Chewing Gum for Intestinal Function Recovery after ...downloads.hindawi.com/journals/grp/2017/3087904.pdf · gum chewing intervention, and 927 received standard post-operative care

Review ArticleChewing Gum for Intestinal Function Recovery after ColorectalCancer Surgery: A Systematic Review and Meta-Analysis

Binbin Mei,1 Wenting Wang,1 Feifei Cui,2 Zunjia Wen,3 and Meifen Shen4

1Department of Neurosurgery, The First Affiliated Hospital of Soochow University & School of Nursing Soochow University,Suzhou 215006, China2Department of Intensive Care Unit, The First Affiliated Hospital of Soochow University, Suzhou 215006, China3Nanjing Children’s Hospital, Nanjing 210000, China4Department of Neurosurgery, The First Affiliated Hospital of Soochow University, Suzhou 215006, China

Correspondence should be addressed to Meifen Shen; [email protected]

Received 18 June 2017; Revised 21 August 2017; Accepted 6 September 2017; Published 8 October 2017

Academic Editor: Per Hellström

Copyright © 2017 Binbin Mei et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background. This meta-analysis was performed to assess the efficacy and safety of chewing gum in intestinal function recovery aftercolorectal cancer surgery. Methods. A systematic search was conducted in PubMed, Embase, Science Direct, and Cochrane libraryfor relevant randomized controlled trials (RCTs) published until April 2017. Summary risk ratios or weighted mean differenceswith 95% confidence intervals were used for continuous and dichotomous outcomes, respectively. Results. 17 RCTs with a totalnumber of 1845 patients were included. Gum chewing following colorectal cancer surgery significantly reduced the time to firstpassage of flatus (WMD −0.55; 95% CI −0.94 to −0.16; P = 0 006), first bowel movement (WMD −0.60; 95% CI −0.87 to −0.33;P < 0 0001), start feeding (WMD −1.32; 95% CI −2.18 to −0.46; P = 0 003), and the length of postoperative hospital stay(WMD −0.88; 95% CI −1.59 to −0.17; P = 0 01), but no obvious differences were found in postoperative nausea, vomiting,abdominal distention, pneumonia, and mortality, which were consistent with the findings of intention to treat analysis.Conclusions. Chewing gum could accelerate the recovery of intestinal function after colorectal cancer surgery. However, itconfers no advantage in postoperative clinical complications. Further large-scale and high-quality RCTs should be conductedto confirm these results.

1. Introduction

Colorectal cancer is one of the most common tumors, whichis associated with multiple risk factors and accounts forapproximately 10% of cancer-related mortality in westerncountries [1, 2]. With increased colorectal cancer incidence,the number of colorectal cancer surgery has also elevateddramatically. Laparoscopic or open colorectal resections, asthe main surgical approach for colorectal cancer, may alsoresult in many serious complications like postoperative ileus,nausea, and vomiting, which could lead to significant post-operative morbidity and a prolonged length of hospital stayand place a significant financial burden on health care facil-ities [3, 4]. Therefore, targeting the recovery of intestinal

function after colorectal cancer surgery may contribute topromote rehabilitation for the patient. Now, it is widelyaccepted that early postoperative feeding is beneficial todecrease the postoperative ileus and shorten the length ofhospital stay, and there is significant interest in identifyingthe measures to stimulate gut function, rather than simplywaiting for it to return spontaneously [5–7].

Gum chewing (GC), a kind of sham feeding alternative toearly feeding, which is expected to stimulate the cephalic-vagal reflex to increase hormone secretion and then enhanceintestinal motility [8], may produce a positive effect on post-operative ileus by reducing postoperative inflammation [9].However, the underlying mechanisms behind the effects ofgum chewing works remain elusive and the results of clinical

HindawiGastroenterology Research and PracticeVolume 2017, Article ID 3087904, 13 pageshttps://doi.org/10.1155/2017/3087904

https://doi.org/10.1155/2017/3087904

studies to date are inconclusive, and thus chewing gum hasnot yet been incorporated into the related guidelines orstandard pathways for postoperative nursing [10, 11].

Previous meta-analyses [7, 12–14] have suggested thatpatients who had gum chewing after surgery might recoverintestinal function earlier; however, the sample sizes of therandomized controlled trials (RCTs) included in theseanalyses were small and an increasing body of relevantresearch recently have been reported, making it worthreconsidering the evidence on this issue. The aims of thisstudy, therefore, were to review the current evidence onthe influence of gum chewing in intestinal function andreassess the efficacy of chewing gum in intestinal functionrecovery after colorectal surgery.

2. Methods

2.1. Search Strategy. A general literature search was con-ducted in PubMed, Embase, Science Direct, and Cochranelibrary (until April 2017), using the following search terms:“gum-chewing,” “chewing-gum,” “sham-feeding,” “bowel,”“colonic,” “rectal,” “resection,” or “surgery.” We combinedthese terms in accordance with the instructions of the data-base. Reference lists and bibliographies from included studiesand relevant reviews were used to find additional articles toreview. The search was limited to articles written in English,but there was no restriction on publication year.

2.2. Study Selection. Two reviewers independently reviewedtitles and abstracts to distinguish potentially relevant studies,and articles for more extensive review were selected using thefollowing criteria. Inclusion criteria were as follows: (1) RCTdesign; (2) study subjects were those who had undergonecolorectal cancer surgery; (3) the study made a comparisonbetween gum chewing and standard nursing care postcolorectal surgery; and (4) the study contained explicit out-come data. Exclusion criteria were as follows: (1) reviews,systematic reviews, meta-analysis, editorials, case studies,and nonhuman studies; (2) studies not focusing on the effectof chewing gum on colorectal cancer surgery; and (3) studieswith no accessible outcome data.

The main outcomes we collected for data analysisincluded (1) the time to first passage of flatus (days); (2) thetime to first defecation (days); (3) the time to first bowelmovement (days); (4) the time to start feeding (days); (5)postoperative ileus (POI); (6) postoperative clinical compli-cations such as nausea, vomiting, abdominal distension,and pneumonia; (7) the length of postoperative hospital stay(days); and (8) mortality.

2.3. Quality Assessment. The methodological quality andrisk of bias of included studies were assessed using theCochrane Collaboration’s “risk of bias” tool, which addressesthe seven specific domains: random sequence generation,allocation concealment, blinding of participants and person-nel, blinding of outcome assessment, incomplete outcomedata, selective reporting, and other sources of bias. Eachdomain in the tool is achieved by assigning a judgement of“low risk” of bias, “high risk” of bias, or “unclear risk” of bias

(Cochrane Handbook for Systematic Reviews of Interven-tion. Part 2: 8.5) [15].

2.4. Data Extraction. Two reviewers independently extractedthe following data information: first author, publication year,study design, participants, population, methods of gumchewing, other concurrent interventions, main outcomes,and finding. Disagreements were resolved by discussion or,when necessary, adjudicated by a third reviewer.

