Modulation of operational lung volumes with the use of salbutamol in COPD patients accomplishing upper limbs exercise tests

Abstract

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

Objective: 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.

Methods: Inspiratory capacity (IC) of 16 patients with COPD (age: 63+/- 13 years; FEV(1) of 1.5+/-0.7 L-41+/-11% predicted) was measured before and after an incremental arm exercise test (diagonal technique) with randomly and double-blinded inhaled placebo or salbutamol.

Results: Rest IC increased from 2.32+/-0.44 L to 2.54+/-0.39 L after inhalation of 400 mcg of salbutamol (p=0.0012). There was a decrease in the IC after a maximal incremental arm exercise test, 222+/-158 ml (p=0.001) with placebo use, but no change was seen after the salbutamol use: 104+/-205 ml (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 FEV(1)/FVC (p=0.0067), FEV(1) predicted (p=0.0091) and IC% predicted (p=0.043) and higher VO(2)ml/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).

Conclusion: 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.