Capnography refers to the noninvasive measurement of the
partial pressure of carbon dioxide (CO2) in exhaled breath expressed as the CO2
concentration over time. The waveform displayed on a capnogram, or capnograph,
is used to identify disease conditions and assess response to treatment.
Capnography is also one of the most reliable indicators that an endotracheal
tube has been correctly placed during intubation.
Pulse oximetry provides instantaneous feedback about
oxygenation in patients receiving general anesthesia.
Capnography distinguishes between oxygenation (how
effectively CO2 is being eliminated by the pulmonary system) and ventilation
(how effectively CO2 is being transported through the vascular system).
Capnography became a routine part of anesthesia practice in Europe and the
United States in the 1970s; it is now part of the standard of care for all
patients receiving general anesthesia.