After how many hours should hyperventilation therapy to reduce ICP be discontinued?

The correct answer is based on the understanding of how hyperventilation therapy influences intracranial pressure (ICP) management in patients with conditions such as traumatic brain injury or other circumstances leading to elevated ICP. Hyperventilation, which leads to respiratory alkalosis, causes vasoconstriction of the cerebral blood vessels, resulting in a decrease in cerebral blood volume and subsequently lowering ICP.

However, this therapy is not intended for long-term use. Prolonged hyperventilation can lead to complications, such as decreased cerebral perfusion and potential ischemia due to excessively low CO2 levels. The safe duration for hyperventilation therapy is generally limited to 24 to 48 hours. Clinical practice guidelines suggest discontinuing hyperventilation after around 48 hours to prevent these unwanted effects while still achieving the desired reduction in ICP.

The correct choice reflects an understanding of the optimal time frame for using this therapeutic intervention. Discontinuing the therapy at this point mitigates risks associated with prolonged respiratory alkalosis while still addressing the immediate need to manage elevated ICP.