Can bronchodilators improve exercise tolerance in COPD patients without dynamic hyperinflation?
OBJECTIVE
To investigate the modulatory effects that dynamic hyperinflation (DH), defined as a reduction in inspiratory capacity (IC), has on exercise tolerance after bronchodilator in patients with COPD.


METHODS
An experimental, randomized study involving 30 COPD patients without severe hypoxemia. At baseline, the patients underwent clinical assessment, spirometry, and incremental cardiopulmonary exercise testing (CPET). On two subsequent visits, the patients were randomized to receive a combination of inhaled fenoterol/ipratropium or placebo. All patients then underwent spirometry and submaximal CPET at constant speed up to the limit of tolerance (Tlim). The patients who showed ΔIC(peak-rest) < 0 were considered to present with DH (DH+).


RESULTS
In this sample, 21 patients (70%) had DH. The DH+ patients had higher airflow obstruction and lower Tlim than did the patients without DH (DH-). Despite equivalent improvement in FEV1 after bronchodilator, the DH- group showed higher ΔIC(bronchodilator-placebo) at rest in relation to the DH+ group (p < 0.05). However, this was not found in relation to ΔIC at peak exercise between DH+ and DH- groups (0.19 ± 0.17 L vs. 0.17 ± 0.15 L, p > 0.05). In addition, both groups showed similar improvements in Tlim after bronchodilator (median [interquartile range]: 22% [3-60%] vs. 10% [3-53%]; p > 0.05).


CONCLUSIONS
Improvement in TLim was associated with an increase in IC at rest after bronchodilator in HD- patients with COPD. However, even without that improvement, COPD patients can present with greater exercise tolerance after bronchodilator provided that they develop DH during exercise.
Paraíba School of Medical Sciences, João Pessoa, Brazil.
Maria Enedina Aquino
ME
Scuarcialupi
Paraíba School of Medical Sciences, João Pessoa, Brazil.
Danilo Cortozi
DC
Berton
Paraíba School of Medical Sciences, João Pessoa, Brazil.
Priscila Kessar
PK
Cordoni
Paraíba School of Medical Sciences, João Pessoa, Brazil.
Selma Denis
SD
Squassoni
Paraíba School of Medical Sciences, João Pessoa, Brazil.
Elie
E
Fiss
Paraíba School of Medical Sciences, João Pessoa, Brazil.
José Alberto
JA
Neder
D000328:Adult; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000187:drug effects*; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D007320:Inspiratory Capacity / Q000187:drug effects; D008168:Lung / Q000503:physiopathology; D010919:Placebos; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000503:physiopathology*; D013147:Spirometry; D014797:Vital Capacity / Q000187:drug effects
D001993:Bronchodilator Agents; D010919:Placebos