Influence of ropivacaine combined with different concentrations of sufentanil on epidural labor analgesic effect

Objective:To investigate the influence of ropivacaine combined with different concentrations of sufentanil on epidural labor analgesic effect.Methods:With the method of multicenter double-blind randomized study,90 ASA Ⅰ~Ⅱ parturients who requested epidural analgesia were randomly divided into 3 groups,with 30 cases in each group.Group S0 received epidural ropivacaine alone;group S1 received epidural ropivacaine combined with sufentanil 0.4 μg/ml;while group S2 epidural ropivacaine combined with sufentail 0.6 μg/ml.Epidural catheter in all parturients was placed at L2~3 and advanced 4 cm into the epidural space in cephalad direction.The medicine solution 15 ml of ropivacaine alone or with sufentanil was given as correct epidural placement was confirmed.EC50 of epidural ropivacaince was determined by up and down sequential test.The initial concentration of ropivacaine was set at 0.12% in all groups,then the concentration of ropivacaine was increased or decreased with increment of 0.01% in a sequential method.The up and down sequences were analysed by Dixon method to determine the EC50 and 95% confidence interval(Cl).The side effects were also recorded.Results:The EC50 of epidural labor analgesia of ropivacaine and 95% confidence interval were 0.100% and 0.1090~0.1116% respectively in group S0,0.058% and 0.056%~0.062% respectively in group S1 and 0.053% and 0.052%~0.055% in group S2.The EC50 was significantly higher in group S0 than in groups S1 and S2(P0.01).The incidence of side effects was significantly higher in group S2 than in group S1(P0.05).Conclusion:The epidural labor analgesic effect of ropivacaine is enhanced by sufentanil in low concentration from 0.4 μg/ml to 0.6 μg/ml.Combined with ropivacaine for epidural labor anagesia,it is suggested that sufentanil 0.4 μg/ml is the suitable concentration.