[Hemodynamic changes during tocolysis with hexoprenaline and fenoterol].

The authors examined two groups of 50 patients each who had been given an average dose of 0.24 microgram/min Hexoprenaline or respectively 1.8 micrograms/min Fenoterol as beta-mimetics for premature labor. The patients who received Fenoterol were also given Verapamil as additional medication in a ratio of 1 : 40. In addition to blood pressure, heart rate, urine elimination and serum or urine osmolarity, the hemodynamic parameters stroke volume, cardiac output and total peripheral resistance were investigated. Stroke volume was measured by means of impedance cardiography. Giving equipotent doses, Hexoprenaline/Fenoterol dose ratio of 1 : 8, there was a slower and smaller increase in heart rate over 24 hours with Hexoprenaline, with identical suppression of uterine contractility (external tocography). This was also reflected in the cardiac output, while there were no differences in the stroke volumes. Inhibition of diuresis was lower with Hexoprenaline. This might be due to the fact that since there is no organ specificity for beta-1 or respectively beta-2 receptors and the patterns of distribution differ, Hexoprenaline has a somewhat less pronounced action on beta-1 receptors than Fenoterol, though the same beta-2 action.