Sevoflurane MAC in Children — FRCA Final MCQ

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EasyGeneral AnaesthesiaSevoflurane MAC in ChildrenFRCA Final

A healthy, unpremedicated 8-year-old child receives sevoflurane in oxygen alone, without nitrous oxide, opioids or other anaesthetic agents. What end-tidal sevoflurane concentration corresponds most closely to 1 MAC, defined as the concentration preventing movement in response to surgical incision in 50% of patients?

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Correct answer: A — 2.5%

The correct answer is A, 2.5%. MAC is the steady-state alveolar concentration that prevents movement in response to a standard surgical stimulus in 50% of patients. It is age-dependent: the current UK SmPC lists an average sevoflurane MAC in oxygen of 2.5% for children aged 3–12 years. The specified absence of nitrous oxide, opioids and other anaesthetic agents is important because these can reduce the sevoflurane requirement. A concentration of 3.0% is closer to the value for younger infants aged 1 to under 6 months. Values of 1.8%, 1.2% and 0.8% are below the expected age-adjusted MAC for an 8-year-old receiving sevoflurane in oxygen alone and would be more compatible with an older patient or substantial MAC-sparing adjuncts.

Reference: Piramal Critical Care Ltd. Sevoflurane 100% Inhalation Vapour, liquid: Summary of Product Characteristics, section 4.2 and Table 1, updated 16 March 2026. https://www.medicines.org.uk/emc/product/9780/smpc