Patent ID: 7387609

Claim:
A method of measuring an absolute lung volume, comprising: connecting a one-way valve to a subject so as to separate an inspiration path from an expiration path; measuring a flow rate of respiratory gas using a flow sensor, which is provided in the expiration path; continuously measuring a concentration (FO 2 ) of oxygen and a concentration (F CO2 ) of carbon dioxide using O 2 and CO 2 sensors provided in the expiration path; correcting dynamic characteristics of the concentration (F O2 ) of oxygen and the concentration (F CO2 ) of carbon dioxide so that the dynamic characteristics agree with each other in terms of time; and analyzing oxygen and carbon dioxide gases using a following Equation FRC = 1 0.79 ⁢ ∫ ( 1 - ( F 02 + F C02 ) ) ⁢ F ⁢ ⅆ t (wherein, the FRC is a functional residual capacity).