Umbilical artery flow velocity waveforms during spinal anesthesia

Abstract

The umbilical artery Doppler flow velocity waveform was recorded during spinal anaesthesia prior to elective caesarean section in 15 uncomplicated pregnancies. Although spinal anaesthesia was associated with a significant fall in maternal systolic and diastolic blood pressure, there was no change in the umbilical artery Pulsatility Index either after preloading the maternal circulation with 750-1000 ml of Hartman's solution or for the first 15 min after subarachnoid injection of 0.5% bupivacaine. The fetal heart rate fell after preloading the maternal circulation, but was unchanged by the administration of bupivacaine. There was a weak negative correlation between fetal heart and the umbilical artery Pulsatility Index. These observations suggest that in normal pregnancy, spinal anaesthesia has no detrimental effect on the umbilical artery Pulsatility Index.