w w w . j c o l . o r g . b r
Journal
of
Coloproctology
Original
Article
Evaluation
of
the
inflammatory
response
induced
by
different
materials
in
the
treatment
of
perianal
fistulas:
experimental
study
in
rats
Mariana
Ocampos
Galvão
a,
Carlos
Henrique
Marques
dos
Santos
b,∗,
Gustavo
Ribeiro
Falcão
baUniversidadeAnhangueraUniderp,CampoGrande,MS,Brazil
bUniversidadeFederaldeMatoGrossodoSul(UFMS),CampoGrande,MS,Brazil
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o
Articlehistory: Received26April2015 Accepted28August2015
Availableonline23December2015
Keywords: Fistula Analcanal Rats Seton
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b
s
t
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t
Themedicalliteraturehasnostudyevaluatingtheeffectivenessofdifferentmaterialsused assetonsinthetreatmentofperianalfistulas;therefore,thereisnoevidenceofavailability ofamoreeffectivematerialthanothersforthispurpose.
Objective:Toevaluatetheinflammatoryresponseinducedbydifferentmaterialsusedas setoninperianalfistulasinrats.
Method:ThirtyWistarrats,whichwereinitiallysubmittedfortheconstructionofaperianal fistulabypassingtransfixingsteelwireintotheanalcanal,wereused.Theratswerekept for30days;afterthisperiod,andwithconfirmationoftheformationoftheperianalfistula, thesetonswereintroduced(10rats–cottonthread#0;10rats–rubber;and10rats–silastic); after30daystheanimalswereeuthanized,andthentheareaofthefistularepairedbythe setonwasresected,andthematerialretrievedwassubmittedtohistologicalanalysis.The resultswereanalyzedstatistically.
Results:Themeandegreeofinflammatoryprocessobservedbyhistologicalanalysisafter30 dayswas2.3forthecottongroup;1fortherubbergroup;and1.2forthesilasticgroup. Conclusion:Agreaterinflammatoryresponsewasobservedinthegrouptreatedwithacotton seton.Intheremaininggroups,alowerinflammatoryresponse,withequalintensityfor rubberandsilastic-treatedrats,wasnoted.
©2015SociedadeBrasileiradeColoproctologia.PublishedbyElsevierEditoraLtda.All rightsreserved.
∗ Correspondingauthor.
E-mail:chenriquems@yahoo.com.br(C.H.M.dosSantos).
http://dx.doi.org/10.1016/j.jcol.2015.08.008
Avaliac¸ão
da
resposta
inflamatória
produzida
por
diferentes
materiais
utilizados
como
sedenho
no
tratamento
de
fístulas
perianais:
estudo
experimental
em
ratos
Palavras-chave: Fístula Canalanal Ratos Sedenho
r
e
s
u
m
o
Nãoforamencontradosnaliteraturamédicaestudosqueavaliassemaeficáciados difer-entesmateriaisutilizadoscomosedenhonotratamentodefístulasperianais,portanto,não havendoevidênciasdequehajaummaterialmaiseficazdoqueoutroparaestafinalidade. Objetivo: avaliararespostainflamatóriainduzidapordiferentesmateriaisutilizadoscomo sedenhosemfístulasperianaisemratos.
Método: foramutilizados30ratosWistar,osquaisforaminicialmentesubmetidosàcriac¸ão defístulaperianalpelapassagemdefiodeac¸otransfixantenocanalanal,mantidopor 30 dias;apósesteperíodo,confirmadaaformac¸ãode fístulaperianal,foram introduzi-dosossedenhos(10ratos–fiodealgodãozero,10ratos–borrachae10ratos–silastic); após30diasosanimaisforamsubmetidosaeutanásia,ressecando-seaáreadafístula reparadapelosedenho,submetendo-seestematerialàanálisehistológica.Osresultados foramsubmetidosatratamentoestatístico.
Resultados: amédiadograudeprocessoinflamatórioobservadopelaanálisehistológica após30diasfoide2,3paraogrupodesedenhodealgodão;de1paraogrupodesedenho deborrachae1,2paraogruposilastic.
Conclusão: Houvemaiorrespostainflamatórianogrupotratadocomsedenhodealgodão. Houverespostainflamatóriamenoredeigualintensidadenosanimaistratadosporsedenho deborrachaesilastic.
©2015SociedadeBrasileiradeColoproctologia.PublicadoporElsevierEditoraLtda. Todososdireitosreservados.
