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1、Continuous Renal Replacement Therapy,Basic Therapy Principles,306100135,Is an extracorporeal blood purification therapy intended to substitute for impaired renal function over an extended period of time and applied for or aimed at being applied for 24 hours a day.*Bellomo R.,Ronco C.,Mehta R,Nomencl
2、ature for Continuous Renal Replacement Therapies,AJKD,Vol 28,No.5,Suppl 3,November 1996,Continuous Renal Replacement Therapy(CRRT),306100135,CRRT Goals,Mimic the functions and physiology of the native organQualitative and quantitative blood purificationRestore and maintain of homeostasisAvoid compli
3、cations and good clinical toleranceProvide conditions favoring recovery of renal function,306100135,Requirements for CRRT,CRRT requires:A central double-lumen veno-venous hemodialysis catheterAn extracorporeal circuit and a hemofilterA blood pump and a effluent pump.With specific CRRT therapies dial
4、ysate and/or replacement pumps are required.,306100135,CRRT Modalities,SCUF-Slow Continuous UltrafiltrationUltrafiltrationCVVH-Continuous Veno-Venous HemofiltrationConvectionCVVHD-Continuous Veno-Venous HemodialysisDiffusionCVVHDF-Continuous Veno-Venous HemodiafiltrationDiffusion and Convection,3061
5、00135,SCUF-Ultrafiltration,Slow continuous ultrafiltration:Requires a blood and an effluent pump.No dialysate or replacement solution.Fluid removal up to 2 liters/hr can be achieved.Primary GoalSafe management of fluid removalLarge fluid removal via ultrafiltration,306100135,Transport mechanism:Ultr
6、afiltration,The movement of fluid through a semi-permeable membrane driven by a pressure gradient(hydrostatic pressure).The effluent pump forces plasma water and solutes across the membrane in the filter.This transport mechanism is used in SCUF,CVVH,CVVHD,and CVVHDF.,306100135,SCUF,Syringe pump,Retu
7、rn Pressure,Air Detector,Blood Pump,Access Pressure,Filter Pressure,BLD,Hemofilter,Patient,Effluent Pump,Return Clamp,Pre Blood Pump,Effluent Pressure,306100135,CVVH-Convection,Continuous veno-venous hemofiltrationRequires blood,effluent and replacement pumps.Dialysate is not required.Plasma water a
8、nd solutes are removed by convection and ultrafiltration.,306100135,Transport Mechanism:Convection,Removal of solutes,especially middle and large molecules,by convection of relatively large volumes of fluid and simultaneous.This transport mechanism is used:CVVH CVVHDF,306100135,Replacement Fluids,Ph
9、ysician Rx and adjusted based on pt.clinical need.Sterile replacement solutions may be:Bicarbonate-based or Lactate-based solutionsElectrolyte solutionsMust be sterile and labeled for IV Use Higher rates increase convective clearancesYou are what you replace,306100135,306100135,CVVH,Return Pressure,
10、Air Detector,Return Clamp,Patient,Access Pressure,Effluent Pump,Syringe Pump,Filter Pressure,Hemofilter,Pre,Post,Post,Replacement Pump,Replacement Pump,Pre Blood Pump,Effluent Pressure,306100135,CVVHD-Diffusion,Continuous veno-venous hemodialysisRequires the use of blood,effluent and dialysis pumps.
