[Effect of preemptive electroacupuncture on pain reactions in primiparous parturients during vaginal delivery]

To investigate the effect of preemptive electroacupuncture (EA) plus epidural block (EB) on pain reactions and stress hormone levels in primiparous parturients during labor.

A total of 104 primiparous parturients undergoing vaginal delivery were randomly divided into PA group (n=31), sham EA group (n=36) and EA group (n=37). EA (2 Hz/100 Hz, a tolerable strength) was applied to bilateral Hegu (LI4) and Sanyinjiao (SP6) beginning from the latency of the 1^st birth process when the orifice of uterus was opened to about 1 cm wider till the active stage when the orifice of the uterus opened about 3 cm wider. Patients in the sham EA group received shallow acupuncture needle stimulation (without cutaneous penetration of the needle tip, and without stimulation electric current output). All the patients of the 3 groups were given EB (1% Lidocaine, 0.05% Sufentanil and 0.1% Ropivacaine) and patient-controlled epidural analgesia (PCEA) when the orifice of the uterus opened about 3 cm wider. The pain severity was assessed by using Visual Analogue Scale (VAS) at time-points of immediately after EA, 1 h after EA, 2 h after EA, immediately after EB, 1 h after EB, 2 h after EB and full open of the uterus orifice. The contents of serum adrenocorticotrophic hormone (ACTH) and cortisol (COR) were assayed by using ELISA.

There was no significant difference in the VAS score at the immediate time of post-EA among the three groups (P>0.05). Compared with the EB group, the VAS scores at all time-points except the immediate time of post-EA were significantly decreased in the EA group (P<0.05). One and 2 h after EB, and after full open of the uterus orifice, the VAS scores in the 3 groups were all evidently decreased (P<0.05), and those of the EA group were significantly lower than those of the sham EA and EB groups (P<0.05). The three groups had a significant increase in the levels of serum ACTH and COR at time-points of 1 and 2 h after EA, immediately after EB, and when the orifice of the uterus was fully opened (P<0.05), presenting a gradual increase of their level during the course of labor. Compared with the EB group, the levels of serum ACTH and COR contents were considerably decreased in the EA group (rather than in the sham EA group) (P<0.05). The dosages of Ropivacaine and Sufentanil, the total pressing times and the effective pressing times of PCEA pump were significantly lower in the EA group than those in the EB and sham EA groups (P<0.05).

EA plus epidural analgesia, given during the latency period of labor, can effectively alleviate pain, inhibit stress response and reduce the dosage of anesthetics in primiparous parturients throughout the labor process.