title: [Conditions under which alveolar air equations are modified and the compensation terms of saturated water vapor in those equations].
abstract: Concentration-pressure conversion by a capnometer is confused even now. This might be attributed to the fact that the alveolar air equation is defined without saturated water vapor. In the present report, alveolar air equations (Riley, Filley and a tidal volume residual type) are modified under the condition that inspired gas is dry (BTPD) and expired gas is saturated by water vapor (BTPS). Consequently only a compensation term of saturated water vapor is simply added to the Riley type alveolar air equation, and two terms to the Filley type. The tidal volume residual type one is simplified. Modification of the equations enables the values of expired volume and expired gas concentration which are measured under the above condition to be substituted directly for variables of these equations written in the form of concentration.
authors.affiliation: Department of Anesthesia, Yokohama Ekisaikai Hospital, Yokohama.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nose
mesh_terms: D000388:Air; D001785:Blood Gas Monitoring, Transcutaneous; D005541:Forced Expiratory Volume; D006801:Humans; D006813:Humidity; D008176:Lung Volume Measurements; D008955:Models, Cardiovascular; D011650:Pulmonary Alveoli / Q000502:physiology; D011659:Pulmonary Gas Exchange; D012126:Respiratory Dead Space; D013990:Tidal Volume; D014867:Water; D014882:Water-Electrolyte Balance
chemical_list: D014867:Water