Efficacy and Safety of Epidural Chloroprocaine for Breakthrough Pain During Labor Analgesia: A Prospective, Double-Blind, Randomized Trial

Introduction: A significant number of women who undergo neuraxial labor analgesia experience breakthrough pain. Prompt mitigation of breakthrough pain is essential to improve maternal and fetal outcomes. We evaluated epidural chloroprocaine compared with ropivacaine in alleviating labor breakthrough pain. Methods: We performed a double-blind randomized controlled clinical trial between May and July 2023. Eligible parturients received epidural analgesia with ropivacaine and sufentanil. Those with breakthrough pain were randomized to receive either 0.125% epidural ropivacaine (group R) or chloroprocaine at concentrations of 0.5% (group C1), 1.0% (group C2), or 1.5% (group C3), all in a volume of 6 mL. The primary outcome was the treatment success rate, indicated by a decrease of at least 4 points on the numerical rating scale pain score 9 min after analgesic injection. Secondary outcomes and adverse effects were also recorded. Results: Out of 323 patients receiving epidural analgesia, 192 experienced breakthrough pain. After exclusion of three patients because of protocol deviation, there were 47, 48, 47, and 47 patients in group R, C1, C2, and C3, respectively. Group C3 demonstrated a higher treatment success rate (39/47, 83.0%) in managing breakthrough pain than group R (26/47, 55.3%), group C1 (12/48, 25.0%), and group C2 (30/47, 63.8%) (p < 0.001). Group C3 had lower numerical rating scale scores at 6 and 9 min after injection and required fewer patient-controlled epidural boluses than other groups. In addition, group C3 reported greater satisfaction than the other groups (p < 0.001). No significant differences were observed in obstetric or neonatal outcomes across these groups. Conclusion: Parturients experiencing breakthrough pain could receive 1.5% epidural chloroprocaine, rather than lower chloroprocaine concentrations and ropivacaine, to achieve more rapid and better pain relief with higher patient satisfaction.