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

SummaryIntroductionPulmonary dynamic hyperinflation (DH) is an important factor limiting the physical capacity of patients with COPD. Inhaled bronchodilator should be able to reduce DH.ObjectiveTo 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.MethodsInspiratory capacity (IC) of 16 patients with COPD (age: 63 ± 13 years; FEV1 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.ResultsRest 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 FEV1/FVC (p = 0.0067), FEV1 predicted (p = 0.0091) and IC% predicted (p = 0.043) and higher VO2 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).ConclusionWe 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.