Expiratory airflow limitation is the pathophysiological hallmark of chronic obstructive pulmonary disease (COPD) that leads to air trapping and increases in dynamic hyperinflation (DH) and consequently causes dyspnea during exercise. Although pursed lips breathing is a simple technique that provides a positive back pressure may retard the airway collapsed, but previous studies showed an unsuccessful reduction of DH which might cause by insufficient back pressure. And thereby a conical positive expiratory pressure (C-PEP) has been developed in our laboratory to generate back pressure higher than pursed lips breathing. Moreover, an effect of PEP on DH has not carried out in patient with COPD. Therefore, the objective of the present study was to examine effects of a C-PEP on DH and respiratory response during exercise in patient with COPD.
