Transcutaneous acupoint electrical stimulation (TAES) for pre-operative anxiety:a prospective observational pilot investigation

Wa Cai,Wei-Ting Huang,Wei-Dong Shen＊

1Department of Acupuncture, Shanghai Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine,Shanghai 201203, China.2Institute of Acupuncture & Anesthesia, Shanghai Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine,Shanghai 201203,China

Abstract

Keywords:Transcutaneous acupoint electrical stimulation, State-Trait Anxiety Inventory, Pre-operative anxiety,Pilot investigation

Background

Pre-operative is described as an unpleasant state of tension resulting from a patient's doubts or fears before undergoing an operation.Statistically, around 25%-73% of patients awaiting surgery are affected by pre-operational anxiety[1],which will start growing as soon as the surgery is arranged and rise to the peak at some time point before surgery [2].Severe pre-anxiety may negatively influence the effectiveness and recovery of anesthesia and reduce patients' comfort during peri-operative period [3].Currently,pre-operative anxiety is routinely treated by sedative premedication such as benzodiazepines [4], which have such serious side effects like drowsiness,dizziness,decreased alertness and concentration[5].

Non-pharmacological treatment methods such as transcutaneous acupoint electrical stimulation (TAES)[6], acupuncture [7], and music [8] were found to effectively alleviate pre-operative anxiety with fewer side effects compared with anti-anxiety agents.TAES is effective and safety for reducing post-hemorrhoidectomy-associated anxiety which was verified in a most recent study [9].Another previous research also confirmed that TAES could modify autonomic nervous system activity, thus effectively alleviating post-operative anxiety and pain [10].Acupuncture at those acupoints such as Hegu (LI4),Neiguan (PC6), Taichong (LV3), Shenmen (HT7),Waiguan (TE5) and Yintang (EX-HN3) was confirmed to effectively treat anxiety before operations [3].An acupoint is stimulated using a needleless electrical impulse in TAES, which has an underlying neurobiological mechanism similar to that of electro-acupuncture [3].Besides,TAES can avoid pain and topical skin tissue injury made by acupuncture as well as quantitatively control intensity and stimulation time, which can increase the acceptability and satisfaction of patients.Thus, this pilot study was designed to investigate the exact effectiveness of TAES on decreasing anxiety in patients before operation in order to test the feasibility of outcome measurements and provide useful data to for calculating the sample size of a future randomized controlled trial(RCT).

Participants and methods

Participants and design

62 surgical patients signed the written consent and volunteered to participant in this pilot investigation,which was performed at Shuguang Hospital, affiliated with Shanghai University of Traditional Chinese Medicine, China.Participants who were in the following conditions were excluded:pregnancy;inability to sign consent; contraindications to TAES;psychiatric conditions; previous experience of TAES;use of any sedative medication.Heart rate, blood pressure, sleep quality and State-Trait Anxiety Inventory (STAI) questionnaire results of participants who signed informed consent were taken before and after they received TAES treatment in the evening of the day before operation.During the whole trial, the place of each participant where all the assessments were conducted was not changed.No intervention was allowed to ensure that there was no difference in the environment which could probably affect the results.

Ethics

The study was approved by the Ethics Committee of Shuguang Hospital affiliated with Shanghai University of Traditional Chinese Medicine on 26 October 2017(certificate number 2017-kykt-12).

Treatment procedures

Experienced acupuncturists were responsible for the acupoints positioning and TAES treatment operation.As shown in Figure 1, after skin sterilization, adhesive electrodes (Shanghai Bo Da Medical Instruments Ltd.Co.)were stuck to acupoints LI4 and PC6 at both sides.Considering that a frequency of 2/100 Hz of TAES has been proven to be most effective for alleviating anxiety[6], all the electrodes will be stimulated using an electric current at a frequency of 2/100 Hz by an low-frequency pulse treatment machine(Shanghai Hua Yi Medical Instruments Ltd.Co.)for about 30 minutes.Those two acupoints were selected according to previous studies using acupuncture in treating with pre-operative anxiety.TAES treatment was conducted for one session in the evening the day before operation.

