Arch Gynecol Obstet (2015) 291:531–536 DOI 10.1007/s00404-014-3427-x

MATERNAL-FETAL MEDICINE

Effects of electro-acupuncture on labor pain management Chris Dong • Linhua Hu • Fengbing Liang Songying Zhang



Received: 9 March 2014 / Accepted: 12 August 2014 / Published online: 20 August 2014 Ó Springer-Verlag Berlin Heidelberg 2014

Abstract Purpose To evaluate the effects of a non-pharmacologic electro-acupuncture method at different acupoints on labor pain management. Methods Nulliparous women under the maternity care of the Department of Obstetrics and Gynecology of Sir Run Run Shaw Hospital were recruited and allocated into two experimental groups (EX-B2 group and SP6 group) and one control group, each with 60 eligible participants. Visual analog scale (VAS) was used to assess the pain during active phase of labor before and 30, 60, 120 min after intervention. The duration of active phase, the duration of second stage of labor, the duration of third stage of labor, use of oxytocin, neonatal birth weight, neonatal Apgar score at 1 and 5 min were considered as secondary outcomes of this study. Results After 30 min intervention, the mean VAS scores of both EX-B2 group and SP6 group were significantly decreased compared with the control group (P \ 0.01); however, no significant difference was observed between

Chris Dong and Linhua Hu contribute equally to this work. C. Dong  S. Zhang (&) Department of Obstetrics and Gynecology, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of China e-mail: [email protected] L. Hu Department of Nursing, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of China F. Liang  S. Zhang Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of China

the two experimental groups (P [ 0.05). After 60 and 120 min intervention, the mean VAS scores of EX-B2 group were significantly lower than SP-6 group (P \ 0.05). Both EX-B2 group and SP6 group had significant lower VAS scores after interventions and shorter time used in active phase of labor than the control group (P \ 0.05). Conclusions The study revealed that the application of electro-acupuncture at EX-B2 and SP6 acupoints could be used as a non-pharmacologic method to reduce labor pain and shorten the duration of active phase of labor. Keywords Labor pain  Electro-acupuncture  Acupoints  EX-B2  SP6

Introduction Pain management during labor is always a controversial topic among obstetricians. Severe labor pain can cause mental distress, exhaustion or abnormal uterine action during labor, which might lead to increased medical interventions and obstetric complications. Fear of labor pain is one of the main reasons that women might choose cesarean section (CS). In China, high CS rate ([50 %) has been reported in many regions [1]. Recent years, many pharmacologic pain control and relief techniques have been studied and developed to cope with labor pain, including epidural analgesia, opioid or nitrous oxide, etc. Their efficacy varies and adverse effects are concerned [2]. Acupuncture is a non-pharmacologic method that has been used to relieve pains in China, since ancient times. Some researches demonstrated the analgesic effects of acupuncture during labor [3, 4]. Rammero¨ et al. [5] also suggested that acupuncture could be used to treat labor pain

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and improve labor progress by enhancing uterine contractions. However, acupuncture techniques require therapists to have professional needling skills to achieve satisfactory results. The quest for a safer and more cost-effective spontaneous vaginal delivery with less pain led us to investigate the efficacy of using an electro-acupuncture method on pain management during labor. The similar method was reported by Fox et al.; they used the combination of a transcutaneous electrical nerve stimulation (TENS) device and acupressure to treat low back pain, and showed that the electro-acupuncture method had better analgesic effects than only using TENS or acupressure alone [6]. Furthermore, Chao et al. [7] reported that application of TENS on acupoints could reduce labor pain. In traditional Chinese medicine (TCM), EX-B2 and SP6 are commonly used acupoints for pain relief during labor. However, comparing these two acupoints in terms of pain relief during active phase of labor has not yet been reported. Therefore, an experimental study was conducted to evaluate the efficacy of these two acupoints combining with electro-acupuncture method on labor pain management and other labor outcomes.

