BLOOD PRESSURE MANAGEMENT IN ACUTE STROKE

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BLOOD PRESSURE MANAGEMENT IN ACUTE STROKE

• Pat Melanson, MD
• McGill University

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Brain Attack

• Paradigm shift - End of nihilism
• Early effective interventions
• Time-sensitive disease
• Chain of recovery
• Stroke units and stroke centers

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Stroke Protocols

• Aspiration pneumonia, UTIs
• DVT prophylaxis
• Glucose control
• Fever control
• BP management
• avoidance of overtreatment

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Cases

• Ischemic CVA, BP 225/105 (145)
• Hemorrhagic CVA, BP 215 /110 (145)
• Would you actively lower the BP?
• What target or threshold level?
• What drug ?
• Which drugs should be avoided?

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Lowering BP in Acute Stroke Pros

• Chronic hypertension
• Rebleed/ increase hematoma size
• Cerebral edema, Raised ICP
• Hemorrhagic transformation
• Decrease bleeding with t-PA

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Lowering BP in Acute Stroke Cons

• Acute hypertension is self-limited
• RISK OF ISCHEMIA
• Reflex response to maintain CBF
• Ischemic penumbra
• Shift in autoregulation curve
• More sensitive to BP decreases

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Cerebral Blood Flow

• CBF CPP / CVR
• CPP MAP - ICP
• MAP DBP 1/3 PP
• Cerebral autoregulation
• normal between 50 - 150
• 70/40 to 200/130

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Cerebral Autoregulation
CBF 50 ml/100g/min
20
150
50
MAP
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Cerebral Autoregulation

• MAP below lower limit
• hypoperfusion with ischemia
• MAP above upper limit
• breakthrough vasodilation
• Segmental pseudospasm
  (sausage-string)
• fluid extravasation

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Cerebral Autoregulation

• Shift to right
• Chronic hypertensives
• ICH, SAH, Ischemic infarct
• Trauma
• Cerebral edema
• Age, atherosclerosis
• Some hypertensives suffer decrease CBF at MAP
  higher than 120 (160/100)

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How far can BP be safely lowered?

• Lower limit usually 25 below MAP
• 50 of chronic hypertensives reached lower
  autoregulation limit with 11 to 20 reduction in
  MAP
• 50 had lower limit above usual mean
• Kanaeko et al J Cereb Blood Flow Metab
  3S51,1983
• Most ischemic complications develop with
  reductions greater than 20 - 30

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Initial Lowering of BP Therapeutic Guidelines

• Do not lower BP more than 15 over the first 1
  to 2 hours unless necessary to protect other
  organs
• Decreasing to DBP of 110 or patients normal
  levels may not be safe
• Further reductions should be very gradual ( days)
• Follow neuro status closely

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Pharmacologic Therapy
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Drugs Best Avoided

• Direct-acting cerebral vasodilators
• adversely affect CBF
• potential to increase ICP
• shift autoregulation curve to the right
• Nitroglycerine
• Nitroprusside
• Hydralazine
• Calcium Channel Blockers

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Nifedipine

• Peripheral, cerebral and coronary arteriolar
  vasodilation
• Rapid onset of antihypertensive effect
• 5-20 minute onset
• peak effect in 30-60 min
• duration 4-5 hr
• Potential severe hypotension
• Several case reports of cerebral or myocardial
  ischemia after rapid decrease

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Sublingual Nifedipine

• Should a Moratorium be Placed on Sublingual
  Nifedipine capsules given for hypertensive
  emergencies and pseudoemergencies?
• Grossman, Messerli, Grodzicki, Kowey
• JAMA, 276 1328 - 1331,1996

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Recommended Antihypertensives

• Beta-blockers
• Alpha-blockers
• ACE inhibitors
• Clonidine

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Labetalol

• Combined a, b adrenergic blockade
• Usual contraindications to b-blockade
• Rapidly effective when given IV
• Onset lt 5 min, peak 5-10 min, duration 2-6 hr
  (sometimes longer)
• 5 - 10 mg iv q10 minutes

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ACE inhibitors

• IV enalaprilat, oral captopril potentially useful
  for acute BP reduction
• Difficult to titrate (sometimes
  ineffective,sometimes excessive BP )
• Positive effects on cerebral autoreg.
• Captopril 12.5 mg S/L

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Recommendations

• MAP of 140 - 145 (220/120)
• Max decrease of 15 MAP
• Avoid direct acting vasodilators
• Avoid sublingual nifedipine
• Labetalol, Captopril
• Cautious reduction with frequent neurologic exams

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Pharmacological Elevation of BP in Acute Stroke

• Pharmacological elevation of blood pressure in
  acute stroke Clinical effects and safety.
  Rordorf, Stroke 1997 282133
• Retrospective review of 63 patients
• Ischemic stroke with normal BP
• 30 received phenylephrine (alpha-agonist)
• 10 demonstrated a BP threshold
• Improved outcome

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Recommendations

• MAP of 140 - 145 ( 220/120)
• Avoid direct acting vasodilators
• Avoid sublingual nifedipine
• Alpha or beta blockers, ACEI
• Cautious reduction with frequent neurologic exams