Effects of acupuncture on post-cesarean section pain
Background Post-operation pain is a very subjective phenomenon. The aim of this study was to find out the effects of acupuncture or electro-acupuncture on post-cesarean pain.
Methods Sixty women, who had had spinal anesthesia during cesarean section at the Department of Obstetrics of China Medical University Hospital, were randomly assigned to the control group, the acupuncture group, and the electro-acupuncture group. After the operation, we applied subjects with acupuncture or electro-acupuncture on the bilateral acupuncture point, San Yin Jiao (Sp6), and the patient controlled analgesia (PCA). The first time of requesting morphine, the frequency of PCA demands in 24 hours, and the doses of PCA used were recorded double blindly. In addition, monitoring the subjects¡ä vital signs, the opioid-related side effects, and the pain scores was done.
Results: The results showed that the acupuncture group and the electro-acupuncture group could delay the time of requesting morphine up to 10¨C11 minutes when compared with the control group. The total dose of PCA used within the first 24 hours was 30%¨C35% less in the acupuncture group and the electro-acupuncture group when compared with the control group, which was indicated in statistical significance. However, there was no significant difference between the acupuncture group and the electro-acupuncture group. The electro-acupuncture group¡äs and the acupuncture group¡äs pain scores were lower than the control group¡äs within the first 2 hours. Both were statistically significant. However, two hours later, there were no significant differences of the visual analogue scale (VAS) scores between either of the treatment groups and the control group. Finally, the incidence of opioid-related side effects, such as dizziness, was less in the acupuncture group and electro-acupuncture group than in the control group.
Conclusions This study shows that the application of acupuncture and electro-acupuncture could definitely delay the time of requesting pain relief medication after cesarean section and decrease the PCA doses used within the first 24 hours.
Everyone experiences pain which relates to the complicated reactions in physiology and in psychology. Post-operation pain, which can be affected by many factors, such as age, personality, sex, education, society status, patient¡äs knowledge, degree of the understanding about the operation, level of discomfort, level of the medical staff¡äs attitude and caring, posture of moving, time, and physical condition, is a very subjective phenomenon. Therefore, for the same type of operation, the degree of pain experienced varies from person to person. In general, the worst post-operation pain was thorax or upper abdominal operation; followed by lower abdominal operation, whereas the superficial operation has the less pain reported.1 Pain can be felt after the operation and when the analgesic drugs were diminished, it can be sensation of the strongest pain for a few hours before it stops. Pain can make patients feel uncomfortable and become sleepless or agitated. In addition, pain also stimulates the sympathetic nervous system which causes increases in the heart rate, blood pressure, sweat production, endocrine hyper-function, and delays the patient¡äs prognosis.2,3
At the present time, acupuncture analgesia and acupuncture pain relief are highly emphasized by the international medical researchers. In 1980, WHO has announced 43 types of different diseases that can be treated by acupuncture 4-6 without any significant side effects. Therefore, the aim of this study was to find out the effect of acupuncture or electro-acupuncture on the acupuncture point San Yin Jiao (Sp6) to alleviate pain after operation with the conjunction of patient controlled analgesia (PCA). It is also suggested to reduce the side effects of opioid-related drugs, such as vomiting which is in 25% of post-operation people.7
In this study, our subjects were pregnant women who had cesarean section for their childbirth. The subjects were randomly assigned to 3 groups: the control group, the acupuncture group and the electro-acupuncture group. The data collected for an index were the time which asked for morphine at first by patients, the frequency of PCA demands within 24 hours, the PCA dose given within 24 hours, and the visual analogue scale (VAS). In addition, some reports pointed out that the amount of morphine demanded by the patient (PCA) was closely related to the incidence of side effects,8,9 and the opioid-related side effects were also monitored.
The study was conducted in China Medical University Hospital, and there were 60 women selected as subjects with the first time pregnancy having cesarean section for childbirth. The selection criterion for their health condition was ASAI-II standard (healthy or with mild systematic disease with no functional restriction). Those people, who would have cesarean section but had diabetes, hypertension, cachexia, cardiovascular disease, or any other systematic disease with the lung, kidney or nerve, were excluded from the study. Before operation, the subjects¡ä age, weight and medical history were all carefully recorded. The time of analgesia and operation was also recorded after the operation. These were the confounding factors that would alter the experiment results. All data collected were put into account for future recording.
