Alternative methods for assessing bronchodilator reversibility in chronic obstructive pulmonary disease.
BACKGROUND
Bronchodilator reversibility testing is recommended in all patients with chronic obstructive pulmonary disease (COPD) but does not predict improvements in breathlessness or exercise performance. Two alternative ways of assessing lung mechanics-measurement of end expiratory lung volume (EELV) using the inspiratory capacity manoeuvre and application of negative expiratory pressure (NEP) during tidal breathing to detect tidal airflow limitation-do relate to the degree of breathlessness in COPD. Their usefulness as end points in bronchodilator reversibility testing has not been examined.


METHODS
We studied 20 patients with clinically stable COPD (mean age 69.9 (1.5) years, 15 men, forced expiratory volume in one second (FEV(1)) 29.5 (1.6)% predicted) with tidal flow limitation as assessed by their maximum flow-volume loop. Spirometric parameters, slow vital capacity (SVC), inspiratory capacity (IC), and NEP were measured seated, before and after nebulised saline, and at intervals after 5 mg nebulised salbutamol and 500 microg nebulised ipratropium bromide. The patients attended twice and the treatment order was randomised.


RESULTS
Mean FEV(1), FVC, SVC, and IC were unchanged after saline but the degree of tidal flow limitation varied. FEV(1) improved significantly after salbutamol and ipratropium (0.11 (0.02) l and 0.09 (0.02) l, respectively) as did the other lung volumes with further significant increases after the combination. Tidal volume and mean expiratory flow increased significantly after all bronchodilators but breathlessness fell significantly only after the combination treatment. The initial NEP score was unrelated to subsequent changes in lung volume.


CONCLUSIONS
NEP is not an appropriate measurement of acute bronchodilator responsiveness. Changes in IC were significantly larger than those in FEV(1) and may be more easily detected. However, our data showed no evidence for separation of "reversible" and "irreversible" groups whatever outcome measure was adopted.
Hadcroft
J
J
Department of Medicine, University of Liverpool, University Hospital Aintree, Liverpool L9 7AL, UK.
Calverley
P M
PM
D000368:Aged; D000420:Albuterol / Q000008:administration & dosage*; D000704:Analysis of Variance; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D002908:Chronic Disease; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D007320:Inspiratory Capacity / Q000187:drug effects; D009241:Ipratropium / Q000008:administration & dosage*; D008173:Lung Diseases, Obstructive / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013147:Spirometry / Q000379:methods; D014797:Vital Capacity / Q000187:drug effects
D001993:Bronchodilator Agents; D009241:Ipratropium; D000420:Albuterol