1、Continuous Renal Replacement TherapyBasic Therapy Principles306100135Is 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,Nomenclatu
2、re for 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 complications
3、 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 and/
4、or replacement pumps are required.306100135CRRT Modalities SCUF-Slow Continuous Ultrafiltration Ultrafiltration CVVH-Continuous Veno-Venous Hemofiltration Convection CVVHD-Continuous Veno-Venous Hemodialysis Diffusion CVVHDF-Continuous Veno-Venous Hemodiafiltration Diffusion and Convection306100135S
5、CUF-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 ultrafiltration306100135 The movement of fluid through a s
6、emi-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.306100135SCUFSyringe pumpReturn Pressure Air Detector Blood Pump Access Pressu
7、re Filter Pressure BLD HemofilterPatient Effluent PumpReturn Clamp Pre Blood PumpEffluent Pressure 306100135CVVH-ConvectionContinuous veno-venous hemofiltrationRequires blood,effluent and replacement pumps.Dialysate is not required.Plasma water and solutes are removed by convection and ultrafiltrati
8、on.306100135Transport 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 CVVHDF306100135Replacement Fluids Physician Rx and adjusted based on pt.clinical need.Sterile
9、replacement solutions may be:Bicarbonate-based or Lactate-based solutions Electrolyte solutions Must be sterile and labeled for IV Use Higher rates increase convective clearances You are what you replace306100135306100135CVVHReturn Pressure Air Detector Return Clamp Patient Access Pressure Effluent
10、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 required.Plasma water and solutes
11、are removed by diffusion and ultrafiltration.306100135Transport 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 gradient across a semi permeable membrane Dialysis uses a semi pe
12、rmeable membrane for selected diffusion This transport mechanism is used in:CVVHD CVVHDF306100135Dialysate Solutions Through diffusion,dialysate corrects underlying metabolic problems Dialysate is dependent on buffering agent,electrolytes,and glucose Dialysate formulas should reflect normal plasma v
13、alues 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 SolutionBicarbonate based solutions are
14、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 pressure remains stableSuperior buffer
15、 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)135-145140140Potassium K+(mEq/L)3.5-5.002.0Chloride Cl
16、-(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 Solution Metabolized into bicarbonate providing its under normal conditions.Lactate is converted in the
17、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-existing lactic acidemia can result in worsening of lactic acidemia
18、306100135CVVHDFContinuous 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 ultrafiltration.306100135Transport Mechanisms:Diffusion and C
19、onvection 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:CVVHDF306100135CRRT Transport MechanismsMolecular adherence to the surface
20、or interior of the membraneThis mechanism is used in:SCUF CVVH CVVHD or CVVHD with ultrafiltration CVVHDF306100135306100135Principles of CRRT clearance CRRT clearance of solute is dependent on the following:The molecule size of the solute The pore size of the semi-permeable membrane The higher the u
21、ltrafiltration 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 molecules are cleared primarily by convection.Semi-permeable membrane remo
22、ve solutes with a molecular weight of up to 50,000 Daltons.Plasma proteins or substances highly proteinbound will not be cleared.306100135Principles of CRRT clearance Sieving Coefficient The ability of a substance to pass through a membrane from the blood compartment of the hemofilter to the fluid c
23、ompartment.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 Cr 0 albumin will not pass306100135Vascular AccessA veno-venous double lumen hemodialysis catheter or two single lumen venous hemodialysis catheters
24、may be used.306100135Access Location Internal Jugular Vein Primary site of choice due to lower associated risk of complication and simplicity of catheter insertion.Femoral Vein Patient immobilized,the femoral vein is optimal and constitutes the easiest site for insertion.Subclavin Vein The least pre
25、ferred 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 is important in the pediatric population.The following are suggested guide
26、lines for the different sites:RIJ=15 cm FrenchLIJ=20 cm FrenchFemoral=25 cm French306100135Membrane types and characteristics Hemofilter membrane are composed of:High flux material Synthetic/biocompatible material Structural design is characterized by:High fluid removal Molecular cut-off weight of 3
