Haemodynamic effects of terbutaline in chronic obstructive airways disease

Abstract

Terbutaline, a cardioselective beta-adrenoceptor agonist, administered intravenously (250 μg) to seven patients with chronic obstructive airways disease (mean FEV1 0 99 1) resulted in reduction of mean pulmonary artery pressure (resting 23±2 to 19±2 mmHg, p<0 05; exercise 43±3 to 35±3 mmHg, p<0 05) and calculated pulmonary vascular resistance (resting 168±27 to 109± 17 dyne s cm-5, p <001; exercise 108±2 to 114±2 per min, p<001) and cardiac output (resting 3-7±0-4 to 4-1±0-4, p<005; exercise 4-9±0-06 to 6-1±6 1, min-1 m-2, p<0-05). The haemodynamic changes were associated with an increase in resting peak expiratory flow rate (184± 20 to 216± 25 I/min, p <0 01), while the calculated indices of ventilation/perfusion relationship remained essentially unchanged. The reduction in mean pulmonary artery pressure after terbutaline observed in the present studies was piobably the result of a combination of simple vasodilator effect, the reduction in airways resistance, and increase in the ventilation.