Abstract: Objective　To investigate the effect of intranasal dexmedetomidine on preventing breakthrough pain of epidural labor analgesia. Methods　Full-term primigravida with singleton fetus and ASA physical status Ⅰ or Ⅱ (n=100) were randomly assigned to control group and intranasal dexmedetomidine group (observation group). The 0.8 µg/kg of dexmedetomidine or equal volume normal saline were administered intranasally 20 minutes after epidural analgesia for observation group and control group, respectively. The incidence of breakthrough pain, the duration from epidural analgesia to the first onset of breakthrough pain, the frequency of patient controlled epidural analgesia (PCEA), the total dosage of analgesics, the maternal satisfaction with analgesia and the duration of labor phrase were recorded. The effect of intranasal dexmedetomidine on breakthrough pain of epidural labor analgesia was evaluated. The VAS scores, the Ramsay scores and FHR before epidural analgesia (T0), and after epidural analgesia at 1 h (T1), 2 h (T2), 3 h (T3), 4 h (T4), full cervical dilation (T5), fetal disengagement (T6), Apgar scores of neonates and umbilical artery blood gas analysis were recorded in the two groups to assess the effect of maternal and neonatal safety. Results　A total of 91 parturients aged 20 to 36 years were included in this study. Compared with the control group (n=45) , the incidence of breakthrough pain was significantly reduced, the duration from epidural analgesia to the first onset of breakthrough pain was significantly prolonged, the frequency of PCEA and the total dosage of analgesics was significantly reduced, the maternal satisfaction with analgesia was significantly increased, the VAS scores were significantly decreased at T1~3 and the Ramsay scores were significantly increased at T1~3 in the observation group (n=46, P＜0.05). There were no significant differences in the duration of labor phrase, FHR, Apgar scores of neonates, umbilical artery blood gas analysis and the adverse reactions between the two groups (P＞0.05). Conclusion　Intranasal dexmedetomidine for epidural labor analgesia can reduce the incidence of breakthrough pain, delay the first onset of breakthrough pain, decrease the dosage of local anesthetic, and have no obvious adverse effects on parturients and newborns.

Key words: labor pain, breakthrough pain, analgesia, obstetrical, analgesia, epidural, dexmedetomidine, administration, intranasal