What is the targeted end-tidal CO2 range for a patient with increased intracranial pressure (ICP)?

• A. 25-30 mmHg
• B. 28-32 mmHg
• C. 30-35 mmHg
• D. 34-40 mmHg

Answer: (C)

When ICP is elevated, briefly using controlled hyperventilation to lower CO2 levels is a common, rapid way to reduce cerebral blood flow and help bring ICP down. The end-tidal CO2 range that achieves this balance is about 30–35 mmHg. This mild hypocapnia causes cerebral vasoconstriction, which reduces blood volume in the brain and lowers ICP without pushing CO2 so low that the brain could suffer ischemia. End-tidal CO2 is used as a surrogate for arterial CO2, so keeping ETCO2 in this range helps ensure PaCO2 is near the desired level as well. Values higher than this range won’t adequately decrease ICP, while values lower than this range increase the risk of ischemia from excessive vasoconstriction. This is typically a temporary measure during acute ICP management, with careful monitoring to avoid duration-dependent harm.