Emergency Medical Technician (EMT) Intermediate Practice Exam

Which physiological response may occur if a head-injured patient is hyperventilated with 100% oxygen?

Vasodilation and increased cerebral perfusion Vasoconstriction and decreased cerebral perfusion Increased intracranial pressure Hypercapnia

Correct Answer:

Vasoconstriction and decreased cerebral perfusion

Explanation:

When a head-injured patient is hyperventilated with 100% oxygen, the most appropriate physiological response is vasoconstriction and decreased cerebral perfusion. Hyperventilation leads to a decrease in carbon dioxide levels (hypocapnia) in the blood. The body responds to low carbon dioxide by causing the cerebral blood vessels to constrict (vasoconstriction). This vasoconstriction reduces blood flow to the brain, which in turn diminishes cerebral perfusion. Maintaining adequate cerebral perfusion is crucial, especially in head-injured patients, as they are already at risk for complications related to cerebral blood flow. Therefore, the action of hyperventilating with 100% oxygen in this context is not beneficial and can lead to further complications.

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