Measurement of gases (O2, CO2, N2, N2O and volatile agents)

The ability to measure gases of clinical significance is key to the practice of anaesthesia and Intensive Care Medicine. Various gas analysers, employing different physical techniques, exist to measure concentrations of these gases.Commonly used techniques in clinical practice include the use of the paramagnetic analyser or galvanic fuel cell to measure oxygen concentration and infrared spectrography to measure carbon dioxide concentration. The Clark electrode and Severinghaus electrode are used to measure oxygen and carbon dioxide tension respectively. Raman spectroscopy and mass spectrometry can be used to measure concentrations of oxygen, carbon dioxide and volatile agents. Piezoelectric gas analysers and refractometers can be used to measure concentrations of volatile agents.