Introduction
Perianalfistulaisaconditioncharacterizedbyanabnormal communicationbetweentheintestinalepithelium(analcanal or rectum) and skin, its primary signal being a foul-odor, pious/bloodtingeddrainagethroughitsperianalexternalos. Thisisarelativelycommonconditionseeninthe coloproctol-ogyoffice,anditsrealincidenceisunknown,butthiscondition occurspredominantlyinmales.Perianalfistulascanoccurat anyage,withanincidencemostcommonlybetweenthethird andfifthdecadesoflifeandrarelyfromthesixthdecade.
The optimal management of perianal fistulas remains a matter relatively controversial, because there is no sin-gletechniquethat canprovideahigh healingratewithout complications,suchasfecalincontinence.Itisknownthat fistulotomy is currently one of the most widely employed techniques worldwide for superficial fistulas, for example, intersphinctericandlowtranssphinctericfistulas.Inthese sit-uations,around95% ofcasesareresolved,withlowriskof fecalincontinence,ofapproximately5%–figuresconsidered verygoodforthisscenario.1
Themajordrawbackinthecareofperianalfistulasrelates to the more complex ones, suchas high transsphincteric, suprasphinctericandextrasphinctericfistulas–situationsin which a fistulectomywould leadto unacceptable levels of fecalincontinence,duetothesphinctericinjuryproduced.For thesetypesoffistulas,manytechniqueshavebeendescribed andusedwithreasonableresults,but neverreachingthose outcomeswithfistulotomy.Techniquessuchasmucosalflap advancement,LIFT(ligationosintersphinctericfistulatract),
andtheuseofgluesandplugs,arebeingusedworldwidewith resolutionratesrangingfrom20%to85%.2
Aresourceusedformanyyearsforthemostcomplexcases consistsintheplacementofsetons,withmultipleobjectives. Thisresourcecansimplybeusedformaintaininganopen fis-tula,whileavoidingtheformationofabscesses,asinthecase ofCrohn’sdisease.Thesetonalsofunctionsasasingle treat-mentforfistula,consideringthat,asaforeignbody,thereisa tendencyforitseliminationbythebody,withconsequent for-mationofscartissuealongthefistulatractandwoundhealing. Anotherpurposeoftheuseofasetonistheinductionofmore fibrosis,producingawell-definedpathwiththickwallsfor fur-thersurgicaltreatment,forexamplewiththeLIFTtechnique. WithLIFT,mostsurgeonsapplyasetonbetween6and8weeks beforetheprocedureitself.3
There is much speculation among coloproctologists as whatisthebestsetonmaterialtobeusedfordifferent pur-poses.Someadvocatethatthebestmaterialwouldbesilastic, thankstoitsveryinterestingcharacteristicsofsmoothness, pliability and relativeresilience. However, rubberseems to havethesame characteristics,butatalowercost. Another widely used material, especially in public services, where silasticisnotalwaysavailable,isthecottonthread,a mate-rial alsoveryflexibleand hard-wearing,butoftencriticized forbeingamultifilamentdevice,thuscapableofinducingan increasedproductionofpus,aquiteunpleasantnuisancefor patients.
maybeused.Thus,itiscriticaltostudytheactionofthese materials,andtheaimofthisstudyistocarryoutsuchan analysisandcomparison.
Objective
Toevaluatetheinflammatoryresponseinducedbythe differ-entmaterialsusedassetonsinperianalfistulasinrats.
Method
ThestudywasapprovedbytheEthicsCommitteeonAnimal Use(CEUA)oftheFederalUniversity ofMatoGrossodoSul (UFMS).
Atotalof30Rattusnorvegicus,Wistaralbinostrain,adult maleratswithanaverageweightof300gwereusedinthis study.Theanimalswerekeptintheexperimentalsectorof CentralAnimalFacility,UFMS,andallrequiredethical stan-dardsweremet.Waterandadlibitumfeedingwasprovided, withdailyexchangeoffoodandwaterandcleaningofcages. The animals were anesthetized with intraperitoneal ketamineand xylazinecombined inthesamesyringe with 1mlsolutionof10%ketamineand1mlof2%xylazine,with infusionof0.1mlofsolutionper100gbodyweight.
Afteranesthesia,theanimalswerekeptinasupine posi-tion with their four extremities in abduction. The entire surgicalprocedurewasperformedunderasepticand antisep-ticconditionsintheoperatedarea.