2.5. Statistical Analysis. Review Manager 5.3 software wasused for statistical analyses. We calculated risk ratio (RR)and weighted mean difference (WMD) to present the dichot-omous and continuous data, respectively, and 95% confidenceinterval (CI)was included for all estimates. “Intention to treat”analysis was also conducted. P < 0 05 indicated statistical sig-nificance. Heterogeneity was tested by applying a chi-squared(χ2) test and I-squared (I2) statistic test. A fixed-effect modelwas adopted when P value of χ2 test> 0.10 and I2≤ 50%, anda random-effect model was adopted otherwise.

3. Results

3.1. Literature Search. Using the search strategy, 295 poten-tially relevant references were identified. Of these, 278 articleswere excluded due to duplicates or their failure to fulfilpredefined inclusion criteria. So finally, we formally included17 trials with 1845 patients in the main analyses of thisreview [16–32] (Figure 1).

3.2. Study Characteristics. The characteristics of 17 includedstudies are presented in Table 1. The included studies com-prised a total of 1845 patients who had received surgicaltreatment for colorectal cancer. Of these, 918 followed agum chewing intervention, and 927 received standard post-operative care. For most studies, gum chewing started fromthe first day post operation, and the frequency varied fromthree to four times per day. Although a lot of researchconfirmed the benefits of chewing gum, the outcomes for theefficacy of gum chewing in each study were still controversial.

3.3. Methodological Quality and Risk of Bias. Figure 2(a)describes all of the bias classifications for the included RCTs,with the summary of qualitative methodological qualityaccording to the bias classification (“low risk,” “unclear risk,”and “highrisk”)whichwaspresented inFigure2(b).Concisely,although all includedRCTsmentioned randomization in theirresearch, only nine studies [17, 19, 20, 24, 25, 27, 29, 31, 32]reported correct method of random sequence generationwhich marked as low risk of selection bias, and only six RCTs[17, 20, 24, 25, 27, 31] described adequate allocation con-cealments, which serves as a strategy to prevent againstascertainment bias and scored as low risk of bias. In gen-eral, sequentially numbered, opaque, sealed envelopes areassigned to each participant to prevent selective bias. Ade-quate blinding of personnel, participants, and outcomeassessment is necessary to prevent against performanceand detection bias; however, only one study [25] explicitlydescribed how to maintain patient blinding in all includedresearch, and six RCTs [17, 24, 25, 27, 29, 31] had mentioned

2 Gastroenterology Research and Practice

the blinding design for assessing the outcomes. Verifica-tion on selective reporting of outcomes is necessarybecause it may help to evaluate the integrity of outcomereporting and protect against bias, yet the majority ofthe included studies [16, 18–23, 25–29, 31, 32] did notprovide sufficient information to assess whether an impor-tant risk of bias exists; thus, we judged the risk of otherpotential sources of bias as unclear. Most of the includedstudies appear to be free of other sources of bias exceptfor two studies [26, 32], so we judged the risk of bias as lowrisk for these trials.

3.4. Publication Bias Analysis. A funnel plot is a simplescatter plot of the intervention effect estimates from indi-vidual studies against some measure of each study’s sizeor precision which is used for indication of publicationbias [15]. Ten or more studies are needed to enable a fun-nel plot to give significant evidence of bias, and in thisstudy, we performed a funnel plot analysis on the timeto first passage of flatus and the length of postoperativehospital stay. Based on Figures 3(a) and 3(b), we foundthat the funnel plots were symmetrical, and no significantpublication bias was found.

3.5. Main Analysis. The effect of gum chewing on multipleparameters of colorectal function following surgery reportedin the included studies was assessed. The RRs or WMDs foreach study were presented in Figures 4–14.

3.5.1. The Time to First Passage of Flatus. All studiesreported the time to the first passage of flatus, yet sevenstudies [17, 18, 20, 22, 24, 29, 31] failed to provide accurate

and necessary data for further analysis. As shown inFigure 4, we found that gum chewing probably shorten thetime to first passage of flatus (WMD −0.55; 95% CI −0.94to −0.16; P = 0 006) with a clear statistical heterogeneityacross the trials (I2 = 78%).

3.5.2. The Time to First Defecation. Four studies reported thetime to first defecation after colorectal surgery under gumchewing intervention or standard nursing. We found noevidence of a statistically significant difference regardingthe time to first defecation between the gum chewinggroup and control group (WMD −0.96; 95% CI −2.74 to0.83; P = 0 29) (Figure 5), with a clear statistical heteroge-neity between trials (I2 = 88%).

3.5.3. The Time to First Bowel Movement. Six studies reportedthe time to first bowel movement; we found that gumchewing shorten the time to first bowel movement com-pared with the control group (WMD −0.60; 95% CI −0.87to −0.33; P < 0 0001) (Figure 6), with a moderate statisticalheterogeneity across the studies (I2 = 41%).

3.5.4. Time to Start Feeding. Only two studies reported thetime to start feeding; the meta-analysis showed a statisticallysignificant reduction in the time to start feeding for thegum chewing group (WMD −1.32; 95% CI −2.18 to −0.46;P = 0 003) (Figure 7), with no evidence of heterogeneityacross the trials (P value of the homogeneity test = 0.79;I2 = 0%).

3.5.5. Postoperative Ileus (POI). No significant difference wasobserved between the gum chewing group and control group

279 of records identi�edthrough database searching

16 of additional records identi�edthrough other sources

(Reference lists and bibliographies)

96 of records a�er duplicatesremoved

199 of recordsscreened

157 of recordsexcluded

42 of full-text articlesassessed for eligibility

25 of full-text articlesexcluded with reasons

17 of studies included inqualitative synthesis

17 of studies included inquantitative synthesis(meta-analysis)

Figure 1: Study flow diagram.

3Gastroenterology Research and Practice

Table1:The

characteristicsof

includ

edstud

ies.

Autho

r(year)

Patient

popu

lation

Num

berof

patients

(GC/N

GC)

GCintervention

Outcomes

Results

Asao2002

[16]

Electivelaparoscop

iccolectom

yfor

colorectalcancer

19(10/9)

Patientschew

edgum

threetimes

aday

from

thefirstpo

stop

erativeAM

untilthe

daythey

beganoralintake.

①②⑤⑦

Gum

chew

ingaids

earlyrecovery

from

postop

erativeileus

andisan

inexpensive

andph

ysiologicmetho

dforstim

ulating

bowelmotility.

Atkinson2016

[17]

Electivecolorectalresection

402(199/203)

Patientschew

edgum

forat

least10

min,

four

times

adayfor5consecutivedays

(orun

tild

ischarge,iflessthan

5days)

from

thefirstpo

stop

erativemorning.

①③⑥⑦⑧⑩⑪

Chewinggum

didno

talterthereturn

ofbowelfunction

orLO

Safter

colorectalresection.

Fernandez2016

[18]

Electivecolorectalsurgery

64(32/32)

Chewinggum

withinthefirst24

hafter

surgery,for15

minutes

everyfour

hours

througho

uttheirho

spitalstay,w

ithsix

restingho

ursat

night.

