Effects of extradural bupivacaine with adrenaline for caesarean section on uteroplacental and fetal circulation

We have studied the effects of an extradural block using bupivacaine with adrenaline 90-100 μg on blood flow in the maternal uterine and placental arcuate arteries and the fetal umbilical, renal and middle cerebral arteries, using a colour Doppler technique in eight healthy parturients undergoing elective Caesarean section. Fetal myocardial function was investigated simultaneously by M-mode echocardiography. Maternal heart rate increased and diastolic arterial pressure decreased after extradural administration of bupivacaine with adrenaline. The latter effect was relieved by increasing the infusion rate in every case and none of the patients required vaso-pressors. There were no significant differences in maternal or fetal blood velocity waveforms, and no significant changes were found in any of the fetal myocardial measurements relative to control values. These observations suggest that extradural anaesthesia using bupivacaine with adrenaline does not have an adverse effect on vascular resistance in the uteroplacental or fetal circulations or on fetal myocardial function in normal pregnancy when bupivacaine-adrenaline is administered fractionally and maternal hypotension is prevented by rapid crystalloid volume loading.