PrismaFlexSTEPP

Basic CRRT Principles

Course ObjectivesBy the end of the Gambro CRRT training course the participant will be able to:

Define CRRT and the associated therapies Discuss the basic CRRT principles Discuss the basic principles of the solute transport mechanisms Identify the clinical indications for administering CRRT, including an overview of patient selection and therapy application Have a working knowledge of basic CRRT machine set up, run, end treatment and troubleshooting skills. Describe the CRRT machines safety management features, pressure monitoring and fluid balance principles.

Continuous Renal Replacement Therapy (CRRT)

Any extracorporeal blood purification therapyintended to substitute for impaired renal function over an extended period of time and applied for or aimed at being applied for 24 hours/day.

Bellomo R., Ronco C., Mehta R, Nomenclature for Continuous Renal Replacement Therapies, AJKD, Vol 28, No. 5, Suppl 3, Nov 1996

Why CRRT?CRRT closely mimics the native kidney in treating ARF and fluid overload

Removes large amounts of fluid and waste products over time Tolerated well by hemodynamically unstable patients

CRRT Treatment Goals Maintain fluid, electrolyte, acid/base balance Prevent further damage to kidney tissue Promote healing and total renal recovery Allow other supportive measures; nutritional support

Determinants of OutcomeInitiation of Therapy Ronco Study Gettings Study ADQI Consensus Initiative - Rifle Criteria

Dose Ronco Study Kellum Meta-Analysis Saudan Study

GFR Criteria Risk Injury Failure LossIncreased creatinine x 1.5 or GFR decrease >25%

Urine Output CriteriaUO 50%

UO 75% or Serum Creatinine > 4mg/dl

UO 4 weeks

ESRD

End-stage renal disease (>3 months)

Effects of different doses in CVVH on outcome of ARF - Ronco & Bellomo study. Lancet . july 00

Cumulative Survival (%) vs Treatment Dose

100 90 80

p < 0.001

Survival (%)

70 60 50 40 30 20 10 0

p < 0.001

p n..s.

41 %

57 %

58 %

Group 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)

SummaryEvidenced Based Research reports that patient survival is improved by: Early initiation: Utilization of RIFLE Criteria Minimum dose delivery of 35 ml/kg/hr eg. 70 kg patient = 2450 ml/hEffects of different doses in CVVH on outcomes of ARF C. Ronco M.D., R. Bellomo M.D. Lancet 2000; 356:26-30.

Anatomy of a Hemofilter 4 External ports blood and dialysis fluid

Potting material support structure

Hollow fibers Semi-permeable membrane

Outer casing

CRRT Transport Mechanisms

Molecular Transport MechanismsUltrafiltration Diffusion Convection Adsorption Fluid Transport

}

Solute Transport

Ultrafiltration Movement of fluid through a semipermeable membrane caused by a pressure gradient Positive, negative and osmotic pressure from non-permeable solutes

UltrafiltrationBlood Out(to patient)

Fluid Volume Reduction to waste Blood In(From patient)

LOW PRESS

HIGH PRESS

Molecular WeightsDaltons

Inflammatory Mediators (1,200-40,000)

large

middle

small

Diffusion Movement of solutes from an area of higher concentration to an area of lower concentration. Dialysate is used to create a concentration gradient across a semipermeable membrane.

Hemodialysis: Diffusion

Dialysate In

Blood Out(to patient)

Dialysate Out(to waste) LOW CONC HIGH CONC

Blood In(from patient)

Convection Movement of solutes with water flow, solvent drag. The more fluid moved through a semipermeable membrane, the more solutes that are removed. Replacement Fluid is used to create convection

Hemofiltration: ConvectionBlood Out(to patient)

Repl. Solution

to waste

Blood In(from patient) LOW PRESS HIGH PRESS

Electrolytes & pH BalanceAnother primary goal for CRRT, specifically: Sodium Potassium Calcium Glucose Phosphate Bicarbonate or lactate buffer

Dialysate and replacement solutions are used in CRRT to attain this goal.

Adsorption

Molecular adherence to the surface or interior of the membrane.

