Effects of tiotropium and formoterol on quiet breathing pattern assessed by optoelectronic plethysmography in COPD patients: a pilot study.

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is a disease characterized by an airflow limitation that is not fully reversible. β(2)-agonists and anticholinergics represent the most effective therapeutic options. Optoelectronic plethysmography (OEP) is a novel technology, which provides noninvasive steady-state measurements of chest wall kinematics, together with the assessment of the relative contribution of all different thoracic and abdominal compartments to tidal volume.

OBJECTIVES

The aim of this pilot study was to investigate the changes in quiet breathing due to different long-acting bronchodilators (namely, formoterol and tiotropium) administered to COPD patients of different severity.

METHODS

Eight moderate-to-severe COPD patients were studied according to a randomized crossover design. All subjects received both the long-acting bronchodilators: formoterol (long-acting β(2)-agonist, 24 µg) and tiotropium (long-acting anticholinergic bronchodilator, 18 µg). The effect of bronchodilators on quiet breathing was evaluated by means of OEP at base conditions, and 2 and 7 hours after inhalation.

RESULTS

Both bronchodilators caused changes in the quiet breathing pattern in COPD patients that had previously reported only negligible changes in FEV(1) (ΔFEV(1) = 2.6% after salbutamol). The main changes were observed in increased ventilation per minute, inspiratory and expiratory flow, and decreased breath-by-breath variability. Formoterol induced its main effects during the first 2 hours after inhalation, while tiotropium caused improvements between 2 and 7 hours.

CONCLUSION

Even though a greater cohort of COPD patients is needed in order to confirm the present results, this pilot study reports a novel piece of evidence concerning the effects of bronchodilators on quiet breathing pattern in severe and very severe COPD patients.