ABSTRACT
Section of Pulmonary and Critical Care Medicine, Dartmouth Medical School, Dartmouth-Hitchcock
Medical Center, Lebanon, New Hampshire, U.S.A.
I. Introduction
The most important benefits of bronchodilator medications in patients with chronic
obstructive pulmonary disease (COPD) are relaxation of bronchial smooth muscle,
which increases lung function and improves lung emptying during tidal breathing. For
a long time the major outcome measure to evaluate the efficacy of a bronchodilator
has been forced expiratory volume in one second (FEV
). However, the goals of treating
COPD have shifted from improving physiological measures to improving clinical
outcomes. There are several reasons for this paradigm shift. First, the individual patient is
interested primarily in being able to breathe easier with activities, have a better quality of
life, and avoid respiratory tract infections. Second, studies have demonstrated that
bronchodilator reversibility (i.e., the acute changes in FEV
after inhalation of albuterol
or ipratropium) does not predict the clinical benefits of long-acting bronchodilators as
experienced directly by the patient (1,2). Moreover, studies have demonstrated that
improvements in breathlessness and exercise tolerance are more importantly related to
enhanced lung emptying rather than the magnitude of the increase in expiratory airflow.
Third, there is no current evidence that bronchodilator therapy slows the progression of
the disease as traditionally measured by the changes in FEV