ABSTRACT
The use of bronchodilator drugs to reduce the symptoms and increase the exercise tolerance of patients with COPD is a cornerstone of management in these patients. The basic pharmacology of these drugs has already been reviewed (see Chapter 23) and this chapter focuses on the physiologic consequences of bronchodilator action as well as considering the evidence for their efficacy and the problems of treatment selection. Although ‘functional’ end-points such as reductions in breathlessness and increases in self-paced waking distance are important to patients, it is only relatively recently that simpler and reliable methods of assessing these variables have been developed. Surrogate end-points such as changes in FEV1 or PEF after active bronchodilator have been reported in most clinical trials, usually over quite short periods of time, and these may underestimate the potential benefit of treatment. Unlike bronchial asthma where drug treatment can restore normal pulmonary function in most mild to moderate cases, the structural changes in COPD (see Chapter 2) preclude this and few studies have considered how effective a dose of bronchodilator is in relation to the maximum attainable bronchodilatation for that subject.1,2 Moreover, clinically relevant changes in FEV1 may be so small in severe COPD patients that they fall within the day-to-day reproducibility of the measurement (see Chapter 20). Problems such as these hamper interpretation of clinical studies of bronchodilator action and lead to an unduly pessimistic view of the benefit of treatment.3
