UTEROPLACENTAL AND FETAL CIRCULATION DURING EXTRADURAL BUPIVACAINE-ADRENALINE AND BUPIVACAINE FOR CAESAREAN SECTION IN HYPERTENSIVE PREGNANCIES WITH CHRONIC FETAL ASPHYXIA

We have studied the effects of an extradural block during Caesareansection using either bupivacaine plain or with adrenaline 85–100µg on blood velocity waveforms of maternal uterine andplacental arcuate arteries and fetal umbilical, renal and middlecerebral arteries, in 20 hypertensive parturients with chronicfetal asphyxia. Fetal myocardial function was investigated atthe same time by M-mode echocardiography. Extradural anaesthesiaresulted in a significant decrease in maternal mean systolicand diastolic arterial pressures in both groups, but this wasmore marked after plain bupivacaine. There were no significantdifferences in any of the Doppler recordings relative to baselinevalues after plain bupivacaine, but after bupivacaine with adrenalinethere were significantly increased blood flow velocity indicesfor the maternal uterine and placental arcuate arteries andsignificantly decreased indices in the fetal renal and middlecerebral arteries. Neonatal outcome as evaluated by Apgar scoresand acid-base values in the umbilical cord were similar in thetwo groups. The results suggest that adrenaline added to thesolution of bupivacaine increased vascular resistance in theuteroplacental circulation, indicating impaired blood flow.