Gas Analysis

Measurement and monitoring of clinically important gases in anaesthesia and critical care are fundamental to patient care. Gases of particular interest are oxygen, carbon dioxide, nitrous oxide, carbon monoxide and volatile anaesthetic gases. Infrared absorption by these gases and utilisation of Beer’s and Lambert’s laws are the basic scientific principles used by the majority of gas analysers in clinical practice. The principles and limitations of main stream, side stream, dispersive and non-dispersive analysers are discussed. Non-infrared gas analysis techniques such as mass spectrometry, gas-liquid chromatography, ultrasound gas analysis, Raman spectrometry and interferometry are also discussed, together with their limitations in clinical practice.