Regulation of Electroacupuncture on Gastric Myoelectrial Activities: Monitered by Electrogastrograms

doi:10.4236/eng.2013.510B018

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Engineering, 2013, 5, 90-93

http://dx.doi.org/10.4236/eng.2013.510B018 Published Online October 2013 (http://www.scirp.org/journal/eng)

Regulation of E lectroacupu ncture on Gastric Myoelectrial

Activities: Monitered by Ele ctrogastrogram s

Peng Cheng1,2

1Research Center of Biomedical Engineering, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China

2Shenzhen Key Laboratory for Minimal Invasive Medical Technologies, Shenzhen, China

Email: [email protected]

Received December 2012

ABSTRACT

It is reported that acupuncture on some acupoints can enhance the regularity of gastric myoelectrical activities, which

can be observed from the electrogastrograms (EEGs). In this paper, the electroacupuncture (EA) treatments were per-

formed on subjects with slight gastric disorders and the EEGs were monitored in the mean while. The EEGs features of

baseline, during and after EA treatments were analyzed. The results show that the EA treatments do enhance the regu-

larity of EEGs. And a highly possible pattern for EA to attain the enhancement is to regulate the pacemaker quantity

and propagation of slow waves rather than regulating the amplitude of slow waves.

Keywords: Acupuncture; Electroacupuncture; Gastric Disorder; Electrogastrog rams; Gastric Myoelectrial Activity

1. Introduction

Being practiced in China for tens of centuries, acupunc-

ture now is accepted to treat some kinds of diseases in

both East and West. Especially, in recent decades, acu-

puncture is becoming a popular non-medication therapy

for the patients with functional gastrointestinal disorders

(FGIDs), which has the prevalence as high as 40% - 70%

in general population. The electroacupuncture (EA) and

cutaneous electrical stimulation on acupoint are applied

and reported as effective as the traditional manual acu-

puncture in the recent decades [1-3]. The acupoints Zu-

sanli (Stomach-36, ST36, at the lower limb) and Neiguan

(Pericardium-6, PC-6, at the wrist) are the most com-

monly used points in treating FGIDs. Ouyang [4] and

Takahashi [5] reviewed the research on applications and

mechanisms of acupuncture for the treatment of FGIDs

respectively. The efficiency of acupuncture on FGIDs is

certified, but its mechanism still remains unc lear .

As a noninvasive measurement of gastric function,

electrogastrograms (EGGs) gain much attention in diag-

nose and treatment of gastric disorders in recent decades.

EGGs are measurements of the gastric myoelectrical ac-

tivities, which are composed of rhythmic slow waves and

spikes. EEGs usually refer to the surface measurements

by placing electrodes on the abdominal skin. As recor ded

cutaneously, the EGGs present a weighted summation of

the electrical activities of var ious regions of the stomach.

Studies have shown that the cutaneous electrodes can

only pick up the rhythm of the slow waves but not that of

the spikes. The normal frequency of slow waves in hu-

man is about 3 cycles per minute (3 cpm or 0.05 Hz).

The slow waves of 2.4 - 3.7 cpm are defined as normal

slow waves, and less than 2.4 cpm as bradygastria, more

than 3.7 as tachygastria [6-8].

It is reported that acupuncture on some acupoints can

enhance the regularity of gastric myoelectrical activities

[1,3-5]. It can be observed from the EEGs. The percen-

tage of normal slow waves is increased significantly

during acupuncture and after acup uncture is increased

slightly or similar to the baseline .

In order to obtain more information from EEGs, some

new methods and parameters were proposed [9-11]. In

this paper, EEGs were monitored before, during and after

acupuncture treatments on subjects with gastric disorder s.

The features of EEGs were studied and compared. The

efficiency of acupuncture on regulating gastric myoelec-

trical activities were certified once more, and a possible

pattern of the regulation can be derived.

2. Materials and Methods

2.1. Subjects

Eleven volunteer subjects with slight gastric disorder or

discomfort participated in this study, including 2 males

and 9 females, aged from 23 to 61 (average 37.5). All

subjects were fasted for more than 10 hours before the

study.

2.2. EEG Measurement

To obtain the EEG data, five Ag/AgCl electrodes were

P. CHENG

placed on the abdomen, including four active electrodes,

and one reference electrode. The first active electrodes

was positioned 45 degree upper left of the midpoint be-

tween the umbilicus and the xiphoid process with an in-

terval of 2 - 3 cm, the last active electrode was positioned

1 - 3 cm right to the midpoint mentioned above. The other

two were placed between them with proper distance. The

reference electrode was positioned on the right ribs with

the same height of the first electrode. Four-channel EGG

signals were derived with sample frequency of 4 Hz by a

multichannel physiological signal recorder (RM6280C

Chengdu Instrument Factory, Chengdu, China) by con-

necting each active electrode to the reference electrode.

2.3. Electroacupuncture Experim en t

Electroacupuncture (EA) was performed on acupoints

Zusanli (ST36) on both legs. The acupuncture needles

were inserted into Zusanli points firstly. When the sub-

jects get the sense of “Deqi”, the needles were connected

to an electrical acupuncture instrument (HANS LH-

202H). The 2-Hz squared pulse was delivered. The cur-

rent of pulse was gently increased from 1mA until the

subject can feel it, then the current kept with such suita-

ble intensity during the EA experiment.

EGGs were recorded before (baseline), during and after

the EA experiment for at least 20 minutes respectively.

2.4. Data Processing and Analysis

After preprocessed by low-pass filter, The EGG raw data

were fed into an adaptive filter [12] and extracted by the

method of independent component analysis with refer-

ence (ICA-R) [9]. The output data were denoised and can

represent the slow waves of the gastric myoelectrical

activities.

