7Alexander JM. The course of labor with and without epidural analgesia [J]. Am J Obstet Gynecol, 1998, 178 (3) : 516
8Chestnut DH. Does epidural analgesia during labor affect the incidence of caesarean delivery[J]. Reg Anaesth, 1997, 22 (6) : 495
9Merborh MK, Bamson S. Managing pain: The fifth vital sign. Nurs Clin Noah Am,2000,35:375-383.
10Buyse I, StzckmanW, ColumbM, et al. Effectof sufentanil on minimum lo- cal analgesic concentrations of epidural bupivacaine, ropivacaine and levobupivacaine in nullipara in early labour. International Journal of Obstetric Anesthesia ,2007,16:22-28.