A Critical Perspective on Trophic Feeding - Lippincott

Trophic feeding is a concept viewed with an almost religious fervor in some nurseries, intensive care units and surgical wards. Indeed, the determination to ... March2004-Volume38-Issue3 Next Article ArticleasEPUB ExportAllImagestoPowerPointFile AddtoMyFavorites Colleague'sE-mailisInvalid YourName: Colleague'sEmail: Separatemultiplee-mailswitha(;). Message: Thoughtyoumightappreciatethisitem(s)IsawinJournalofPediatricGastroenterologyandNutrition. Yourmessagehasbeensuccessfullysenttoyourcolleague. Someerrorhasoccurredwhileprocessingyourrequest.Pleasetryaftersometime. EndNoteProciteReferenceManager Savemyselection NewsandViews Editor(s):Finkel,YigaelM.D.,Ph.D.;Baker,,RobertD.Jr.M.D.,Ph.D.;Rosenthal,PhilipM.D.;Sherman,PhilipM.M.D.,F.R.C.P.C.;Sondheimer,JudithM.M.D. AuthorInformation SectionofGastroenterology,HepatologyandNutrition, UniversityofColoradoHealthSciencesCenterandThe Children'sHospital,Denver,CO JournalofPediatricGastroenterologyandNutrition: March2004-Volume38-Issue3-p237-238 Free Trophicfeedingisaconceptviewedwithanalmostreligiousfervorinsomenurseries,intensivecareunitsandsurgicalwards.Indeed,thedeterminationtogivetrophicfeedingsoccasionallyapproachesfanaticism.Havingjustbeentoldbyadieticianthataneonatewitharecentintestinalresectionwouldexperiencerapidatrophyofhisremaining16cmofsmallbowelifhedidn'tgetimmediatetrophicfeedings,Ithoughtsomeperspectiveonthismisunderstoodconceptwaswarranted. Thegenerallyaccepteddefinitionoftrophicfeedingisasmallvolumeofbalancedenteralnutritioninsufficientforthepatient'snutritionalneedsbutproducingsomepositivegastrointestinalorsystemicbenefit.Thevolumeoffeedingconsideredtrophicinmostneonatalnurseriesis10–12cc/Kg/dor1cc/h.Ifmorethan25%ofthepatient'snutritionalneedsareadministeredenterally,thefeedingshouldnolongerbeconsideredtrophic.Thecommonlyidentifiedbenefitsoftrophicfeedingintheintactintestinearematurationofneonatalintestinaldigestive,absorptive,motorandimmunefunction;improvedneonatalfeedingtoleranceandeatingbehavior;maintenanceofintestinalfunctionduringstarvationandcatabolicstates;andpreventionofintestinalbacterialovergrowthandbacterialtranslocation. Thereisanextensiveliteratureontheimportanceofluminalnutritioninpromotingmucosalhypertrophyafterintestinalresection.Itmaybesemantic,butthiskindofnutritionisnottrophiceitherinvolumeorcaloriccontent.Mostanimalexperimentsofpostresectionintestinaladaptationhaveusedthemaximumenteralfeedingtheanimalcantolerate,generallymorethan30%ofnutritionalneeds.Todate,nostudiesofpost-resectionintestinaladaptationinresponsetostrictlydefinedtrophicfeedingshavebeenperformed.Partofthedietician'sanxietyoverthefailuretoinstituteenteralfeedingsquicklywasherconcernthattherewasacriticaltimebeyondwhichintestinaladaptationwouldnotoccur.Thisisamisconception.Thepotentialforhypertrophyofresidualbowelinresponsetoluminalnutritionisalwaysthere,readytostartupinresponsetoluminalfeedingseveniftheyaredelayedformonths(oryears?)afterresection. Thereareproblemswiththeattractiveconceptoftrophicfeedings.First,thepresumedbenefitsarepoorlydefined.Forexample,trophicfeedingsaresaidtopromoteintestinalimmunefunctionorintestinalmaturation,bothofwhichareincrediblycomplexprocesses.Animalandhumanstudiesontheroleoftrophicfeedingsinpromotingthesecomplexfunctionsareinadequatetoisolateauniquecontributionoftrophicfeedings.Second,thecatabolicimpactofstarvationontheorganismandonthegastrointestinaltractisoftennotconsideredintheselectionofcontrolsinsuchstudies.Ifthenegativeimpactofwithholdingtrophicfeedingsfromtheintestineistobeisolatedfromthecatabolicimpactofundernutritionortheabsenceofanessentialluminalnutrient,thenadequatenutritionbytheparenteralroutemustbepartofanyhumanoranimalstudy. AnimalStudies