The following parameters are analyzed (see Figures

1-5):

1) The dominant frequencies (DFs) over whole data

[7].

2) The instability coefficients (ICs) of subsection DFs

[7].

3) The time percentages (TPs) and relative power per-

centages (R-PPs) of normal slow waves, they pr esent the

proportions of normal slow waves in time duration and

power respectively [10].

4) The time-p ower percentages map of normal slow

waves, which is plotted by TPs of normal slow wav es on

the horizontal axis and R-PPs on the vertical. From the

map, it can be derived that the amplitudes of normal slow

waves are higher or lower than those of abnormal slow

waves (bradygastria or tachygastria). If the power in unit

time or amplitude of different kinds of slow waves is

(normal, bradygastria or tachygastria) close to each other,

TPs and R-PPs should be close, and the point in Time-

Figure 1. DFs of baseline, duri ng EA and after EA. The box

presents the median and the standard deviation; the whisker

presents the maximum and minimum; the symbol ‘+’ pre-

sents the mean value.

Figure 2. DFs over whole data of each subject.

Figure 3. TPs and R-PPs of normal slow waves. (a) TP of

normal slow waves; (b) R-PP of normal slow waves. The

symbols are the same as Figure 1.

Figure 4. ICs of subsection DFs. (a) ICs of all subsec tio n DF s;

(b) ICs of subsection DFs within the normal range. The

symbols are the same as Figure 1 .

Power map of normal slow waves should be near the

diagonal. If the amplitude of normal slow waves is higher

than that of abnormal slow waves, the point should be

above of the diagona l, vice versa [10].

P. CHENG

Figure 5. Time-power percentages map of normal slow

waves.

3. Results

3.1. DFs over Whole Data

The distributions and statistic boxes of DFs over whole

data are shown in Figure 1, and for each subjects in

Figure 2. The box presents the median and the standard

deviation; the whisker presents the maximu m and mini-

mum ; the symbol “+” presents the mean value. The DFs

are raised slightly during EA than b aseline. But the re are

no significant differences between each two sections.

3.2. TPs and R-PPs of Normal Slow Waves

The results of TPs and R-PPs of normal slow waves are

shown in Figure 3. Compared with baseline, the TPs and

R-PPs of normal slow waves increase both during and

after EA. It means that the regularity of EGG slow waves

or the regularity of gastric myoelectrical activities are

enhanced by EA, and the effect works on both time dur a-

tion and power proportions can sustain at least 20 mi-

nutes after the EA.

3.3. ICs of All Subsection DFs and of Subsections

DFs within the Normal Range

The ICs of all subsection DFs including normal slow

waves, tachygastria and bradygastria are analyzed (Fig-

ure 4(a)). The ICs during and after EA are much lower

than baseline, which means the DFs of subsections were

more stable under the regulation of EA, and the effect

can sustain at least 20 minutes after the EA. That is in

accord with the results of TPs and R-PPs of normal slow

waves.

Particularly, the subsection DFs only of normal slow

waves were analyzed to see if the acupuncture affects the

regularity of normal slow waves (Figure 4( b)). The re-

sult show that the stability of subsections DFs of normal

slow waves are not increased by EA, which means the

EA does not make the normal slow waves “more regular”.

Hence, it may be derived that the EA enhances the regu-

larity of EGGs by making the abnormal slow waves (ta-

chygastria and bradygastria) “more regular” and tending

to be normal.

3.4. Time-Power Percenta ges Map of Normal

Slow Waves

The time-power percentages map of normal slow waves

of baseline, during EA section and after EA section is

shown in Figure 5. Compared with baseline, the points

of during and after EA section are centralized to the di-

agonal obviously. It means that both duration and power

are regulated, and the amplitudes of normal slow waves

and abnormal slow waves tend to be equal to each other

during and after the EA treatment.

4. Conclusions and Discussion

In this paper, the EA treatments were performed on sub-

jects with slight gastric disorders and the EEGs were

monitored before, during and after the EA treatments.

Besides the commonly used dominant frequencies, insta-

bility coefficients of subsection dominant frequencies

and time percentages of normal slow waves, we intro-

duced relative power percentages of normal slow waves

and time-power percentages map.

It is certified that acupuncture can enhance the regu-

larities of gastric myoelectrical activities, as in the cur-

rent paper. Assuming there are several possible ways for

acupuncture to attain the enhancement, a) by inhibiting

the generation of abnormal slow waves, so that the ab-

normal pacemakers are reduced or converted to normal;

b) by decreasing the amplitude of abnormal slow waves

or increasing that of normal ones; c) by decreasing the

propagation range of abnormal slow waves or extend that

of normal ones. The assumption b) has been disproved

by Result D Time-power percentages map of normal

slow waves, which tells us the amplitudes of normal slow

waves and abnormal slow waves tend to be equal to each

other during and after the EA treatments. Hence, a possi-

ble pattern is that the EA treatments regulate the pace-

maker quantity and propagation of slow waves rather

than regulating the amplitude of slow waves to attain the

regularity enhancement of EEGs.

The generation and propagation details of gastric

myoelectrical activities seem difficult to be figured out

by the surface recorded EEGs which essentially are con-

volutional results of loca l gastric myoelectrical activities.

The multichannel intraluminal (serosal or mucosal) re-

cordings of gastric myoelectrical activities could be

much more accurate in localization of myoelectrical ac-

tivities and with the potential in research on generation

and propagation of myoelectrical activities.

P. CHENG

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