[Pulmonary blood flow measurement by acetylene rebreathing method in subjects without respiratory function...

Simultaneous measurement of pulmonary blood flow by the acetylene rebreathing method and cardiac output by the thermodilution method was performed in subjects without respiratory function disturbance during right heart catheterization. After the measurement of cardiac output, the subjects rebreathing a gas mixture containing acetylene and argon from the end tidal level. The inspiratory and expiratory gases were measured by a mass-spectrometer. Results were analyzed by a lung model consisting of two compartments (rebreathing bag compartment and lung compartment), while taking into account the volume reduction due to O2 and CO2 exchange and the fluctuation of end tidal gas concentration until equilibrium between the bag and the lung. The correlation coefficient between these two methods was 0.944, which was statistically significant. The regression line was near the line of identity. The measurement of pulmonary blood flow by the acetylene rebreathing method was applicable in cases without lung function disturbance.