HEMODYNAMIC-EFFECTS OF REPEATED EPIDURAL TEST-DOSES OF ADRENALINE IN THE CHRONIC MATERNAL-FETAL SHEEP PREPARATION

A randomized crossover study was designed using the chronically instru mented pregnant sheep preparation to study the possible effects of epi dural injection of adrenaline as a single compound on the circulation of mother and fetus. Three consecutive identical doses of adrenaline w ere administered epidurally with a 30 min interval between treatments. In a randomized crossover fashion two dosages (10 and 15 mu g) were t ested on different days. The day after the last epidural experiment th e same doses of adrenaline were given intravenously (i.v.). Between th e two i.v. doses a 30 min interval was allowed for values to return to baseline. Twenty-seven experiments were performed in eight ewes. Epid ural administration of adrenaline did not affect maternal mean arteria l pressure, maternal heart rate, uterine blood flow, fetal mean arteri al pressure, fetal heat rate, or maternal and fetal blood gases and ac id-base status. After i.v. administration of adrenaline the uterine bl ood flow decreased in a dose-dependent fashion, but the other haemodyn amic variables were not affected. In conclusion, this study indicates that consecutive epidural injections of adrenaline have no significant effect on maternal and fetal haemodynamic responses, uterine blood fl ow, blood gases and acid-base status in the gravid ewe. However, an i. v. injection of 10 or 15 mu g adrenaline decreases the uterine blood f low and could compromise the fetus.