Leo 2010.

Study characteristics
Methods	Randomised controlled trial
Participants	Setting: recruited from KK Women's and Children's Hospital, Singapore Sample size: N = 62 Participants: age not provided Inclusion criteria: healthy ASA I nulliparous parturients with term (> 36 weeks of gestation), singleton fetuses in the vertex presentation, who were in early labour (cervical dilation < 5 cm) and requested labour epidural analgesia
Interventions	AMB (n = 31): 0.1% ropivacaine + fentanyl 2 µg/mL. PCEA algorithm initiated immediately after completion of CSE. Participants in this group received automated mandatory boluses (AMB) of 5 mL every hour instead of a basal infusion. The first AMB dose was delivered 30 min from CSE and epidural catheter placement and every hour subsequently if no PCEA demands were made. If the participant had made a successful PCEA self‐bolus, the next AMB bolus would be delivered 30 min after the last successful PCEA self‐bolus and every hour thereafter. The lockout period for both PCEA and AMB boluses was 10 min. If a PCEA demand was made within 10 min of an AMB dose, no further bolus would be given. This would be recorded as an unsuccessful PCEA attempt. PCEA bolus was set at 5 mL and maximal hourly limit at 20 mL/h (inclusive of basal infusion and automated boluses) BI (n = 31): 0.1% ropivacaine + fentanyl 2 μg/mL. PCEA with basal infusion 5 mL/h initiated immediately after intrathecal drug administration and epidural catheter placement. PCEA bolus was set at 5 mL, lockout interval at 10 min and maximal dose at 20 mL/h
Outcomes	Rate of breakthrough pain with need for anaesthetic intervention Rate of caesarean delivery Rate of instrumental delivery Duration of labour Total LA/hour (time weighted hourly consumption of ropivacaine) Maternal satisfaction Apgar scores
Notes	Study dates not stated Funding sources not declared No conflict of interests declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation by computer generated random numbers: Quote:"Parturients were randomly allocated into two groups using sealed opaque envelopes and computer‐generated random number tables by an independent assistant, who then programmed the epidural drug delivery system according to group assignment."
Allocation concealment (selection bias)	Low risk	Allocation concealment by sealed opaque envelopes: Quote:"Parturients were randomly allocated into two groups using sealed opaque envelopes..."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Pumps were programmed by a blinded assistant. The patients were blinded. Quote:"...independent assistant, who then programmed the epidural drug delivery system according to group assignment." Quote:"Neither the parturients nor the anesthesiologists who monitored and collected post‐block data were aware of group assignments."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors were blinded: Quote:"Neither the parturients nor the anesthesiologists who monitored and collected post‐block data were aware of group assignments."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts
Selective reporting (reporting bias)	Low risk	All a priori outcomes reported based on published protocol
Other bias	Low risk	Appears to be free of other sources of bias. Sample size calculation: sample size of 30 participants in each group was calculated to detect a 30% reduction in the incidence of breakthrough pain requiring physician top‐up for participants in the PCEA + AMB arm compared with those in the PCEA + BI arm (α = 0.05, ß = 0.2)