skip to main content

Sevoflurane and soda lime — FRCA Primary MCQ

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

HardPhysics and Clinical MeasurementSevoflurane and soda limeFRCA Primary

A child is maintained on sevoflurane with very low fresh gas flows through a dry absorbent canister. The anaesthetist increases fresh gas flow and changes the absorbent. Which concern is being reduced?

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

Reveal the answer and explanation

Correct answer: E — Compound A and heat generation

Sevoflurane can degrade in alkaline absorbents to Compound A, and desiccated absorbents can generate heat with volatile agents. Carbon monoxide is more associated with desiccated absorbent and some volatile agents, especially desflurane, but nitrous oxide is not the source. Ozone and helium accumulation are not relevant. Avoiding desiccated absorbent and using appropriate flows reduces risk.

Reference: Dorsch and Dorsch Understanding Anesthesia Equipment; Peck, Hill & Williams Pharmacology