In the present study, airflow limitation may have been
a more important cause of clinical dyspnea than static
hyperinflation. This clearly contradicts the above mentioned
hypothesis, and the results of the laboratory exercise
tests that are based upon it. Why is our result
different? The first issue to consider is the different dyspnea
evaluation methods used. We wanted to assess
overall breathlessness during daily activities (clinical dyspnea)
using the BDI score in the present study, whereas
the Borg dyspnea ratings at isotime exercise has been
used in most laboratory studies. Dyspnea during exercise
using the Borg scale may provide a different type of
information regarding dyspnea than clinical dyspnea
[11]. Therefore, if the cause of COPD dyspnea is
hypothesized to be dynamic hyperinflation, then it is
necessary to evaluate clinical dyspnea instead of laboratory
dyspnea