ContinuousRenalReplacementTherapyBasicTherapyPrinciplesIsanextracorporealbloodpurificationtherapyintendedtosubstituteforimpairedrenalfunctionoveranextendedperiodoftimeandappliedfororaimedatbeingappliedfor24hoursaday.*BellomoR.,RoncoC.,MehtaR,NomenclatureforContinuousRenal

ReplacementTherapies,AJKD,Vol28,No.5,Suppl3,November1996ContinuousRenalReplacementTherapy(CRRT)306100135CRRTGoalsMimicthefunctionsandphysiologyofthenativeorganQualitativeandquantitativebloodpurificationRestoreandmaintainofhomeostasisAvoidcomplicationsandgoodclinicaltoleranceProvideconditionsfavoringrecoveryofrenalfunction306100135RequirementsforCRRTCRRTrequires:Acentraldouble-lumenveno-venoushemodialysiscatheterAnextracorporealcircuitandahemofilterAbloodpumpandaeffluentpump.WithspecificCRRTtherapiesdialysateand/orreplacementpumpsarerequired.306100135CRRTModalitiesSCUF-SlowContinuousUltrafiltrationUltrafiltrationCVVH-ContinuousVeno-VenousHemofiltrationConvectionCVVHD-ContinuousVeno-VenousHemodialysisDiffusionCVVHDF-ContinuousVeno-VenousHemodiafiltrationDiffusionandConvection306100135SCUF-UltrafiltrationSlowcontinuousultrafiltration:Requiresabloodandaneffluentpump.Nodialysateorreplacementsolution.Fluidremovalupto2liters/hrcanbeachieved.PrimaryGoalSafemanagementoffluidremovalLargefluidremovalviaultrafiltration306100135Transportmechanism:UltrafiltrationThemovementoffluidthroughasemi-permeablemembranedrivenbyapressuregradient(hydrostaticpressure).Theeffluentpumpforcesplasmawaterandsolutesacrossthemembraneinthefilter.ThistransportmechanismisusedinSCUF,CVVH,CVVHD,andCVVHDF.306100135306100135SCUFSyringepumpReturnPressureAirDetectorBloodPumpAccessPressureFilterPressureBLDHemofilterPatientEffluentPumpReturnClampPreBloodPumpEffluentPressureCVVH-ConvectionContinuousveno-venoushemofiltrationRequiresblood,effluentandreplacementpumps.Dialysateisnotrequired.Plasmawaterandsolutesareremovedbyconvectionandultrafiltration.306100135TransportMechanism:ConvectionRemovalofsolutes,especiallymiddleandlargemolecules,byconvectionofrelativelylargevolumesoffluidandsimultaneous.Thistransportmechanismisused:CVVHCVVHDF306100135ReplacementFluidsPhysicianRxandadjustedbasedonpt.clinicalneed.Sterilereplacementsolutionsmaybe:Bicarbonate-basedorLactate-basedsolutionsElectrolytesolutionsMustbesterileandlabeledforIVUseHigherratesincreaseconvectiveclearancesYouarewhatyoureplace306100135CVVHReturnPressureAirDetectorReturnClampPatientAccessPressureEffluentPumpSyringePumpFilterPressureHemofilterPrePostPostReplacementPumpReplacementPumpPreBloodPumpEffluentPressure306100135CVVHD-DiffusionContinuousveno-venoushemodialysisRequirestheuseofblood,effluentanddialysispumps.Replacementsolutionisnotrequired.Plasmawaterandsolutesareremovedbydiffusionandultrafiltration.306100135TransportMechanisms:DiffusionRemovalofsmallmoleculesbydiffusionthroughtheadditionofdialysatetothefluidsideofthefilter.DialysateisusedtocreateaconcentrationgradientacrossasemipermeablemembraneDialysisusesasemipermeablemembraneforselecteddiffusionThistransportmechanismisusedin:CVVHDCVVHDF306100135DialysateSolutionsThroughdiffusion,dialysatecorrectsunderlyingmetabolicproblemsDialysateisdependentonbufferingagent,electrolytes,andglucoseDialysateformulasshouldreflectnormalplasmavaluestoachievehomeostasis306100135306100135CVVHDReturnPressureAirDetectorReturnClampAccessPressureBloodPumpSyringePumpFilterPressureHemofilterPatientEffluentPumpDialysatePumpPreBloodPumpBLDEffluentPressure306100135BicarbonateBasedSolutionBicarbonatebasedsolutionsarephysiologicandreplacelostbicarbonateimmediately.EffectivetooltocorrectacidosisConcentrationof30-35mEq/Lcorrectsacidosisin24to48hours.306100135BicarbonateBasedSolutionPreferredbufferforpatientswithcompromisedliverfunction.MeanarterialpressureremainsstableSuperiorbufferinnormalizingacidosiswithouttheriskofalkalosisImprovedhemodynamicstability,andfewercardiovascularevents.306100135PlasmaPrismaSate

