A concentration-response observation of hydromorphone combined with ropivacaine in labor analgesia

To investigate the median effective dose (ED(50)) of hydromorphone and the appropriate concentration of ropivacaine combined with hydromorphone in epidural labor analgesia. One hundred and forty nulliparous women undergoing labor selected for delivery with epidural analgesia were enrolled in our hospital from January to June 2016. The first of top 50 women received 0.12% ropivacaine plus 20 μg/ml hydromorphone complex solution, then sequential women were used the modified sequential method to determine the ED(50) and ED(95) of hydromorphone. The other 90 women were randomly divided and receieved 0.08% ropivacaine and 15 μg/ml hydromorphone(H1 group), 0.10% ropivacaine and 15 μg/ml hydromorphone (H2 group), 0.12% ropivacaine and 15 μg/ml hydromorphone (group H3) respectively for epidural labor analgesia. In the course of labor, block levels of epidural analgesia, the Bromage scores, analgesia scores and fetal heart rate-uterine concraction were monitored. In addition, onset time of anesthesia, labor time, mode