Abstract Background: Postoperative nausea and vomiting (PONV) refers to a problem commonly occurring after surgery. Acupuncture is considered a critical complementary alternative therapy for PONV. The acupoints selection critically determines the efficacy of acupuncture, whereas the selection rules remain unclear. The objective of the present study was to delve into the principles of acupoints selection for PONV using data mining technology. Methods: The clinical trials assessing the acupuncture effect for PONV were searched with the use of computer in PubMed, China National Knowledge Infrastructure, and Chinese Biomedical Database; the time span was confined as 2009–2019. The database of acupuncture prescriptions for PONV was built using Excel 2016; the description and association were analyzed by IBM SPSS modeler 18. Result: Eighty-three relevant literatures were screened out. The number of specific acupoints took up 72.5% of all acupoints; specific acupoints exhibited the frequency taking up 91.30% of the total frequency. As revealed from the result, Neiguan (PC 6), Zusanli (ST 36), Hegu (LI 4), and Zhongwan (CV 12) were most frequently applied, suggesting the tightest associations. Most acupoints were taken from the stomach meridian and pericardium meridian. The common acupoints were concentrated in the lower limbs, chest, as well as abdomen. Conclusion: Data mining acts as a feasible method to identify acupoints selection and compatibility characteristics. As suggested from our study, the acupoints selection for PONV prioritizes specific acupoints and related meridians. The selection and combination of acupoints comply with the theory of traditional Chinese medicine.

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Traditional Chinese Medicine
The selection rules of acupoints and meridians of traditional
acupuncture for postoperative nausea and vomiting: a data
mining-based literature study
Li-Sha Liu1*#
, Jian Huo2#
, Xiu-Li Yuan1
, Yi Lan1
, Jing-Yuan Zhang1
, Hong-Mei Zhong1
, Yu Wang3
, Yun-Sheng He1
1
Mianyang Affiliated Hospital, Chengdu University of Traditional Chinese Medicine, Mianyang, 621000, China; 2
Chengdu
Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China,
Chengdu, 611731, China;3
Sichuan Second Traditional Chinese Medicine Hospital, Chengdu, 610031, China.
#
These authors are co-first authors on this work.
*Corresponding to: Li-Sha Liu. Mianyang Affiliated Hospital, Chengdu University of Traditional Chinese Medicine, No.14,
Fucheng Road, Fucheng District, Mianyang, 621000, China. E-mail: wenliyinyusha@163.com.
Highlights
The present study collected the clinical researches regarding acupuncture for postoperative nausea and
vomiting in the recent decade and explored the selection rules based on data mining technology, to give
scientific guide and evidence to clinical researchers.
Traditionality
The acupoints selection principles for nausea and vomiting was initially documented in the book Huangdi
Neijing (Yellow Emperor's Canon of Internal Classic) (221 B.C.E.–220 C.E.), valuably inspiring doctors of
later generations. As revealed from the book Zhenjiu Jiayi Jing (A-B Classic of Acupuncture and
Moxibustion) of Mi Huangpu in 282 C.E., nausea and vomiting displayed associations with the Zangfu (the
general name of human internal organs in traditional Chinese medicine theory) and 18 core acupoints to
treat nausea and vomiting were developed. In the 1950s, JF Xu adopted acupuncture at Neiguan (PC 6),
Tianshu (ST 25) and chewed ginger to achieve nausea and vomiting treatment. In 1997, National Institutes
of Health confirmed the role of acupuncture to treat nausea and vomiting. The mechanism of acupuncture
may display associations with the enhancing effect on gastric motility and suppressing effect on temporary
lower esophageal sphincter relaxation. The acupoints selection refers to the fundamental step of the effect,
whereas the selection rules for postoperative nausea and vomiting remain unclear.

2. REVIEW
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Abstract
Background: Postoperative nausea and vomiting (PONV) refers to a problem commonly occurring after surgery.
Acupuncture is considered a critical complementary alternative therapy for PONV. The acupoints selection
critically determines the efficacy of acupuncture, whereas the selection rules remain unclear. The objective of the
present study was to delve into the principles of acupoints selection for PONV using data mining technology.
