Effect of salbutamol on the measurement of single-breath diffusing capacity

Background and objective The bronchodilation and cardiovascular effects of bronchodilators may alter alveolar ventilation and perfusion distribution, which could subsequently affect single‐breath diffusing capacity of the lungs for carbon monoxide (DL,CO) measurements. The aim of this study was to investigate the effect of salbutamol on DL,CO in subjects with and without airway obstruction and reversibility. Methods Sixty subjects were investigated with 20 in each of the three groups: normal spirometry; irreversible obstruction; and reversible obstruction. Baseline spirometry, plethysmographic lung volumes, DL,CO, pulse rate and arterial blood gases were measured. The same testing sequence was repeated after administration of a placebo inhaler and again after 400 μg salbutamol. Results Salbutamol did not affect the mean alveolar volume (VA) (P > 0.05), transfer coefficient for carbon monoxide (DL,CO/VA, KCO) (P > 0.05) or DL,CO (P > 0.05) in the normal and irreversible obstruction groups. In the reversible obstruction group, salbutamol caused an increase in the mean VA compared with placebo (P