MAC-BAR 1.5-1.7 — FRCA Primary MCQ

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ModeratePharmacology - Inhalational AgentsMAC-BAR 1.5-1.7FRCA Primary

Regarding MAC-BAR (MAC that blocks autonomic response) its value relative to MAC is approximately:

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Correct answer: C — 1.5-1.7 MAC

MAC-BAR is approximately 1.5-1.7 MAC. It blocks the autonomic (sympathetic) response to skin incision (tachycardia / hypertension). MAC-awake is ~0.3-0.4 MAC. MAC-intubation is ~1.3 MAC. These multiple MAC endpoints demonstrate that different responses require different anaesthetic depths.

Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care