ABSTRACT
INTRODUCTION The British Thoracic Society guidelines define chronic obstructive pulmonary disease (COPD) as ‘a chronic slowly progressive disorder characterized by airways obstruction (FEV1 < 80% predicted and FEV1/VC ratio of < 70%) which does not change markedly over several months’. In contrast to the airflow obstruction produced by asthma, airflow obstruction due to COPD is largely fixed.