Small vs. Large Molecules Clearance100

Kidney Convection

80

Clearance in %

60

40

20

Diffusion0 Urea (60) 2.500 Creatinine (113) 5.000 20.000 Myoglobin (17.000) 35.000 55.000 65.000 Albumin (66.000)

What is the transport mechanism associated with dialysate and replacement solutions?

Flow Control Unit Pumps

Effluent Pre Blood Pump

Dialysate: Diffusion Replacement: Convection Blood

Effluent Flow RateEffluent = Total Fluid Volume: Patient Fluid Removal Dialysate Flow Replacement Flow Pre-Blood Pump Flow

CRRT Modes of TherapySCUF - Slow Continuous Ultrafiltration CVVH - Continuous Veno-Venous Hemofiltration CVVHD - Continuous Veno-Venous HemoDialysis CVVHDF - Continuous Veno-Venous HemoDiaFiltration

SCUF Slow Continuous UltraFiltration Primary therapeutic goal: Safe and effective management of fluid removal from the patient

SCUF Slow Continuous UltraFiltrationReturn Acces s

Blood Pump

Effluent Pump

PBP Pump

Effluent

Infusion or Anticoagul ant

CVVHD Continuous VV HemoDialysisPrimary therapeutic goal: Small solute removal by diffusion Safe fluid volume management

Dialysate volume automatically removed through the Effluent pump

Solute removal determined by Dialysate Flow Rate.

CVVHD Continuous VV HemoDialysisReturnHemofilter

Blood Pump

Acces s

Dialysat e Pump

Efflue nt Pump

PBP Pum p

Dialysat e Fluid

Efflue nt

Infusion or Anticoagul ant

Dialysate Solutions Flows counter-current to blood flow Remains separated by a semi-permeable membrane Drives diffusive transport dependent on concentration gradient and flow rate

Facilitates removal of small solutes Physician prescribed Contains physiologic electrolyte levels Components adjusted to meet patient needs

CVVH: Continuous VV HemofiltrationPrimary Therapeutic Goal: Removal of small, middle and large sized solutes Safe fluid volume management

Replacement solution is infused into blood compartment pre or post filter Drives convective transport Replacement fluid volume automatically removed by effluent pump

Solute removal determined by Replacement Flow Rate.

CVVH Continuous VV HemofiltrationReturn

Blood Pump

Acces s

Replacemen t Pump 2

Efflue nt Pump

Replacemen t Pump 1

PBP Pum p

Replacemen t2

Efflue nt

Replacemen t1

Infusion or Anticoagul ant

Pre-Dilution Replacement SolutionReturn Acces s

Hemofilter

Blood Pump

Decreases risk of clotting Higher UF capabilities Decreases Hct. In filter

Efflue nt Pump

Replacemen t Pump

PBP Pum p

Efflue nt

Replacemen t Fluid

Infusion or Anticoagul ant

Post-Dilution Replacement SolutionConsider lowering replacement rates (filtration %) Higher BFR (filtration %) Higher anticoagulation More efficient clearance (>15%)Hemofilter

Return

Blood Pump

Acces s

Replacemen Efflue t nt Pump Pump

Replacemen t Pump

PBP Pum p

Replacemen t Fluid

Efflue nt

Replacemen t Fluid

Infusion or Anticoagul ant

Replacement Solutions Infused directly into the blood at points along the blood pathway Drives convective transport Facilitates the removal of small middle and large solutes Physician Prescribed Contains electrolytes at physiological levels Components adjusted to meet patient needs

CVVHDFPrimary therapeutic goal: Solute removal by diffusion and convection Safe fluid volume management Efficient removal of small, middle and large molecules Replacement and dialysate fluid volume automatically removed by effluent pump

Solute removal determined by Replacement + Dialysate Flow Rates.

CVVHDF Continuous VV HemoDiaFiltrationReturn

Blood Pump

Acces s

Dialysat e Pump

Efflue nt Pump

Replacemen t Pump

PBP Pum p

Dialysat e Fluid

Efflue nt

Replacemen t Fluid

Infusion or Anticoagul ant