Cardiopulmonary effects of betamimetic tocolytic and glucocorticoid therapy in pregnant women.

In 35 present women, undergoing tocolytic treatment with betamimetics had intensive monitoring by balloon-tipped catheter. After the administration of 2-4 micrograms/min of fenoterol the cardiac output (CO) increased from 8.2 l/min to over 11 l/min with a corresponding increase in mean pulmonary artery pressure (MPAP) from 11.7 mmHg to over 18 mmHg. The correlation coefficient between MPAP/CO was highly significant. In the 10 patients in whom we were able to monitor pulmonary capillary pressure (PCP), we observed no significant increase to suggest compromised cardiac performance. The calculated total resistance of the pulmonary vessels (TPR) decreased during the first 24 h followed by a return to initial values. Our investigations suggest that the principal cardiovascular effect of betamimetics in pregnant women is a volume-dependent increase in pressure in the pulmonary circulation. The simultaneous administration of betamethasone had no additional effects.