BLOOD PRESSURE
MANAGEMENT IN ACUTE
STROKE
Pat Melanson, MD
McGill University
“Brain Attack”
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Paradigm shift - End of nihilism
Early effective interventions
Time-sensitive disease
Chain of recovery
Stroke units and stroke centers
Stroke Protocols
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Aspiration pneumonia, UTI’s
DVT prophylaxis
Glucose control
Fever control
BP management
– avoidance of overtreatment
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?
Lowering BP in Acute Stroke:
Pros
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Chronic hypertension
Rebleed/ increase hematoma size
Cerebral edema, Raised ICP
Hemorrhagic transformation
– Decrease bleeding with t-PA
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
Cerebral Blood Flow
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CBF = CPP / CVR
CPP = MAP - ICP
MAP = DBP + 1/3 PP
Cerebral autoregulation
– normal between 50 - 150
– 70/40 to 200/130
Cerebral Autoregulation
CBF
50
ml/100g/min
20
50
MAP
150
Cerebral Autoregulation
• MAP below lower limit
– hypoperfusion with ischemia
• MAP above upper limit
– “breakthrough” vasodilation
– Segmental pseudospasm
(“sausage-string”)
– fluid extravasation
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)
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 3:S51,1983
• Most ischemic complications
develop with reductions greater than
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
Pharmacologic
Therapy
Drugs Best Avoided
• Direct-acting cerebral vasodilators
– adversely affect CBF
– potential to increase ICP
– shift autoregulation curve to the right
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Nitroglycerine
Nitroprusside
Hydralazine
Calcium Channel Blockers
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
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
Recommended
Antihypertensives
• Beta-blockers
• Alpha-blockers
• ACE inhibitors
• Clonidine
Labetalol
• Combined a, b adrenergic
blockade
• Usual contraindications to bblockade
• Rapidly effective when given IV;
• Onset < 5 min, peak 5-10 min,
duration 2-6 hr (sometimes longer)
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.
Recommendations
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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
Pharmacological Elevation of
BP in Acute Stroke
• Pharmacological elevation of blood
pressure in acute stroke: Clinical effects
and safety. Rordorf, Stroke 1997; 28:2133
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Retrospective review of 63 patients
Ischemic stroke with normal BP
30 received phenylephrine (alpha-agonist)
10 demonstrated a BP threshold
• Improved outcome
Recommendations
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MAP of 140 - 145 ( 220/120)
Avoid direct acting vasodilators
Avoid sublingual nifedipine
Alpha or beta blockers, ACEI
Cautious reduction with frequent
neurologic exams