Epidural infusions of bupivacaine and diamorphine in labour

Three different concentrations of bupivacaine, 0.125%, 0.062% and 0.031%, all with diamorphine 0.0025%, were given as an epidural infusion at 10 ml.h-1 to 63 mothers in labour. When the three infusions were compared, significant differences were found in maternal requirements for top-ups and the degree of motor block, but there were no differences in the pain scores. The reduced motor block was not associated with a reduction in the instrumental delivery rate.