Effects of extradural anaesthesia on human fetal blood flow in utero. Comparison of three local anaesthetic solutions.

Twenty-seven women, scheduled for elective Caesarean section under extradural anaesthesia were allocated randomly to one of three groups: group Ea received 1.5% etidocaine with adrenaline, group Bp 0.5% bupivacaine plain, and group Ba 0.5% bupivacaine with adrenaline. There was no difference in the quality and distribution of sensory blockade between the three groups. Motor blockade was most profound in group Ea. Maternal heart rate and arterial pressure were only slightly affected in the three groups. Before induction of extradural anaesthesia, and 15 and 30 min after, fetal umbilical and aortic blood flows were examined using a combination of real-time ultrasonography and the pulsed Doppler technique. Blood flow in the umbilical vein was not affected in any of the groups, and blood flow in the fetal aorta remained unchanged in groups Ea and Bp, but was increased by 12% after 30 min in group Ba. We conclude that, with the three local anaesthetic solutions studied during extradural anaesthesia for elective Caesarean section, fetal circulatory variables remained stable and within normal limits, when in association with normal values of maternal arterial pressure.