In which scenario should you hyperventilate a patient with a head injury?

Hyperventilating a patient with a head injury is indicated when there are signs of herniation, such as unequal pupils. This condition can occur when there is increased intracranial pressure, which can compress the brain and impact its function. By hyperventilating the patient, you help to lower the carbon dioxide levels in the blood, which can lead to vasoconstriction of the cerebral blood vessels. This action may reduce intracranial pressure temporarily and potentially provide a critical intervention in the case of impending herniation.

Recognizing signs of herniation is crucial because it signals a medical emergency where immediate corrective measures may be needed to prevent further neurologic damage or death. Hyperventilation in this context can be a life-saving maneuver until more definitive treatment can be provided.