①⑤⑥⑦⑧

The

useof

chew

inggum

aftercolorectal

surgerywas

associated

withless

postop

erative

ileus

andvomiting,andwithan

increased

passageof

flatus

withinthefirst48

hours

aftersurgery.

Forrester2014

[19]

Opencolonresection

oralaparoscop

icsigm

oidcolectom

y31

(13/18)

Gum

chew

ingbeganon

themorning

ofthefirstpo

stop

erativedayor

after

removalof

thenasogastrictube,and

the

times

ofgum

chew

ingcorrespo

nded

with

routinemedicationadministrationtimes.

①③④⑦⑨

Postoperative

gum

chew

ingwas

notmore

effective

than

standard

postop

erativecare

orattention-controlinterventionin

redu

cing

thedu

ration

ofpo

stop

erativeileus

symptom

s,length

ofstay,orcomplications

amon

gpatientsfollowingop

enlaparoscop

icsigm

oidcolectom

y.

Heijkant2015

[20]

Electivecolorectalsurgery

120(58/62)

Patientsstartedchew

inggum

3hbefore

andaftersurgery.The

frequencyand

duration

ofgum

chew

ingwere

notstandardized.

①②⑤⑦⑧⑫

Gum

chew

ingisasafeandsimpletreatm

ent

toredu

cePOIandisassociated

witha

redu

ctionin

system

icinflam

matorymarkers

andcomplications.

Hirayam

a2006

[21]

Electiveop

ensurgery

forcolorectalcancer

24(10/14)

Patientschew

edgum

threetimes

daily

for30

minutes

everytime.

①②⑥

Gum

-chewingprovides

asimpleandeffective

metho

dto

improvethepo

stop

erativestate

ofpatients.

Hwang2013

[22]

Laparoscop

iccolorectal

cancer

surgery

132(65/67)

Patientsstartedto

chew

gum

onthefirst

postop

erativeday,3times

aday,

approxim

ately10–20minutes

atatime,

untiln

ormalfeedingwas

resumed.

①⑦

Gum

chew

ingisan

easy

andcost-effective

metho

dto

redu

cethelength

ofthe

postop

erativeho

spitalstay

forlaparoscop

iccolorectalcancer

surgery.

Kob

ayashi

2015

[23]

Left-sided

resectionfor

colorectalcancer

43(21/22)

Patientschew

edgum

threetimes

daily

for≥5

minutes

(morning,n

oon,

and

evening)

untilthe

firstdayof

regularoral

dietaryintake.

①③⑦⑬

Gum

chew

ingchangedtheserum

levelsof

des-acylghrelin

andgastrin,

butwewere

unableto

demon

stratean

effecton

the

recovery

ofbowelfunction

.

Lim

2013

[24]

Colorectalresection

157(77/80)

Chewinggum

for15

minutes

4times

aday(8AM,12PM,4PM,and

8PM).

①③⑥⑦⑧

Chewinggum

issafe,but

does

nothasten

thereturn

ofgastrointestinalfunction

inpatientswho

receiveaccelerated

postop

erativefeeding.


Table1:Con

tinu

ed.

Autho

r(year)

Patient

popu

lation

Num

berof

patients

(GC/N

GC)

GCintervention

Outcomes

Results

Matros2006

[25]

Electivepartialcolectomy

forcolorectalcancer

43(22/21)

Chewinggum

for45

minutes

threetimes

daily

at9AM,4

PM,and

8PM.

①③⑦

Gum

chew

ing,althou

ghsafe,d

oesno

tredu

cedu

ration

ofpo

stcolectom

yileus.

McC

ormick2005

[26]

Electivecolonresection

88(53/35)

Gum

chew

ing4times

adayfor15

min.

①③⑦

Chewinggum

inthepo

stop

erativeperiod

may

bean

inexpensiveintervention

tofacilitaterecovery

anddecrease

hospitalcost.

Quah2006

[27]

Opensurgery

forleft-sided

colorectalcancer

38(19/19)

The

patientschew

edgum

forat

least5min,

threetimes

daily

from

thefirstpo

stop

erative

morning

untilthe

intake

ofasolid

dietorally.

①②⑦⑧⑭

The

addition

ofgum

chew

ingto

astandardized

postop

erativeregimen

didno

tredu

cetheperiod

ofpo

stop

erativeileus

orshortenlength

ofstay

followingop

ensurgery

forleft-sided

colorectalcancer.

Schu

ster

2006

[28]

Electiveop

ensigm

oidresections

34(17/17)

Chewinggum

3times

daily

for1ho

ureach

timeun

tild

ischarge.

①③⑦⑨

Gum

chew

ingspeeds

recovery

afterelective

open

sigm

oidresectionby

stim

ulating

bowelmotility.

Shum

2016

[29]

Laparoscop

iccolorectal

resection

82(41/41)

Chewinggum

threetimes

daily

for30

min

each

timefrom

day1un

tild

ischarge.

①③⑦⑨

Chewinggum

isasimpleintervention

that

speeds

intestinaltransitin

patientsmanaged

witharecovery

programmeafterlaparoscop

iccolorectalresection

Top

cu2016

[30]

Plann

edop

encolorectalsurgery

60(30/30)

Patientschew

edgum

threetimes

adayafter

mealsforaperiod

of15

min

from

thefirstm

orning

aftertheop

erationun

tilthe

timeof

theirdischarge.

①②④⑦

Chewinggum

isasimpleintervention

for

redu

cing

postop

erativeileus

after

colorectalsurgery.

Yang2017

[31]

Openor

laparoscopic

resection

394(197/197)

Chewinggum

threetimes

daily

forat

least

10min,startingon

postop

erativeday1and

continuing

for5consecutivedays

orun

tilfl

atus.

①③⑥⑦⑧

Chewinggum

does

notappear

toaffect

recovery

ofbowelfunction

orho

spitalstay,

thou

ghitmay

benefitpatientswho

undergo

open

resection.

Zaghiyan2013

[32]

Major

colorectalsurgery

114(54/60)

Chewinggum

for45

minutes,3

times

daily

onpo

stop

erativedays

1to

7.①③⑥⑦

There

does

notappear

tobe

anybenefitto

sugaredchew

inggum

incomparison

withno

gum

inpatientsun

dergoing

major

colorectalsurgery

Note:①

thetimeto

firstp

assage

offlatus;②

thetimeto

firstd

efecation;③

thetimeto

firstb

owelmovem

ent;④

timeto

startfeeding;⑤

postop

erativeileus

(POI);⑥

clinicalcomplications

such

asnausea,vom

iting,

abdo

minaldistension

,pain,pn

eumon

ia,w

ound

infection,bleeding,and

others;⑦

thelength

ofpo

stop

erativeho

spitalstay;⑧

mortality;⑨

timetofirsth

unger;⑩

firstd

ayofauscultatedbowelsoun

ds;⑪

solid

food

consum

ptionandtolerance;⑫

localand

system

icinflam

mationandgastricem

ptying;⑬

gutho

rmon

es;⑭

toleranceandsatisfaction

ofgum

chew

ing.


in the incidence of POI (RR 0.29; 95% CI 0.08 to 1.11;P = 0 07) (Figure 8), with no statistical heterogeneity betweentrials (P = 0 97; I2 = 0%).