Methods: The clinical trials assessing the acupuncture effect for PONV were searched with the use of computer in
PubMed, China National Knowledge Infrastructure, and Chinese Biomedical Database; the time span was confined
as 2009–2019. The database of acupuncture prescriptions for PONV was built using Excel 2016; the description
and association were analyzed by IBM SPSS modeler 18. Result: Eighty-three relevant literatures were screened
out. The number of specific acupoints took up 72.5% of all acupoints; specific acupoints exhibited the frequency
taking up 91.30% of the total frequency. As revealed from the result, Neiguan (PC 6), Zusanli (ST 36), Hegu (LI 4),
and Zhongwan (CV 12) were most frequently applied, suggesting the tightest associations. Most acupoints were
taken from the stomach meridian and pericardium meridian. The common acupoints were concentrated in the lower
limbs, chest, as well as abdomen. Conclusion: Data mining acts as a feasible method to identify acupoints selection
and compatibility characteristics. As suggested from our study, the acupoints selection for PONV prioritizes
specific acupoints and related meridians. The selection and combination of acupoints comply with the theory of
traditional Chinese medicine.
Keywords: Postoperative nausea and vomiting, Acupuncture, Data mining, Regularity, Clinical research
Acknowledgments:
This study was supported by the Major projects of Sichuan Science and Technology Department of China (No.
18ZDYF0347) and Mianyang Science and Technology Bureau of China (No. 17YFHM008).
Abbreviations:
PONV, postoperative nausea and vomiting; TCM, traditional Chinese medicine; ST, stomach meridian; PC,
pericardium meridian; LI, large intestine meridian; GV, governor meridian.
Competing interests:
The authors declare that they have no conflict of interest.
Citation:
Li-Sha Liu, Jian Huo, Xiu-Li Yuan, et al. The selection rules of acupoints and meridians of traditional
acupuncture for postoperative nausea and vomiting: a data mining-based literature study. Traditional Medicine
Research 2020, 5 (4): 272–281.
Executive editor: Xiao-Hong Sheng
Submitted: 23 December 2019, Accepted: 11 January 2020, Online: 16 January 2020.

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Background
Postoperative nausea and vomiting (PONV) is
defined as nausea or vomiting in 24 h postoperatively,
one of the commonest complications after surgery or
general anesthesia [1]. PONV is likely to cause
numerous complications for patients (e.g., aspiration,
wound dehiscence, hematoma, bleeding, dehydration,
and electrolyte imbalance) [2]. The incidence of
PONV follows the range from 20% to 30% in
general patients and even up to 80% of the patients
having undergone laparoscopic surgery [3]. PONV
can adversely affect the rehabilitation after surgery
and noticeably prolong the hospitalization length. In
several cases, PONV might even induce mental
symptoms (e.g., depression and anxiety) [4]. PONV
has now aroused extensive attention from the
researchers worldwide [5–7]. The typical antiemetic
drug, ondansetron, has been extensively used after
surgery, whereas it brings the side effects (e.g.,
headache, constipation and abdominal pain) [8].
According to the history of acupuncture, the
acupoints selection principles for nausea and
vomiting was initially documented in the book
Huangdi Neijing [9] (Yellow Emperor's Canon of
Internal Classic) (221 B.C.E.–220 C.E.). As
highlighted, the nausea and vomiting should be
treated by acupuncture at Zusanli (ST 36) as well as
bleeding at the gallbladder meridian, valuably
inspiring doctors of later generations. As revealed
from the book Zhenjiu Jiayi Jing [10] (A-B Classic of
Acupuncture and Moxibustion) of Mi Huangpu in
282 C.E., nausea and vomiting displayed associations
with the Zangfu (the general name of human internal
organs in traditional Chinese medicine (TCM)), and
18 core acupoints to treat nausea and vomiting were
developed. As the modern medicine has been leaping
forward, acupuncture therapies to treat nausea and
vomiting have been extensively performed clinically.
