What are the guidelines for blood pressure (BP) management in stroke patients?

Blood Pressure Management in Acute Stroke

Blood pressure management in acute stroke depends critically on whether the patient is receiving reperfusion therapy: for patients receiving IV thrombolysis, BP must be lowered to <185/110 mmHg before treatment and maintained <180/105 mmHg for 24 hours afterward; for patients NOT receiving reperfusion therapy, BP should not be treated unless it exceeds 220/120 mmHg, in which case it should be carefully reduced by approximately 15% over the first 24 hours. 1

Management Algorithm Based on Reperfusion Status

Patients Receiving IV Thrombolysis (rtPA)

Pre-thrombolysis BP targets:

• BP must be lowered to <185/110 mmHg before initiating rtPA 1
• This threshold corresponds to study inclusion criteria in pivotal thrombolysis trials and reflects the increased risk of hemorrhagic transformation with higher BP 1, 2

Post-thrombolysis BP targets:

• Maintain BP <180/105 mmHg for at least 24 hours after rtPA administration 1
• High BP during the initial 24 hours is linked to greater risk of symptomatic intracranial hemorrhage 1

Monitoring protocol:

• Check BP every 15 minutes for 2 hours from start of rtPA 1
• Then every 30 minutes for 6 hours 1
• Then hourly for 16 hours 1

Patients Receiving Mechanical Thrombectomy

• Lower BP to <180/105 mmHg prior to thrombectomy and maintain for 24 hours 1
• Limited trial evidence exists, but consensus supports similar targets as thrombolysis 1

Patients NOT Receiving Reperfusion Therapy

For BP <220/120 mmHg:

• Do NOT treat BP during the first 48-72 hours 1, 2, 3
• Initiating or reinitiating antihypertensive therapy in this timeframe is ineffective to prevent death or dependency (Class III: No Benefit) 1, 2
• Permissive hypertension maintains cerebral perfusion to the ischemic penumbra where autoregulation is impaired 1, 2, 3

For BP ≥220/120 mmHg:

• Carefully lower BP by approximately 15% during the first 24 hours 1, 3
• This moderate reduction balances the risk of extreme hypertension against compromising cerebral perfusion 1, 3

Pharmacological Agents for Acute BP Lowering

First-line agent: Labetalol

• Dose: 10-20 mg IV over 1-2 minutes, may repeat once 1, 2
• Or continuous infusion: 2-8 mg/min IV 1
• Preferred due to ease of titration and minimal vasodilatory effects on cerebral vessels 2, 3

Alternative agent: Nicardipine

• Start at 5 mg/h IV, titrate up by 2.5 mg/h every 5-15 minutes 1, 2
• Maximum 15 mg/h 1
• Especially useful if bradycardia or heart failure is present 2, 3

Other options:

• Hydralazine or enalaprilat may be considered when appropriate 1
• Sodium nitroprusside reserved for refractory cases (diastolic BP >140 mmHg) 1

Timing of Antihypertensive Therapy Initiation/Resumption

During acute phase (first 72 hours):

• Patients with BP <180/105 mmHg do NOT benefit from introducing or reintroducing BP medications 1, 3

After acute phase (≥3 days):

• Initiate or reintroduce BP-lowering medication for stable patients with BP ≥140/90 mmHg 1, 2, 3
• This timing allows for neurological stabilization while addressing long-term BP control 1, 2

Before hospital discharge:

• BP-lowering therapy should be commenced before discharge in patients with ischemic stroke/TIA and an indication for BP lowering (Class I recommendation) 1, 3

Physiological Rationale for Conservative Approach

Impaired cerebral autoregulation:

• In acute stroke, autoregulation in the ischemic penumbra is grossly abnormal 1, 2, 3
• Cerebral perfusion becomes directly dependent on systemic BP 1, 3
• Normal autoregulation maintains constant cerebral blood flow across BP range of 50-150 mmHg, but this is lost in ischemic zones 2

U-shaped relationship with outcomes:

• Studies show optimal admission SBP ranges from 121-200 mmHg and DBP from 81-110 mmHg 1
• Both excessively high and low BP are associated with poor outcomes 1, 3

Critical Pitfalls to Avoid

Overly aggressive BP lowering in non-reperfusion patients:

• Treating BP <220/120 mmHg in the first 48-72 hours without reperfusion therapy has been shown ineffective and potentially harmful 1, 2, 3
• Rapid BP reduction can compromise perfusion to the ischemic penumbra 1, 3

Excessive acute BP drops:

• Avoid acute systolic BP reduction >70 mmHg within 1 hour, as this may cause acute renal injury and early neurological deterioration 1

Incorrect BP measurement:

• Never use the affected limb for BP measurement, as it can result in falsely low readings leading to inappropriate treatment decisions 2

Failure to restart medications after acute phase:

• Neglecting to reinitiate antihypertensives after ≥3 days in patients with pre-existing hypertension is a common error 3

Management of Hypotension

Hypotension is rare but serious:

• Occurs in only 0.6-2.5% of acute ischemic stroke patients 1
• Investigate underlying causes: aortic dissection, volume depletion, myocardial ischemia, cardiac arrhythmias 1, 2

Treatment approach:

• Correct hypovolemia with IV normal saline 1, 2
• Treat cardiac arrhythmias that may reduce cardiac output 1
• The brain is especially vulnerable to hypotension during acute stroke due to impaired autoregulation 1

Intracerebral Hemorrhage (ICH) - Key Differences

More aggressive BP lowering is appropriate:

• Immediate BP lowering (within 6 hours) to systolic target 140-160 mmHg should be considered to prevent hematoma expansion 1
• No perihematomal penumbra exists in ICH, so rapid BP reduction is generally well tolerated 4

Avoid excessive drops:

• In ICH with systolic BP ≥220 mmHg, acute reduction >70 mmHg within 1 hour is not recommended 1