SINGLE BOLUS COMPARED WITH A FRACTIONATED DOSE INJECTION TECHNIQUE OFBUPIVACAINE FOR EXTRADURAL CESAREAN-SECTION - EFFECT ON UTEROPLACENTAL AND FETAL HEMODYNAMIC STATE

We studied 26 healthy parturients undergoing elective Caesarean sectio n, allocated randomly to receive extradural block with 0.5% plain bupi vacaine in a double-blind manner in either a single bolus or fractiona ted doses. After a 3-ml test dose, an additional 20 ml of bupivacaine were given over a 5-min period in the single bolus group (n = 13) and over a 25-min period in the fractionated dose group (n = 13). We studi ed the effects of bupivacaine on blood flow velocities in the maternal placental and non-placental uterine and fetal umbilical arteries befo re and four times during establishment of extradural block using a pul sed colour Doppler technique. Median sensory block reached T3 in the s ingle-dose group compared with T4 in the fractionated-dose group. Two subjects in each group required i.v. ephedrine to correct transient hy potension (systolic arterial pressure < 90 mm Hg). Blood flow velocity waveform indices of the uterine and umbilical arteries did not differ significantly within or between groups during the study. There was no significant difference-in neonatal outcome, as assessed by Apgar scor es and umbilical artery pH values. In conclusion, we observed no deter ioration in uteroplacental circulation after administration of a singl e bolus dose of bupivacaine.