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Flowmeter Gas Leak — FRCA Final MCQ

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ModerateAnaesthetic Equipment & SafetyFlowmeter Gas LeakFRCA Final

An anaesthetist notices that the bobbin on the oxygen flowmeter is reading 2 L/min but the patient is receiving much less oxygen than expected. The pipeline pressure gauge shows 400 kPa (normal). Which fault is most likely?

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

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Correct answer: E — Cracked flowmeter tube causing gas leak

A cracked or damaged flowmeter tube is the most common cause of discrepancy between displayed and actual gas flow in the anaesthetic machine. Gas leaks from the crack, bypassing the flowmeter outlet and delivering less gas than indicated. This is a serious safety hazard as the patient receives less oxygen than the anaesthetist believes. The flowmeter assembly downstream of the crack delivers to the patient; gas upstream leaks to atmosphere. This is why the oxygen flowmeter is positioned downstream (nearest the common gas outlet) in most modern machines.

Reference: AAGBI – 2019 – Checking anaesthetic equipment; RCOA – 2023 – Equipment safety