Fetal acid-base state following spinal or epidural anesthesia for cesarean section.

The authors compared fetal acid-base state and maternal blood pressure response in 111 women undergoing repeat cesarean section with either epidural or spinal anesthesia. Fetal umbilical acidemia (umbilical venous pH less than 7.25 or umbilical arterial pH less than 7.20) was more commonly observed following spinal anesthesia with a preanesthetic fluid load of 500 to 999 ml (20% of cases) than with epidural anesthesia (4% of cases. P > .05, chi 2). The incidence of fetal acidemia following spinal anesthesia was similar to that following epidural anesthesia when 1000 to 1500 ml of fluid was infused prior to spinal anesthesia. The maximum reduction in systolic blood pressure following spinal anesthesia was not related to preanesthetic fluid load; however, in cases of severe hypotension the hypotensive episode was shorter and easier to treat when the preanesthetic fluid load was 1000 to 1500 ml rather than 500 to 999 ml. These data suggest that women receiving spinal anesthesia for repeat cesarean section should be given an intravenous fluid load of 1 liter or more.