The effects of regional anaesthesia for caesarean section on maternal and fetal blood flow velocities measured by Doppler ultrasound.

We studied the effects of spinal anaesthesia (Group S), epidural anaesthesia (Group E), and combined spinal and epidural anaesthesia (Group SE), on maternal and fetal blood flow in 24 healthy parturients (n = 8/group) with uncomplicated singleton pregnancies using Doppler technique. Prior to the induction of anaesthesia, the patients were prehydrated with balanced electrolyte solution 15 ml.kg-1 over a period of 15 min. After the induction of regional anaesthesia, the systolic blood pressure was maintained within 15% limits of the preoperative values using prophylactic etilefrine infusion in Groups S and SE. The flow velocity waveforms of the maternal femoral artery, the main branch of the uterine artery (placental side), the foetal umbilical and middle cerebral arteries were recorded by Doppler technique before and after prehydration as well as after onset of T7 analgesia and the pulsatility indices (PI) were derived. Rapid intravenous prehydration had no effects on uteroplacental or fetal circulation as indicated by unaltered uterine, umbilical, and fetal middle cerebral artery PIs. After the onset of T7 analgesia, the uterine artery PI was increased in Group S indicating increased uterine vascular resistance while no changes occurred in Groups E and SE. No adverse effects were observed on the neonates as indicated by the Apgar score and the umbilical artery and vein acid-base status in any of the groups.