Fig. 2From: Volumetric capnography: lessons from the past and current clinical applicationsConcentration of CO2 during a tidal expiration. Phase I: beginning of expiration; expired gas represents contents of the conduction compartment of the respiratory system. Phase II: transition between anatomic and alveolar dead space. Phase III: alveolar gas. Expired FCO 2 (%) fraction of expired CO2, SIII slope of phase III, VTCO 2 ,br CO2 elimination per breathBack to article page