Background and objective: To evaluate the efficacy, delay and duration of analgesia of three equianalgesic epidural doses of levobupivacaine, ropivacaine and bupivacaine during the first stage of labour.
Methods: One hundred and twenty-nine healthy primigravida in spontaneous labour who requested epidural analgesia were enrolled in a randomized observer-blinded study. Parturients were allocated to receive epidural levobupivacaine 0.0625%, ropivacaine 0.1% or bupivacaine 0.0625%. Sufentanil 10 μg was added to all solutions; the total volume of epidural solution was 20 mL. Pain was measured using a 100 mm visual analogue pain scale immediately before the epidural block, and at 5, 10, 15, 20 and 30 min thereafter. Motor block was evaluated using a modified Bromage scoring system. The adequacy of motor function for ambulation was also evaluated. Delay of analgesia was the time interval between the injection of the solution and the first painless contraction. Duration of analgesia was the time from the first painless contraction to the parturients' requests for further analgesia.
Results: Twelve parturients failed to complete the study. Eleven parturients had inadequate analgesia (four in Group Levobupivacaine, four in Group Ropivacaine and three in Group Bupivacaine; P > 0.05). Data was analysed from 34 parturients in Group Levobupivacaine, from 37 in Group Ropivacaine and from 35 in Group Bupivacaine. There were no differences in the delay of analgesia or in the number of parturients who were able to walk unaided. Levobupivacaine and ropivacaine produced more prolonged analgesia than bupivacaine (114 and 119 min, respectively, versus 89 min; P < 0.01).
Conclusions: During early labour, equipotent low concentrations of levobupivacaine, ropivacaine and bupivacaine, all with the addition of sufentanil 10 μg, produced similar pain relief and motor block, but levobupivacaine and ropivacaine produced a longer lasting analgesia. About 10% of parturients had inadequate analgesia with a single bolus of the tested solutions.