During clipping of a cerebral aneurysm, the surgeon requests a period of deliberate temporary vascular occlusion. Which pharmacological agent can be used for cerebral protection during this occlusion period?

• A Ketamine to increase cerebral blood flow
• B Neostigmine to enhance ACh-mediated neuroprotection
• C N2O to reduce cerebral vasospasm
• D High-dose barbiturate (thiopentone) to produce EEG burst suppression — reduces CMRO2 ✓

Explanation

Barbiturate-induced EEG burst suppression reduces cerebral metabolic rate of oxygen consumption (CMRO2) by up to 50%, thereby providing tolerance for brief periods of temporary vascular occlusion during aneurysm surgery. Thiopentone is infused to achieve burst suppression on EEG (isoelectric pattern), reducing metabolic demand to match decreased supply. Ketamine increases CMRO2 and is contraindicated in raised ICP. N2O increases cerebral blood flow and CMRO2, making it unfavourable in neuroanaesthesia. Modern practice increasingly uses TIVA with propofol (which also reduces CMRO2) as an alternative.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.