3.5.6. Postoperative Nausea. There was no significant dif-ference between the groups in the incidence of postoper-ative nausea (RR 0.97; 95% CI 0.82 to 1.15; P = 0 74)

Random sequence generation (selection bias)

Allocation concealment (selection bias)

Blinding of outcome assessment (detection bias)

Blinding of participants and personnel (performance bias)

Incomplete outcome data (attrition bias)

Selective reporting (reporting bias)

Other bias

Low risk of biasUnclear risk of biasHigh risk of bias

0 25

(%)

50 75 100

(a) Risk of bias graph

Random sequence generation (selection bias)

Allocation concealment (selection bias)

Blinding of outcome assessment (detection bias)

Blinding of participants and personnel (performance bias)

Incomplete outcome data (attrition bias)

Selective reporting (reporting bias)

Other bias

Asa

o 20

02

Atki

nson

201

6

Fern

201

6

Forr

este

r 201

4

Hei

jkan

t 201

5

Hira

yam

a 200

6

Hw

ang

2013

Koba

yash

i 201

5

Lim

201

3

Mat

ros 2

006

McC

orm

ick

2005

Qua

h 20

06

Schu

ster 2

006

Shum

201

6

Topc

u 20

16

Yang

201

7

Zagh

iyan

201

3

+?

‒‒

+?

?

+?

‒+

+?

+

??

??

++

+

++

‒+

+?

+

??

??

+?

+

??

??

+?

?

??

??

+?

+

+?

??

+?

+

??

??

+?

+

??

??

+?

+

??

??

+?

+

??

??

+?

+

++

?+

+?

+

++

++

+?

+

++

‒+

+?

+

++

‒+

++

+

++

‒‒

+?

+

(b) Risk of bias summary

Figure 2: Methodological quality and risk of the included studies.

0

0

0.5

1

‒1 1

1.5

2‒2 2

MD

SE (MD)

(a) Funnel plot for the time to first passage of flatus

0

0

1

2

‒2 2

3

4

5‒4 4

MD

SE (MD)

(b) Funnel plot for the length of postoperative hospital stay

Figure 3


0‒1 1‒2 2

Favours [GC] Favours [NGC]

Study or subgroup Mean SD Total Mean SDNGC

Total Weight Mean differenceIV, random, 95% CI

Mean differenceIV, random, 95% CI

GC

Asao 2002Forrester 2014Hirayama 2006Kobayashi 2015Matros 2006McCormick 2005Quah 2006Schuster 2006Topcu 2016Zaghiyan 2013

Total (95% CI) 249 244 100.0% ‒0.55 [‒0.94, ‒0.16]

2.12.992.312.212.752.552.1

2.732.132.03

0.53.270.630.080.921.05

10.620.821.39

10131021225319173054

3.23.423.752.04

32.62.7

3.343.361.96

0.92.180.751.081.181.45

10.8

1.081.23

9171422213519173060

9.8%2.9%

10.8%11.6%10.1%10.7%10.1%11.4%11.3%11.3%

‒1.10 [‒1.76, ‒0.44]‒0.43 [‒2.49, 1.63]‒0.44 [‒1.99, ‒0.89]0.17 [‒0.28, 0.89]‒0.25 [‒0.88, 0.38]‒0.05 [‒0.61, 0.51]‒0.60 [‒1.24, 0.04]‒0.61 [‒1.09, ‒0.13]‒1.23 [‒1.72, ‒0.74]0.07 [‒0.41, 0.89]

Test for overall effect: Heterogeneity:

Z =2.75 (P = 0.006)�휏2=0.29; �휒2=40.01, df =9 (P < 0.00001); I2 = 78%

Figure 4: Forest plot for the time to first passage of flatus.

0‒2 2‒4 4



Total Weight Mean differenceIV, random, 95% CI

Mean differenceIV, random, 95% CI

GC

Asao 2002Hirayama 2006Quah 2006Topcu 2016

‒2.70 [‒4.29, ‒1.11]‒2.15 [‒3.73, ‒0.57]‒0.70 [‒1.65, 0.25]1.38 [0.39, 2.37]

Total (95% CI)

Test for overall effect: Z = 1.05 (P = 0.29)Heterogeneity: �휏2 = 2.88; �휒2 = 25.56, df = 3 (P < 0.00001); I2 = 88%

69 72 100.0% ‒0.96 [‒2.74, ‒0.16]

3.13.523.2

5.77

1.11.581.5

1.84

10101930

5.85.673.9

4.39

2.22.371.5

2.06

9141930

23.4%23.5%26.6%26.5%

Figure 5: Forest plot for the time to first defecation.

1.88 [‒1.23, 4.99]‒0.62 [‒1.61, ‒0.37]‒0.28 [‒1.11, 0.55]‒0.50 [‒1.03, 0.03]‒1.10 [‒1.59, ‒0.03]‒0.26 [‒0.84, 0.32]

Total (95% CI)

Test for overall effect: Z = 4.31 (P < 0.0001)Heterogeneity: �휒2 = 8.53, df = 5 (P = 0.13); I2 = 41%

176 170 100.0% ‒0.60 [‒0.87, ‒0.33]

0.8%7.6%

10.9%26.7%31.4%22.6%

Forrester 2014Kobayashi 2015Matros 2006McCormick 2005Schuster 2006Zaghiyan 2013


Total Weight Mean differenceIV, fixed, 95% CI

Mean differenceIV, fixed, 95% CI

GC

0‒2 2‒4 4


5.213.923.583.1

2.632.37

4.621.831.251.050.231.56

92122531754

152221351760

3.334.543.863.6

3.732.63

1.521.461.5

1.351

1.57

Figure 6: Forest plot for the time to first bowel movement.

‒2.04 [‒7.29, 3.21]‒1.30 [‒2.17, ‒0.43]

Total (95% CI)

Test for overall effect: Z = 3.00 (P = 0.003)Heterogeneity: �휒2 = 0.07, df = 1 (P = 0.79); I2 = 0%

40 40 100.0% ‒1.32 [‒2.18, ‒0.46]

2.7%97.3%Topcu 2016

Forrester 2014

0‒5 5‒10 10


4.153.07

3.911.53

1030

1030

6.194.37

7.511.9


Total Weight Mean differenceIV, fixed, 95% CI

Mean differenceIV, fixed, 95% CI

GC

Figure 7: Forest plot for the time to start feeding.