11、Replacement solution is not required.Plasma water and solutes are removed by diffusion and ultrafiltration.,306100135,Transport Mechanisms:Diffusion,Removal of small molecules by diffusion through the addition of dialysate to the fluid side of the filter.Dialysate is used to create a concentration g
12、radient across a semi permeable membraneDialysis uses a semi permeable membrane for selected diffusionThis transport mechanism is used in:CVVHD CVVHDF,306100135,Dialysate Solutions,Through diffusion,dialysate corrects underlying metabolic problemsDialysate is dependent on buffering agent,electrolyte
13、s,and glucoseDialysate formulas should reflect normal plasma values to achieve homeostasis,306100135,306100135,CVVHD,Return Pressure,Air Detector,Return Clamp,Access Pressure,Blood Pump,Syringe Pump,Filter Pressure,Hemofilter,Patient,Effluent Pump,Dialysate Pump,Pre Blood Pump,BLD,Effluent Pressure,
14、306100135,Bicarbonate Based Solution,Bicarbonate based solutions are physiologic and replace lost bicarbonate immediately.Effective tool to correct acidosisConcentration of 30-35mEq/L corrects acidosis in 24 to 48 hours.,306100135,Bicarbonate Based Solution,Preferred buffer for patients with comprom
15、ised liver function.Mean arterial pressure remains stableSuperior buffer in normalizing acidosis without the risk of alkalosisImproved hemodynamic stability,and fewer cardiovascular events.,306100135,PrismaSate Solution,306100135,Lactate-based Solution,Metabolized into bicarbonate providing its unde
16、r normal conditions.Lactate is converted in the liver on a 1:1 basis to bicarbonate and can sufficiently correct acidemia.,306100135,Lactate Based Solution,Non physiologic pH value of 5.4Is a powerful peripheral vasodilator Further acidemia for patients in:HypoxiaLiver impairmentPre-existing lactic
17、acidemia can result in worsening of lactic acidemia,306100135,CVVHDF,Continuous veno-venous hemodiafiltrationRequires the use of a blood,effluent,dialysate and replacement pumps.Both dialysate and replacement solutions are used.Plasma water and solutes are removed by diffusion,convection and ultrafi
18、ltration.,306100135,Transport Mechanisms:Diffusion and Convection,Removal of small molecules by diffusion through the addition of dialysate solution.Removal of middle to large molecules by convection through the addition of replacement solution.This transport mechanism is used in:CVVHDF,306100135,CR
19、RT Transport Mechanisms,AdsorptionMolecular adherence to the surface or interior of the membraneThis mechanism is used in:SCUFCVVHCVVHD or CVVHD with ultrafiltrationCVVHDF,306100135,306100135,Principles of CRRT clearance,CRRT clearance of solute is dependent on the following:The molecule size of the
20、 soluteThe pore size of the semi-permeable membrane The higher the ultrafiltration rate(UFR),the greater the solute clearance.,306100135,306100135,306100135,306100135,Principles of CRRT clearance,Small molecules easily pass through a membrane driven by diffusion and convection.Middle and large size
21、molecules are cleared primarily by convection.Semi-permeable membrane remove solutes with a molecular weight of up to 50,000 Daltons.Plasma proteins or substances highly proteinbound will not be cleared.,306100135,Principles of CRRT clearance,Sieving CoefficientThe ability of a substance to pass thr
22、ough a membrane from the blood compartment of the hemofilter to the fluid compartment.A sieving coefficient of 1 will allow free passage of a substance;but at a coefficient of 0,the substance is unable to pass.94 Na+1.0 K+1.0 Cr0 albumin will not pass,306100135,Vascular Access,A veno-venous double l
23、umen hemodialysis catheter or two single lumen venous hemodialysis catheters may be used.,306100135,Access Location,Internal Jugular VeinPrimary site of choice due to lower associated risk of complication and simplicity of catheter insertion.Femoral VeinPatient immobilized,the femoral vein is optima
24、l and constitutes the easiest site for insertion.Subclavin VeinThe least preferred site given its higher risk of pneumo/hemothorax and its association with central venous stenosis.,306100135,Choosing the right catheter,The length of the catheter chosen will depend upon the site used Size of the cath
25、eter is important in the pediatric population.The following are suggested guidelines for the different sites:RIJ=15 cm FrenchLIJ=20 cm FrenchFemoral=25 cm French,306100135,Membrane types and characteristics,Hemofilter membrane are composed of:High flux materialSynthetic/biocompatible materialStructu
26、ral design is characterized by:High fluid removal Molecular cut-off weight of 30,000-50,000 Daltons.,306100135,Semi-permeable Membrane,The semi-permeable membrane provides:An interface between the blood and dialysate compartment.Biocompatibility minimizes:Severe patient reactions Decreases the compl
27、ement activation,306100135,Complications,Vascular access Vascular spasm(initial BFR too high)Movement of catheter against vessel wall Improper length of hemodialysis catheter insertedFluid volume deficitExcessive fluid removal without appropriate fluid replenishment,306100135,Complications,Hypotensi