In the 1950s, JF Xu [11] adopted acupuncture at
Neiguan (PC 6), Tianshu (ST 25) and chewed ginger
to achieve nausea and vomiting treatment. In 1997,
National Institutes of Health confirmed the role of
acupuncture to treat nausea and vomiting [12]. The
mechanism of acupuncture for PONV remains
unclear. According to several studies, the mechanism
of acupuncture might display associations with the
enhancing effect on gastric motility and suppressing
effect on temporary lower esophageal sphincter
relaxation [13]. The acupoints selection refers to the
fundamental step of the effect, whereas the selection
rules for PONV remain unclear. Nevertheless, as
fueled by the development of data mining,
researchers are allowed to use novel methods to
investigate the information of acupuncture. Data
mining, i.e., knowledge discovery in databases, is
considered the nontrivial extraction of implicit,
previously unknown and potentially valuable data
[14]. To give evidences to clinical researchers, the
present study collected the clinical researches
regarding acupuncture for PONV in the recent
decade and explored the selection rules based on data
mining technology.
Materials and methods
Data sources
The following databases were searched by computer:
PubMed (http://www.pubmed.com), China
Biomedical Database (http://www.sinomed.ac.cn),
and China National Knowledge Infrastructure
(http://www.cnki.net) for the period from 2009 to
2019. The searching target was confined into the
modern literatures regarding traditional acupuncture
for PONV. Besides, the language was set as English
and Chinese.
Literature search strategy
The subject words were searched in accordance with
the name of disease and conventional acupuncture
treatments. The searching mechanism of PubMed
included: (warm acupuncture OR moxibustion OR
acupuncture OR electroacupuncture OR meridian OR
acupoint OR needle) AND (postoperative vomiting
OR postoperative nausea OR postoperative nausea
and vomiting OR PONV) AND (observational
studies OR clinical trial OR trial OR randomized
controlled trial OR clinical research), with unlimited
subheadings. Similar search strategies were used in
other databases. English medical subject words were
referenced from the Medical Subject Headings [15]
and limited to “postoperative nausea and vomiting”.
Chinese medical subject words were referenced from
the Chinese translation of the Medical Subject
Headings and limited to “ 手 术 后 恶 心 呕 吐 ”
(postoperative nausea and vomiting). Table 1
presents the retrieval strategy for PubMed.
Data screening
Types of studies. Inclusion criteria covered clinical
trials that assess the effect of acupuncture for PONV,
clinical trials with or without randomization and/or
control can be covered. The latest one literature was
selected for duplicate publications of the identical
author. Participants with nausea and vomiting after
operation were the research objects. Exclusion
criteria consisted of reviews, animal trials, case
reports, systematic reviews, and meta-analyses.
Types of intervention. Inclusion criteria covered
clinical trials with acupuncture as the primary
therapies. Acupuncture and moxibustion can be
adopted independently or jointly with other types of
interventions. Traditional acupuncture therapies
included: needle insertion into traditional meridian
acupoints and extraordinary acupoints; electric

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Table 1 The retrieval strategy for PubMed
Number Search terms
#1 Warm acupuncture (mesh)
#2 Moxibustion (mesh)
#3 Acupuncture (mesh)
#4 Electroacupuncture (mesh)
#5 Meridian (mesh)
#6 Acupoint (mesh)
#7 Needle (mesh)
#8 #1 or #2 or #3 or #4 or #5 or #6 or #7
#9 Postoperative vomiting (mesh)
#10 Postoperative nausea (mesh)
#11 Postoperative nausea and vomiting (mesh)
#12 PONV (mesh)
#13 #10 or #11 or #12 or #13
#14 Observational studies (mesh)
#15 Clinical trial (mesh)
#16 Trial (mesh)
#17 Randomized controlled trial (mesh)
#18 Clinical research (mesh)
#19 #14 or #15 or #16 or #17 or #18
#20 #8 and #13 and #19
stimulation of needle insertion into acupoints or
meridians; moxibustion; simultaneous intervention of
acupuncture/electroacupuncture and moxibustion.
Exclusion criteria consisted of trials of stimulating
Ashi acupoint (a kind of acupoint that you will feel
pain when pressing it) alone; trials of dry needling or
trigger point therapy complying with anatomy and
physiology; trials of laser acupuncture and
non-invasive electrical stimulation (e.g.,
transcutaneous acupoint electrical stimulation);
acupoint massage (finger-pressing acupoint); studies
assessing micro-acupuncture for different theoretical
basis from TCM [16]. The focus of this trial is
limited to traditional acupuncture by screening
therapies.