Pythonseathugemealsandthenfastforlongperiodsduringwhichintestinalvillousatrophydevelops.Histologicabnormalities,mucosalmassandmucosalnutrienttransportallimproverapidlyinthepythonwhensmall,balanced,nutritionallyinadequatefeedingsaregivenenterally,butnotwhenglucose,lipid,bileorsalinealonearegiven(SecorSMetal.AmJPhysiolGastrointestLiverPhysiol2002;283:G1298).Inpiglets,whoexperienceverymodestmucosalatrophywithfasting,itrequirestheenteraladministrationofatleast40%ofthedailynutritionaltoproduceanyincreaseinvillousheightinthejejunumand60%ofdailyneedstoproducemucosalproliferationintheileum(BasuR,etal.AmJClinNutr2000;71:1603)Thissuggeststhatmucosalatrophyisareflectionofgeneralundernutritionandnotaresultoftheabsenceoftrophicfeedingssinceitisonlyreversedbyalargeenteralintake.Inenterallyfastedpuppiesnourishedbytotalparenteralnutrition(TPN),itlikewisetakesanenteralfeedingofatleast30%ofdailynutritionalneedstoproducemucosalgrowthabovethatofcontrols.TheredoesappeartobeamorerapiddevelopmentofmaturemotoractivityinthestomachanduppersmallbowelofpuppiesreceivingtrophicfeedingsplusTPNthanisobservedinpupsonTPNalone(OwensLetal.JNutr2002;132:2717). Someclaimthattrophicfeedingswillpreventcholestasisorotherliverinjuryassociatedwithparenteralnutrition.Themechanismsforthisbenefitaresaidtobethepreventionofbacterialovergrowth,bacterialtranslocationandenterotoxinabsorptionortheaugmentationofintraandextrahepaticbiliaryexcretionviapositiveimpactsonmucosalintegrity,motorfunctionandhormonerelease.Theanimaldatatosupporttheseassumptionsisweak.OnestudyinadultratsreceivingTPNfor7daysshowedthattherewasmoreglutathioneintheliverofanimalswhoreceived“targeted”trophicfeedingsofalaninewhencomparedtoanimalsreceivingsaline.Hepaticsensitivitytoexogenouslyadministeredendotoxinwaslessintheanimalswhoreceivedalanine(DzakovicAetal.JPediatrSurg2003;38:844).Alaninewouldnotfitmostpeople'sdefinitionoftrophicfeeding.Itismoreanessentialprecursor.Theappropriatecontrolwouldbeananimalreceivingextraalaninebyvein.Thereisverylittleinformationabouttheimpactoftrophicfeedingsonbiliaryflowandgallbladderfunction. Iconcludefromanimalstudiesthatintestinalmucosalatrophymayaccompanyenteralfastinginsomespecieswith(pups,ratsandpiglets)orwithout(pythons)adequateIVnutritionandthatfeedingamixedmealofsignificantcaloricmagnitudestimulatesmucosalgrowthandfunction.Theredoesnotappeartobeanyimpactoffeedingsprovidinglessthan30%ofdailynutritionalneedsexceptintheareaofneonatalgastroduodenalmotility. HumanStudies DoesmucosalatrophyactuallyoccurinhumansfromwhomenteralnutritioniswithheldwithorwithoutIVnutritionalsupport?Alpersreportsthatthereatmosta10%decreaseintheadultbowelwallthicknessduringcatabolicstatesintheintensivecaresetting(AlpersDH.CurrOpinClinNutrMetabCare2002;5:697).AccordingtoAlpers,reversalofthismodestatrophywithtrophicfeedingshasnotbeendocumented.Alpersfeels,afterareviewoftheadultICUliterature,thatmucosalatrophyissimplyamanifestationofacatabolicstateasismusclewastingandfatstoredepletion,whichcanbepreventedbyadequateIVnutritionwithnouniquecontributionfromtrophicfeeding. Inthe1980sseveralgoodstudiesevaluatedtrophicfeedingsinprematureneonates.Theprimaryobjectivewastoseewhetherearlysmallenteralfeedingsincreasedtheincidenceofnecrotizingenterocolitis.Moststudiesconfirmedthattheydidnot.TheunexpectedresultofthesestudieswasthatbabiesgivenadequateIVnutritionplusbalancedminimalenteralfeedingsprogressedfastertofullenteralnutrition.Feedingbehaviorandtolerancewerebetterandbabiesweredischargedfromthehospitalfasterthanthosenotreceivingminimalenteralfeedings.Inonestudy,hospitaldischargewas22daysearlierthancontrols.Peakdirectbilirubinwaslowerinprematureneonatesreceivingtrophicfeedings(.7mg/dLvs2.5mg/dL)andfewerdaysofphototherapywererequiredforindirecthyperbilirubinemia(6.8daysvs9.5days