Do intravenous anesthetics abolish the cerebrovascular response to CO2 changes?

Do intravenous anesthetics abolish the cerebrovascular response to CO2 changes?

• A. Yes
• B. No
• C. Only at high doses
• D. Not studied

Answer: (B)

The key idea is that cerebral blood vessels still respond to CO2 under intravenous anesthesia. CO2 reactivity is a fundamental control of cerebral blood flow: when CO2 rises, vessels dilate and cerebral blood flow increases; when CO2 falls, they constrict and flow decreases. Intravenous anesthetics like propofol reduce baseline cerebral blood flow and metabolic demand, but they do not eliminate the CO2-evoked vasodilation. Hypercapnia will still raise cerebral blood flow and hypocapnia will lower it, though the overall magnitude of the change may be smaller. Therefore, intravenous anesthetics do not abolish the cerebrovascular response to CO2 changes.

The key idea is that cerebral blood vessels still respond to CO2 under intravenous anesthesia. CO2 reactivity is a fundamental control of cerebral blood flow: when CO2 rises, vessels dilate and cerebral blood flow increases; when CO2 falls, they constrict and flow decreases. Intravenous anesthetics like propofol reduce baseline cerebral blood flow and metabolic demand, but they do not eliminate the CO2-evoked vasodilation. Hypercapnia will still raise cerebral blood flow and hypocapnia will lower it, though the overall magnitude of the change may be smaller. Therefore, intravenous anesthetics do not abolish the cerebrovascular response to CO2 changes.