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

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