Thiopentone is infused to achieve electroencephalographic burst suppression before application of a temporary aneurysm clip. At this endpoint, the reduction in cerebral metabolic rate for oxygen achieved is approximately:
- A 15 percent
- B 30 percent
- C 50 percent ✓
- D 90 percent
Correct answer: C. 50 percent
Explanation
Barbiturates suppress synaptic electrical activity, and complete burst suppression corresponds to a fall in cerebral metabolic rate for oxygen of about 50 percent. The remaining half represents obligatory basal cellular metabolism, which anaesthetic agents cannot reduce. This is why pushing thiopentone beyond burst suppression offers no additional cerebral protection while adding cardiovascular toxicity, a concept repeatedly tested in neuroanaesthesia.
Reference: Miller's Anesthesia, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.