The Effect of Six Months of Daily Treatment with the Beta-2 Agonist Oral Pirbuterol on Pulmonary Hemodynamics in Patients with Chronic Hypoxic Cor Pulmonale Receiving Long-term Oxygen Therapy

We studied the acute and long-term effect of the oral beta-2 agonist pirbuterol on pulmonary hemodynamics and right and left ventricular ejection fractions in 11 patients with stable hypoxic chronic bronchitis and emphysema who were maintained on long-term oxygen therapy. We have used a double-blind study with random allocation of patients to receive either pirbuterol or an identical-appearing placebo. Six patients received 15 mg pirbuterol thrice daily, and five patients received a similar placebo thrice daily, over a 6-month period. The first 15-mg dose of pirbuterol by mouth at the beginning of the study raised the heart rate from 84 ± 13 to 100 ±16 beats/min (mean ± SD) (p < 0.01), and cardiac output from 5.2 ± 0.9 to 6.4 ± 0.8 L/min (p < 0.01) and right ventricular ejection fraction (RVEF) from 0.28 ± 0.10 to 0.33 ± 0.12 (p < 0.01) within 120 min after receiving the drug, but without significant change in the mean pulmonary arterial pressure. None of these variables changed significantly after an acu...