Abstract
BACKGROUND: This study aims to determine the 90% effective doses (ED(90)) of the initial ropivacaine volume at varying concentrations (0.075%, 0.1%, 0.125%) administered under dural puncture epidural (DPE) for epidural labor analgesia. METHODS: Ninety ASA II-class patients with cervical dilation < 5 cm and VAS scores >5 were allocated into three groups (0.075%, 0.1%, and 0.125% ropivacaine concentrations) for epidural labor analgesia. The first patient in each group received an initial bolus of ropivacaine combined with sufentanil 0.3 µg/mL in a 10 mL volume. Subsequent doses were determined by an up-and-down sequential allocation method based on adequate analgesia (VAS score <3) within 30 minutes post-administration, using 2 mL incremental/decremental adjustments. The primary outcome was the ED90s of the initial ropivacaine bolus required for effective analgesia under DPE. Maternal analgesia characteristics and neonatal outcomes were recorded. RESULTS: The ED90 values for the 0.075%, 0.1%, and 0.125% ropivacaine groups were 13.30 mL (95% CI, 10.00-14.00), 10.80 mL (95% CI, 8.00-12.00), and 8.90 mL (95% CI, 8.00-10.00), respectively. Maternal and neonatal outcomes were comparable across groups. CONCLUSION: Compared to 0.075% concentration of ropivacaine, the 0.1% and 0.125% concentrations achieved 18.8% and 33.0% reductions in initial analgesic volume requirements. However, comparable analgesic effects and maternal satisfaction were observed across all groups.