Abstract
Background and objectiveThe 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 (D-L,CO) measurements. The aim of this study was to investigate the effect of salbutamol on D-L,CO in subjects with and without airway obstruction and reversibility.
MethodsSixty subjects were investigated with 20 in each of the three groups: normal spirometry; irreversible obstruction; and reversible obstruction. Baseline spirometry, plethysmographic lung volumes, D-L,CO, pulse rate and arterial blood gases were measured. The same testing sequence was repeated after administration of a placebo inhaler and again after 400g salbutamol.
ResultsSalbutamol did not affect the mean alveolar volume (V-A) (P>0.05), transfer coefficient for carbon monoxide (D-L,CO/V-A, KCO) (P>0.05) or D-L,CO (P>0.05) in the normal and irreversible obstruction groups. In the reversible obstruction group, salbutamol caused an increase in the mean V-A compared with placebo (P<0.001). However, the mean KCO was reduced (P<0.001). The mean change in D-L,CO was not significant (P>0.05). A considerable reduction in D-L,CO was found after salbutamol in four subjects in the reversible group as a result of a minor increase in V-A and substantial decrease in KCO. No statistical difference in pulse rate or arterial blood gases values was detected.
ConclusionsSalbutamol had no effect on the mean D-L,CO in any group. However, salbutamol may considerably reduce D-L,CO in some individuals with reversibility secondary to its effects on V-A and KCO.