Influences of initiation of epidural analgesia pain relief in early labor on uterine myoelectrical activity

Objective To assess the influences of early implementation of patient-controlled epidural analgesia (PCEA) in labor on uterine myoelectrical activity and delivery outcomes. Methods A prospective study was conducted on 240 singleton cephalic primiparae with spontaneous labor at Guangzhou Women and Children's Medical Center from January 2015 to October 2018. Those women, who were ready to accept PCEA, were randomly assigned to early- or late-PCEA group based on cervical dilation of 0-3 cm or 3-6 cm at the time of commencing PCEA, while those who refused PCEA in labor were classified as non-PCEA group. Uterine electromyographic activity and visual analogue score (VAS) were recorded before and 1 h and 2 h after PCEA. Patient satisfaction with labor, duration of the first stage of labor, volume of postpartum bleeding within 2 h after delivery and neonatal Apgar score were compared between different groups using multivariate analysis of variance, repeated measures analysis of variance, LSD-t test or Chi-square test. Results The VAS values 1 h after PCEA in the early- and late-PCEA group were both lower than that in the non-PCEA group (2.08±1.34 and 2.00±1.28 vs 7.65±1.04, LSD-t were -27.713 and -27.663, P 0.05). There was also no significant difference in uterine electromyographic parameters among the three groups before or 2 h after PCEA (all P>0.05). The number and duration of burst, power density spectrum peak frequency, root mean square and total power 1 h after PCEA in the early- and later-PCEA group were all lower than those in the non-PCEA group [4.80±2.49 and 5.54±3.04 vs 9.67±2.44; (34.41±1.21) and (36.94±1.18) vs (41.68±1.53) s; (0.36±0.08) and (0.36±0.07) vs (0.48±0.05) Hz ; (0.05±0.04) and (0.05±0.05) vs (0.07±0.05) mV; (4.33±0.51) and (5.36 ±0.59) vs (9.90±1.43) pV2; all P<0.05]. Conclusions The effect of PCEA on uterine myoelectrical activity has no association with the commencing time. While early PCEA could alleviate the labor pain as soon as possible, which enable us to improve the efficacy of labor analgesia, patient satisfaction and maternal and neonatal safety without increasing cesarean section rate. Key words: Analgesia, epidural; Analgesia, patient-controlled; Uterine contraction; Electromyography