The optimal concentration of bupivacaine and levobupivacaine for labor pain management using patient-controlled epidural analgesia: a double-blind, randomized controlled trial

Abstract Background The study aim was to evaluate the efficacy and safety of different low concentrations of two local anesthetics for labor analgesia using patient-contolled epidural analgesia. Methods A double-blind, randomized controlled trial recruiting healthy nulliparous women was conducted from 2014 to 2016. Epidural analgesia was provided using local anesthetic and fentanyl. Patients were allocated to six groups, according to the concentration of bupivacaine or levobupivacaine (0.0625%, 0.1%, 0.125%). Analgesic efficacy, vital parameters, and side effects were evaluated at different time points. Satisfaction was evaluated using verbal and written scores. The primary outcome was the total dose of local anesthetic used. Results Two-hundred-and-thirty-seven cases were analyzed. The total dose of local anesthetic was significantly lower in the two lower concentration groups ( P P =0.005), 0.125% levobupivacaine ( P =0.049) and 0.125% bupivacaine ( P =0.002) groups. Pain breakthrough, patient-controlled and rescue boluses were significantly different between groups ( P =0.03, P =0.003 and P P =0.033), but the incidence of other maternal and fetal side effects were not significantly different. Satisfaction with labor analgesia did not differ across groups. Satisfaction score 72 hours after delivery was significantly lower than that two hours after delivery ( P Conclusions Higher local anesthetic concentration resulted in higher total doses infused and greater motor block. Labor analgesia was less effective when the lowest concentrations were used, but patient satisfaction was unaffected.