What is capnography?

The activity of measuring the concentration of carbon dioxide (CO 2 ) in respiratory gases during the respiratory cycle of a patient is called capnography. The equipment used in capnography usually plots the partial pressure of CO 2 in the exhaled breath as a wave form, with time on the x-axis and pressure of carbon dioxide on the y-axis. Infrared radiation is passed through exhaled breath, the CO 2 of which absorbs some of the radiation. The remaining radiation is detected by making it fall on a sensor, and used as a measure of the level of CO 2 present in the breath. Capnography is used as a monitoring tool during anaesthesia and intensive care.