EFFECTS OF EXTRADURAL BUPIVACAINE WITH ADRENALINE FOR CAESAREAN SECTION ON UTEROPLACENTAL AND FETAL CIRCULATION

We have studied the effects of an extradural block using bupivacainewith adrenaline 90–100 µg on blood flow in the maternaluterine and placental arcuate arteries and the fetal umbilical,renal and middle cerebral arteries, using a colour Doppler techniquein eight healthy parturients undergoing elective Caesarean section.Fetal myocardial function was investigated simultaneously byM-mode echocardiography. Maternal heart rate increased and diastolicarterial pressure decreased after extradural administrationof bupivacaine with adrenaline. The latter effect was relievedby increasing the infusion rate in every case and none of thepatients required vaso-pressors. There were no significant differencesin maternal or fetal blood velocity waveforms, and no significantchanges were found in any of the fetal myocardial measurementsrelative to control values. These observations suggest thatextradural anaesthesia using bupivacaine with adrenaline doesnot have an adverse effect on vascular resistance in the uteroplacentalor fetal circulations or on fetal myocardial function in normalpregnancy when bupivacaine-adrenaline is administered fractionallyand maternal hypotension is prevented by rapid crystalloid volumeloading.