Effective Dose 90 of Programmed Intermittent Epidural Bolus Volume at Three Ropivacaine Concentrations with Dural Puncture Epidural for Labor Analgesia: A Randomized Sequential Allocation Study.

BACKGROUND: This study aimed to explore the ED90 of programmed intermittent epidural bolus (PIEB) volume for labor analgesia with different concentrations of ropivacaine when combining with dural puncture epidural (DPE) techniques. METHODS: Ninety patients were randomized to three groups (n=30 each) to receive an initial 12-mL bolus of ropivacaine (0.075%, 0.1%, or 0.125%) with 0.3 μg/mL sufentanil. PIEB began at 60 min after the initial bolus, with 45-min intervals; the first patient in each group received 10 mL ropivacaine‑sufentanil solution, and subsequent volumes were adjusted by ± 2 mL via sequential allocation based on effective labor analgesia (no epidural bolus intervention administered). The primary and secondary outcomes were, respectively, the ED90 of PIEB volume at different ropivacaine concentrations for effective labor analgesia, and maternal analgesia quality and neonatal outcomes. RESULTS: The ED90 of PIEB volume for achieving effective labor analgesia was 13.2 mL (95% CI, 11.9-14.5), 11.1 mL (95% CI, 10.0-12.2), and 9.4 mL (95% CI, 8.4-10.3) in the 0.075%, 0.1%, and 0.125% groups, respectively. No statistically significant differences in maternal analgesia quality and neonatal outcomes were identified among groups. CONCLUSION: When the combined DPE and PIEB technique is applied for effective labor analgesia, the ED90 of PIEB volume at concentrations of 0.075%, 0.1%, and 0.125% is 13.2 mL, 11.1 mL, and 9.4 mL respectively. Since higher concentration corresponds to a higher administered dose of ropivacaine, the ED90 of PIEB volume decreases as concentration increases.