Am. J. Respir. Crit. Care Med.,
Volume 160, Number 3, September 1999, 1028-1030
Effects of Salmeterol on Arterial Blood Gases in
Patients with Stable Chronic Obstructive
Pulmonary Disease
Comparison with Albuterol and Ipratropium
GHASSAN
KHOUKAZ
and
NICHOLAS J.
GROSS
Division of Pulmonary and Critical Medicine, Hines Veterans Affairs Hospital, Hines; and Department of Medicine,
Stritch School of Medicine, Loyola University of Chicago, Maywood, Illinois
Administration of
-adrenergic agonist bronchodilators to patients with airways obstruction commonly results in transient decreases in PaO2 levels despite bronchodilation, an effect that has been attributed to these drugs' pulmonary vasodilator action. We compared the acute effects on gas exchange of salmeterol with those of albuterol and the anticholinergic agent ipratropium in 20 patients
with stable chronic obstructive pulmonary disease (COPD). Each agent was given in recommended
dosage on separate days in a double-blind, crossover format, and the patients' arterial blood gases
(ABGs) were measured at baseline and at intervals to 120 min. Small but statistically significant declines in PaO2, the primary outcome variable, were found after administration of both salmeterol and
albuterol. The decline in PaO2 after salmeterol was of lesser magnitude but was more prolonged than
that after albuterol, the greatest mean change being
2.74 ± 0.89 mm Hg (mean ± SEM) at 30 min
after salmeterol, and
3.45 ± 0.92 mm Hg at 20 min after albuterol. Following ipratropium, the corresponding change was
1.32 ± 0.85 mm Hg at 20 min. These declines, which were almost entirely
attributable to increases in the alveolar-arterial difference in oxygen tension
(A-a)DO2 tended to be
more marked in subjects with higher baseline PaO2 values. No subject experienced a decline in PaO2 to
levels below 59 mm Hg. There were no significant differences among the three drugs studied. We
conclude that despite small decreases in PaO2 after each of the three drugs, the declines were small,
transient, and of doubtful clinical significance.