Maintenance of labor with epidural analgesia

Depending on the solution concentrations used in the study groups, the maintenance of labor with epidural analgesia was achieved using ropivacaine with dexmedetomidine at 0.4 μg mL⁻¹. The study solution was delivered using the epidural infusion pump (Apon MC ZZB-IV, Jiangsu Apon Medical Technology Co., Ltd., Nantong, China) that was programmed to administer a PIEB dose of 10 mL at an infusion rate of 500 mL h⁻¹, which was initiated 1 h after the first loading bolus.

Patients were allowed 5 mL boluses of patient-controlled epidural analgesia (PCEA) with a 10-min lockout interval. The patient was guided to press the PCEA button if she felt pain. If no pain relief was noted, clinicians administered a 10 mL bolus of 0.25% ropivacaine with 100 μg fentanyl according to the principles in our hospital. If pain persisted despite these boluses, it was considered a displacement of an epidural catheter. Thereafter, the patient could not participate in this study.