Methods Participants Nulliparous women under the maternity care of the Department of Obstetrics and Gynecology of Sir Run Run Shaw Hospital from October 2012 to September 2013 were recruited and randomly allocated into two experimental groups and one control group by lottery, each with 60 eligible participants. Totally 180 participants completed the study based on following criteria. The inclusion criteria were: (1) signed informed consent; (2) age from 20 to 35; (3) planned vaginal delivery with a singleton pregnancy; (4) had a gestational age of 37–42 week; (5) had fetal vertex presentation; (6) without any obstetrical or nonobstetrical complications; and (7) had cervical dilation C3 cm with regular contractions. The exclusion criteria were: (1) precipitated labor; (2) instrumental delivery or CS during labor; (3) history of electro-acupuncture experience for pain relief; (4) wound scars or inflammation on application sites; and (5) pacemaker users.

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contraction before the intervention and 30, 60, 120 min after the intervention in active phase of labor by the same trained midwife. The protocol of VAS was thoroughly explained to each participant before the intervention. VAS scores decreased C3 at the last VAS measurement was considered effective. Apparatus and treatments An electro-acupuncture device (HANS-100B, China) provides electrical current with intensity range from 5 to 40 mA. The frequency of 100 Hz with a burst frequency of 2 Hz (dense-dispersed waveform), pulse duration of 0.5 ms (ms) was used. In this study, the intensity of the current was set at 15 mA at the starting point of the active phase of labor and can be adjusted to higher intensity upon request. The device was run by experienced midwives who had been adequately trained in acupuncture before the study. In EX-B2 (Appointed Jiaji acupoints, approximately 1.7 cm lateral to the posterior median line, from tenth thoracic vertebral to third lumbar vertebral) group, two electrodes which connected to the device were attached on the bilateral EX-B2 acupoints. In SP6 (Sanyinjiao acupoints, 5 cm above medial malleolus in lower leg) group, two electrodes were attached on SP6 acupoints of both legs. Control group received routine intrapartum care. All deliveries took place in the same private delivery room of the maternity ward. The duration of active phase, the duration of second stage of labor, the duration of third stage of labor, use of oxytocin, neonatal birth weight, and neonatal Apgar score at 1 and 5 min were considered as secondary outcomes of this study. Date analysis The data were analyzed using SPSS 19.0 software; comparisons among groups were performed by v2 test, one-way ANOVA analysis and LSD test; P \ 0.05 was defined as statistically significant. Ethics This study was approved by the Ethic Committee of the Sir Run Run Shaw Hospital. Both verbal and written consent was obtained from each participant.

Visual analog scale Visual analog scale (VAS) was the main assessment tool of pain relief efficacy by having a standard 0–10 cm scale presenting different degrees of pain in an ascending order, where 0 presented no pain and 10 presented the most painful. VAS scores were recorded during the last

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Results Originally, 188 nulliparous women were recruited in this study, 63 were randomly allocated to the EX-B2 group, 61 to SP6 group, and 64 to control group. Eight nulliparous

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533

188 randomized

63 allocated EX-B2

61 allocated SP6

2 inevitable for CS

64 allocated Control

1 inevitable for

1 inevitable for

3 inevitable for CS

Precipitated labor

1 inevitable for

Precipitated labor

Precipitated labor

60 analyzed

60 analyzed

60 analyzed

Fig. 1 Trial profile

Table 1 Main characteristics

Characteristic

EX-B2 group (N = 60)

SP6 group (N = 60)

Control group (N = 60)

P value

Age (years, mean ± SD)

29.40 ± 2.96

29.12 ± 2.88

28.98 ± 2.64

0.71

Tertiary education (%)

48 (80.0 %)

51 (85.0 %)

44 (73.3 %)

0.29

Others (%)

12 (20.0 %)

9 (15.0 %)

16 (26.7 %)

23.90 ± 3.08

23.99 ± 3.46

24.15 ± 3.91

Educational level

BMI (mean ± SD)

0.92

Induction of labor (%)

43 (71.7 %)

36 (60.0 %)

45 (75 %)

0.18

Cervical dilation (cm, mean ± SD)

