Comparison of median effective concentration of ropivacaine in multiparas or primiparas during epidural labor analgesia

The documents on the median effective concentration of local analgesic were many in primiparas during labor analgesia. However, the studies were fewer in multiparas. To explore the analgesic requirements in multiparas during epidural labor analgesia, we investigated the median effective concentration of ropivacaine with 2 μg/mL fentanyl for epidural labor analgesia in multiparas.Sixty-two women were recruited and assigned to the primipara group and multipara group in this prospective study. All the parturients received ropivacaine combined with 2 μg/mL fentanyl for epidural labor analgesia. The concentration of ropivacaine was determined by the up and down method and an initial concentration was set as 0.1% with a 0.01% interval. Effective analgesia was defined as the visual analog scale (VAS) ≤3 within 30 minutes after epidural administration when cervical dilatation is about 2 cm. The median effective concentration of ropivacaine was calculated by the up and down sequential method. The pain intensity was assessed using VAS. Hemodynamic parameters, the labor stages, and neonatal Apgar scores were recorded. Umbilical artery blood was drawn to analyze. The side effects, if any, were also recorded.The median effective concentration of ropivacaine was 0.057% (95% confidence interval [CI], 0.051-0.064%) in primiparas during epidural labor analgesia, and 0.068% (95% CI, 0.063-0.072%) in multiparas during epidural labor analgesia, there was significant difference between the groups (P = .02).This study indicated that the median effective concentration of ropivacaine with fentanyl for epidural labor analgesia was 0.068% (95% CI, 0.063-0.072%) and increased in multiparas compared with the primiparas (www.chictr.org.cn, registration number: ChiCTR-1800016486).