The effects of epidural anesthesia on the doppler velocimetry of umbilical and uterine arteries in normal term labor

To study the possible effects of epidural anesthesia on the Doppler velocimetry of the fetal umbilical and maternal uterine arteries, 15 normal term parturients were examined during active labor. Each Doppler study, conducted over 90 minutes after a 500-mL intravenous volume pre-load, was divided into three phases: 30 minutes of pre-anesthetic control, 30 minutes during epidural catheter placement and dosing, and 30 minutes after establishing effective regional blockade. During each phase, maternal blood pressure and pulse were monitored every 5 minutes, and continuouswave Doppler recordings of the umbilical and uterine arteries were made at three separate intervals. Epidural placement and dosage techniques were similar for all patients; 0.25% bupivacaine solution was used and sensory levels of T₆obtained. The mean maternal systolic and diastolic blood pressures and pulse rate declined significantly, but no woman experienced hypotension. Mean systolic/diastolic ratios and pulsatility indices of the umbilical and uterine arteries did not change significantly during the study. We conclude that effective epidural anesthesia does not have a significant impact on Doppler flow characteristics of either the maternal or fetal umbilical vasculature, despite lowered maternal blood pressure and pulse rate.