)aswell(DunnLetal.JPediatr1988;112:622–9).Voluntaryenergyintakewasbetterinbabiesreceivingearlyminimalenteralfeedingsevenbriefly,aresultattributedtooverallbetterfeedingbehavior.Onestudyfoundthattheweightofprematureneonateswhohadreceivedonly7daysoftrophicfeedingwas225goverbirthweightat30daysofagewhilethebodyweightofthosereceivingnotrophicfeedingswasonly95gabovebirthweight.Theaveragecaloricintakeofthesebabieswasidenticalforthe30days.Somatomedinlevelswerethesameinthetwogroups,suggestingthatmaturationofhormonesecretionwasnotthecauseofbettergrowth(TrocheBetal.BiolNeonate1995;67:172–81).Theauthorswonderedwhetherefficiencyofabsorptionwasbetterintheneonateswhogottrophicfeedingsthusincreasingtheiractualcalorieintake.Asinpuppies,theuseofminimalenteralnutritioninneonatesisassociatedwithanearlierappearanceofamatureantro-duodenalmotilitypattern.Salineperfusedcontrolshavenotbeenstudied,sotheimpactofvolumeasopposedtoluminalnutrientcannotbeassessed(BersethCLetal.Pediatrics2003;111:529). Trophicfeedingsaresaidtopromotematurationofintestinalabsorptivefunction,butharddataarescanty.Onestudyhasshownindirectlythatabsorptionofleucineisbetterinpretermsreceivingtrophicfeedings(SaenzdePipaonMetal.PedRes2003;53:281).Thereareveryfewotherstudiesthathaveassessedtheimpactofminimalenteralnutritiononanyaspectofdigestiveorabsorptivefunction. Theclaimsforimprovedimmunityininfantsandadultsreceivingtrophicfeedingsareweak,becauseofthecomplexityoftheprocessandtheinadequatescopeoftheoutcomemeasuresused.InonestudyofinfantsonTPN,bactericidalactivityofneutrophilsagainstcoagulasepositivestaphandreleaseofTNFαwasbetterafter7daysoftrophicfeedingsbutneitherfunctionapproachedthelevelofenterallyfedcontrols.Theincidenceofsepticeventsininfantswithandwithouttrophicfeedingsisthesame(OcadaYetal.JPediatrSurg1998;33:16).Therearenostudiesevaluatingintestinalresponsestoinfectiousagents,thedevelopmentoffoodallergyorthenatureoftheintestinalimmunefunctionininfantsreceivingtrophicfeedings. TheCochranegroupreviewedthehumanliteratureontrophicfeedings(definedaslessthan25calories/Kgformorethan5days).Theyagreedthattotalhospitalstay,daystoachievefullenteralnutritionanddaysfeedingswerewithheldbecauseofintolerancewerefewerinneonateswhoreceivedtrophicfeedings.Inallotherclinicalstudies,theyconcludedthatmethodologicproblemspreventedtheconclusionthattrophicfeedingshadanyotherbenefitsandthatenteralfastinguntilthechildwasreadyfor“realfeedings”wasstillanappropriateclinicalapproach(TysonJEetal.CochraneDatabaseSystRev2:CD000504,2000). Itwouldfacilitatemanagementplanninginmanyclinicalsituationsiftheconfusionbetweenthethreeconceptsofluminalnutrition,specificluminalnutrientsessentialforenterocytefunctionandtrophicfeedingwereclarifiedandifwordslikeatrophyandhypertrophywereusedwithmoreprecision.Mostofthesupposedbenefitsoftrophicfeedingsstillrequireconfirmationbygoodclinicalstudies.Thesestudiesaredoable.Isubmitthatassessingintestinalabsorptivefunctionistediousbutpossible.Assessingthebiochemicalandhistologicevidenceofliverinjuryshouldbeeasy.Evaluatinghistologicchangesbeforeandaftertrophicfeedingsispossibleincarefullyselectedsituations,forexamplebymonitoringthebiopsiesoftheeasilyaccessibledistalsmallintestineininfantswithileostomies.Themeasuresofimmunefunctionmustbemorecarefullyselectedsinceendpointslikeinfectionratearetooinsensitivetorevealpossibledifferences.ThechallengetopediatricgastroenterologyisevaluatetheunconfirmedbenefitsoftrophicfeedingbeforeinsistingonitsuseinfragilepatientswhomightbebetterofffastingandsupportedbyTPNuntiltrulyreadytofeed.©2004LippincottWilliams&Wilkins,Inc.Viewfullarticletext Source ACriticalPerspectiveonTrophicFeeding JournalofPediatricGastroenterologyandNutrition38(3):237-238,March2004. 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