Effect of terbutaline on cardiovascular state and uterine blood flow in pregnant ewes.

The cardiovascular and uterine hemodynamic effects of terbutaline, a beta-adrenergic receptor stimulant and labor inhibiting agent, were evaluated in the chronically instrumented, near-term pregnant ewe. The administration of terbutaline in the dose range required for labor inhibition in this species resulted in a mild maternal tachycardia and increase in pulse pressure without significant changes in uterine blood flow; uterine vascular resistance; or systolic, diastolic, or mean blood pressures. With infusion rates of terbutaline in excess of those required for labor inhibition, significant increases in maternal heart rate, pulse pressure, and systolic blood pressure were observed. Diastolic blood pressure decreased significantly during the higher infusion rates; however, uterine blood flow was unaffected. The minimal cardiovascular and uterine blood flow was unaffected. The minimal cardiovascular and uterine hemodynamic effects noted with the administration of terbutaline in the dose range necessary for labor inhibition indicate that this agent may possess advantages over several others currently in use for the treatment of premature labor.