Types of outcome measurements. The following
was the inclusion criteria. Studies were covered if
reporting at least one clinical outcome regarding
PONV (e.g., nausea, vomiting, abdominal distention,
abdominal pain, and use of antiemetic drugs). In the
case of controlled trials, acupoints selection without
statistical improvement in symptoms could be
incorporated into prescriptions. Several studies drew
the comparison of the therapeutic effects of various
acupoints. Only the prescriptions with optimal
efficacy should be covered. The following was the
exclusion criteria. Trials reported only physiological
or laboratory parameters were excluded. Acupoint
prescriptions were excluded except for the most
feasible one if 1 study drew the comparison of the
therapeutic effects of a range of prescriptions.
Data collection. All the titles and abstracts of
respective record retrieved from the literature search
screened by Lisha Liu. who excluded those
noticeably unrelated abstracts (e.g., studies focusing
on case reports reviews, experiments, animal),
reviewed the full text of all potentially relevant
articles, and then re-screened these articles to
exclude the unrelated ones. Subsequently, Jian Huo
made a formal check of the eligibility of all articles
in accordance with the mentioned screening criteria.
If differences existed between the 2 researchers, they
decided to include or exclude the literatures given the
discussion or after the third researcher reviewed the
information. Literature information, covering title,
author, journal name, intervention measures and
results (e.g., number of acupoints, location of
acupoints, meridians of acupoints, and specific
acupoints) were standardized prior to processing. The
names of acupoints were standardized in line with
the basic principles of Fundamentals of Acupuncture
[17].
Data processing. The prescriptions of acupuncture
for PONV were inputted into Microsoft Excel 2016.
IBM SPSS modeler 18 was employed to calculate the
frequency, support, confidence, as well as lift level
[18]. Support refers to an index expressing the
probability of event A and event B that appear
simultaneously under specific conditions. Confidence
refers to the probability of event B that appears in
event A [19]. Lift displays the ratio of confidence for
the rule to the prior probability of having the
consequent [20]. On the whole, rules with lift
different from 1 will be more noteworthy than those
with lift close to 1. Lift indicates the ratio of
confidence of the rule to the previous probability of
generating the result. Association rules are useful
only when the support degree and confidence level
satisfy the minimal requirements. Apriori algorithm,
a common algorithm to mine association rules, was
adopted to analyze the frequencies and support of
acupoint combinations. Given the definition of
association rules mining [21], the following can be a
statement to mine association principles for acupoint
combination. Set I = {i 1, i 2, …, i m} as a set of
acupoints. Set D as a group of acupoint prescriptions,
in which each acupoint prescription T denotes a set
of acupoints, so T ⊆ I. Each acupoint prescription is
associated with a unique identifier, termed as TID.
An acupoint prescription T covers X, a set of some
acupoints in I, if X ⊆ T. The rule X–Y has support s
in the acupoint prescription set D if s% of acupoint
prescriptions in D contain X ⋃ Y. Figure 1 presents
the steps of data processing.
Results
Overall profile of acupuncture prescriptions
Database searching identified 160 records in PubMed,
148 records in China National Knowledge
Infrastructure, and 277 records in Chinese
Biomedical Database. Eighty-three acupuncture
prescriptions were covered in the present study after

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Figure 1 The steps of data processing. CNKI, China National Knowledge Infrastructure; CBM, Chinese
Biomedical Database; PONV, postoperative nausea and vomiting.
filtering (Figure 1).
Application of acupoints
This analysis aimed to provide the acupoints
selections and their frequencies when treating PONV
by acupuncture. Statistics revealed that acupuncture
prescriptions for PONV covered 40 acupoints in the
whole body, and the total application frequency of
the acupoints reached 230 times. The commonest
acupoints for PONV in descending order included
Neiguan (PC 6), Zusanli (ST 36), Hegu (LI 4),
Zhongwan (CV 12), Shangjuxu (ST 37), Sanyinjiao
(SP 6), Taichong (LR 3), Yanglingquan (GB 34),
Quchi (LI 11) and Xiajuxu (ST 39) (Table 2).
Application of meridians
The taken acupoints displayed the distribution among
12 meridians, covering 10 regular meridians,
governor vessel, and conception vessel. The
commonest meridians included large intestine
meridian (LI), pericardium meridian (PC), and
stomach meridian (ST). Table 3 lists in the
application of meridians.
