FETAL ACIDEMIA ASSOCIATED WITH REGIONAL ANESTHESIA FOR ELECTIVE CESAREAN DELIVERY

Objective: To determine the prevalence, magnitude, and type of fetal a cidemia associated with contemporary obstetric anesthetic techniques. Methods: Umbilical artery blood gases were obtained in 1601 singleton pregnancies delivered by elective cesarean. Results: General anesthesi a was used in 371 (23%) women, epidural in 286 (18%), combined spinal- epidural in 659 (41%), and spinal in 231 (14%). Approximately 18% of i nfants exposed to regional anesthetics had umbilical artery blood pH v alues 7.19 or less, 42 (3%) infants had pH values less than 7.10, and nine (1%) had values 6.99 or less. The incidence of fetal acidemia was greater in spinal and combined spinal-epidural procedures compared to epidural anesthetics. Fetal acidemia was predominantly respiratory in type because carbon dioxide pressure was abnormally increased when fe tal acidemia was diagnosed. Conclusions: Regional anesthesia is associ ated with fetal acidemia, occasionally severe, and has features of an acute respiratory type of acidemia. Fetal acidemia is less frequent wi th epidural anesthesia compared to subarachnoid techniques.