BLOOD PRESSURE MANAGEMENT IN ACUTE

STROKE

Pat Melanson, MD

McGill University

“Brain Attack”

• Paradigm shift - End of nihilism

• Early effective interventions

• Time-sensitive disease

• Chain of recovery

• Stroke units and stroke centers

Stroke Protocols

• 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

• 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• CBF = CPP / CVR

• CPP = MAP - ICP

• MAP = DBP + 1/3 PP

• Cerebral autoregulation– normal between 50 - 150

– 70/40 to 200/130

50 150

Cerebral Autoregulation

CBF50

ml/100g/min

MAP

20

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 20 - 30 %

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

• 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 decrease

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 , adrenergic blockade

• Usual contraindications to -blockade

• Rapidly effective when given IV;

• Onset < 5 min, peak 5-10 min, duration 2-6 hr (sometimes longer)

• 5 - 10 mg iv q10 minutes

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

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

Pharmacological Elevation of BP in Acute Stroke

• Pharmacological elevation of blood pressure in acute stroke: Clinical effects and safety. Rordorf, Stroke 1997; 28:2133– Retrospective review of 63 patients– Ischemic stroke with normal BP– 30 received phenylephrine (alpha-agonist)– 10 demonstrated a BP threshold

• Improved outcome

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