Obstetrical analgesia assessed by free fatty acid mobilisation

Two groups of six parturients each have been compared. One group received centrally acting analgesics, sedatives and intermittent nitrous oxide and the other group was given epidural anaesthesia. The serum free fatty acid (FFA) concentrations of the parturients in the former group increased steadily during labour, attaining peak values between 1050 and 1750 mumol/l at delivery. In parturients belonging to the epidural group, the serum FFA concentrations remained level or even fell towards the time of delivery. It is suggested that the increase in serum FFA reflects a stress induced adrenergic lipolysis which may be used to assiss the various methods for obstetrical analgesia. It is concluded that epidural anaesthesia is superior to the conventional methods of pain relief. Analyses of blood sampled from the unbilical veins show that the concentrations of FFA in the blood of the newborns do not reflect the corresponding maternal values. Thus, epidural anaesthesia does not seem to deprive the fetus of FFA during labour since the factor limiting its transfer appears to be independent of the concentration gradient over the placental membrane.