28、on Intravascular volume depletionUnderlying cardiac dysfunctionElectrolyte imbalances High ultrafiltration rates(high clearance)Inadequate replenishment of electrolytes by intravenous infusion,Inadequate replenishment of bicarbonate loss during CRRT,306100135,Acid/base imbalance Renal dysfunction Re
29、spiratory compromiseBlood loss Ineffective anticoagulation therapyClotting of hemofilter Inadvertent disconnection in the CRRT system Hemorrhage due to over-anticoagulation Blood filter leaks,Complications,306100135,Complications,Air embolus Leaks or faulty connections in tubing Line separation.Card
30、iac arrest Hypotension/hypertensionHemolysisAir embolismCirculatory overloadArrhythmias,306100135,Clinical Conditions to Consider,ARF and need for fluid management related to:SIRSUnstable on IHDOrgan transplantsCHF/volume overloadPost CV surgeryPost trauma patientsSevere Burns,306100135,Fluid Manage
31、ment in CRRT,Goal of Fluid Management“The patient will achieve and maintain fluid volume balance within planned or anticipated goals”(ANNA Standards of Clinical Practice for Continuous Renal Replacement Therapy”)ConsiderationsIntakes and outputs(I&O),306100135,I&O Formula,Net fluid removal hourly(ph
32、ysician order)+Nonprisma intake(IV,TPN,etc.)-Nonprisma output(urine,etc.)=Patient Fluid Removal Rate(set in prisma),306100135,Hypothermia in CRRT,CausesPatients blood in extracorporeal circuit at room temperatureAdministration of large volumes of room temperature fluids(replacement and dialysate)Sig
33、ns and SymptomsHemodynamic instabilityChilling,shiveringSkin pallor,coolness and cyanosis,306100135,Hypothermia,Treatment measuresWarming blanketsPrismatherm II Blood WarmerPrismaflo Blood Warmer,306100135,Initiation of Therapy,Assess and record the patients vital signs and hemodynamic parameters pr
34、ior to initiation of therapy.Review physician orders and lab dataPrepare vascular access using unit protocol.Set fluid removal,dialysate and replacement solution flow rates as prescribed.Administer anticoagulant and initiate infusion if applicable.Document patients hemodynamic stability with initiat
35、ion of therapy.,306100135,Intratherapy MonitoringThe critical care nurse must continuously monitor the following parameters during CRRT,Blood pressurePatency of circuitHemodynamic stabilityLevel of consciousnessAcid/base balanceElectrolyte balanceHematological statusInfectionNutritional statusAir em
36、bolus,Blood flow rateUltrafiltration flow rateDialysate/replacement flow rateAlarms and responsesColor of ultrafiltrate/filter blood leakColor of CRRT circuit,306100135,Termination of Therapy,The decision to terminate CRRT is made by the nephrologist or an intensivist based on the patients renal rec
37、overy or the patients status-recovery or decision of the patient and family.Extracorporeal circuit will be discontinued as per established protocol.Vascular access care administered as per unit protocol,Current Research,FAQs,How much replacement and dialysate do you use?,Roncos research,306100135,Ef
38、fects of different doses in CVVH on outcome of ARF-Ronco&Bellomo study.Lancet.july 00,Prospective study on 425 patients-3 groups:Study:survival after 15 days of HF stoprecovery of renal function,306100135,Effects of different doses in CVVH on outcome of ARF-Ronco&Bellomo study.Lancet.july 00,3061001
39、35,Effect of BUN at CVVH Initiation on Survival,Group 1,Group 2,Group 3,Survivors,Non Survivors,p 0.01,Blood Urea Nitrogen(mg/dl),p 0.01,p 0.01,Effects of different doses in CVVH on outcome of ARF-Ronco&Bellomo study.Lancet.july 00,306100135,RIFLE Criteria,306100135,RIFLE Stratification in Patients
40、Treated with CRRTBell et al,Nephrol Dial Transplant 2005,306100135,Conclusions:,An increased treatment dose from 20 ml/h/kg to 35 ml/h/kg significantly improved survival.A delivery of 45ml/kg/hr did not result in further benefit in terms of survival,but in the septic patient an improvement was obser
41、ved.Our data suggest an early initiation of treatment and a minimum dose delivery of 35 ml/h/kg(ex.70 kg patient=2450 ml/h)improve patient survival rate.,Effects of different doses in CVVH on outcome of ARF-Ronco&Bellomo study.Lancet.july 00,Renal Recovery?,CRRT does affect resumption of function.,3
42、06100135,By avoiding hypotensive episodes,the risk of further kidney damage is reduced and the chance for renal recovery is enhanced,306100135,0,.2,.4,.6,.8,1,0,20,40,60,80,100,days,Recovery from Dialysis Dependence:BEST Kidney Data,Recovery from dialysis dependence,Manuscript under review,Leading t
43、he way,306100135,CRRT vs.IHD in Renal Recovery,Recent studies suggest that CRRT is superior to IHD with respect to recovery of renal functionImplications go far beyond just“hard”endpoint of renal recovery Need for chronic dialysis impairs quality of lifeIf length of stay(LOS)in ICU can be reduced this will have a major impact on hospital budgetPatients dependent on chronic dialysis will consume significant health care resources and have an impact on the community health care budget,Leading the way,306100135,Questions?,
