Patient controlled epidural analgesia during labour: choice of solution

Epidural characteristics, when using different solutions for patient controlled epidural analgesia (PCEA), were compared in a randomised, blinded study in labour. Women in group 1 (n=23) self-administered 0.25% plain bupivacaine, in group 2 (n=23) 0.125% plain bupivacaine plus fentanyl 3 microg/ml and in group 3 (n=20) 0.0625% bupivacaine with adrenaline 1:250,000 plus fentanyl 3 microg/ml. There were no significant differences between groups with respect to the quality of obstetric pain relief or maternal satisfaction, the requirement for supplementary boluses of staff-administered solution or the incidence of side effects. There was more intense motor block after 3 hours of PCEA (odds ratio 3.33 for score 0 versus 1, 2 or 3) and a significantly higher ratio of demands received to demands made (P<0.03) in group 1 compared groups 2 and 3. The rate of bupivacaine utilisation was significantly higher in group 1 compared to groups 2 and 3 and lower in group 3 compared to 1 and 2 (median+interquartile range: 16+11-21 vs 9+6-11 vs 4+3-8 mg/hr, P<0.0002). Although all solutions provided effective pain relief for PCEA during labour, the use of a low-dose bupivacaine-fentanyl combination offers clinical advantages and further evaluation of such solutions is warranted.