3.13 ± 0.39

3.08 ± 0.33

3.12 ± 0.42

0.77

women were not considered eligible due to CS delivery (5 cases) and precipitated labor (3 cases). The trail profile was depicted in Fig. 1. Table 1 summarizes the main characteristics of the three groups. There was no significant difference observed in age, educational level, body mass index (BMI), gestational age, induction of labor, and cervical dilation at the starting point of the study (P [ 0.05). No significant difference in mean VAS scores was observed at the starting point (P [ 0.05, Table 2). After 30 min intervention, the mean VAS scores of both EX-B2 group and SP6 group were significantly decreased compared with the control group (P \ 0.01); however, no significant difference was observed between the two experimental groups (P [ 0.05). After 60 and 120 min intervention, the mean VAS scores of EX-B2 group were significantly lower than SP-6 group (P \ 0.05), also the mean VAS scores of the two experimental groups were significantly lower than the control group (P \ 0.05). At

the last measurement, the proportion of VAS score reduction C3 was 33.3 % in EX-B2 group, 21.7 % in SP6 group, and 1.7 % in control group, respectively (P \ 0.01). In EX-B2 group, the time used in active phase of labor was shorter than in SP6 group, but no significant difference was observed between the two experimental groups (P [ 0.05). Both EX-B2 group and SP6 group had significantly shorter time used in active phase than the control group (P \ 0.05). There was no significant difference regarding to duration of second stage of labor, duration of third stage of labor, use of oxytocin, neonatal birth weight, and Apgar score at 1 and 5 min among the three groups (P [ 0.05, Table 3).

Discussion In this study, the effects of labor pain relief and other labor outcomes were investigated by application of electro-

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534 Table 2 VAS Scores

Table 3 Main characteristics of labor course and neonatal outcomes

* P value (LSD): EX-B2 vs. SP6 = 0.24; EX-B2 vs. control \0.01; SP6 vs. control = 0.03

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Outcome parameter (mean ± SD)

EX-B2 group (N = 60)

Control group (N = 60)

P value EX-B2 vs. SP6

EX-B2 vs. control

SP6 vs. control

At starting point

7.71 ± 1.26

7.98 ± 0.94

7.80 ± 1.19

0.21

0.69

0.38

After 30 min intervention

6.70 ± 1,28

6.57 ± 1.42

7.85 ± 1.22

0.58

\0.01

\0.01

After 60 min intervention

5.57 ± 1.11

6.05 ± 1.08

7.88 ± 1.14

0.02

\0.01

\0.01

After 120 min intervention

6.15 ± 1.18

6.59 ± 1.09

8.16 ± 0.95

0.04

\0.01

\0.01

VAS score reduction C3 (%)

20 (33.3 %)

13 (21.7 %)

1 (1.7 %)

\0.01

Characteristic

EX-B2 group (N = 60)

SP6 group (N = 60)

Control group (N = 60)

P value

Duration of active phase (min, mean ± SD)

151.47 ± 55.52

163.35 ± 61.96

184.92 ± 46.52

\0.01*

Duration of second stage of labor (min, mean ± SD)

45.78 ± 15.76

48.80 ± 21.35

49.31 ± 18.86

0.54

Duration of third stage of labor (min, mean ± SD)

9.93 ± 4.13

10.21 ± 3.91

11.08 ± 3.89

0.87

Use of oxytocin (%)

33 (55.0 %)

32 (53.3 %)

39 (65.0 %)

0.38

Neonatal birth weight (g, mean ± SD)

3,381.33 ± 309.17

3,445.00 ± 269.60

3,422.50 ± 288.84

0.48

Apgar score at 1 min (mean ± SD) Apgar score at 5 min (mean ± SD)

9.90 ± 0.30

9.93 ± 0.31

9.88 ± 0.37

0.70

9.99 ± 0.13

10.00 ± 0.00

9.97 ± 0.13

0.37

acupuncture method at EX-B2 and SP6 acupoints during labor. There was a significant difference between the experimental groups and the control group in terms of pain relief during the active phase of labor (P \ 0.01). It was consistent with the results found in previous studies, which suggested that electro-acupuncture method could reduce the pain during labor [7–9]. The analgesic effects of electro-acupuncture method could be mainly explained by either through stimulating local release of endorphins [10] or blocking pain impulses to the brain which is known as the gate theory [11]. The electro-acupuncture device with a dense-dispersed waveform, which is a at frequency of 100 Hz increases the release of dynorphin in the spinal cord and a frequency of 2 Hz causes the release of enkephalins and b-endorphins; together both frequencies lead to interaction of the opioid peptides and exert analgesic effects [12]. In this study, the mean VAS scores of both experimental groups after 60 min intervention were lower than the mean VAS score after 30 min intervention. Peng et al. [13] reported that an average of 57 min was required to achieve the maximum analgesic effects which could last for 5 h by using electro-acupuncture method during labor. However, after 120 min intervention, the

