What is the recommended blood pressure management strategy for patients with traumatic brain injury?

Blood Pressure Management in Traumatic Brain Injury

For patients with traumatic brain injury, maintaining cerebral perfusion pressure (CPP) between 60 and 70 mmHg is recommended to optimize neurological outcomes and reduce mortality.1, 2

Initial Assessment and Management

• Arterial hypotension is a key issue associated with poor prognosis at 6 months in TBI patients, with episodes of systolic blood pressure <90 mmHg for at least 5 minutes significantly increasing neurological morbidity and mortality 1
• Both prehospital and in-hospital hypotension are associated with increased mortality rates 1
• The combination of arterial hypotension and hypoxemia is particularly dangerous, with mortality rates reaching 75% 1
• Immediate correction of hypotension and hypoxemia should be prioritized as part of the initial management 1

Cerebral Perfusion Pressure Targets

• CPP is calculated as the difference between mean arterial pressure (MAP) and intracranial pressure (ICP): CPP = MAP - ICP 2
• The reference point for measuring MAP should be placed at the external ear tragus for accurate CPP calculations 1, 2
• For adults with TBI, maintain CPP between 60 and 70 mmHg in the absence of multi-modal monitoring 1, 2
• CPP <60 mmHg is associated with poor neurological outcomes due to inadequate cerebral blood flow 1, 2
• CPP >70 mmHg is not recommended routinely as it has been associated with a 5 times higher incidence of respiratory distress syndrome without improving neurological outcomes 1, 2
• CPP exceeding 90 mmHg may worsen vasogenic cerebral edema and neurological outcomes 1

Individualized Management Based on Cerebral Autoregulation

• Patients with preserved cerebral autoregulation may benefit from CPP-based protocols targeting higher CPP values 1, 2
• Patients with impaired autoregulation tend to have better outcomes with ICP-based protocols targeting lower CPP around 60 mmHg 1, 2
• When cerebral autoregulation status is unknown, maintaining CPP between 60-70 mmHg is the safest approach 1, 2

Management of Intracranial Hypertension

• For signs of brain herniation (mydriasis, anisocoria) or threatened intracranial hypertension, use osmotherapy with either:
  • Mannitol 20% or hypertonic saline solution at a dose of 250 mOsm, infused over 15-20 minutes 1
• These osmotic agents reduce ICP with maximum effect observed after 10-15 minutes and duration of 2-4 hours 1
• When using osmotic agents, monitor fluid, sodium, and chloride balances carefully 1
• Avoid prolonged hypocapnia for treating intracranial hypertension as it may worsen outcomes 1

Vasopressor Selection

• When vasopressors are needed to maintain adequate CPP, either phenylephrine or norepinephrine can be used 3
• A multicenter study found no significant difference in 6-month Glasgow Outcome Scale Extended scores between patients receiving phenylephrine versus norepinephrine as initial vasopressors 3

Common Pitfalls to Avoid

• Setting CPP targets too high (>70 mmHg) increases risk of ARDS without improving neurological outcomes 2
• Setting CPP targets too low (<60 mmHg) may lead to cerebral ischemia and worsen secondary brain injury 2
• Failing to place the reference point for MAP measurement at the external ear tragus can lead to inaccurate CPP calculations 2
• Excessive blood pressure reduction may compromise cerebral perfusion and potentially worsen brain injury 4
• Rapid, profound reductions in blood pressure (>70 mmHg in 1 hour) should be avoided as they may compromise cerebral perfusion 4

Special Considerations

• For patients with combined hemorrhagic shock and severe TBI, maintain mean arterial pressure ≥80 mmHg 4
• Protocols focused on detection and correction of secondary insults (hypotension, hypoxemia) are associated with improved outcomes and reduced mortality 1