Initially,aperianalfistulaconstructionwasmadeinall ani-malsthroughthepassageofaneedledsteelwire#5(ACIFLEX®)
withtransfixionoftheperianalarea;thewirewasinsertedinto thepectinealline,crossingtheanalsphincterwiththeneedle exitingatapoint1cmlateraltotheleftanalmargin.Then, theoperatorsectionedthesteelwireandsecureditbyloosely rotatingitsends,withnocompressionofthesphincter(Fig.1). Theratswerekeptundertheconditionsdescribedabove for30days,andafterthisperiod,allanimalswereagain anes-thetizedbythetechniquedescribedabove,withreplacement ofthesteelwirebyaseton,withthefollowingdistribution:
– GroupA:10animalswithcotton#0seton – GroupB:10animalswithrubberseton – GroupC:10animalswithsilasticseton
Allsetonsweretiedlooselyandwithnosphincteric com-pression,andwerethuskeptforanother30days.Theouter portionofeachseton,whichwasnotincontactwiththe fis-tula,wascoveredwithbraidedsteelwire,sothattheratcould notremoveit(Figs.2–4). Afterthis periodoftime, the ani-malswereeuthanizedwithanintracardiacinjectionofsodium thiopental,afterbeinganesthetizedbythetechnique previ-ouslydescribed.Aftertheeuthanasia,theareacontainingthe fistulaandthesetonwasresectedenblocandthesetonwas thenremoved,after identificationofthe vials intendedfor reception ofthe material,which was maintainedin a10% solutionofformaldehydeforsubsequenthistologicalanalysis. Theresectedspecimenswerethensubjectedto4-mcuts andthenstainedwithhematoxylinandeosin;mountedslides
Fig.1–Perianalregionafterthepassageofsteelwirefor makingafistula.
wereanalyzedbyanexperiencedpathologistusinganEclipse E200microscopeat100×and400×.
Theobservedinflammatoryresponsewasclassified into grades,accordingtothegreaterorlesserpresenceof inflam-matorycells:
– Grade0:noinflammatoryresponse
– Grade1:mildinflammatoryresponse,withlowcelldensity presentinupto25%oftheanalyzedarea
Fig.3–Silasticsetoninposition,beforeametalliccoating application.
– Grade2:moderate inflammatoryresponse,withmedium celldensitypresentin26–75%oftheanalyzedarea – Grade3:severeinflammatoryresponse,withhighcell
den-sityinover75%oftheanalyzedarea
Inthestatisticalanalysisoftheresults,theKruskal–Wallis testwasapplied,consideringasstatisticallysignificantap -value<0.05.
Results
IngroupA(cotton),threeanimalshadagrade1 inflamma-toryresponse,threeanimalsweregrade2andfouranimals were grade 3(mean=2.3). In group B(rubber), all animals hadagrade1inflammatoryresponse(mean=1).IngroupC
Fig.4–Cottonsetoninposition,beforeametalliccoating application.
Table1–Inflammatoryresponsetotheuseofsetonin thegroupsstudied.
Rats Gradesofinflammatoryresponse
GroupA GroupB GroupC
1 1 1 2
2 1 1 1
3 1 1 1
4 2 1 1
5 3 1 1
6 3 1 1
7 2 1 2
8 3 1 1
9 2 1 1
10 3 1 1
Mean 2.3 1 1.2
Note:BetweengroupsAandB,p<0.05;betweengroupsAandC,
p<0.05;betweengroupsBandC,p>0.05.
(silastic), only two animals had a grade 2 inflammatory response,whiletheothershadagrade1answer(mean=1.2) (Table1).
Discussion
Recently,Subhasetal.1 publishedareviewoftheliterature analyzingthedifferentmaterialsusedassetonsinthe correc-tionofanorectalfistulas.Althoughthiswasacomprehensive reviewthatincludedmostofthematerialsused,itsauthors didnotfindadirectcomparisonbetweensuchproductsinthe literature;therefore,currentlyitisnotknownwhetherornot thereissomedifferenceintheeffectivenessofthesedevices. InProctologypractice,itwasobservedthatmany practi-tionershavepersonalpreferencesastothematerialtobeused asaseton,withargumentsinfavorofsiliconizedproductsor rubber,becausetheseproductsarepotentiallymore comfort-ableforpatientsandalsobyproducinglesssecretion,thanks totheabsenceofporosity.However,thesepotential advan-tagesdidnotfindaclearscientificsupport,astheyarebased onlyonthesurgeons’personalexperienceandonsomecase reports.2 Therefore,theimportanceofourstudy;butonthe otherhand,itdoesnotallowacomparisonofitsresults.
