What is the role of hyperventilation in acute TBI management, and what are its risks?

• A. Long-term reduction of ICP via cerebral vasodilation; increases edema.
• B. Temporary reduction of ICP via cerebral vasoconstriction; long-term use is avoided due to risk of cerebral ischemia.
• C. Prevents seizures; risk of respiratory acidosis.
• D. A first-line therapy for all TBI cases.

Answer: (B)

In acute TBI, hyperventilation is used to rapidly lower intracranial pressure by causing cerebral vasoconstriction through a drop in arterial CO2 (PaCO2). This vasoconstriction reduces cerebral blood volume and helps decrease ICP quickly, which can buy time to implement definitive treatments.

But this is a temporary maneuver, not a long-term solution. If hyperventilation is used for too long or too aggressively, cerebral blood flow can drop too much, leading to cerebral ischemia—especially in areas where autoregulation is impaired after injury. That risk of ischemia is why hyperventilation is avoided as a routine, long-term therapy and reserved for short-term use during severe ICP elevations or when other measures aren’t enough.

It also typically causes respiratory alkalosis rather than acidosis, and it’s not a universal first-line therapy for all TBI cases. This combination of a brief, targeted ICP reduction with significant ischemia risk when prolonged is why the described approach is considered correct.