Determination of Motor Block Minimal Local Analgesic Concentration of Epidural Levobupivacaine in First Stage of Labor

Objective To determine the motor block minimal local analgesic concentration of epidural levobupivacaine in the first stage of labor.Methods Thirty ASA I nulliparous women with 2-3 cm cervical dilatation who requested epidural analgesia were enrolled in the study.The load amount of levobupivacaine was administered for epidural analgesia.Each received a 10 ml bolus of epidural levobupivacaine.The first woman received 0.5% levobupivacaine.Up-down sequential allocation was used to determine subsequent concentration:to increase the concentration one level if the previous woman did not respond or reduce the concentration one 1eve1 if the previous woman did respond.The Brownlee method was used to quantify the motor block minimal local analgesic concentration 30 min after injection.Results The motor block concentration of epidural levobupivacaine in the first stage of labor in China was 0.562% wt/vol(95%confidence interval[CI],0.542% ～ 0.584%).Conclusion In the first stage of labor the motor block concentration of eprdural levobupivacaine was 0.562%,this result can provide pharmacody namics reference for the clinical application.