BK0/3.5PrismaSate

BGK2/0CalciumCa2+(mEq/L)4.3-5.33.50MagnesiumMg2+(mEq/L)1.5-2.51.01.0SodiumNa+(mEq/L)135-145140140PotassiumK+(mEq/L)3.5-5.002.0ChlorideCl-(mEq/L)95-108109.5108Lactate(mEq/L)0.5-2.033BicarbonateHCO3-(mEq/L)22-263232Glucose(mg/dL)65-1100110Osmolarity(mOsm/L)280-300287292pH7.35-7.45~7.40~7.40PrismaSateSolution306100135Lactate-basedSolution Metabolizedintobicarbonateprovidingit’sundernormalconditions.Lactateisconvertedintheliverona1:1basistobicarbonateandcansufficientlycorrectacidemia.306100135LactateBasedSolutionNonphysiologicpHvalueof5.4IsapowerfulperipheralvasodilatorFurtheracidemiaforpatientsin:HypoxiaLiverimpairmentPre-existinglacticacidemiacanresultinworseningoflacticacidemia306100135CVVHDFContinuousveno-venoushemodiafiltrationRequirestheuseofablood,effluent,dialysateandreplacementpumps.Bothdialysateandreplacementsolutionsareused.Plasmawaterandsolutesareremovedbydiffusion,convectionandultrafiltration.306100135TransportMechanisms:

DiffusionandConvectionRemovalofsmallmoleculesbydiffusionthroughtheadditionofdialysatesolution.Removalofmiddletolargemoleculesbyconvectionthroughtheadditionofreplacementsolution.Thistransportmechanismisusedin:CVVHDF306100135CRRTTransportMechanismsAdsorptionMolecularadherencetothesurfaceorinteriorofthemembraneThismechanismisusedin:SCUFCVVHCVVHDorCVVHDwithultrafiltrationCVVHDF306100135306100135PrinciplesofCRRTclearanceCRRTclearanceofsoluteisdependentonthefollowing:ThemoleculesizeofthesoluteTheporesizeofthesemi-permeablemembraneThehighertheultrafiltrationrate(UFR),thegreaterthesoluteclearance.

306100135306100135306100135306100135PrinciplesofCRRTclearanceSmallmoleculeseasilypassthroughamembranedrivenbydiffusionandconvection.Middleandlargesizemoleculesareclearedprimarilybyconvection.Semi-permeablemembraneremovesoluteswithamolecularweightofupto50,000Daltons.Plasmaproteinsorsubstanceshighlyprotein—boundwillnotbecleared.306100135PrinciplesofCRRTclearanceSievingCoefficientTheabilityofasubstancetopassthroughamembranefromthebloodcompartmentofthehemofiltertothefluidcompartment.Asievingcoefficientof1willallowfreepassageofasubstance;butatacoefficientof0,thesubstanceisunabletopass..94Na+1.0K+1.0Cr0albuminwillnotpass306100135VascularAccessAveno-venousdoublelumenhemodialysiscatheterortwosinglelumenvenoushemodialysiscathetersmaybeused.306100135AccessLocationInternalJugularVeinPrimarysiteofchoiceduetolowerassociatedriskofcomplicationandsimplicityofcatheterinsertion.FemoralVeinPatientimmobilized,thefemoralveinisoptimalandconstitutestheeasiestsiteforinsertion.SubclavinVeinTheleastpreferredsitegivenitshigherriskofpneumo/hemothoraxanditsassociationwithcentralvenousstenosis.306100135ChoosingtherightcatheterThelengthofthecatheterchosenwilldependuponthesiteusedSizeofthecatheterisimportantinthepediatricpopulation.Thefollowingaresuggestedguidelinesforthedifferentsites:RIJ=15cmFrenchLIJ=20cmFrenchFemoral=25cmFrench306100135MembranetypesandcharacteristicsHemofiltermembranearecomposedof:HighfluxmaterialSynthetic/biocompatiblematerialStructuraldesignischaracterizedby:HighfluidremovalMolecularcut-offweightof30,000-50,000Daltons.306100135Semi-permeableMembrane Thesemi-permeablemembraneprovides:Aninterfacebetweenthebloodanddialysatecompartment.Biocompatibilityminimizes:SeverepatientreactionsDecreasesthecomplementactivation306100135ComplicationsVascularaccessVascularspasm(initialBFRtoohigh)MovementofcatheteragainstvesselwallImproperlengthofhemodialysiscatheterinsertedFluidvolumedeficitExcessivefluidremovalwithoutappropriatefluidreplenishment306100135ComplicationsHypotensionIntravascularvolumedepletionUnderlyingcardiacdysfunctionElectrolyteimbalancesHighultrafiltrationrates(highclearance)Inadequatereplenishmentofelectrolytesbyintravenousinfusion,InadequatereplenishmentofbicarbonatelossduringCRRT306100135Acid/baseimbalanceRenaldysfunctionRespiratorycompromiseBloodlossIneffectiveanticoagulationtherapyClottingofhemofilterInadvertentdisconnectionintheCRRTsystemHemorrhageduetoover-anticoagulationBloodfilterleaksComplications306100135ComplicationsAirembolusLeaksorfaultyconnectionsintubingLineseparation.CardiacarrestHypotension/hypertensionHemolysisAirembolismCirculatoryoverloadArrhythmias306100135ClinicalConditionstoConsiderARFandneedforfluidmanagementrelatedto:SIRSUnstableonIHDOrgantransplantsCHF/volumeoverloadPostCVsurgeryPosttraumapatientsSevereBurnsFluidManagementinCRRTGoalofFluidManagement“Thepatientwillachieveandmaintainfluidvolumebalancewithinplannedoranticipatedgoals” (ANNAStandardsofClinicalPracticeforContinuousRenalReplacementTherapy”)ConsiderationsIntakesandoutputs(I&O)I&OFormulaNetfluidremovalhourly(physicianorder)+Nonprismaintake(IV,TPN,etc.)-Nonprismaoutput(urine,etc.)=PatientFluidRemovalRate(setinprisma)306100135HypothermiainCRRTCausesPatient’sbloodinextracorporealcircuitatroomtemperatureAdministrationoflargevolumesofroomtemperaturefluids(replacementanddialysate)SignsandSymptomsHemodynamicinstabilityChilling,shiveringSkinpallor,coolnessandcyanosisHypothermiaTreatmentmeasuresWarmingblanketsPrismatherm?