Application of special acupoints
The number of specific acupoints took up 29
(72.50%) of the 40 acupoints, and the frequency (210
times) took up 91.30% of the total frequencies.
Crossing acupoints were the commonest specific
acupoints, exhibiting the frequency of 92 times. They
were followed with Luo-connecting point, five-Mu
point, eight-convergent points, lower He-sea point
and Yuan-source point (they are the specific
acupoints are a group of acupoints with particular
treating effect on 14 meridians) (Table 4).
Specific acupoints refer to a group of acupoints
with particular treating effect on 14 meridians.
Specific acupoints consisted of ten types, namely,
back-Shu points (the acupoints on the back where the
Qi of Zangfu gathers), Xi-cleft points (the acupoints
where the meridian Qi is deeply gathered),
eight-confluent points (8 specific acupoints on the
four limbs that connecting 8 extra meridians and the
12 regular meridians), front-Mu points (the acupoints
located on the chest and abdomen where the Qi of
Zangfu gathers), Yuan-source points (the acupoints
located near the wrist or ankle where the Qi of
Zangfu passes and gathers), lower He-sea points (the
specific acupoints reflect the 6 Fu (viscera) in the
lower limbs), eight convergent points (the 8 specific
points located on the four limbs where the twelve
meridians communicates with the eight extra

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channels), five-Shu points (the 5 acupoints located
below the elbow and knee joints of the 12 regular
meridians), Luo-connecting points (the acupoints
linking the inner and outer meridians), crossing
points (the acupoints where 2 or more meridians
cross).
Application of acupoints on different body parts
Given the analysis and statistics of the location of
acupoints, acupoints on the lower limbs have been
used most frequently, with 11 acupoints and a
frequency of 100 times in total, followed by
acupoints on the chest and abdominal (used 25 times),
back and lumbar (used 3 times), and the head, face,
and neck (used 3 times) (Table 5).
Association of acupoint compatibilities
IBM SPSS Modeler 18 was employed for the
analysis of the association rules of acupoints with
frequencies 2 times or more. The minimal support
degree was set to 10%, the minimal confidence level
was set to 20%, and the maximal preceding item was
set to 5. The support degree suggested that Hegu (LI
4)-Neiguan (PC 6), and Zusanli (ST 36)-Neiguan
(PC 6) appeared together in the 83 prescriptions
77.11% of the time. The maximal confidence level
was Zusanli (ST 36)-Zhongwan (CV 12), and
Neiguan (PC 6)-Zhongwan (CV 12), revealing that
when Zusanli (ST 36) and Neiguan (PC 6) appeared,
the probability of Zhongwan (CV 12) was 88.89%.
Lift was different from 1, revealing that the results
were reliable. Table 6 lists the 21 most commonly
used acupoint combination, support, and confidence,
and Figure 2 presents the network map according to
the combination result.
Table 2 Twenty commonest acupoints identified
by data mining
Number Acupoint Frequency
Support
(%)
1 Neiguan (PC 6) 64 77.11
2 Zusanli (ST 36) 45 54.22
3 Hegu (LI 4) 21 25.30
4 Zhongwan (CV 12) 9 10.84
5 Shangjuxu (ST 37) 8 9.64
6 Sanyinjiao (SP 6) 8 9.64
7 Taichong (LR 3) 7 8.43
8 Yanglingquan (GB 34) 6 7.23
9 Quchi (LI 11) 5 6.02
10 Xiajuxu (ST 39) 4 4.82
11 Tianshu (ST 25) 4 4.82
12 Zhigou (TE 6) 4 4.82
13 Liangqiu (ST 34) 4 4.82
14 Yinlingquan (SP 9) 4 4.82
15 Gongsun (SP 4) 3 3.61
16 Qiuxu (GB 40) 3 3.61
17 Renzhong (GV 26) 2 2.41
18 Fenglong (SP 40) 2 2.41
19 Shenque (CV 8) 2 2.41
