Infrared capnography — FRCA Primary MCQ

Correct answer: D — Infrared gas analyser

CO2 absorbs infrared radiation at characteristic wavelengths. Non-interchangeable screw thread is less appropriate because it would fit a different clinical clue or a separate anaesthetic problem. Desflurane heated pressurised vaporiser 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. Pressure transducer damping 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