Evaluation of the beta 2 adrenoceptor agonist/antagonist activity of formoterol and salmeterol.

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Abstract
BACKGROUND--The pathogenesis of dyspnoea in patients with chronic heart failure is poorly understood. Static lung compliance is reduced in chronic heart failure. The relation between static lung compliance and exercise capacity and dyspnoea in chronic heart failure has been investigated. METHODS--Static lung compliance was calculated from expiratory pressure-volume curves in 18 patients with chronic heart failure (three women, mean age 62 years). Catheter mounted pressure transducers were used to measure changes in oesophageal pressure. Changes in lung volume were determined by integrating flow at the mouth, measured by a pneumotachograph. New York Heart Association (NYHA) class for dyspnoea was determined by a single observer. Patients underwent treadmill exercise to symptom limited maximum using staged and fixed rate protocols. Borg ratings for dyspnoea at submaximal exercise were measured. RESULTS--Static lung compliance, whether expressed as % total lung capacity (TLC)/cm H2O or % predicted TLC/cm H2O, was unrelated to NYHA class. Similarly, there was no relation between static lung compliance and exercise capacity with either protocol or with Borg ratings for dyspnoea at submaximal exercise, with the exception of that measured after 11 minutes of the staged protocol. CONCLUSIONS--Static lung compliance at rest has no relation with treadmill exercise capacity in chronic heart failure, and its relation with measures of dyspnoea is variable. No role for lung elasticity in determining the symptomatology of chronic heart failure was found.