How does hyperventilation affect ICP levels?

Hyperventilation affects intracranial pressure (ICP) primarily through changes in cerebral blood flow resulting from alterations in carbon dioxide (CO2) levels. When a person hyperventilates, the rapid breathing leads to decreased levels of CO2 (hypocapnia) in the blood. This drop in CO2 concentration causes vasoconstriction of cerebral blood vessels, thereby reducing cerebral blood flow. Since less blood volume in the cranial cavity translates to lower intracranial pressure, hyperventilation is effective in decreasing ICP.

Furthermore, by reducing the volume of blood in the brain, hyperventilation can alleviate pressure on brain tissues and help mitigate conditions that cause elevated ICP. This physiological response is particularly useful in clinical scenarios where management of high ICP is crucial, such as in traumatic brain injury or after neurosurgical procedures.

The other potential impacts mentioned in the options are not aligned with the physiological response seen during hyperventilation.