After operation, the patients in the post-anesthesia room (PAR) were assigned to 3 groups in a randomization sequence based on the table of randomly generated number: the control group, the acupuncture group and the electro-acupuncture group. Every group had 20 subjects (Table 1).
In the control group, after recovering from the anesthesia, no any special treatments were given, and then a PCA machine was applied 30 minutes later. In the acupuncture group, after recovering from the anesthesia, acupuncture point, San Yin Jiao (Sp6), was applied bilaterally. After the points were stimulated until feeling De-Qi sensation, the needles were applied for 30 minutes, and then the PCA machine was applied. In the electro- acupuncture group, after applied the acupuncture points on the bilateral sides and feeling De-Qi sensation, a low frequency of 2 Hz with a suitable current, based on the degree of the muscle twitching, was connected. The points were stimulated for 30 minutes before the PCA machine was applied. The subjects were told how to use the VAS, which was the pain scale. All acupuncture and electro-acupuncture were done by one well trained doctor.
In the PAR, the data collected were the first time of requesting analgesics, the vital signs (such as blood pressure, heart rates, and blood oxygen level) and the VAS score. In the ward, the dosage of PCA morphine demand, the frequency of PCA intake, and the valid and invalid demands within 24 hours were also recorded. The vital signs, VAS scores, opioid-related side effects, such as nausea, vomiting, dizziness and pruritus were also documented. All data were collected by another well trained doctor double blindly.
The demographic data, time of analgesic, duration of operation, and the outcome records including the time of the first request for morphine (if no request in the PAR, 120 minutes after operation was used as the first requesting time), the frequency of PCA request, the morphine dosage given, and the VAS data were screened by D’Agostino-Pearson omnibus K2 normality test first to assess whether the data in each group were deviated from a Gaussian distribution. For those variables which failed to reject the null hypothesis in normality test (i.e. data are consistent with a Gaussian distribution) in all of the three groups, one way analysis of variance (ANOVA) was used to investigate if all the three groups had the same mean. If the results of ANOVA were concluded statistically significant, then the Student-Newman-Keuls (SNK) test was used as the post test to identify if there were differences between two groups. For those variables with data in any one of the three groups that deviated significantly from Gaussian distributions, the Kruskal-Wallis nonparametric test instead of ANOVA was used to compare the three groups, and Dunn’s post test was used to compare the difference in the sum of ranks between two groups with the expected average difference. For opioid-related side effects, chi-square test was used to test their statistical significance. P <0.05 was considered statistically significant.
The data of the three experimental groups were analyzed and compared with each other. When discussing variables which might interfere with the results of the experiment, the demographic data showed no statistically significant differences in the age, body weight, height, the time of analgesic, and the duration of operation (Table 2).
When the subjects entered the post analgesia room, the subjects¡ä first requesting time of the addicted analgesic drug, morphine, was recorded. The results showed that the acupuncture group ((40.3¡À13.8) minutes) and the electro-acupuncture group ((39.5¡À16.9) minutes) were significantly delayed in their demands for morphine, when compared with the control group ((29.0¡À15.0) minutes) (Figure 1).