27、0,000-50,000 Daltons.306100135Semi-permeable Membrane The semi-permeable membrane provides:An interface between the blood and dialysate compartment.Biocompatibility minimizes:Severe patient reactions Decreases the complement activation 306100135Complications Vascular access Vascular spasm(initial BF
28、R too high)Movement of catheter against vessel wall Improper length of hemodialysis catheter inserted Fluid volume deficit Excessive fluid removal without appropriate fluid replenishment306100135Complications Hypotension Intravascular volume depletion Underlying cardiac dysfunction Electrolyte imbal
29、ances High ultrafiltration rates(high clearance)Inadequate replenishment of electrolytes by intravenous infusion,Inadequate replenishment of bicarbonate loss during CRRT306100135Acid/base imbalance Renal dysfunction Respiratory compromiseBlood loss Ineffective anticoagulation therapyClotting of hemo
30、filter Inadvertent disconnection in the CRRT system Hemorrhage due to over-anticoagulation Blood filter leaksComplications306100135Complications Air embolus Leaks or faulty connections in tubing Line separation.Cardiac arrest Hypotension/hypertension Hemolysis Air embolism Circulatory overload Arrhy
31、thmias306100135Clinical Conditions to ConsiderARF and need for fluid management related to:SIRS Unstable on IHD Organ transplants CHF/volume overload Post CV surgery Post trauma patients Severe Burns306100135Fluid Management in CRRTGoal of Fluid Management“The patient will achieve and maintain fluid
32、 volume balance within planned or anticipated goals”(ANNA Standards of Clinical Practice for Continuous Renal Replacement Therapy”)ConsiderationsIntakes and outputs(I&O)306100135I&O FormulaNet fluid removal hourly(physician order)+Nonprisma intake(IV,TPN,etc.)-Nonprisma output(urine,etc.)=Patient Fl
33、uid Removal Rate(set in prisma)306100135Hypothermia in CRRTCauses Patients blood in extracorporeal circuit at room temperature Administration of large volumes of room temperature fluids(replacement and dialysate)Signs and Symptoms Hemodynamic instability Chilling,shivering Skin pallor,coolness and c
34、yanosis306100135HypothermiaTreatment measuresWarming blanketsPrismatherm II Blood WarmerPrismaflo Blood Warmer306100135Initiation of Therapy Assess and record the patients vital signs and hemodynamic parameters prior to initiation of therapy.Review physician orders and lab data Prepare vascular acce
35、ss 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 critical care nurse must continuous
36、ly monitor the following parameters during CRRT Blood pressure Patency of circuit Hemodynamic stability Level of consciousness Acid/base balance Electrolyte balance Hematological status Infection Nutritional status Air embolus Blood flow rate Ultrafiltration flow rate Dialysate/replacement flow rate
37、 Alarms and responses Color of ultrafiltrate/filter blood leak Color of CRRT circuit306100135Termination of Therapy The 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 patient and family.
38、Extracorporeal circuit will be discontinued as per established protocol.Vascular access care administered as per unit protocolCurrent ResearchFAQsHow much replacement and dialysate do you use?Roncos research306100135Effects of different doses in CVVH on outcome of ARF-Ronco&Bellomo study.Lancet.july
39、 00Prospective study on 425 patients-3 groups:Study:survival after 15 days of HF stop recovery 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 0.001 Effects of different doses in CVVH on out
40、come of ARF-Ronco&Bellomo study.Lancet.july 00306100135Effect of BUN at CVVH Initiation on Survival80706050403020100Group 1Group 2Group 3Blood Urea Nitrogen(mg/dl)Effects of different doses in CVVH on outcome of ARF-Ronco&Bellomo study.Lancet.july 00306100135RIFLE Criteria306100135RIFLE Stratificati
41、on in Patients Treated with CRRTBell et al,Nephrol Dial Transplant 2005306100135Conclusions: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 improveme
42、nt was observed.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 00Renal Recovery?CRRT does affect resumption of fu
43、nction.306100135By avoiding hypotensive episodes,the risk of further kidney damage is reduced and the chance for renal recovery is enhanced3061001350.2.4.6.81020406080100IRRTCRRTdaysRecovery from Dialysis Dependence:BEST Kidney DataRecovery from dialysis dependenceManuscript under reviewLeading the
44、way306100135CRRT vs.IHD in Renal RecoveryRecent 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 life If length of stay(LOS)in ICU can be reduced this will have a major impact on hospital budget Patients dependent on chronic dialysis will consume significant health care resources and have an impact on the community health care budgetLeading the way306100135Questions?
