Abstract
Background: COPD is characterized by not fully reversible airflow limitation and defined with the decrease in FEV1 by spirometry. The Forced Oscillation Technique (FOT) can detect impairments of lung function by measuring lung resistance and reactance during normal tidal breathing. A MostGraph is one of the FOT, using multi-spectrum oscillation technique, and demonstrates the frequency-dependent and time-dependent respiratory impedance in 3-dimensional graphics.
We evaluated the respiratory impedance during inspiratory and expiratory phase of normal breathing in COPD patients.
Methods: We recruited 26 outpatients with stable mild (n=13) and moderate (n=13) COPD at the University of Tokyo Hospital. The impedance of respiratory system was measured by FOT using a MostGraph. Respiratory resistance (Rrs) and respiratory reactance (Xrs) during inspiration and expiration were evaluated at 5 Hz and at 20 Hz of oscillatory frequency.
Results: All indices of respiratory resistance, such as Rrs5 and Rrs20, were slightly higher in moderate COPD than mild, although there were no significant differences. There was a tendency that the ratio between the difference of Rrs5max-min and the difference of Rrs20max-min within tidal breathing was higher in mild COPD than moderate (p=0.08).
Conclusion: The larger difference in Rrs5-20 during tidal breathing might be useful property to distinguish the severity of COPD.
- © 2011 ERS