20 Qichong (ST 30) 2 2.41
Table 3 Meridians and acupoints used in acupuncture therapy for postoperative nausea and vomiting
Num
-ber
Meri
-dian
Frequ-
encies
PCT
(%)
Acupoint
number
PCT
(%)
Selected acupoints and their frequencies
1 ST 69 30.00 8 20.00
Zusanli (ST 36) 45, Shangjuxu (ST 37) 8, Xiajuxu (ST
39) 4, Tianshu (ST 25) 4, Liangqiu (ST 34) 4,
Qichong (ST 30) 2, Burong (ST 19) 1, Taiyi (ST 23) 1
2 PC 64 27.83 1 2.50 Neiguan (PC 6) 64
3 LI 27 11.74 3 7.50 Hegu (LI 4) 21, Quchi (LI 11) 5, Yangxi (LI 5) 1
4 SP 19 8.26 5 12.50
Sanyinjiao (SP 6) 8, Yinlingquan (SP 9) 4, Gongsun
(SP 4) 3, Fenglong (SP 40) 2, Xuehai (SP 10) 2
5 CV 16 6.96 6 12.50
Zhongwan (CV 12) 9, Shenque (CV 8) 2, Xiawan (CV
10) 2, Danzhong (CV 17) 1, Tiantu (CV 22) 1, Juque
(CV14) 1
6 GB 10 4.35 3 7.50
Yanglingquan (GB 34) 6, Qiuxu (GB 40) 3, Riyue
(GB 24) 1
7 LR 9 3.91 3 7.50
Taichong (LR 3) 7, Zuwuli (LR 10) 1, Xiguan (LR 7)
1
8 TE 6 2.61 2 0.50 Zhigou (TE 6) 4, Waiguan (TE 5) 2
9 BL 5 2.17 5 12.50
Ganshu (BL 18) 1, Danshu (BL 19) 1, Dachangshu
(BL 25) 1, Jinmen (BL 63) 1, Weizhong (BL 40) 1
10 GV 3 1.30 2 0.50 Renzhong (GV 26) 2, Baihui (GV 20) 1
11 LU 1 0.43 1 2.50 Chize (LU 5) 1
12 HT 1 0.43 1 2.50 Shenmen (HT 7) 1
13 Total 230 40

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Frequencies of meridians mean that the total frequency of acupoints on the same meridian; PCT indicates the
percentage of a specific meridian frequency taking up the total frequency of all meridians. The number of acupoints
represents the total number of selected acupoints on the same meridian. PCT of acupoints indicates the percentage
of number of acupoints taking up the total number of taken acupoints in all meridians.
ST, stomach meridian, PC, pericardium meridian, LI, large intestine meridian, SP, spleen meridian, GB, gallbladder
meridian, LR, liver meridian, TE, triple energizer, BL, bladder meridian; LU, lung meridian; HT, heart meridian,
CV, conception vessel, GV, governor meridian; PCT, percent.
Table 4 Frequencies and numbers of different types of acupoints
Number Special point Frequencies Number
1 Crossing point 92 10
2 Luo-connecting point 71 4
3 Five-Shu point 69 7
4 Eight convergent points 69 3
5 Lower He-sea point 63 4
6 Yuan-source point 42 4
7 Front-Mu point 16 5
8 Eight-confluent points 16 3
9 Xi-cleft point 5 2
10 Back-Shu point 3 3
Table 5 The frequencies and numbers of acupoints on different body parts
Number Body part Frequencies Number
1 Lower limbs 100 11
2 Upper limbs 99 8
3 Chest and abdomen 25 16
4 Back and lumbar 3 3
5 Head, face, and neck 3 2
Table 6 Combinations of the 21 commonest acupoints
Number Combination of acupoints Support (%) Confidence (%) Lift
1 Hegu (LI 4) → Neiguan (PC 6) 77.11 28.13 0.84
2 Zusanli (ST 36) → Neiguan (PC 6) 77.11 45.31 1.11
3 Hegu (LI 4) → Zusanli (ST 36) 54.22 22.22 0.84
4 Neiguan (PC 6) → Zusanli (ST 36) 54.22 64.44 0.88
5 Zhongwan (CV 12) → Zusanli (ST 36), Neiguan (PC 6) 34.94 24.14 2.23
6 Hegu (LI 4) → Zusanli (ST 36), Neiguan (PC 6) 34.94 24.14 0.95
7 Quchi (LI 11) → Hegu (LI 4) 25.30 23.81 1.11
8 Zusanli (ST 36) → Hegu (LI 4) 25.30 47.62 0.88
9 Neiguan (PC 6) → Hegu (LI 4) 25.30 85.71 3.95
10 Quchi (LI 11) → Hegu (LI 4), Neiguan (PC 6) 21.69 22.22 0.72
11 Zusanli (ST 36) → Hegu (LI 4), Neiguan (PC 6) 21.69 38.89 3.69
12 Yinlingquan (SP 9) → Hegu (LI 4), Zusanli (ST 36) 12.05 20.00 0.91
13 Quchi (LI 11) → Hegu (LI 4), Zusanli (ST 36) 12.05 30.00 4.98
14 Taichong (LR 3) → Hegu (LI 4), Zusanli (ST 36) 12.05 20.00 3.11
15 Sanyinjiao (SP 6) → Hegu (LI 4), Zusanli (ST 36) 12.05 20.00 4.15
