Effects of salbutamol and ipratropium bromide on arterial blood gases in patients with stable COPD

The aim of this study was to evaluate the acute effects of inhaled salbutamol and ipratropium bromide on arterial blood gases in patients with chronic obstructive pulmonary disease (COPD). We measured arterial blood gases and spirometry after inhalation of salbutamol (200 micro g) or ipratropium bromide (36 micro g) in 25 patients with COPD. After at least 2 days of washout period, the same patients inhaled the other drug, and the procedure of study was repeated. Blood specimens were taken just before the inhalation and at 5, 10, 20, 30, 60, 90,120 minutes after inhalation, and spirometry was done before and 60 minutes after inhalation. Both drugs caused a small decrease in PaO(2) levels, however the decrease in PaO(2) after inhalation of salbutamol was significantly higher than that after ipratropium (p< 0.05). Both drugs caused a little, but not statistically significant decrease in D(A-a)DO(2) and PaCO(2) (p> 0.05). There were a little increase in FEV1 and FVC at 60 minutes after inhalation of both drugs, especially with salbutamol, compared to ipratropium bromide; but both increases were statistically insignificant (p> 0.05). The results revealed that, salbutamol caused a significant, but small and transient decrease in PaO2 and a little, but insignificant increase in D(A-a)DO(2) when used in recommended doses. Although salbutamol and ipratropium bromide which are used in treatment of COPD, can cause small decreases in PaO(2) after inhalation, the declines are trancient and clinically insignificant.