Study or subgroup Events TotalNGC

Total WeightRisk ratio

M-H, fixed, 95% CIRisk ratio

M-H, fixed, 95% CIGC

Events

Asao 2002Fern 2016

02

17

82

1032

932

0.30 [0.01, 6.62]0.29 [0.06, 1.27]

18.3%81.7%

Total (95% CI)


42 41 100.0% 0.29 [0.08, 1.11]Total events

10.1 100.01 100


Figure 8: Forest plot for postoperative ileus.





Events

Fern 2016Hirayama 2006Lim 2013

60

64

321077

321480

112

62

0.55 [0.23, 1.30]0.27 [0.01, 5.13]1.07 [0.92, 1.25]

14.9%2.9%

82.3%

7570Total (95% CI)


119 126 100.0% 0.97 [0.82, 1.15]Total events

10.1 100.01 100


Figure 9: Forest plot for postoperative nausea.



M-H, random, 95% CIRisk ratio

M-H, random, 95% CIGC

Events

Fern 2016Lim 2013

236

835

4338

3277

3280

0.25 [0.06, 1.09]1.07 [0.76, 1.51]

38.1%61.9%

Total (95% CI)

Test for overall effect: Z = 0.67 (P = 0.50)Heterogeneity: �휏2 = 0.82; �휒2 = 3.78, df = 1 (P = 0.05); I2 = 74%

109 112 100.0% 0.61 [0.15, 2.55]Total events

10.1 100.01 100


Figure 10: Forest plot for postoperative vomiting.





Events

Fern 2016Lim 2013

454

758

6558

3277

3280

0.57 [0.19, 1.76]0.29 [0.79, 1.18]

11.0%89.0%

Total (95% CI)


109 112 100.0% 0.92 [0.75, 1.13]Total events

10.1 100.01 100


Figure 11: Forest plot for postoperative abdominal distention.


(Figure 9), with a moderate statistical heterogeneity acrossthe trials (I2 = 50%).

3.5.7. Postoperative Vomiting. There was no significant differ-ence between the groups in the incidence of postoperativevomiting (RR 0.61; 95% CI 0.15 to 2.55; P = 0 50)

(Figure 10), with a clear statistical heterogeneity betweentrials (I2 = 74%).

3.5.8. Postoperative Abdominal Distension. There was nosignificant difference between the groups in the incidence ofpostoperative abdominal distension (RR 0.92; 95% CI 0.75

Risk ratioM-H, fixed, 95% CI

10.1 100.01 100

Favours [experimental] Favours [control]




Events

Fern 2016Yang 2017

33

24

66

32190

32189

1.50 [0.27, 8.38]0.75 [0.17, 3.29]

33.3%66.7%

Total (95% CI)


222 221 100.0% 1.00 [0.33, 3.02]Total events

Figure 12: Forest plot for postoperative pneumonia.


Total WeightMean difference

IV, random, 95% CIMean difference

IV, random, 95% CIGC

Asao 2002Fern 2016Forrester 2014Heijkant 2015Kobayashi 2015Matros 2006McCormick 2005Quah 2006Schuster 2016

Yang 2017Topcu 2016

Zaghiyan 2013 4.7 0.7 54 4.5 19 60 14.6% 0.20 [‒0.32, 0.72]

Total (95% CI)

Test for overall effect: Z = 2.43 (P = 0.01)Heterogeneity: �휏2 = 0.83; �휒2 = 75.34, df = 11 (P < 0.00001); I2 = 85%

519 514 100.0% ‒0.88 [‒1.59, ‒0.17]

13.57.5

6.319.5

19.84.924.89.44.3

7.6310.5

35.1

5.474.9

12.60.421.32.5

0.431.472.5

10321358212253191730

190

14.59

6.2614

16.44.735.3

11.16.8

9.4710.9

6.15.7

5.8314.516.90.271.957.3

1.382.672.4

9321862222135191730

189

2.2%4.9%2.6%2.8%0.6%

15.6%13.5%3.3%

13.7%11.5%14.7%

‒1.00 [‒5.40, 3.40]‒1.50 [‒4.15, 1.15]0.05 [‒3.96, 4.06]

‒4.50 [‒8.32, ‒0.68]3.40 [‒5.48, 12.18]0.19 [‒0.02, 0.40]‒0.50 [‒1.23, 0.23]‒1.70 [‒5.17, 1.77]‒2.50 [‒3.19, ‒1.81]‒1.84 [‒2.93, ‒0.75]‒0.40 [‒0.89, 0.09]

0‒2 2‒4 4


Figure 13: Forest plot for the length postoperative hospital stay.





Events

Atkinson 2016Heijkant 2015Lim 2013

Yang 2017Quah 2006

32

2

01

199587719

190

203628019

189

01100

7.14 [0.37, 137.34]2.14 [0.20, 22.95]0.35 [0.01, 8.37]

3.00 [0.013, 69.31]4.97 [0.24, 102.91]

12.6%24.6%37.4%12.7%12.7%

28Total (95% CI)


543 553 100.0% 2.57 [0.81, 8.15]Total events

10.1 100.01 100


Figure 14: Forest plot for mortality.


to 1.13; P = 0 45) (Figure 11), with no statistical heterogene-ity between trials (P = 0 34; I2 = 0%).

3.5.9. Postoperative Pneumonia.No significant difference wasobserved between the gum chewing group and control groupin the incidence of postoperative pneumonia (RR 1.00; 95%CI 0.33 to 3.02; P = 1 00) (Figure 12), with no statisticalheterogeneity between trials (P = 0 55; I2 = 0%).

3.5.10. The Length of Postoperative Hospital Stay. Twelvestudies reported the length of postoperative hospital stayafter colorectal surgery under gum chewing intervention orstandard nursing. The meta-analysis showed a statisticallysignificant reduction in the length of postoperative hospitalstay for the gum chewing group (WMD −0.88; 95% CI −1.59to −0.17; P = 0 01) (Figure 13), with a clear statistical hetero-geneity across the studies (I2 = 85%).

3.5.11. Mortality. There was no significant difference betweenthe groups in the incidence of mortality (RR 2.57; 95% CI0.81 to 8.15; P = 0 11) (Figure 14), with no evidence ofheterogeneity across the trials (P = 0 70; I2 = 0%).

3.6. Intention to Treat Analysis. In the included studies, tenstudies reported the individual withdrawal after randomiza-tion. In order to provide unbiased assessments of treatmentefficacy, intention to treat analysis was conducted. Theresult showed that no obvious differences were found inpostoperative nausea, vomiting, abdominal distention, andmortality between the gum chewing group and control group(P > 0 05), which was consistent with the aforementionedfindings (Figure 15).

