Blood Pressure in Stroke

Today’s discussion: Why and How do you control the blood pressure in both ischemic and hemorrhagic stroke?


To know the rationale behind the need to lower the blood pressure in stroke and the limitations, we have to review the cerebral physiology and cerebral autoregulation.

Where CBF: cerebral blood flow
CPP: cerebal perfusion pressure
CVR: cerebral vascular resistance



The issue in ischemia is that it disrupts that cerebral autoregulation, so the CVR does not respond to changes in CPP.

Another thing to consider is that the impact of decreased cerebral blood flow (CBF) is related to both the magnitude and duration , therefore:
- CBF <10-15 mL for more than a short time = neuronal death. Labeled as “infarct”
- CBF 15-20 mL = neuronal functional impairment. Labeled as “penumbra”

The “Penumbra” is an area of high CBF, high O2 consumption, and preserved metabolic rate. This area is seen by PET, and sometimes with MRI. It’s ischemic, but not infarcted. It is very vulnerable to any decrease in blood pressure.

On the other hand, leaving the blood pressure too high predisposes the patient to more bleeding and hematoma formation in hemorrhagic stroke, and to more edema and hemorrhagic transformation in ischemic stroke. However, clinical data supporting this theory is sparse.

A few pointers to keep in mind:

- Patients with chronically uncontrolled HTN have “reset” their “normal” CPP to a higher level, so their CBF decreases at a relatively higher MAP. Therefore, lowering their blood pressure too much can be detrimental.

- Patients with carotid stenosis will have even more compromised cerebral blood flow with acute reduction in blood pressure.

Now that we’re done with the logic behind it, here’s the most consistent data for management of BP in stroke (according to Rosen’s 6th Edition); most of it was reached by consensus:

As for ischemic strokes;

As for hemorrhagic strokes, these are the latest AHA guidelines:

A few pointers to remember:
- MAP= 1/3 SBP + 2/3 DBP
- Labetalol should be avoided in asthma, acute heart failure, or severe cardiac conduction abnormalities.
- In refractory HTN, other agents may be considered. However, drugs that cause precipitous decrease in bp should be avoided, such as sublingual nitroglycerin and calcium channel blockers (CCB)

So to sum it up:
- If the blood pressure is too high, the patient will rebleed (especially in hemorrhagic strokes).
- If the pressure is too low, the patient will infarct his penumbra (especially in ischemic stroke)
- Therefore, blood pressure must be controlled in acute stroke; in hemorrhagic stroke more than ischemic, and in patients managed with tPA more than non-thrombolytic candidates