16 Shangjuxu (ST 37) → Hegu (LI 4), Zusanli (ST 36) 12.05 30.00 2.37
17 Neiguan (PC 6) → Hegu (LI 4), Zusanli (ST 36) 12.05 70.00 2.08
18 Gongsun (SP 4) → Zhongwan (CV 12) 10.84 22.22 1.64
19 Tianshu (ST 25) → Zhongwan (CV 12) 10.84 33.33 1.15
20 Zusanli (ST 36) → Zhongwan (CV 12) 10.84 88.89 6.92
21 Neiguan (PC 6) → Zhongwan (CV 12) 10.84 88.89 6.15

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Figure 2 Network map of acupoint combinations
Discussion
Patients are now inclined to look for less harmful,
more acceptable, and more feasible therapies [22]. In
the present paper, the clinical literatures of
acupuncture for PONV were searched, and the
following rules of acupoints selection were identified
based on data mining technology.
Application of meridian and acupoints for PONV
According to the results of acupoint location analysis,
acupuncture for PONV is characterized by selecting
acupoint according to the disease location. The sites
of acupoints concentrated in the lower limb, chest
and abdomen. PONV belongs to the category of
“epigastric fullness” and “vomiting” in TCM,
locating in the stomach. According to modern
research, acupoints selection complying with the
location of disease is capable of stimulating the
nearby acupoints to exert a good target effect, e.g.,
taking Tianshu (ST 25) to treat abdominal disease,
taking Baihui (GV-20) to treat head disease, and
Zusanli (ST 36) to treat knee joint disease [23]. The
absorption function of small intestine was reported to
be enhanced, and the content of D-xylose in serum
was up-regulated after electroacupuncture at
Zhongwan (CV 12) and Tianshu (ST 25) in rats with
functional diarrhea [24]. Acupoints selection for
PONV complies with the fundamental rule of “the
location of acupoints is the range of indications” in
TCM theory. The results of meridians analysis
suggest another rule that “selecting acupoints in line
with the meridians involved in the disease”. The
main acupoints were from ST and PC, the frequency
percentages of the 2 meridians were 30.00% and
27.83%, respectively. The direction of ST is from
head to foot, following the stomach. PC originates is
from the chest, going through the heart, chest, and
stomach. Modern clinical researches suggested that
the treating effect of acupoints of ST for functional
dyspepsia were significantly better than acupoints of
other meridians [25]. A number of experimental
studies also verified the specificity effect of a range
of meridians, the rats received ligation of ST had
defecation and diet changes, remarkably different
from those received ligation of other meridians [26].
The acupuncture for PONV complies with the
principle of selecting acupoints in theory of TCM, as
well as with the basic law that “the indication
extends to where the meridian reaches”.
Acupoint compatibility in treatment of PONV
Acupoints exhibit specificity in morphological
structure, biophysical characteristics, pathological
response and stimulation; such specificity is capable
of distinguishing acupoints and non-acupoints [27].
Accordingly, the proper selection of acupoints is
critical to the treating effect of acupuncture for
PONV. Specific acupoints are a group of acupoints
with specific treating effect on 14 meridians. There
are 10 types of specific acupoints, namely, crossing
points, Luo-connecting points, five-Mu points, eight
convergent points, lower He-sea points, Yuan-source
points, front-Mu points, Xi-cleft points, back-Shu
points. The result revealed that the specific acupoints
took up 72.50% of the total number of acupoints.