4. Discussion

The results of our meta-analysis have authenticated thatchewing gum after colorectal cancer surgery is helpful forthe recovery of the patient, which was associated with thereduction of the time to first passage of flatus, first bowelmovement, start feeding, and the length of postoperativehospital stay. However, no difference was observed in theincidence of postoperative nausea, vomiting, abdominal dis-tension, pneumonia, and mortality. In the included studies,most of them described the inclusion and exclusion criteriafor disease, age, and informed consent, yet only one study[19] mentioned that patients were excluded if they had aller-gies to chewing gum, and just one research [17] presented theacceptability and compliance of chewing gum, which mayresult in a risk of selection bias. Additionally, ten studiesreported the individual withdrawal after randomization.Remarkably, the main reasons for the patient’s withdrawalfrom the study or not included in the analyses were thatpatients did not receive chewing gum and inability to chewgum. In order to provide unbiased assessments of treatmentefficacy, intention to treat analysis was also conducted inour study. Similarly, we found that there were no obviousdifferences in postoperative nausea, vomiting, abdominaldistention, and mortality between two arms. Complexand various influencing factors of long-term outcome andfewer data were incorporated regarding the outcome of

postoperative complications that may account for the phe-nomenon. In our study, we only included the colorectalsurgery but not the whole abdominal surgery (cesareansection, and others) with the following consideration. Onthe one hand, not all abdominal surgery actually relate tothe gastrointestinal tract, and the process of intestinal func-tion recovery may be different following different surgery.Chewing gum acts as sham feeding which, therefore, maypromote the recovery of gastrointestinal function throughvarious ways. On the other hand, colorectal surgery changesand affects the integrity of the intestinal tract. The recovery ofintestinal function may mainly depend on the process ofintestinal tract itself, and chewing gum may provide limitedeffects on reducing some complications, which just couldexplain our findings.

How gum chewing works remains unclear. The possiblepresupposition is that gum chewing mimics the mechanismof food intake, which may significantly stimulate motility inthe stomach, duodenum, and rectum [33]; promote gastric,pancreatic, and duodenal secretion [34, 35]; and enhancethe release of neuropeptides [33]. The proposed physiologicmechanism is that gum chewing activates the cephalic-vagalaxis, which stimulates intestinal myoelectric activity to offsetthe activation of gastrointestinal opioid receptors [36]. Inaddition, gum chewing may also stimulate the saliva secre-tion, resulting in the production of nitrous oxide in sufficientquantities to combat the pathogens in the mouth and gut[37]. Furthermore, gum chewing may offer a better optionto regulate a potential risk which is associated with earlypostoperative enteral or oral feeding.

Recently, a significant amount of research focused on thepossible role of chewing gum in the intestinal function recov-ery, yet the evidence from RCTs remains inconclusive; there-upon, several meta-analyses of the efficacy of gum chewingwere published. The meta-analysis by Su’a et al. [12]described the effects of chewing gum on postoperative ileusin adults, showing that chewing gum is beneficial to reducingthe time to flatus and the time to bowel motion, but not thelength of hospital stay or complications. It is noteworthy thatthe included patients in this meta-analysis receiving eithercolorectal surgery or cesarean sections resulted in a heteroge-neous patient group. Another meta-analysis [7] of 10 RCTssuggested that sham feeding following colorectal surgery issafe, leading to the improvement in GI recovery, and is asso-ciated with the reduction in the length of hospital stay, whichis in consistent with our results. Nevertheless, this studyfound that gum chewing conferred no advantage if patientsare placed on a rapid postoperative feeding regime; whileour study revealed that gum chewing might accelerate thetime to first feeding, the difference may be explained by per-forming subgroup analysis on whether the rapid postopera-tive feeding was given to patients, which is just one of thelimitations of our research that the corresponding analysiswas not implemented. An earlier meta-analysis by Nobleet al. [13] identifying nine eligible trials also showed thatchewing sugarless gum following elective intestinal resectionwas associated with improved outcomes, but the efficacy on areduced rate of clinical complications or reduced cost was notconfirmed, which is also in line with our findings. Other


previous meta-analyses [38–44] that focused on the effectsof gum chewing on the recovery of intestinal functionafter abdominal surgery (e.g., cesarean delivery) also con-firmed the beneficial role of gum chewing after surgery.Currently, several RCTs with moderate or large sample

size investigating the efficacy of chewing gum in patientsundergoing colorectal resection have been published, how-ever, which has not been included for synthesized analysisin the latest meta-analysis by Song et al. [45]. Consequently,we launch this updated meta-analysis to comprehensively





Events

Fern 2016Hirayama 2006Lim 2013

60

64

321080

321484

112

62

0.55 [0.23, 1.30]0.27 [0.01, 5.13]1.08 [0.92, 1.28]

14.9%2.9%

82.3%

7570Total (95% CI)


122 130 100.0% 0.98 [0.82, 1.17]Total events

10.1 100.01 100


(a) Forest plot for postoperative nausea



M-H, random, 95% CIRisk ratio

M-H, random, 95% CIGC

Events

Fern 2016Lim 2013

236

835

4338

3280

3284

0.25 [0.06, 1.09]1.08 [0.76, 1.53]

38.3%61.7%

Total (95% CI)

Test for overall effect: Z = 0.66 (P = 0.51)Heterogeneity: �휏2 = 0.83; �휒2 = 3.81, df = 1 (P = 0.05); I2 = 74%

112 116 100.0% 0.62 [0.15, 2.59]Total events

10.1 100.01 100


(b) Forest plot for postoperative vomiting





Events

Fern 2016Lim 2013

454

758

6558

3280

3284

0.57 [0.19, 1.76]0.98 [0.79, 1.20]

11.0%89.0%

Total (95% CI)


112 116 100.0% 0.93 [0.75, 1.16]Total events

10.1 100.01 100


(c) Forest plot for postoperative abdominal distention





Events

Atkinson 2016Heijkant 2015Lim 2013

Yang 2017Quah 2006

32

2

01

199588019

190

203628419

189

01100

7.14 [0.37, 137.34]2.14 [0.20, 22.95]0.35 [0.01, 8.46]

3.00 [0.013, 69.31]4.97 [0.24, 102.91]

12.6%24.6%37.4%12.7%12.8%

28Total (95% CI)


546 557 100.0% 2.57 [0.81, 8.18]Total events

10.1 100.01 100


(d) Forest plot for mortality

Figure 15: Intention to treat analysis.


evaluate the effect and safety of chewing gum for patientsundergoing colorectal resection, which may have moreadvantages in reducing heterogeneity and publication bias.

Several limitations of this study should be addressed.Firstly, owing to the differences in patient population andsurgery approaches involved, this meta-analysis is limitedby the significant heterogeneity of the included studies. Addi-tionally, limited included data subgroup analysis regardingdifferent interventions (e.g., initiation and frequency) ingum chewing was not performed. Besides, there was a lackof blinding in most included studies which may have resultedin significant performance and detection bias. Althoughblinding participants may be difficult in this setting, blindingobservers should be feasible and necessary which is condu-cive to increasing the reliability of the findings. Therefore,to improve the applicability of study results to individualpatients and provide potentially feasible clinical practiceguidelines for postoperative nursing, investigators shouldimprove study design to ensure protocol adherence withminimal loss to selection bias risk and follow-up. Moreover,based on the distribution characteristics of prognostic fea-tures, how to explore potential causes and search for morepowerful evidence still remain to be explored further.

