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1、Continuous Renal Replacement TherapyBasic Therapy PrinciplesIs 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, Nomenclature fo
2、r Continuous Renal Replacement Therapies, AJKD, Vol 28, No. 5, Suppl 3, November 1996Continuous Renal Replacement Therapy (CRRT)306100135CRRT GoalsMimic the functions and physiology of the native organQualitative and quantitative blood purificationRestore and maintain of homeostasisAvoid complicatio
3、ns and good clinical toleranceProvide conditions favoring recovery of renal function306100135Requirements for CRRTCRRT requires:A central double-lumen veno-venous hemodialysis catheterAn extracorporeal circuit and a hemofilterA blood pump and a effluent pump. With specific CRRT therapies dialysate a
4、nd/or replacement pumps are required.306100135CRRT ModalitiesSCUF- Slow Continuous UltrafiltrationUltrafiltrationCVVH- Continuous Veno-Venous HemofiltrationConvectionCVVHD- Continuous Veno-Venous HemodialysisDiffusionCVVHDF- Continuous Veno-Venous HemodiafiltrationDiffusion and Convection306100135SC
5、UF-UltrafiltrationSlow 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 ultrafiltration306100135Transport mechanism: Ultrafiltratio
6、nThe 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.306100135306100135SCUFSyringe pumpRetu
7、rn Pressure Air Detector Blood Pump Access Pressure Filter Pressure BLD HemofilterPatient Effluent PumpReturn Clamp Pre Blood PumpEffluent Pressure CVVH-ConvectionContinuous veno-venous hemofiltrationRequires blood, effluent and replacement pumps.Dialysate is not required.Plasma water and solutes ar
8、e removed by convection and ultrafiltration.306100135Transport Mechanism: ConvectionRemoval of solutes, especially middle and large molecules, by convection of relatively large volumes of fluid and simultaneous.This transport mechanism is used:CVVH CVVHDF306100135Replacement FluidsPhysician Rx and a
9、djusted 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 replace306100135CVVHReturn Pressure Air Detector Return Clamp Pa
10、tient Access Pressure Effluent Pump Syringe Pump Filter PressureHemofilter Pre Post Post Replacement Pump Replacement Pump Pre Blood Pump Effluent Pressure 306100135CVVHD-DiffusionContinuous veno-venous hemodialysisRequires the use of blood, effluent and dialysis pumps. Replacement solution is not r
11、equired.Plasma water and solutes are removed by diffusion and ultrafiltration.306100135Transport Mechanisms: DiffusionRemoval of small molecules by diffusion through the addition of dialysate to the fluid side of the filter.Dialysate is used to create a concentration gradient across a semi permeable
12、 membraneDialysis uses a semi permeable membrane for selected diffusionThis transport mechanism is used in: CVVHD CVVHDF306100135Dialysate SolutionsThrough diffusion, dialysate corrects underlying metabolic problemsDialysate is dependent on buffering agent, electrolytes, and glucoseDialysate formula
13、s should reflect normal plasma values to achieve homeostasis306100135306100135CVVHDReturn Pressure Air DetectorReturn Clamp Access Pressure Blood Pump Syringe Pump Filter Pressure Hemofilter Patient Effluent Pump Dialysate Pump Pre Blood Pump BLD Effluent Pressure 306100135Bicarbonate Based Solution
14、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.306100135Bicarbonate Based SolutionPreferred buffer for patients with compromised liver function.Mean arterial pressu
15、re remains stableSuperior buffer in normalizing acidosis without the risk of alkalosisImproved hemodynamic stability, and fewer cardiovascular events.306100135PlasmaPrismaSateBK0/3.5PrismaSateBGK2/0Calcium Ca2+ (mEq/L)4.3 - 5.33.50Magnesium Mg2+ (mEq/L)1.5 - 2.51.01.0Sodium Na+ (mEq/L)135 - 14514014
16、0Potassium K+ (mEq/L)3.5 - 5.002.0Chloride Cl- (mEq/L)95 - 108109.5108Lactate (mEq/L)0.5 - 2.033Bicarbonate HCO3- (mEq/L)22 - 263232Glucose (mg/dL)65 - 1100110Osmolarity (mOsm/L)280 - 300287292pH7.35 - 7.45 7.40 7.40PrismaSate Solution306100135Lactate-based SolutionMetabolized into bicarbonate provi
17、ding its under normal conditions.Lactate is converted in the liver on a 1:1 basis to bicarbonate and can sufficiently correct acidemia.306100135Lactate Based SolutionNon physiologic pH value of 5.4Is a powerful peripheral vasodilator Further acidemia for patients in:HypoxiaLiver impairmentPre-existi
18、ng lactic acidemia can result in worsening of lactic acidemia306100135CVVHDFContinuous 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 a
19、nd ultrafiltration.306100135Transport Mechanisms: Diffusion and ConvectionRemoval 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: CVVHDF306
20、100135CRRT Transport MechanismsAdsorptionMolecular adherence to the surface or interior of the membraneThis mechanism is used in:SCUFCVVHCVVHD or CVVHD with ultrafiltrationCVVHDF306100135306100135Principles of CRRT clearanceCRRT clearance of solute is dependent on the following:The molecule size of
21、the soluteThe pore size of the semi-permeable membrane The higher the ultrafiltration rate (UFR), the greater the solute clearance. 306100135306100135306100135306100135Principles of CRRT clearanceSmall molecules easily pass through a membrane driven by diffusion and convection.Middle and large size
22、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. 306100135Principles of CRRT clearanceSieving CoefficientThe ability of a substance to pass thro
23、ugh 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 pass306100135Vascular AccessA veno-venous double lum