Someauthorsreportedtheirexperiencewiththeuseofa rubberseton(Penrosedrain)withsatisfactoryresults.In fulfill-ingitsroleasaseton,withasimilarefficacytoothermaterials, it shouldbeborne inmindthe greatadvantageinthe use ofthis product,because ofits low cost and its availability inmostoffistulatreatmentcenters.Especiallyindeveloping countries, thisfactor isquiterelevantand shouldbetaken intoconsiderationwhenchoosingthematerial.Furthermore, rubberisaninert,veryflexible,non-porousmaterialand,in theory,itgenerateslesspurulentdischargeduringthetimein whichthesetonisapplied.3
curettageofthefistulaandplacementofasetonisthefirst choice. In this particular situation, there is no interest in producingintensefibrosis,norinobtaininganintense inflam-matoryresponse;onthecontrary,thesmallerthisresponse, the betterfor thepatient. Inthis scenario, the seton used shouldbe soft,tough, and should cause littleforeign body reaction,sinceitwillremainfixedtothefistulous tractfor relativelylongperiods.4Extrapolatingthistothefindingsin thisstudy,themostappropriatematerialstobeusedwould besilasticandrubber(cottonbeingtheworseoption).
Onthe other hand,when oneuses aseton aiming bet-terdefinition ofthe fistula,withamoreconsistentfibrosis toassistduringthesurgicalprocedureonthefistuloustract, theoretically cotton setons best fulfill this function, since thepresentresultsdemonstratedincreasedformationofthe inflammatoryprocessand,byinference,morefibrosiswiththe useofthismaterial.ThiswouldbethecaseofLIFT(ligationof intersphinctericfistulatract),atechniquewhich,althoughit testedyetwithdifferentsetonmaterials,hasbeenwidelyused worldwide.Inthistechnique,theuseofasetonisnotan abso-lutecondition,butmostsurgeonswhopracticeLIFTadvocate itsuse,6–8weeksaheadtheLIFTprocedureitself.The pres-enceofaforeignbodyrepairingthefistuloustractwouldlead togreaterfibrosis,withimprovedsafetyintheapplicationof suturesfortheligationofthetract.5,6
Anotherapproachtoafistularequiringtheuseofaseton consistsin a “tight” application ofthis device, in order to graduallycutoff the muscle containedbythe fistula. This ancienttechniquehasresultedinhugelyconflictingresultsin theliterature,especiallyinthefaceofthepotentialforfecal incontinence.7Ontheotherhand,theliteraturehasnot pro-ducedadirectcomparisonbetweendifferentmaterialsused, butitcanbeinferredthatthisfactorcouldinfluencethe out-come,sincethepresenceofgreaterfibrosiscould,intheory,fix themusclecables,withlowerratesofincontinence.Moreover, byinducingagreaterinflammatoryresponse,theprocedure couldlead(alsotheoretically)atafasterresolutionofthe fis-tula–anoutcomewhichwouldbenefitthepatient.setonsare alsousefulwhenappliedloosely,precedingadefinitive surgi-calprocedure.InadditiontotheLIFTtechnique,mentionedin apreviousparagraph,anothertime-provensurgicalprocedure istheskinormucosalflapadvancement.Theseapproaches canalsobeperformedwithorwithouttheprevioususeofa seton,butapparentlythereexistsagreatertendencyinfavor ofthe use of this device.8 Tothis end, basically the seton wouldpreparethe sitetobeoperated, keepingitfreefrom residuesand especially from infection;thus,someauthors recommenditsplacementalreadyatthetimeoftheperianal abscessdrainage.Withthispurpose,therewouldbenoneed toinduceagreaterfibrosis,butsimplytomaintainapatent anddrainedtract.Thus,insuchcasesthesoft,inertmaterials wouldbebetteroptions.
Thisstudyshowednodifferencebetweensilasticand rub-ber in the production of the inflammatory process, when thesematerialsareusedassetons.Whileonemusttakeinto accountthefactthatoursisasolitarystudy,suchevidence
speakinfavoroftherubberseton,thankstoitswidespread availabilityandlowercost.Bothmaterials(silasticandrubber) inducedlessinflammationversuscotton,butthisfindingin nowaygivessuperioritytothesematerials,takinginaccount that,dependingonthepurposeintheuseoftheseton,the cot-tondevicewouldbethebestalternative,asalreadymentioned above,withrespecttotechniquessuchasLIFT,forinstance. These resultsshould serve –if notforobtaining a conclu-siveanswertothequestionaboutthedifferencesbetweenthe materialsanalyzed,atleastasastartingpointforthe conduc-tionoffurtherstudies,withtheaimtoadvanceinthiscritical knowledgeforthe careofavery commonand challenging disease.
Conclusion
Thecottonstrandinducedagreaterinflammatoryresponsein comparisonwithsilasticandrubbersetonsinthetreatment ofperianalfistulasinrats.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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