Abstract Rationale Evidence is limited on the effects of bronchodilators on respiratory dynamics in chronic obstructive pulmonary disease (COPD). Dynamic chest radiography (DCR) is a novel radiographic modality that provides real-time, objective, and quantifiable kinetic data, such as changes in the lung area (Rs) and diaphragmatic kinetics during respiration, at a lower radiation dose than that used in fluoroscopic or CT imaging. However, the therapeutic effects of dual bronchodilators on respiratory kinetics are not fully understood. AIM: The effects of bronchodilator therapy on respiratory kinetics in patients with COPD were evaluated using DCR. Methods An open-label, prospective, single-center, non-controlled comparative study was conducted. A total of 35 patients with COPD, aged 40-85 years, with a forced expiratory volume (FEV1) of 30%-80%, were enrolled. The patients received tiotropium/olodaterol therapy for 6 weeks after a 2-4-week washout period. The effects of treatment were evaluated using pulmonary function tests (PFTs) and DCR findings. The primary endpoint was the change in Rs after therapy. The secondary endpoints included differences in PFTs and other DCR parameters, such as lung surface area and diaphragmatic kinetics. Results A total of 33 participants with COPD (mean age, 71.8 ± 6.6 years; 2 women) completed this study. The primary endpoint, Rs, was insignificantly lower after than before treatment (-0.258 ± 0.071 to -0.275 ± 0.069; p = 0.0997). The PFT scores significantly increased for FEV1 and residual volume/total lung capacity from before to after treatment (1.44 ± 0.47 to 1.65 ± 0.49 L; p 0.0001, and 44.91 ± 7.03 to 41.80 ± 7.29 %; p 0.0001, respectively). The DCR results showed that inspiratory and expiratory lung surface areas were significantly lower after than before treatment (50029.89 ± 6991.36 to 49321.94 ± 6914.38 mm2; p 0.05, and 37382.31 ± 7856.83 to 35969.78 ± 7334.98 mm2; p 0.05, respectively). DCR demonstrated increases in the mean breathing excursion and the mean peak inspiratory motion speed of left hemidiaphragm after treatment (47.31 ± 12.35 to 51.62 ± 12.35 mm; p 0.05, and 20.77 ± 7.32 to 24.55 ± 9.78 mm/s; p 0.05, respectively). Conclusion In people with COPD, DCR demonstrated a non-significant trend toward reduction in Rs, along with notable improvements in lung area dynamics and diaphragmatic motion following dual bronchodilator therapy. These findings suggest that DCR is a valuable tool for assessing the physiological effects of bronchodilators on the respiratory mechanics in this population. This abstract is funded by: Nippon Boehringer Ingelheim
Ikari et al. (Fri,) studied this question.