Hemodialysis Adequacy

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Hemodialysis Adequacy. Lutfi Alkorbi MD King Faisal Specialist Hospital Riyadh Saudi Arabia. Global dialysis population. Cardiovascular mortality in general population VS ESRD patients. Mortality in Hemodialysis Patients in Europe, Japan, and the United States. DOPPS 2006. - PowerPoint PPT Presentation


  • Hemodialysis AdequacyLutfi Alkorbi MDKing Faisal Specialist HospitalRiyadh Saudi Arabia

  • Global dialysis population

  • Cardiovascular mortality in general population VS ESRD patients

  • Mortality in Hemodialysis Patients in Europe, Japan, and the United StatesDOPPS 2006

  • Dialysis adequacy and death The effect of dialysis dose on survival

  • First Randomised Controlled Trial In DialysisThe National Cooperative Dialysis Study (NCDS) was the first multicentric, randomized and controlled trial to investigate the impact of dialysis dose on patients' outcome. 160 patients were randomized to two different urea timeaveraged concentrations (TAC; 100vs50mg/dl) and to two different treatment times (2.53.5vs4.55.5h) and followedup for 6months.NCDS 1980

  • First Randomised Controlled Trial In DialysisNCDS 1980Predialysis urea 38 vs 26 mmol. Dialysis 2.5-35h vs 4.5-5 hhigh kt/v and long dialysis high kt/v and short dialysis

    low kt/v and long dialysis

    low kt/v and short dialysis

  • Secondary analysis of NCDSA quantification of dialysis dose using spKt/V was first proposed by Gotch in a secondary analysis of NCDS data. In his analysis, probability of dialysis failure was higher for Kt/V 0.8 and abruptly decreased for Kt/V >0.9.

  • Higher Kt/V has better outcome Gotch FA,Sargent Kidney Int 1985;28:526Kt/v=1.2

  • NCDS ConclusionThus, according to NCDS patient morbidity and treatment failure are related to the dialysis dose

  • Why Should We Measure Dialysis Dose?There is a correlation between delivered dose of hemodialysis and patient morbidity and mortalityClinical symptoms are not reliable

  • Increasing dialysis dose improved survivaldialysis dose Kidney Int 1996; 50:550

  • Measures of dialysis adequacy SpKt/VeKt/VStdKt/VURR

  • Hemodialysis Dose MeasurementKt/V K= dialyzer urea clearance L/h t = dialysis session length hr v = distribution volume of urea L URR

  • Urea reduction Ratio(URR)URR = 100 x (1-Ct/Co)

    Ct = postdialysis BUNCo = predialysis BUN

  • Urea Reduction Volume (URR)SimplePrediction of mortality

    Limitation:Does not account for the contribution of UF to dialysis dose Kt/V=1.1 (UF=0) Kt/v = 1.35 (UF=10%BW)URR=65

  • URR & Kt/V

  • Hemodialysis Dose MeasurementThe preferred method is by formal kinetic urea modeling

    K/DOQI 2006

  • Kt/VComputerized softwareMathematical logarithm Kt/v = -Ln (R-0.008t)+(4-3.5xR) x UF WLn=natural logarithmR=postdialysis BUNpredialysis BUN UF =Ultrafiltration volume in litersW=Postdialysis weight in kg

  • BUN SamplingPredialysisPostdialysisImmediate predialysisSlow flow/stop pump

  • Urea Rebound

    Organs with low blood flow (skin, bone, muscles) may serve as reservoir for urea 70% of TBW is contained in organs that receive only 20% of COSo: during HD, there is loss of urea from well perfused areas, this result in in BUN over 60 minutes post dialysis.

  • Post Dialysis BUN SamplingAvoid 2 rebound:

    Early (3 min)Completed within 30-60 minutes due to flow-volume disequilibrium.

  • Urea Rebound65% rebound ( >50% is AR,15%CP,31% D)

  • Single-Compartment Fixed VolumeSolute Kinetic Mode

  • Single-Pool vs Double-PoolSingle-poolDoes not account for urea transfer between fluid compartmentsWith dialyzer clearance, urea removed from extracellular compartment can exceed transfer from intracellular compartment Urea rebound (30-60 min)So: Dialysis dose will be overestimated if this urea pool is large (underestimated of true V)

  • Two-Compartment Variable VolumeSolute Kinetic Model

  • Equilibrated Kt/VeKt/v is 0.2 units less than single-pool kt/v, but it can be as great 0.6 unit less.For most patient, urea rebound is nearly complete in 15 minutes after hemodialysis but for minority, it may require up to 50-60 minutesThe degree of rebound is high in small patienteKt/V= spKt/V - 0.6 x (spKt/V) / t + 0.03 (for arterial access) eKt/V= spKt/V - 0.47 x (spKt/V) / t + 0.02 (for venous access)

  • Minimum dialysis dose SpKt/V > 1.2 US

    eKt/V > 1.2 Europe

    StdKt/V 2.14

  • Daugirdas Formula

  • Daugirdas Formula

  • Prescribed vs. delivered Kt/VPrescribed Kt/V is a computerized estimation of what the patients Kt/V would be, based on the prescription

    Delivered Kt/V is actual results based onhow the patient really dialyzed the day thekinetic labs were drawn

  • Discrepancies Between Delivered and Prescribed Dialysis DoseDelivered less than the prescribed:Low blood flowInadequate dialyzer performanceLow dialysate flowDialysis machine programmed incorrectlyHemodialysis ended prematurelyThe predialysis BUN was drained after initiation of hemodialysisAccess recirculation

  • Discrepancies Between Delivered and Prescribed Dialysis DoseDelivered Dose More than the Prescribed:Postdialysis BUN was drained from venous bloodlineThe post dialysis BUN was diluted with salineSmall (V)

  • Low kt/v

  • How to improve clearanceBlood flowDialysate flowDialyzerDuration frequency

  • Blood flow and Clearance

  • Blood flow and Clearance

  • Dialysate flow and clearance

  • The HEMO Study (2002)

  • The HEMO Study (2002) Standard dose groupSpKt/V 1.3

    eKt/V 1.16

    URR 66.3

    Dialysis T 190 min High dose groupSpKt/V 1.7

    eKt/V 1.53

    URR 75.2

    Dialysis T 219 min

  • The HEMO Study (2002)EKNOYAN et al N Engl j Med .2002;347:2010

  • Optimal Dialysis Anemia management Good nutritionBP controlAdequate solute removalFluid and electrolytes hemostasisBMDmanagementDialysisadequacy

  • Optimal Dialysis Anemia management Good nutritionBP controlAdequate solute removalFluid and electrolytes hemostasisBMDmanagementDialysisadequacyKt/v

  • Filters Efficiency and Flux Efficiency: ability to achieve large small solute clearance withhigh blood flows (all filters are high efficiency these days) Flux: ability to achieve high middle molecule clearance andultrafiltration rate (determined by the average pore size)Diffusion and Convection Diffusion: solutes move by diffusion between blocks of fluidseparated by the membrane Convection: solutes move en mass with a block of fluid acrossthe membrane (more effective for moving large molecules)

  • The HEMO Study (2002)EKNOYAN et al N Engl j Med.2002 ;347:2010

  • The MPO Study (2009)

  • Standard Kt/V

  • Standard Kt/Vwhy Hemo study is negative ?

  • FHN

  • Better survival with long dialysisUpToDate

  • Residual renal function

  • Residual renal function

  • Time is important

  • What about hemodiafiltration ?