term disability

5th leading cause of death in the US (following CV disease and cancer)

795,000 people experience a new or recurrent stroke – over 1 million strokes or TIA/year

*every minute a stroke pt loses about 2 million neurons

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2
Q

What is the Limbic System of the brain?

A

Functional system – communication network for behavioral function

Hypothalamus and Thalamus involved

Emotions are generated here

Memory and learning require interaction with limbic system

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3
Q

What is the Circle of Willis?

A

Interconnection between internal carotid arteries and vertebral arteries

Divided into anterior and posterior circulation

Principle pathway of collateral blood flow – allows for collateral perfusion if the ICA or Vertebral arteries become blocked

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4
Q

What arteries make up the anterior circulation of the Circle of Willis?

A

– Anterior Communicating Artery
– Anterior Cerebral Artery
– Middle Cerebral Artery
– Internal Carotid Artery

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5
Q

What arteries make up the posterior circulation of the Circle of Willis?

A 
– Posterior Communicating Artery
– Posterior Cerebral Artery
– Posterior Inferior Cerebellar Artery
– Basilar
– Vertebral
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6
Q

What is Vertebrobasilar Disease? What are its symptoms?

A

Atheromatous disease of the vertebrobasilar system

  • may be responsible for TIA’s
  • emboli or hypoperfusion of vertebral and basilar arteries

Symptoms:

  • manifests as “drop attacks” – loss of postural tone in legs
  • bilateral visual disturbance
  • transient global amnesia
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7
Q

What is Amaurosis Fugax?

A

Retinal ischemia manifests as temporary loss of vision in the ipsilateral side from microembolus that travel to the ophthalmic artery

Symptoms are “shade descending over one eye” - often lasts less than 10-20 min

  • *common in patients with carotid artery disease
  • often a sign of impending stroke – indication of evolving arterial thrombus in the ICA (main blood supply to optic nerve and retina)
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8
Q

What are the different treatment options for intracranial atherosclerosis?

A

Medical: medications (ASA, plavix, aggrenox, coumadin), lifestyle modification (smoking cessation, low fat diet, exercise), risk factor modification (hyperlipidemia, DM, HTN0

Surgical: endarterectomy, EC-IC bypass

Endovascular: carotid angioplasty/stenting, intracranial stenting

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9
Q

What do carotid artery stump pressures indicate perfusion of?

A

Circle of Willis

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10
Q

What are the determinates of cerebral blood flow?

A
  • Metabolic -CMRO2
  • Autoregulation (maintenance of constant blood flow despite alteration in arterial blood pressure)
  • Neural Regulation (sympathetic nerves accompany carotid arteries – SNS = vasoconstriction, PSNS = vasodilation)
  • Chemical Control (PaO2 - no change in CBF until <50 torr, then CBF will double; PaCO2 - 4% change in CBF per mmHg change in CO2)
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11
Q

What is a Trans Ischemic Attack (TIA)? What is it caused by?

A

Temporary impairment of cerebral function lasting less than 24 hours

Caused by thromboembolism from an ulcerative lesion in the internal carotid artery or vertebrobasilar system

*warning sign to stroke

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12
Q

What is a stroke?

A

Occurs when an artery is blocked or damaged

  • can lead to vessel rupture
  • interruption of blood flow leads to death of surrounding tissues

Causes irreversible damage due to lack of glucose and oxygen

88% are ischemic strokes
12% are hemorrhagic strokes

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13
Q

What are the two types of hemorrhagic stroke?

A

Subarachnoid hemorrhage

Intracerebral hemorrhage

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14
Q

What are the two causes of an ischemic stroke?

A

Cerebral Thrombosis: blood clot that develops in an artery supplying the brain

Cerebral Embolism: typically caused by a clot that formed at another location, breaks loose, and enters the bloodstream, passes into the brain, and blocks an artery
*A-fib

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15
Q

What are the non modifiable risk factors for a stroke?

A
  • Age
  • Gender
  • Family History
  • Race
  • Prior stroke or heart attack
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16
Q

What are the modifiable risk factors for a stroke?

A
  • Diabetes
  • Excessive alcohol consumption
  • Heart disease (especially A-Fib)
  • High blood pressure
  • High total cholesterol
  • High levels of C-reactive protein (CRP)
  • Metabolic syndrome
  • Obesity or inactivity
  • Smoking
17
Q

What are the signs and symptoms of an ischemic stroke?

A
  • Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body
  • Sudden trouble seeing in one or both eyes
  • Sudden confusion or trouble speaking or understanding
  • Sudden trouble with walking, dizziness, or loss of balance or coordination
  • Sudden, severe headache with no known cause
  • Loss of consciousness
18
Q

What does the saying “Time is Brain” mean?

A

When an artery is blocked (occlusion) and brain cells do not receive the oxygen they need, brain cells in the infarct (ischemic core of the stroke) may be damaged beyond recovery

  • The brain cells in the penumbra (the area that surrounds the ischemic core) still receive some blood
  • Cells in the penumbra have the potential to recover under the right conditions
19
Q

What is the ischemic core of a stroke?