Measurements and statistical analysis

The STAI, described as stable individual differences in the tendency to experience anxiety, is a self-testing questionnaire that contains two 20-item subscales measuring anxiety.The higher the score of STAI, the more anxious the participant is [3].Apart from STAI,heart rate and blood pressure which can also reflect the severity of anxiety were also measured and recorded before and after TAES treatment.Basic information including body temperature, respiratory rate and Pittsburgh sleep quality index (PSQI) score was also recorded pre-and post-treatment.

An independent statistician used SPSS 24.0 (SPSS Inc., Chicago, IL, USA) to conduct the whole data analysis deferring to the intention-to-treat (ITT)principle.Presented as mean±standard deviation(SD),the continuous variables will be compared before and after TAES treatment by the paired t-test.Pvalues that are less than 0.05 will be regarded as statistically significant.

Results

It has been demonstrated in Table 1 that 39 of 62 participants(aged 45 ±13)are females and the rest of them are males.Most of them underwent general anesthesia (50 out of 62).All the participants tolerated TAES well and finished all the measurements before and after treatment.

According to Figure 2, STAI scores of state anxiety dropped significantly after TAES (Figure 2A;P=0.047).In comparison to the baseline, both the heart rate(Figure 2B;P=0.014)and systolic blood pressure(Figure 2C;P= 0.037) decreased significantly.There was no significant changes in diastolic blood pressure before and after TAES (Figure 2D;P＞ 0.05).Furthermore, no significant change was found in body temperature, respiratory rate and PSQI score pre- and post-TAES(allP＞0.05).

Figure 1 The instructions of transcutaneous acupoint electrical stimulation treatment.(A)Adhesive electrodes were stuck to acupoints LI4 (Hegu) and PC6 (Neiguan) at both sides.(B)All the electrodes will be stimulated using an electric current at a frequency of 2/100 Hz by a low-frequency pulse treatment machine.

Table 1 Demographic and clinic data of the surgical patients

Discussion

The pilot investigation showed that TAES was simple to perform to the surgical patients and turned out to be safe without side effects.The measurement of STAI indicated that pre-operative anxiety was alleviated by around 12% after TAES.The efficacy of TAES in decreasing pre-operative anxiety was confirmed in the pilot study.The degree of the effectiveness was not so significant in comparison to a recent randomized controlled trial of acupuncture for pre-operative anxiety which led to a 30% reduction in Amsterdam Pre-operative Anxiety and Information Scale(APAIS)scores,a 17%decrease in STAI-6 anxiety scores[7].

Currently, there is no previous researches regarding the exact mechanisms of TAES for pre-operative anxiety.It has been indicated in several studies involving acupuncture that the release of neurotransmitters like serotonin can influence the mental health [3].It ought to be verified in further researches that TAES may have similar mechanisms.

Based on the indispensable pilot study, a multi-centered and large-sized RCT will be designed to further our study.The measurement of STAI, heart rate and blood pressure will be assessed at more endpoints in order to figure out the sustained efficacy of TAES treatment for pre-operative anxiety.Besides,stress-specific biomarker salivary α-amylase [11] and heart rate variability [3] will also be measured or monitored in the RCT so as to assess the degree of pre-operative anxiety at a deeper level.The fact that most of the participants were females in the pilot study might lead to bias of the clinical results for the reason that female patients are more sensitive and emotionally fragile, tending to lose self-confidence and increase anxiety [12].The average age of the participants was around 45 years old which indicated the middle age,and middle-aged people are easier to lose temper and become anxious than youngsters [13].Our subsequent RCT will enroll patients of both sexes and all ages evenly in order to avoid gender and age bias.

Figure 2 The changes of State-Trait Anxiety Inventory (STAI) scores, heart rate, systolic blood pressure and diastolic blood pressure before and after TAES.Data are presented as mean±SD(n=62 in total).(A)STAI scores.(B) Heart rate (bmp).(C) Systolic blood pressure (mmHg).(D) Diastolic blood pressure (mmHg).* P＜0.05 vs.baseline.TAES,transcutaneous acupoint electrical stimulation;SD,standard deviation;bpm,beats/min.

Conclusion

TAES, well accepted by volunteered surgical patients,can effectively reduce pre-operative anxiety.In addition,it should be considered as a useful therapy for the anxious patients during pre-operative period due to its cheap price,simple operation and fewer side effects.It was proven in the pilot study that the outcome measurements were feasible to reflect the anxiety levels of patients and the data could facilitate the calculation of the sample size for a subsequent RCT of TAES treatment for pre-operative anxiety.