Isoflurane is preferred over halothane for neurosurgical procedures because of which specific cerebral haemodynamic advantage?

• A Isoflurane does not increase intracranial pressure at equipotent doses
• B Isoflurane lowers cerebral metabolic rate more than halothane
• C Isoflurane does not cross the blood-brain barrier
• D Isoflurane preserves cerebrovascular autoregulation better and causes less cerebral vasodilation at clinical doses ✓

Explanation

All potent inhalational agents increase cerebral blood flow (CBF) by direct vasodilation and can raise ICP. Halothane causes the most pronounced cerebral vasodilation, significantly impairing cerebrovascular autoregulation. Isoflurane (and desflurane/sevoflurane) at <1 MAC preserves autoregulation better and has a higher threshold for disrupting CO2 reactivity, making them safer for neurological cases. While isoflurane does reduce CMRO2 (cerebral metabolic rate), the key distinction from halothane is the lesser degree of vasodilation.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.