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SP6 group (N = 60)

mean VAS score slightly went up in both experimental groups comparing with the mean VAS score after 60 min. It was probably because of the intensity of contraction increased as labor course progressed. Interestingly, no significant difference was observed on VAS scores between the two experimental groups after 30 min intervention (P [ 0.05), however, EX-B2 group showed significant lower VAS scores than SP6 group after 60 and 120 min intervention (P \ 0.05). EX-B2 are acupoints traditionally used for labor pain relief. These acupoints correspond to the pathways of A fibers into either an inhibitory circuit or an excitatory circuit in the dorsal horn of spinal cord [14]. In this study, EX-B2 acupoints had better analgesic effects than SP6 acupoints after 60 and 120 min intervention, it was likely that the pain caused by contraction was mainly related to the lower back. The application of electro-acupuncture device at EX-B2 acupoints on the lower back could be considered as a nonnoxious input which probably could suppress the pain by blocking the pain impulses to the brain. There was a significant difference in duration of active phase between the experimental groups and the control group (P \ 0.05). It was consistent with previous studies,

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which reported that stimulations made on the acupoints significantly shortened labor duration [15–17]. However, there were other studies reporting that stimulations made on the acupoints had some differences between groups on labor duration, but not statistically significant [5, 7, 18]. Stimulating certain acupoints might shorten the labor duration is probably because acupuncture could provide relaxation during labor [3, 19]; given the women more control of the pain, consequently more energy could be spent on each contraction, efficient uterine contraction lead to an easier smoother labor. The electro-acupuncture method used in this study did not change the course of the second and third stage of labor, neither the use of oxytocin nor the neonatal outcomes (P [ 0.05). In addition, no notable adverse effect was observed during the study time. In summary, the application of electro-acupuncture method at EX-B2 and SP6 acupoints could exert analgesic effects during the active phase of labor. However, the maximum reduction in pain intensity was only 27.8 % in EX-B2 group after 60 min intervention versus baseline; the overall analgesic effects might not be so prominent. Meanwhile, the EX-B2 acupoints had a statistically better analgesic effects than the SP6 acupoints after 60 and 120 min intervention, but the difference was small (DVAS scores \0.5). It might not be considered as a clinical importance. On the other hand, the application of electro-acupuncture method at EX-B2 and SP6 acupoints could shorten the duration of the active phase of labor by nearly 30 min, which means the intervention could reduce pain in terms of time during the active phase of labor. The labor pain is mainly caused by contraction of the uterus and dilation of the cervix. There are many factors which could have influences on the pain perception of each individual, including the difference in pain threshold, the intensity of the contractions, the cervical dilating speed, the mental and physical status of the women during the labor, the cultural factors, etc. These factors are the limitations of the study. In Chinese culture, acupuncture is traditionally used to relieve labor pain since ancient times, and is more likely to be accepted than other cultures. In this study, the psychological effects might play a role in pain relief during labor. In addition, it was difficult to conduct blinding protocols in this study, since the participants were fully aware of the treatments. The lack of objective assessment tool to measure the pain during labor is another limitation. Although VAS tool is a valid instrument to assess the pain, its subjectivity could lead to bias, especially when psychological or social factors were involved. Small sample size and only researching one set of acupoints for each experimental group might be other limitations of the present study.

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Conclusions The results of this study revealed that electro-acupuncture on EX-B2 and SP6 acupoints could be used as a nonpharmacologic method to reduce labor pain and shorten the active phase of labor during labor. Stimulation on EX-B2 acupoints was statistically more effective than on SP6 acupoints in terms of pain relief. In addition, electro-acupuncture method is safer, less expensive, and easier to practice. It has a particular significance in most hospitals in China where pharmacologic methods are not commonly used to manage labor pain due to specialist shortage, high costs and concerns about adverse effects. Further randomized study with large sample size is required to clarify the role of this electro-acupuncture method in labor pain management. Acknowledgments We appreciate the help and support from the nursing staff of the maternity ward of Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University. Conflict of interest The authors have no conflict of interest to declare.

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Effects of electro-acupuncture on labor pain management.

To evaluate the effects of a non-pharmacologic electro-acupuncture method at different acupoints on labor pain management...
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