Sevoflurane MAC reduction — FRCA Primary MCQ

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HardPharmacologySevoflurane MAC reductionFRCA Primary

A 79-year-old undergoing hip fracture fixation receives sevoflurane with fentanyl after induction. The end-tidal sevoflurane concentration required to prevent movement is lower than in a young adult. Which factor best explains this?

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Correct answer: E — Increasing age

Minimum alveolar concentration falls with increasing age and is also reduced by opioids and many sedatives. Hyperthermia tends to increase anaesthetic requirement rather than reduce it. Hypoxaemia by itself is not used clinically as a reliable MAC-reducing strategy, and red hair phenotype may increase requirement for some agents. MAC is a population measure, so elderly patients need careful titration rather than adult-standard concentrations.

Reference: Peck, Hill & Williams Pharmacology for Anaesthesia and Intensive Care; RCoA Primary FRCA Syllabus