Effects of ropivacaine combined with fentanyl for epidural labor analgesia / 中华麻醉学杂志

ABSTRACT

Objective To evaluate effects of ropivacaine combined with different concentrations of fentanyl for epidural labor analgesia. Methods In this multicenter double-blinded randomized study 128 parturients at full term and 2-3 cm of cervical dilatation who requested epidural analgesia were randomly allocated to one of 4 groups group F0 received epidural ropivacaine alone (n = 33); group F1 received epidural ropivacaine with fentanyl 1 ?g?ml-1 (n = 30) ; group F2 epidural ropivacaine + fentanyl 2?g?ml-1(n = 33) and group F3 epidural ropivacaine + fentanyl 3 ?g?ml-1(n = 32). Epidural catheter was placed at L2,3 and advanced 4 cm into the epidural space in cephalad direction. A bolus of 15 ml of ropivacaine alone or with fentanyl was given after correct epidural placement was confirmed. EC50 of epidural ropivacaine was determined by up-and-down sequential experiment. The initial concentration of epidural ropivacaine was 0. 12% . If effective the next parturient received ropivacaine of lower concentration; if ineffective the ropivacaine concentration was increased. Each time the concentration of epidural ropivacaine increased/decreased by 0.01% . The analgesia was assessed using VAS score (0-10 0 = no pain, 10 = worst pain) . If VAS score was less than 3 within 30 min of ropivacaine administration, analgesia was defined as effective. EC50 of ropivacaine was calculated according to Dixon and Massey. Results Four of the 128 parturients enrolled were excluded because of uncertain results of interrupted observation. The EC50 of epidural ropivacaine for labor analgesia and the 95% confidence interval (95% CI) of EC50 were 0.110% (95% CI 0.109 0%-0.111 6%) in group F0; 0.089% (95% CI 0.087 7%-0.091 1%) in group F1; 0.073% (95% CI 0. 071 7%-0.0744%) in group F2 and 0.060% (95% CI 0.056 0%-0.634%) in group F3 respectively. The EC50 was significantly higher in group F0 than in group F1, F2 and F3 (P0.05) . The incidence of side-effect was significantly higher in group F3 than in group F0(P