In addition, the number of the morphine requested among the three treatment groups was compared within the first 24 hours after the operation. The results showed that in the 1¨C8 hours, the demands of morphine for the acupuncture and electro-acupuncture groups were less frequent than the control group. The acupuncture group requested for (20.1¡À9.1) times, the electro-acupuncture group requested for (18.4¡À9.9) times and the control group requested for (29.0¡À11.5) times. These data reached statistical significance. In the 9¨C16 hours, the electro-acupuncture group was lower ((9.8¡À6.8) times) than the control group ((17.3¡À7.9) times). In the 17¨C24 hours, the acupuncture group was (4.4¡À2.8) times and the electro-acupuncture group was (4.9¡À4.7) times, which were again less than the control group ((9.4¡À6.5) times). These also reached statistical significance. As for the sum of analgesic demands within 24 hours after the operation, the acupuncture group was (37.4¡À15.9) times, and the electro-acupuncture group was (33.1¡À19.7) times which were both significantly less than the control group, (55.7¡À20.3) times. The dosage of PCA morphine was also compared within 24 hours (Table 3). In the 1¨C8 hours, the electro-acupuncture group was given (5.47¡À2.79) mg while the control group was given (7.88¡À2.84) mg. The dosage of the experiment group was significantly lower than that of the control group. In the 9¨C16 hours, the dosage given in the electro-acupuncture group had reduced to (2.87¡À1.66) mg while the control group had (4.22¡À1.82) mg. In the 17¨C24 hours, the dosage given in the acupuncture group was (1.18¡À0.74) mg, the electro-acupuncture group was (1.56¡À1.48) mg while the control group was (3.18¡À2.08) mg. When comparing the total dosage for the PCA morphine given within the post-operative 24 hours among the groups, the acupuncture group was (10.66¡À4.68) mg, the electro-acupuncture was (9.89¡À5.18) mg, and the control group was (15.28¡À4.99) mg. On the other hand, the total dose of PCA used within the first 24 hours was 30% less in the acupuncture group and 35% less in the electro-acupuncture group than the control group (Table 3).
After the operation, the valid and invalid demands of PCA within 24 hours were also compared. The total valid demand of the acupuncture group was (26.7¡À11.7) times, the total valid demand of the electro-acupuncture group was (24.7¡À13.0) times, and the total valid demand of the control group was (38.2¡À12.5) times. For invalid demands, the acupuncture group was (10.8¡À6.3) times and the electro-acupuncture group was (8.5¡À7.8) times whereas the control group was (17.5¡À8.9) times. All the data reached statistical significance (Table 4).
The pain scores of the treatment groups in every 30 minutes were also recorded and compared with the control group within the post-operative 24 hours. In both of the acupuncture group and the electro-acupuncture group, the VAS pain scores were significantly lower than the control group at 0.5, 1, 1.5 and 2 hours post-operation. However, after 2 hours, there were no significant differences of the VAS scores between either of the treatment groups and the control group (Figure 2).
When the opioid-related side effects were compared with each group, the results showed that the number of subjects with dizziness in the acupuncture and the electro-acupuncture group was significantly lower than the control group (Table 5).
In this experiment, the acupuncture point, San Yin Jiao (Sp6), was selected. The point which belongs to the Foot Tai Yin Spleen meridian is located at 3 cm superior to the tip of the medial malleolus, and on the posterior border of the tibia. The reasons why selecting the point in the experiment were three major issues: childbirth, lower abdominal area and analgesic effect. San Yin Jiao was one of the best points to choose.10-12 In fact, the results of the experiment showed that this acupuncture point did have analgesic effect for post-cesarean section pain.
Many studies showed that age affects the sensation of pain. Therefore, in many PCA studies, to compare with the effective dosage of morphine given for people older than 55 years, the effective dosage of morphine given for people less than 55 years old was double.13,14 However, in this research, the differences in the age, height and body weight for the 60 subjects were not large, and this effect was not considered in this experiment. In addition, the duration of analgesic and the time of operation also had no significant difference.
In this study, the results showed that the acupuncture group and the electro-acupuncture group both delayed the first time of requesting analgesic. This means that acupuncture and electro-acupuncture can effectively delay the pain similar to the opioid drugs in preventing pain.15,16 When the PCA demands were compared among the groups, the results showed that the subjects in the control group were more demanding for pain relief than the other two experimental groups.
Furthermore, the total dose of morphine used in the electro-acupuncture group was significantly lower than the control group in all stages. The results for the acupuncture group also showed the total morphine demand was lower than the control group especially in the 17¨C24 hours. On the other hand, the total dose of PCA used for the acupuncture group was 30% and for the electro-acupuncture group was 35% less than the control group. These indicated that with the application of either acupuncture or electro-acupuncture can reduce pain. In early researches, the application of electro-acupuncture on the rat spine with the use of 2 Hz with ¦Ì and ¦Ä opioid related medium and 100 Hz with opiate related medium had been investigated.17-19 Other researchers also pointed out that when currents of different frequencies were used on the acupuncture point, they resulted in the acceptance of the secondary opioid or serotonin to transmit analgesic function.20-22
In addition, when comparing the results of PCA demands, while the electro-acupuncture group was significantly lower than the control group in all stages, the acupuncture group was significantly lower than the control group in the 1¨C8 hours, 17¨C24 hours and within 24 hours. Regarding the number of valid and invalid demands of PCA, both the acupuncture and electro-acupuncture groups were lower than the control group. This proved that the control group was in more desperate need for analgesics and the electro-acupuncture and acupuncture groups both had better pain relieving effects.
