Wrong Volatile in Vaporiser — FRCA Final MCQ

Instant feedback + full explanation. One question, done properly.

HardAnaesthetic Equipment & SafetyWrong Volatile in VaporiserFRCA Final

A wrong-side vaporiser filling has occurred: isoflurane put into sevoflurane vaporiser. Clinical risk?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Over-dosing (isoflurane higher SVP than sevoflurane)

Isoflurane SVP (~240 mmHg) > sevoflurane SVP (~160 mmHg). Sevoflurane vaporiser with isoflurane delivers higher concentration than dialled → overdose. Also isoflurane MAC (1.15%) < sevoflurane (2.0%), compounding the problem. Keyed filling system prevents this error.

Reference: MHRA – 2023 – Anaesthetic vaporiser filling errors