Oxytocinase activity in the course of continuous lumbar epidural analgesia.

The oxytocinase activity in the blood serum, umbilical blood and homogenates from the placenta and umbilical cord was determined in 34 women in labor subjected to continuous lumbar epidural analgesia with 0.125 per cent bupivacaine and 1:800 000 epinephrine. The results obtained were subjected to statistical analysis and compared with a group of 30 patients in spontaneous labor without any drugs. Significantly higher oxytocinase activity was found in the women subjected to epidural analgesia. The increased oxytocinase activity was found to correlate with the duration of the first stage of labor. It is assumed that the increase in the oxytocinase activity in the course of continuous epidural analgesia is associated with diminished uterine contractions and is related to the effect of the particular anesthetic agent.