IIBloodWarmerPrismaflo?BloodWarmerInitiationofTherapyAssessandrecordthepatient’svitalsignsandhemodynamicparameterspriortoinitiationoftherapy.ReviewphysicianordersandlabdataPreparevascularaccessusingunitprotocol.Setfluidremoval,dialysateandreplacementsolutionflowratesasprescribed.Administeranticoagulantandinitiateinfusionifapplicable.Documentpatient’shemodynamicstabilitywithinitiationoftherapy.306100135Intratherapy

Monitoring

ThecriticalcarenursemustcontinuouslymonitorthefollowingparametersduringCRRTBloodpressure PatencyofcircuitHemodynamicstabilityLevelofconsciousnessAcid/basebalanceElectrolytebalanceHematologicalstatusInfectionNutritionalstatusAirembolusBloodflowrateUltrafiltrationflowrateDialysate/replacementflowrateAlarmsandresponsesColorofultrafiltrate/filterbloodleakColorofCRRTcircuit306100135TerminationofTherapyThedecisiontoterminateCRRTismadebythenephrologistoranintensivistbasedonthepatient’srenalrecoveryorthepatient’sstatus-recoveryordecisionofthepatientandfamily.Extracorporealcircuitwillbediscontinuedasperestablishedprotocol.Vascularaccesscareadministeredasperunitprotocol306100135CurrentResearchFAQsHowmuchreplacementanddialysatedoyouuse?Ronco’sresearchEffectsofdifferentdosesinCVVHonoutcomeofARF-Ronco&Bellomo

study.Lancet.july00Prospectivestudyon425patients-3groups:Study:survival

after15daysofHFstoprecoveryofrenal

function3061001351009080706050403020100Group1(n=146)(Uf

=20ml/h/Kg)Group2(n=139)(Uf

=35ml/h/Kg)Group3(n=140)(Uf

=45ml/h/Kg)41%57%58%p<0.001pn..s.p<0.001Survival(%)

EffectsofdifferentdosesinCVVHonoutcomeofARF-Ronco&Bellomo

study.Lancet.july00306100135EffectofBUNatCVVHInitiationonSurvival80706050403020100Group1Group2Group3

SurvivorsNonSurvivorsp<0.01

BloodUreaNitrogen(mg/dl)p<0.01p<0.01EffectsofdifferentdosesinCVVHonoutcomeofARF-Ronco&Bellomo

study.Lancet.july00306100135RIFLECriteria306100135RIFLEStratificationinPatientsTreatedwithCRRT

Belletal,NephrolDialTransplant2005306100135Conclusions