Abstract
Purpose: Spirometry which requires maximum effort tasks COPD patients. In this study, we proposed a new method for detection of flow limitation without effort breathing.
Subjects: Dynamic chest X-ray from 10 normal volunteers, 16 mild COPD patients (GOLD Stage I or II) and 12 severe COPD patients (GOLD Stage III or IV) were obtained in the upright position in about 10 seconds of tidal breathing at rest. The dynamic image data captured at 7.5 frames per second was synchronized with the pulsed X-ray. The institutional review board approval and written informed consent were obtained in all persons.
Methods: We calculated the maximal differential values in each ventilation phase at the corresponding small local area of lung in the series of dynamic chest X-ray. The regional relative flow rate ratio was obtained from the peak values of inspiratory phase divided by the peak values of expiratory phase. All groups were compared about the average of flow rate ratio.
Results: The regional changes in inspiratory/expiratory flow rate ratio had larger values and broader distribution in COPD patients than those of normal volunteers. The average of the ratio in normal volunteers, in mild COPD patients and in severe COPD patients were 1.08±0.09, 1.17±0.08 and 1.19±0.13 (mean±SD), respectively. A significant difference was confirmed between the normal volunteers and the COPD patients (p = 0.031).
Conclusion: The inspiratory/expiratory flow rate ratios in COPD patients were larger than those of healthy volunteers. The new method for ventilation function has possibility to evaluate flow limitation without effort breathing.
- © 2011 ERS