Neiguan (PC 6) and Zusanli (ST 36) were the most
commonly used specific acupoints. According to the
attribution of specific acupoints, Neiguan (PC 6) was
the acupoint with the maximal frequency, which is
one of the Luo-connecting points and eight confluent
points of PC. Zusanli (ST 36) is one of the lower

9. REVIEW
TMR | July 2020 | vol. 5 | no. 4 | 280
doi: 10.12032/TMR20200114154
Submit a manuscript: https://www.tmrjournals.com/tmr
He-sea points of ST. According to the analysis of the
compatibility, the combination of Neiguan (PC 6),
Zusanli (ST 36), Hegu (LI 4), Zhongwan (CV 12)
might has the potential for PONV. Most prescriptions
of acupuncture for PONV included acupoint
combinations while few of them cover single
acupoint. For instance, patients received acupuncture
at Neiguan (PC 6) and Hegu (LI 4) displayed a lower
incidence of PONV in contrast to the patients
received acupuncture at Neiguan (PC 6) [28].
Clinical studies also revealed that electroacupuncture
on Neiguan (PC 6) and Zusanli (ST 36) for 30 min
before anesthesia could effectively reduce PONV,
and the plasma concentration of serotonin [29]. One
study reported that there were somatic visceral
convergent neurons in the paraventricular nucleus of
the inferior colliculus, capable of responding to both
gastric distensible and acupuncture stimulation,
probably associating with the regulatory effects of
Neiguan (PC 6) and Zusanli (ST 36) for
gastrointestinal function [30]. Electroacupuncture at
Zusanli (ST 36) was reported to be able to suppress
stress through receptor type 1 of corticotropin
releasing factor and relieve delayed gastric emptying
via receptor type 2 of corticotropin releasing factor,
thereby facilitating colonic transport and relieving
gastrointestinal conduction disorder after abdominal
operation [31]. Nevertheless, several
experiment-based studies have reported antagonistic
effects that one acupoint weakens the treating effect
of another. For instance, electroacupuncture could
improve gastrointestinal motility in rats, while the
effect of single acupuncture at Pishu (BL 20) was
better than that of simultaneous at Pishu (BL 20) and
Zusanli (ST 36) [32]. Moxibustion at Zusanli (ST 36)
was reported to be able to noticeably enhance gastric
motility of rats at the temperature of thermal
stimulation as 43°C and 45 °C, while moxibustion at
Zhongwan (CV 12) could inhibit gastric motility at
the identical temperature level [33]. Accordingly,
whether the acupoint combination outperforms single
acupoint require in-depth studies.
Limitations
First, the evidence-based medicine method based on
randomized control in many literatures included in
the present study was not available, so the present
study did not assess the quality of the included
literatures. The uneven quality of the literatures may
affect scientific and objective outcomes. Second,
some literatures did not report specific operations,
treatment frequency and treatment time, so the
present study did not analyze these information,
requiring in-depth studies. Lastly, preoperative or
postoperative intervention of acupuncture remains
controversial and the optimal intervention time
remains unclear. According to the mentioned results,
potential acupoints and combinations will be
explored in future clinical trials to verify the effects
of acupuncture for PONV. The data can be extracted
not only from literatures, but also from clinical
practices and optimized acupoint prescription by data
mining in the future.
Conclusions
In the present study, data mining was employed to
identify the commonest acupoints, meridians,
specific points, as well as the acupoints combination
of acupuncture for PONV. The commonest acupoints
were Neiguan (PC 6), Zusanli (ST 36), and Hegu (LI
4). The commonest meridians were ST, PC, and LI.
Acupoints used were primarily specific acupoints,
and the acupoints on the lower limbs. As revealed
from the findings here, Neiguan (PC 6), Zusanli (ST
36), Hegu (LI 4), and Zhongwan (CV 12) require
in-depth investigation in forthcoming trials or
employed clinically for PONV.
Data Availability
Some or all data, models, or code generated or used
during the study are available in a repository or
online in accordance with funder data retention
policies. DOI: 10.6084/m9.figshare.10171304.
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