24、en hemodialysis catheter or two single lumen venous hemodialysis catheters may be used.306100135Access LocationInternal Jugular VeinPrimary site of choice due to lower associated risk of complication and simplicity of catheter insertion. Femoral VeinPatient immobilized, the femoral vein is optimal a
25、nd 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.306100135Choosing the right catheterThe length of the catheter chosen will depend upon the site used Size of the catheter
26、is important in the pediatric population. The following are suggested guidelines for the different sites:RIJ= 15 cm FrenchLIJ= 20 cm FrenchFemoral= 25 cm French306100135Membrane types and characteristicsHemofilter membrane are composed of:High flux materialSynthetic/biocompatible materialStructural
27、design is characterized by: High fluid removal Molecular cut-off weight of 30,000-50,000 Daltons.306100135Semi-permeable MembraneThe semi-permeable membrane provides: An interface between the blood and dialysate compartment.Biocompatibility minimizes:Severe patient reactions Decreases the complement
28、 activation 306100135ComplicationsVascular 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 replenishment306100135ComplicationsHypotension Intrava
29、scular volume depletionUnderlying cardiac dysfunctionElectrolyte imbalances High ultrafiltration rates (high clearance) Inadequate replenishment of electrolytes by intravenous infusion, Inadequate replenishment of bicarbonate loss during CRRT306100135Acid/base imbalance Renal dysfunction Respiratory
30、 compromiseBlood loss Ineffective anticoagulation therapyClotting of hemofilter Inadvertent disconnection in the CRRT system Hemorrhage due to over-anticoagulation Blood filter leaksComplications306100135ComplicationsAir embolus Leaks or faulty connections in tubing Line separation.Cardiac arrest Hy
31、potension/hypertensionHemolysisAir embolismCirculatory overloadArrhythmias306100135Clinical Conditions to ConsiderARF and need for fluid management related to:SIRSUnstable on IHDOrgan transplantsCHF /volume overloadPost CV surgeryPost trauma patientsSevere BurnsFluid Management in CRRTGoal of Fluid
32、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)I & O FormulaNet fluid removal hourly (physician order)+Nonprisma intake (IV
33、, TPN, etc.)-Nonprisma output (urine, etc.)=Patient Fluid Removal Rate (set in prisma)306100135Hypothermia in CRRTCausesPatients blood in extracorporeal circuit at room temperatureAdministration of large volumes of room temperature fluids (replacement and dialysate)Signs and SymptomsHemodynamic inst
34、abilityChilling, shiveringSkin pallor, coolness and cyanosisHypothermiaTreatment measuresWarming blanketsPrismatherm II Blood WarmerPrismaflo Blood WarmerInitiation of TherapyAssess and record the patients vital signs and hemodynamic parameters prior to initiation of therapy.Review physician orders
35、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 initiation of therapy.306100135Intratherapy MonitoringThe c
36、ritical care nurse must continuously monitor the following parameters during CRRTBlood pressurePatency of circuitHemodynamic stabilityLevel of consciousnessAcid/base balanceElectrolyte balanceHematological statusInfectionNutritional statusAir embolusBlood flow rateUltrafiltration flow rateDialysate/
37、replacement flow rateAlarms and responsesColor of ultrafiltrate/filter blood leakColor of CRRT circuit306100135Termination of TherapyThe decision to terminate CRRT is made by the nephrologist or an intensivist based on the patients renal recovery or the patients status-recovery or decision of the pa
38、tient and family.Extracorporeal circuit will be discontinued as per established protocol.Vascular access care administered as per unit protocol306100135Current ResearchFAQsHow much replacement and dialysate do you use?Roncos researchEffects of different doses in CVVH on outcome of ARF - Ronco & Bell
39、omo study. Lancet . july 00Prospective study on 425 patients - 3 groups:Study: survival after 15 days of HF stoprecovery of renal function3061001351009080706050403020100Group 1(n=146)( (Uf = = 20 ml/h/Kg)Group 2 (n=139)(Uf = 35 ml/h/Kg)Group 3 (n=140)(Uf = 45 ml/h/Kg) 41 % 57 % 58 %p 0.001p n.s.p 0.
40、001Survival (%)Survival (%) Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00306100135Effect of BUN at CVVH Initiation on Survival80706050403020100Group 1Group 2Group 3 SurvivorsSurvivorsNon SurvivorsNon Survivorsp 0.01p 0.01 Blood Urea Nitrogen (mg/dl)p
41、0.01p 0.01p 0.01p 0.01Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00306100135RIFLE Criteria306100135RIFLE Stratification in Patients Treated with CRRTBell et al, Nephrol Dial Transplant 2005306100135Conclusions:An increased treatment dose from 20 ml/h/
42、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 observed. Our data suggest an early initiation of treatment and a minimum dose delivery of 35 ml/h/kg (ex. 70 kg patient = 24
43、50 ml/h) improve patient survival rate.Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00306100135Renal Recovery? CRRT does affect resumption of function.By avoiding hypotensive episodes, the risk of further kidney damage is reduced and the chance for rena
44、l recovery is enhanced3061001350.2.4.6.81020406080100IRRTCRRTdaysRecovery from Dialysis Dependence: BEST Kidney DataRecovery from dialysis dependenceManuscript under reviewLeading the way306100135CRRT vs. IHD in Renal RecoveryRecent studies suggest that CRRT is superior to IHD with respect to recove
45、ry 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 budgetLeading the way306100135Questions?306100135