What is the target cerebral perfusion pressure (CPP) for a patient with a severe traumatic brain injury (TBI)?

Target Cerebral Perfusion Pressure in Severe TBI

The correct answer is B: 60 to 70 mmHg is the recommended target CPP for adults with severe traumatic brain injury. 1, 2

Evidence-Based Rationale

Maintaining CPP between 60-70 mmHg optimizes neurological outcomes in severe TBI patients while avoiding the complications associated with both inadequate cerebral perfusion and excessive pressure targets. 1

Why This Range Is Optimal

• CPP < 60 mmHg leads to poor neurological outcomes due to inadequate cerebral blood flow and risk of cerebral ischemia, making this the critical lower threshold that must be maintained. 1, 2

• CPP > 70 mmHg is not routinely recommended because it increases the risk of acute respiratory distress syndrome (ARDS) by 5-fold without providing any improvement in neurological outcomes compared to the 60-70 mmHg target range. 1, 2

• CPP exceeding 90 mmHg may worsen vasogenic cerebral edema, further supporting the upper limit of 70 mmHg as appropriate for most patients. 1

Critical Implementation Details

The reference point for measuring mean arterial pressure (MAP) must be placed at the external ear tragus to ensure accurate CPP calculations (CPP = MAP - ICP), as failure to use this anatomical landmark leads to inaccurate CPP values and inappropriate management. 1, 2

Emerging Considerations for Individualization

While the standard 60-70 mmHg target applies to most patients, recent evidence suggests that cerebral autoregulation status affects optimal targets:

• Patients with preserved cerebral autoregulation may benefit from CPP-based protocols targeting higher CPP values within or slightly above this range. 1, 2

• Patients with impaired autoregulation may have better outcomes with ICP-based protocols targeting CPP around 60 mmHg (the lower end of the recommended range). 1, 2

• Recent research demonstrates an asymmetric relationship where decreases below optimal CPP are more harmful than elevations above it, suggesting that when in doubt, erring toward the higher end of the 60-70 mmHg range may be safer than the lower end. 3

Common Pitfalls to Avoid

• Setting targets too high (>70 mmHg) increases ARDS risk without neurological benefit. 1

• Allowing CPP to fall below 60 mmHg risks cerebral ischemia and worsens secondary brain injury. 1, 2

• Incorrect MAP measurement reference point (not using the external ear tragus) produces inaccurate CPP calculations and inappropriate treatment decisions. 1, 4