Ventilation-perfusion response after fenoterol in hypoxemic patients with stable COPD.
BACKGROUND
The effects of vasoactive drugs, including bronchodilators, on vascular and pulmonary dynamics are interrelated, complex and difficult to measure, but important because of potential deleterious effects on gas exchange.


METHODS
To assess the effects of fenoterol at both high and low dose on pulmonary gas exchange in 24 hypoxemic patients with stable COPD: fenoterol, 5 mg; fenoterol, 1 mg and ipratropium bromide, 0.5 mg; ipratropium bromide, 0.5 mg; or matched placebo were nebulized in a double-blind, placebo-controlled fashion. Spirometry, ventilation, systemic hemodynamics, and respiratory and inert gases were measured before and 15, 60, and 120 min after each treatment.


RESULTS
Compared with placebo, heart rate (p < 0.002) and cardiac output (p = 0.05) increased after high-dose fenoterol therapy to return to baseline values by 120 min. Following fenoterol at high dose, mean maximum PaO2 change from baseline decreased by 6.3 +/- 1.1 mm Hg (SD) and both alveolararterial oxygen pressure difference (P[A-a]O2), by 8.3 +/- 4.0 mm Hg, and ventilation-perfusion (VA/Q) mismatching increased, as evidenced by increments of the dispersion of pulmonary blood flow, without reaching significance; likewise, low-dose fenoterol therapy increased VA/Q inequalities while both PaO2 and P(A-a)O2 remained unchanged.


CONCLUSIONS
In this population of COPD patients, high-dose fenoterol therapy [corrected] significantly increased heart rate and cardiac output resulting in minor adverse consequences on arterial oxygenation and VA/Q relationships.
Viegas
C A
CA
Department de Medicine, Hospital Clinic, Universitat de Barcelona, Spain.
Ferrer
A
A
Montserrat
J M
JM
Barberà
J A
JA
Roca
J
J
Rodriguez-Roisin
R
R
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000368:Aged; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D005280:Fenoterol / Q000008:administration & dosage / Q000627:therapeutic use*; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D009241:Ipratropium / Q000008:administration & dosage / Q000627:therapeutic use; D008173:Lung Diseases, Obstructive / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D013147:Spirometry; D013997:Time Factors; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects*
D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D005280:Fenoterol; D009241:Ipratropium