5. Conclusions

This meta-analysis indicates that gum chewing in patientsundergoing colorectal cancer surgery has a beneficial role inintestinal function recovery. However, the limited data sug-gests that it offers no benefit in reducing postoperative clinicalcomplications such as nausea, vomiting, abdominal disten-sion, pneumonia, and mortality. Prospective and blindedRCTs are warranted to further clarify the role of chewinggum in the postoperative care in colorectal cancer patients.

Conflicts of Interest

The authors declare that they have no conflict of interest.

Authors’ Contributions

Binbin Mei and Wenting Wang are co-first authors. FeifeiCui and Zunjia Wen contributed equally to this work.

References

[1] C. J. van de Velde, C. Aristei, P. G. Boelens et al., “EURECCAcolorectal: multidisciplinary mission statement on better carefor patients with colon and rectal cancer in Europe,” EuropeanJournal of Cancer, vol. 49, no. 13, pp. 2784–2790, 2013.

[2] E. J. Kuipers, W. M. Grady, D. Lieberman et al., “Colorectalcancer,”Nature Reviews Disease Primers, vol. 1, p. 15065, 2015.

[3] A. Cimitan, T. Contardo, R. Molaro, and E. Morpurgo, “Therole of laparoscopy in the treatment of anastomotic leaks afterminimally invasive colorectal resections for cancer,” SurgicalLaparoscopy, Endoscopy & Percutaneous Techniques, vol. 26,no. 4, pp. e80–e84, 2016.

[4] W. J. Tan, M. H. Chew, A. R. Dharmawan et al., “Criticalappraisal of laparoscopic vs open rectal cancer surgery,”

World Journal of Gastrointestinal Surgery, vol. 8, no. 6,pp. 452–460, 2016.

[5] H. K. Andersen, S. J. Lewis, and S. Thomas, “Early enteralnutrition within 24h of colorectal surgery versus latercommencement of feeding for postoperative complications,”The Cochrane Database of Systematic Reviews, vol. 18, no. 4,article CD004080, 2006.

[6] D. G. Watt, S. T. McSorley, P. G. Horgan, and M. M. DC,“Enhanced recovery after surgery: which components, if any,impact on the systemic inflammatory response followingcolorectal surgery?: a systematic review,” Medicine, vol. 94,no. 36, article e1286, 2015.

[7] Y. M. Ho, S. R. Smith, P. Pockney, P. Lim, and J. Attia, “Ameta-analysis on the effect of sham feeding following colect-omy: should gum chewing be included in enhanced recoveryafter surgery protocols?,” Diseases of the Colon and Rectum,vol. 57, no. 1, pp. 115–126, 2014.

[8] J. A. Lunding, L. M. Nordstrom, A. O. Haukelid, O. H. Gilja,A. Berstad, and T. Hausken, “Vagal activation by sham feedingimproves gastric motility in functional dyspepsia,” Neurogas-troenterology & Motility, vol. 20, no. 6, pp. 618–624, 2008.

[9] B. U. Su'a and A. G. Hill, “Perioperative use of chewing gumaffects the inflammatory response and reduces postoperativeileus following major colorectal surgery,” Evidence-BasedMedicine, vol. 20, no. 5, pp. 185-186, 2015.

[10] P. Alfonsi, K. Slim, M. Chauvin et al., “Guidelines forenhanced recovery after elective colorectal surgery,” Annalesfrancaises d'anesthesie et de reanimation, vol. 33, no. 5,pp. 370–384, 2014.

[11] N. Jain and S. Mercer, “The chewing gum controversy—timefor a consensus?,” Journal of Clinical Anesthesia, vol. 27,no. 6, pp. 531-532, 2015.

[12] B. U. Su'a, T. T. Pollock, D. P. Lemanu, A. D. MacCormick,A. B. Connolly, and A. G. Hill, “Chewing gum and postop-erative ileus in adults: a systematic literature review andmeta-analysis,” International Journal of Surgery, vol. 14,pp. 49–55, 2015.

[13] E. J. Noble, R. Harris, K. B. Hosie, S. Thomas, and S. J. Lewis,“Gum chewing reduces postoperative ileus? A systematicreview and meta-analysis,” International Journal of Surgery,vol. 7, no. 2, pp. 100–105, 2009.

[14] S. M. de Castro, J. W. van den Esschert, N. T. van Heek et al.,“A systematic review of the efficacy of gum chewing for theamelioration of postoperative ileus,” Digestive Surgery, vol. 25,no. 1, pp. 39–45, 2008.

[15] J. P. T. Higgins and S. Green, Cochrane Handbook forSystematic Reviews of Interventions Version 5.1.0 [updatedMarch 2011], The Cochrane Collaboration, 2011.

[16] T. Asao, H. Kuwano, J. Nakamura, N. Morinaga, I. Hirayama,andM. Ide, “Gum chewing enhances early recovery from post-operative ileus after laparoscopic colectomy,” Journal of theAmerican College of Surgeons, vol. 195, no. 1, pp. 30–32, 2002.

[17] C. Atkinson, C. M. Penfold, A. R. Ness et al., “Randomizedclinical trial of postoperative chewing gum versus standardcare after colorectal resection,” The British Journal of Surgery,vol. 103, no. 8, pp. 962–970, 2016.

[18] O. Vergara-Fernandez, A. P. Gonzalez-Vargas, J. C.Castellanos-Juarez, N. Salgado-Nesme, and E. Sanchez-GarciaRamos, “Usefulness of gum chewing to decrease postoperativeileus in colorectal surgery with primary anastomosis: a ran-domized controlled trial,” Revista de Investigacion Clinica;


organo del Hospital de Enfermedades de la Nutricion,vol. 68, no. 6, pp. 314–318, 2016.

[19] D. A. Forrester, J. Doyle-Munoz, T. McTigue, S. D'Andrea, andA. Natale-Ryan, “The efficacy of gum chewing in reducingpostoperative ileus: a multisite randomized controlled trial,”Journal of Wound, Ostomy & Continence Nursing, vol. 41,no. 3, pp. 227–232, 2014.

[20] T. C. van den Heijkant, L. M. Costes, D. G. van der Lee et al.,“Randomized clinical trial of the effect of gum chewing onpostoperative ileus and inflammation in colorectal surgery,”The British Journal of Surgery, vol. 102, no. 3, pp. 202–211, 2015.

[21] I. Hirayama, M. Suzuki, M. Ide, T. Asao, and H. Kuwano,“Gum-chewing stimulates bowel motility after surgery forcolorectal cancer,” Hepato-Gastroenterology, vol. 53, no. 68,pp. 206–208, 2006.

[22] D. Y. Hwang,H. Y. Kim, J. H. Kim et al., “Effect of gum chewingon the recovery from laparoscopic colorectal cancer surgery,”Annals of Coloproctology, vol. 29, no. 6, pp. 248–251, 2013.

