High-volume patient-controlled epidural vs. programmed intermittent epidural bolus for labour analgesia: a randomised controlled study

The aim of neuraxial analgesia is to achieve excellent pain relief with the fewest adverse effects. The most recently introduced technique for epidural analgesia maintenance is the programmed intermittent epidural bolus. In a recent study, we compared this with patient-controlled epidural analgesia without a background infusion and found that a programmed intermittent epidural bolus was associated with less breakthrough pain, lower pain scores, higher local anaesthetic consumption and comparable motor block. However, we had compared 10 ml programmed intermittent epidural boluses with 5 ml patient-controlled epidural analgesia boluses. To overcome this potential limitation, we designed a randomised, multicentre non-inferiority trial using 10 ml boluses in each group. The primary outcome was the incidence of breakthrough pain and total analgesic intake. Secondary outcomes included motor block; pain scores; patient satisfaction; and obstetric and neonatal outcomes. The trial was considered positive if two endpoints were met: non-inferiority of patient-controlled epidural analgesia with respect to breakthrough pain; and superiority of patient-controlled epidural analgesia with respect to local anaesthetic consumption. A total of 360 nulliparous women were allocated randomly to patient-controlled epidural analgesia-only or programmed intermittent epidural bolus groups. The patient-controlled group received 10 ml boluses of ropivacaine 0.12% with sufentanil 0.75 μg.ml^-1 ; the programmed intermittent group received 10 ml boluses supplemented by 5 ml patient-controlled boluses. The lockout period was 30 min in each group and the maximum allowed hourly local anaesthetic/opioid consumption was identical between the groups. Breakthrough pain was similar between groups (11.2% patient controlled vs. 10.8% programmed intermittent, p = 0.003 for non-inferiority). Total ropivacaine consumption was lower in the PCEA-group (mean difference 15.3 mg, p < 0.001). Motor block, patient satisfaction scores and maternal and neonatal outcomes were similar across both groups. In conclusion, patient-controlled epidural analgesia is non-inferior to programmed intermittent epidural bolus if equal volumes of patient-controlled epidural analgesia are used to maintain labour analgesia and superior with respect to local anaesthetic consumption.