What is the goal blood pressure in subarachnoid hemorrhage?

Blood Pressure Management in Subarachnoid Hemorrhage

In subarachnoid hemorrhage (SAH), systolic blood pressure should be maintained below 160 mmHg before aneurysm securing, and then adjusted based on the phase of treatment, with a minimum systolic pressure of 110-140 mmHg to prevent cerebral ischemia. 1

Pre-Aneurysm Securing Phase

Blood Pressure Targets

• Upper limit: Systolic BP <160 mmHg 1
  • American Heart Association/American Stroke Association (AHA/ASA) recommends systolic BP <160 mmHg 1
  • European Stroke Organization recommends treatment if systolic BP exceeds 180 mmHg 1
• Lower limit: Maintain systolic BP >110 mmHg to avoid hypotension 1
  • Avoid systolic BP <110 mmHg to prevent cerebral hypoperfusion 1

Rationale

• High BP is associated with increased risk of aneurysm rebleeding 1
• Rebleeding risk is highest in first 2-12 hours after initial hemorrhage 1
• Systolic BP >160 mmHg has been associated with higher rebleeding rates 1
• Recent survey data shows that most practitioners target systolic BP of 140-160 mmHg before aneurysm securing 2

Medication Selection

• Use titratable, short-acting continuous-infusion IV agents 1
• Preferred agents:
  • Nicardipine: Provides smoother BP control 1
  • Labetalol: Effective alternative 1
  • Esmolol: Good for rapid titration 1
• Avoid sodium nitroprusside due to risk of increased intracranial pressure and toxicity with prolonged infusion 1

Post-Aneurysm Securing Phase

Blood Pressure Management

• After securing the aneurysm, BP targets can be liberalized 1, 2
• Upper limits can be increased to 180-200 mmHg if needed to manage delayed cerebral ischemia (DCI) 2, 3
• Lower limit should maintain cerebral perfusion pressure (CPP) >60 mmHg 1

Delayed Cerebral Ischemia Management

• For patients with symptoms of DCI (typically days 4-12 after SAH):
  • Induced hypertension may be considered to improve cerebral perfusion 1
  • Maintain mean arterial pressure >90 mmHg 1
  • Avoid MAP <60 mmHg as it's associated with increased risk of DCI 4

Important Considerations and Pitfalls

Balancing Risks

• Key pitfall: Overly aggressive BP lowering may worsen cerebral perfusion and lead to ischemia 1
• Key pitfall: Insufficient BP control increases risk of rebleeding 1
• Balance must be maintained between:
  1. Preventing rebleeding (requires lower BP)
  2. Maintaining cerebral perfusion (requires adequate BP)
  3. Managing DCI (may require induced hypertension) 1

Special Situations

• Patients with severe SAH (World Federation of Neurosurgical Societies grade V) often present with very high BP (≥220 mmHg) and have worse outcomes 5
• Initial systolic BP ≥189 mmHg may predict poor outcomes 5
• Recent data suggests MAP <100 mmHg is associated with decreased rebleeding risk, while MAP <60 mmHg increases DCI risk 4

Monitoring and Implementation

• Continuous arterial BP monitoring is recommended in ICU setting
• Frequent reassessment of neurological status during BP manipulation
• Adjust targets based on:
  1. Time since initial hemorrhage
  2. Aneurysm securing status
  3. Presence of DCI or vasospasm
  4. Patient's neurological status

Despite the common practice of setting BP goals in SAH patients, there is significant practice variation 6, 2, 3, highlighting the need for more definitive clinical trials. Current recommendations are based primarily on observational studies and expert consensus rather than large randomized trials.