Critical temperature — FRCA Primary MCQ

Correct answer: C — Nitrous oxide liquid-vapour cylinder

Critical temperature explains why nitrous oxide liquefies at room temperature. Pressure transducer damping is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Heat and moisture exchanger is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Ferromagnetic projectile risk is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. EMG activity can falsely raise the index is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. In Primary FRCA physics and measurement, the safest answer is the one that follows the underlying physical principle and the limitations of the device.

Reference: Davis and Kenny Basic Physics and Measurement in Anaesthesia; RCoA Primary FRCA syllabus