Motor blockade is reduced with ropivacaine 0.125% for parturient-controlled epidural analgesia during labour

To compare the effect on the incidence of motor block by reducing the concentration of ropivacaine from 0.2% to 0.125% in parturient-controlled epidural analgesia (PCEA) for labour.

Randomized, controlled and double-blind trial involving parturients in early labour who received demand-only PCEA regimen (bolus 5 ml, lockout 10 min, maximum volume per hour of 20 ml) with either 0.2% (R0.2 group, n = 25) or 0.125% (R0.125 group, n = 25) ropivacaine. Pain scores, the degree of motor block, the rate of drug consumption, the proportion of good to total PCEA demands and the overall satisfaction scores were documented.

Fewer parturients in the R0.125 group had lower limb motor block (4 vs. 11, P<0.05) although the degree of block was mild in all the affected parturients. The ratio of good to total PCEA demands was more favourable in the R0.2% group (median 0.72 vs. 0.52, P<0.01) although the hourly rate of ropivacaine consumption, the degree of pain relief, the maternal-fetal outcome and the overall satisfaction scores were similar.

Both ropivacaine 0.2% and 0.125% provided comparably effective analgesia but motor block occurred more commonly in the 0.2% group.