The relationship between pulmonary function and dyspnea in obstructive lung disease

Abstract

Increased importance is now being placed on evaluating dyspnea in patients with obstructive lung disease (OLD). We measured breathlessness at rest, using a Borg scale dyspnea index (BSDI) before and after bronchodilator albuterol [salbutamol] 200 micrograms) in 93 patients with OLD drawn from a larger population undergoing routine spirometry. The median BSDI declined from 3 to 1 before and after bronchodilator, suggesting improvement in dyspnea. However, there was no correlation between initial or postbronchodilator spirometry and BSDI. The change in FEV1 similarly did not correlate with the change in BSDI (r = 0.05). A large bronchodilator response was usually associated with improvement in dyspnea, but the converse was not observed. Thus, of ten patients with an improvement in BSDI of more than two categories, six had a change in FEV1 of 0.1 L or less after bronchodilator. Analyzing a subgroup of 65 dyspneic patients with an initial BSDI of 2 or more revealed the following response groups: those with either a bronchodilator or dyspnea response alone, both together, or neither. Twenty-eight patients (43 percent) responded both subjectively and objectively. Eleven (17 percent) had a bronchodilator response only, 17 (26 percent) had a dyspnea response only, while nine (14 percent) had neither measurable response. We conclude that dyspnea is poorly correlated with results of routine spirometry in patients with OLD. The use of dyspnea ratings may yield information about bronchodilator responsiveness not appreciated by spirometry alone.