Pulmonary dynamic hyperinflation (DH) is an important factor limiting the physical capacity of patients with COPD. Inhaled bronchodilator should be able to reduce DH.

To measure DH in COPD patients during upper limbs exercise tests with previous use of bronchodilator or placebo, and to evaluate the respiratory pattern to justify the dynamics of hyperinflation.

Inspiratory capacity (IC) of 16 patients with COPD (age: 63± 13 years; FEV₁ of 1.5±0.7L–41±11% predicted) was measured before and after an incremental arm exercise test (diagonal technique) with randomly and double-blinded inhaled placebo or salbutamol.

Rest IC increased from 2.32±0.44L to 2.54±0.39L after inhalation of 400mcg of salbutamol (p=0.0012). There was a decrease in the IC after a maximal incremental arm exercise test, 222±158ml (p=0.001) with placebo use, but no change was seen after the salbutamol use: 104±205ml (p=0.41); 62% of the patients presented a 10% or more reduction in the IC after the exercise with placebo. There was a correlation between DH and lower FEV₁/FVC (p=0.0067), FEV₁ predicted (p=0.0091) and IC% predicted (p=0.043) and higher VO₂ml/Kg/min % predicted (p=0.05). Minute ventilation and respiratory rate were higher during the exercise with placebo (p=0.002) whereas VE/MVV ratio was lower in the exercise after salbutamol (p>0.05).

We conclude that the use of bronchodilator increases the IC of patient with COPD and may help not to increase the DH during a maximal exercise with the arms.