Background and goal of study: The aim was to compare PIEB vs PCEA for labour analgesia measuring the incidence of breakthrough pain (BP). The influence of the neuraxial block (NB) was also assessed.
Materials and methods: A randomised double blind clinical trial was conducted on nulliparous women (18-40 yrs old), with cervical dilation < 4 cm at singleton term pregnancy (Clinical Trials NCT 02768272). Systemic disease or contraindicated NB were exclusion criteria. Patients were randomised to receive epidural analgesia (EA) + PCEA (group 1), EA + PIEB (group 2), combined spinal-epidural (CSE) + PCEA (group 3), or CSE + PIEB (group 4). All patients had a 5 ml/h background epidural infusion (0.125% levo-bupivacaine + 1.45 mcg/ml fentanyl). PCEA pumps were set up to dispense 10 ml boluses (20 min lockout interval). Patients in PIEB groups received 10 ml bolus per hour (20 min lock time with PCEA). BP was defined as ≥4 in visual analog scale (VAS) and treated with a 10 ml epidural top-up. Block failure (BF) was diagnosed as a VAS >3 sixty minutes after the NB and patients were excluded from the analysis. The anaesthesiologist who performed the NB was blinded for the selected group and pain was assessed by other colleague blinded for the NB and group.
Results: 175 patients were randomized. 22 were not analysed due to BF (12%). A relevant reduction of BP episodes was observed in PIEB (mean 0.45 ± 0.8 in group 2; 0.71 ± 1.3 in group 4) compared with PCEA (2.4 ± 1.7 in group 1; 2.9 ± 1.7 in group 3) (P < 0.01). 65% patients in PIEB groups had no BP episodes whereas only 13% in PCEA had no pain (P < 0.01). Epidural top-ups volume was significantly lower in PIEB (mean 4.1 ± 8.2 ml in group 2; 6.2 ± 13 ml in group 4) compared with PCEA (25.9 ± 20.5 ml in group 1; 25.5 ± 17.9 ml in group 3) (P < 0.01). Time from epidural to first BP episode was higher in PIEB (mean 213.6 ± 197.2 ml in group 2; 317.3 ± 177.3 ml in group 4) compared with PCEA (145.2 ± 60 ml in group 1; 157.7 ± 64.6 ml in group 3) (P < 0.01). No differences were observed between CSE vs EA in BP episodes and top-ups. VAS were lower in CSE vs EA at 30 min (P < 0.001), but they were similar after 60 min and the rest of labour.
Conclusion: PIEB reduces the incidence of BP in labour compared to PCEA. Pain scores in CSE vs EA are similar after the first hour despite PIEB or PCEA.

Programmed Intermittent Epidural Bolus (PIEB) versus Patient Controlled Epidural Analgesia (PCEA) plus background infusion for labour analgesia. A randomised double blind clinical trial