In this experiment, 2 Hz frequency was chosen to apply to subjects in the electro-acupuncture group. It was pointed out that the ¦Ì acceptor was the most similar to opioid-related analgesic receptor.23 In addition, Sun and Han17 also proved that in the rat¡äs spine analgesic experiment the electro-acupuncture worked well in 2 Hz frequency with ¦Ì and ¦Ä opioid related receptors. To compare the electro-acupuncture group with the acupuncture group on the number of PCA demands and the dosage used, we found that the results of the electro-acupuncture group were lower than those of the acupuncture group. However, these data did not reach statistical significance.
The results for the opioid-related side-effects, the subjects in the acupuncture group and the electro-acupuncture group had less dizziness when compared to other subjects in the control group. It had statistical significance. This could be due to the dosages of morphine applied in the acupuncture and electro-acupuncture groups, which were significantly lower than in the control group. The side effects were mostly caused by morphine; thus, lower dosage of morphine used led to less side effects. In addition, San Yin Jiao (Sp6), which belongs to the Foot Tai Yin Spleen meridian, has clinical application of treating nausea, dizziness and vomiting.24,25 Therefore, the side effects were reduced either because of the application of acupuncture that reduced the dosage of morphine demand or because of the acupuncture point itself. In this experiment, it certainly approved clinical effects of acupuncture.
Similar studies had conducted by other researchers, such as Lin et al26 in 2002 and Wang et al13 in 1997. In this study, we had an extra experimental group, the acupuncture group which was different from the previous studies. Our results showed that acupuncture alone also had analgesic effects. In the future studies, different acupoints can be applied for different types of operations so as to find the best point for electro-acupuncture. Furthermore, we will make more studies to investigate the changes of physical mechanism when acupuncture is applied as the analgesic, hopefully to reduce the use of analgesic drugs and to widely use acupuncture in clinical situations.
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WU Hung-chien, LIU Yu-chi, OU Keng-liang, CHANG Yung-hsien, HSIEH Ching-liang, TSAI Angela Hsin-chieh, TSAI Hong-te, CHIU Tsan-hung, HUNG Chih-jen, LEE Chien-chung , LIN Jaung-geng WU Hung-chien College of Dental Medicine, Kaohsiung Medical University, Taiwan, China; LIU Yu-chi School of Post Baccalaureate Chinese Medicine, China Medical University, Taiwan, China; OU Keng-liang Research Center for Biomedical Implants and Microsurgery Devices, College of Oral Medicine, Taipei Medical University, Taiwan, China; CHANG Yung-hsien China Medical University Hospital, China Medical University, Taiwan, China; HSIEH Ching-liang China Medical University Hospital, China Medical University, Taiwan, China; TSAI Angela Hsin-chieh Meridian Medical Centre, Australia; TSAI Hong-te Department of Obstetrics and Gynecology, China Medical University Hospital, Taiwan, China; CHIU Tsan-hung Department of Anesthesiology, Taichung Veterans General Hospital, Taiwan, China; HUNG Chih-jen Mei-Tsung Obstetrics and Gynecology Clinic, Taiwan, China; LEE Chien-chung Graduate Institute of Acupuncture Science, China Medical University, Taiwan, China; LIN Jaung-geng Graduate Institute of Acupuncture Science, China Medical University, Taiwan, China
Correspondence to: LIN Jaung-geng Graduate Institute of Acupuncture Science, China Medical University, Taichung 404, Taiwan, China (Email:firstname.lastname@example.org )
This study was supported by : Kaohsiung Medical University Hospital, Taiwan, China(No. KMUH96-6G12)
Keywords: cesarean-section childbirth¡¤acupuncture¡¤electro-acupuncture¡¤pain