A

The area receiving little or no blood flow, where cells die rapidly

**Blood flow is severely reduced to less than 15-20%

20
Q

During ischemia, _____ is the cornerstone of cerebral blood flow compensation.

A

During ischemia, collateral flow is the cornerstone of cerebral blood flow compensation

21
Q

What is the Ischemic Penumbra of a stroke?

A

Area of reduced blood flow surrounding the ischemic core

**Receive suboptimal blood flow – < 40%

22
Q

What is the acute management of ischemic stroke?

A
  • Stabilize the patient
  • Initial medical evaluation including imaging and labs

60 minutes to complete these tasks – critical decisions regarding stroke severity/location, airway management, BP management and determination for thrombolytic therapy

*Ideal to get pt to stroke center ASAP

23
Q

What are the goals of management of ischemic stroke?

A
  • Minimize or reduce ischemic damage (save the penumbra)
  • Reduce cerebral edema
  • Determine etiology of stroke
  • Prevent secondary complications
  • Prevent recurrent stroke
  • Facilitate access to comprehensive stroke care and rehabilitation
  • Reintegration into community
24
Q

What is the National Institute of Neurological Disorders and Stroke Recommended Stroke Evaluation Time Benchmarks for Potential Thrombolysis?

A 
10 min = Door to Treatment
15 min = Access to Neuro expertise
25 min = Door to CT scan
45 min = Door to CT complete
60 min = Door to treatment
3 hours = Admission to stroke unit/ICU
25
Q

What does rural management of acute stroke look like?

A
  • Focus on getting pt stabilized and prepared for transport to stroke center
  • Monitor cardiac status (watch for ischemia/A-fib)
  • Blood glucose management (treat hyperglycemia if >200 – ideal range = 140-180)
  • IV fluids (avoid D5W) – isotonic fluids (LR/NS) – avoid excessive fluid administration
  • NPO status (high risk aspiration)
  • Provide supplemental O2
26
Q

What is the BP control (goal BP) for non tPA candidates in acute ischemic stroke? Which medications are used to treat HTN?

A

Treat BP if systolic is >220 mmHg and/or diastolic is >120 mmHg

  • Labetalol is drug of choice unless contraindicated – 10-20mg IV Q1-2 min (max 300mg)
  • Nicardipine may be given IV – 5 mg/hr to start and titrated to max of 15 mg/hr
  • Nitroprusside may also be used
27
Q

What is the BP control (goal BP) for tPA candidates in acute ischemic stroke? Which medications are used to treat HTN?

A

Treat BP if systolic is >185 mmHg and/or diastolic is >110 mmHg
*monitoring BP during therapy is vital!

  • Labetalol is drug of choice unless contraindicated – 10-20mg IV Q1-2 min (max 300mg)
  • Nitroglycerine paste may be used
  • Nicardipine infusion at 5mg/hr titrated to max of 15 mg/hr

*BP should be monitored at least Q15 min for first 2 hours then Q30 min for next 6 hours

28
Q

What are the current treatment options for acute ischemic stroke?

A

IV thrombolytic therapy

tPA therapy

Endovascular neurosurgical therapies

*pts who are eligible to receive tPA should receive it even if endovascular management is being considered

29
Q

What is the goal of thrombolytic therapy in acute ischemic stroke?

A

Restore blood flow to the stroke region before nerve cells are irreversibly damaged – may prevent or reduce functional disability

IV tPA – can be given within 4.5 hours of onset of stroke (initial symptoms)
*must meet criteria

30
Q

What is tissue plasminogen activator (tPA)?

A

Serine protease found on endothelial cells – enzyme that catalyzes the conversion of plasminogen to plasmin which is responsible for clot breakdown

  • Used in clinical medicine to treat embolic or thrombotic stroke
  • contraindicated in hemorrhagic stroke and head trauma
31
Q

What are the main inclusion and exclusion criteria for tPA use?

A

Inclusion: onset of symptoms less than 4.5 hours before beginning treatment or if unknown onset, last time pt was known to be normal

Exclusion:

  • symptoms suggestive of subarachnoid hemorrhage
  • platelet count <100,000
  • current anticoagulant use w/ INR >1.7 or PT >15 seconds or aPTT >40 seconds
  • evidence of hemorrhage on CT
32
Q

What are the endovascular treatments for ischemic stroke?

A

Mechanical clot removal devices – “Thrombectomy”

*multiple on the market

33
Q

What is a Transcarotid Artery Revascularization (TCAR)?

A

Minimally invasive treatment for carotid artery disease – helps prevent future strokes

  • blood temporarily reversed during procedure to prevent plaque that breaks off going to brain
  • may be done under GETA or even local

Risks include stroke, MI, death, damage to carotid artery or cranial nerves, bleeding, bruising, swelling at neck/groin

Advanced Principles of Anesthesia (31 decks)

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