[23] T. Kobayashi, T. Masaki, K. Kogawa, H. Matsuoka, andM. Sugiyama, “Efficacy of gum chewing on bowel movementafter open colectomy for left-sided colorectal cancer: arandomized clinical trial,” Diseases of the Colon and Rectum,vol. 58, no. 11, pp. 1058–1063, 2015.

[24] P. Lim, O. J. Morris, G. Nolan, S. Moore, B. Draganic, andS. R. Smith, “Sham feeding with chewing gum after electivecolorectal resectional surgery: a randomized clinical trial,”Annals of Surgery, vol. 257, no. 6, pp. 1016–1024, 2013.

[25] E. Matros, F. Rocha, M. Zinner et al., “Does gum chewingameliorate postoperative ileus? Results of a prospective,randomized, placebo-controlled trial,” Journal of the AmericanCollege of Surgeons, vol. 202, no. 5, pp. 773–778, 2006.

[26] J. T. McCormick, R. Garvin, P. Caushaj et al., “The effects ofgum-chewing on bowel function and hospital stay after laparo-scopic vs open colectomy: a multi-institution prospectiverandomized trial,” Journal of the American College of Surgeons,vol. 201, no. 3, Supplement 3, pp. S66–S67, 2005.

[27] H. M. Quah, A. Samad, A. J. Neathey, D. J. Hay, and A. Maw,“Does gum chewing reduce postoperative ileus following opencolectomy for left-sided colon and rectal cancer? A prospectiverandomized controlled trial,” Colorectal Disease, vol. 8, no. 1,pp. 64–70, 2006.

[28] R. Schuster, N. Grewal, G. C. Greaney, and K. Waxman, “Gumchewing reduces ileus after elective open sigmoid colectomy,”Archives of Surgery, vol. 141, no. 2, pp. 174–176, 2006.

[29] N. F. Shum, H. K. Choi, J. C. Mak, D. C. Foo, W. C. Li, andW. L. Law, “Randomized clinical trial of chewing gum afterlaparoscopic colorectal resection,” The British Journal ofSurgery, vol. 103, no. 11, pp. 1447–1452, 2016.

[30] S. Y. Topcu and S. D. Oztekin, “Effect of gum chewing onreducing postoperative ileus and recovery after colorectalsurgery: a randomised controlled trial,” ComplementaryTherapies in Clinical Practice, vol. 23, pp. 21–25, 2016.

[31] Y. Yang, H. Q. Zuo, Z. Li et al., “Comparison of efficacy of simodecoction and acupuncture or chewing gum alone on postop-erative ileus in colorectal cancer resection: a randomized trial,”Scientific Reports, vol. 7, article 37826, 2017.

[32] K. Zaghiyan, S. Felder, G. Ovsepyan et al., “A prospectiverandomized controlled trial of sugared chewing gum ongastrointestinal recovery after major colorectal surgery inpatients managed with early enteral feeding,” Diseases of theColon and Rectum, vol. 56, no. 3, pp. 328–335, 2013.

[33] E. E. Soffer and T. E. Adrian, “Effect of meal composition andsham feeding on duodenojejunal motility in humans,” Diges-tive Diseases and Sciences, vol. 37, no. 7, pp. 1009–1014, 1992.

[34] S. J. Konturek and P. Thor, “Relation between duodenalalkaline secretion and motility in fasted and sham-fed dogs,”The American Journal of Physiology, vol. 251, 5 Part 1,pp. G591–G596, 1986.

[35] J. M. Jepsen, E. Skoubo-Kristensen, and L. Elsborg, “Rectosig-moid motility response to sham feeding in irritable bowelsyndrome. Evidence of a cephalic phase,” ScandinavianJournal of Gastroenterology, vol. 24, no. 1, pp. 53–56, 1989.

[36] J. Fanning and F. A. Valea, “Perioperative bowel managementfor gynecologic surgery,” American Journal of Obstetrics andGynecology, vol. 205, no. 4, pp. 309–314, 2011.

[37] C. Duncan, H. Dougall, P. Johnston et al., “Chemical genera-tion of nitric oxide in the mouth from the enterosalivarycirculation of dietary nitrate,” Nature Medicine, vol. 1, no. 6,pp. 546–551, 1995.

[38] H. P. Huang and M. He, “Usefulness of chewing gum forrecovering intestinal function after cesarean delivery: asystematic review and meta-analysis of randomized controlledtrials,” Taiwanese Journal of Obstetrics & Gynecology, vol. 54,no. 2, pp. 116–121, 2015.

[39] Y. P. Zhu, W. J. Wang, S. L. Zhang, B. Dai, and D. W. Ye,“Effects of gum chewing on postoperative bowel motility aftercaesarean section: a meta-analysis of randomised controlledtrials,” BJOG : An International Journal of Obstetrics & Gynae-cology, vol. 121, no. 7, pp. 787–792, 2014.

[40] H. Hochner, S. M. Tenfelde, W. Abu Ahmad, andM. Liebergall-Wischnitzer, “Gum chewing and gastrointesti-nal function following caesarean delivery: a systematic reviewand meta-analysis,” Journal of Clinical Nursing, vol. 24,no. 13-14, pp. 1795–1804, 2015.

[41] Z. Wen, M. Shen, C. Wu, J. Ding, and B. Mei, “Chewing gumfor intestinal function recovery after caesarean section: asystematic review and meta-analysis,” BMC Pregnancy andChildbirth, vol. 17, no. 1, p. 105, 2017.

[42] S. Li, Y. Liu, Q. Peng, L. Xie, J. Wang, and X. Qin, “Chewinggum reduces postoperative ileus following abdominal surgery:a meta-analysis of 17 randomized controlled trials,” Journal ofGastroenterology and Hepatology, vol. 28, no. 7, pp. 1122–1132, 2013.

[43] W. Vasquez, A. V. Hernandez, and J. L. Garcia-Sabrido, “Isgum chewing useful for ileus after elective colorectal surgery?A systematic review and meta-analysis of randomized clinicaltrials,” Journal of Gastrointestinal Surgery, vol. 13, no. 4,pp. 649–656, 2009.

[44] E. Sahin and F. Terzioglu, “The effect of gum chewing, earlyoral hydration, and early mobilization on intestinal motilityafter cesarean birth,” Worldviews on Evidence-Based Nursing,vol. 12, no. 6, pp. 380–388, 2015.

[45] G. M. Song, Y. H. Deng, Y. H. Jin, J. G. Zhou, and X. Tian,“Meta-analysis comparing chewing gum versus standardpostoperative care after colorectal resection,” Oncotarget,vol. 7, no. 43, pp. 70066–70079, 2016.


Submit your manuscripts athttps://www.hindawi.com

Stem CellsInternational

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation http://www.hindawi.com Volume 2014

Immunology ResearchHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinson’s Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttp://www.hindawi.com

Documents

Chewing Gum for Intestinal Function Recovery after ...downloads.hindawi.com/journals/grp/2017/3087904.pdf · gum chewing intervention, and 927 received standard post-operative care