Compare and Compare and Contrast 3 Modalities Contrast 3 Modalities

of Renal of Renal Replacement TherapyReplacement Therapy

CRRT/SLED/IHDCRRT/SLED/IHD

Explain the AcronymExplain the Acronym

IHD IHD – Intermittent HaemodialysisIntermittent Haemodialysis

SLEDDSLEDD– Slow Low Efficiency Daily DialysisSlow Low Efficiency Daily Dialysis

CRRTCRRT– Continuous Renal Replacement TherapyContinuous Renal Replacement Therapy

Haemodialysis vs Haemodialysis vs HaemofiltrationHaemofiltration

DialysisDialysis

Electrochemical Electrochemical gradient across the gradient across the membranemembrane

DIFFUSION across DIFFUSION across the membranethe membrane

Eg, IHD, CAPDEg, IHD, CAPD Good for small Good for small

molecules eg Ureamolecules eg Urea

FiltrationFiltration ““Solvent drag” Solvent drag”

driven by driven by transmembrane transmembrane pressure (solute pressure (solute carried in solution)carried in solution)

Solute and solvent Solute and solvent move across porous move across porous membrane membrane (CONVECTION)(CONVECTION)

Good for fluid and Good for fluid and middle sized middle sized moleculesmolecules

Convection of a SoluteConvection of a Solute

Depends onDepends on– Hydraulic permeability coefficient Hydraulic permeability coefficient

(sieving Coefficient)(sieving Coefficient)– Membrane Surface areaMembrane Surface area– Transmembrane pressureTransmembrane pressure

Patient Type- IHDPatient Type- IHD

Patient Type- CRRTPatient Type- CRRT

Outline the differences in Outline the differences in membranes between IHD and membranes between IHD and

CRRTCRRT

IHD membranesIHD membranes

Low fluxLow flux Cellulose based Cellulose based

(cuprophane)(cuprophane) Unable to remove Unable to remove

middle molecules middle molecules >500kD>500kD

Haemodynamic Haemodynamic instability and SIRS instability and SIRS response…response…

Need large SA if high Need large SA if high volume…1.6-2mvolume…1.6-2m22

CRRT membranesCRRT membranes

High fluxHigh flux SyntheticSynthetic Remove up to 20-Remove up to 20-

30kD30kD Convection superior to Convection superior to

diffusiondiffusion Membrane size not Membrane size not

standard. 1.2mstandard. 1.2m22

AN69, polyamide, polysulphone,AN69, polyamide, polysulphone, cellulose triacetatecellulose triacetate

Time for some evidence:Time for some evidence:

HEMO study: no impact on morbidity HEMO study: no impact on morbidity with high or low flux filterswith high or low flux filters Eknoyan G et al, Eknoyan G et al, Effect of dialysis dose and membrane flux in maintenance Effect of dialysis dose and membrane flux in maintenance hemodialysis NEJM, 2002 347:2010-9hemodialysis NEJM, 2002 347:2010-9

Cochrane data base review: no Cochrane data base review: no benefit in terms of mortality or benefit in terms of mortality or dialysis related adverse eventsdialysis related adverse events

MPO study: mortality benefit in MPO study: mortality benefit in Alb<40 or B2M. Alb<40 or B2M. Locatelli F et al, Membrane Locatelli F et al, Membrane permiability outcome group: Effect of membrane permiability outcome group: Effect of membrane permiability on survival of haemodialysis patients. J Am Soc permiability on survival of haemodialysis patients. J Am Soc Nephrol 2009; 20: 645-654Nephrol 2009; 20: 645-654

Blood flow rateBlood flow rate

3 Modalities and Clotting3 Modalities and Clotting

3 Modalities and Access 3 Modalities and Access devicesdevices

Dialysis RateDialysis Rate

TYPES of BufferTYPES of Buffer

• LACTATE-> bicarb LACTATE-> bicarb 1:1 by liver1:1 by liver

BICARB-> BICARB-> expensive, expensive, reserved for those reserved for those unable process unable process lactate or high lactate or high lactate lactate producing…..(7) producing…..(7) short shelf lifeshort shelf life

Other AdditivesOther Additives

K+K+ No K added for use in hyperkalaemic statesNo K added for use in hyperkalaemic states

PO4PO4– Would precipitate out with Ca++ so is replaced Would precipitate out with Ca++ so is replaced

systemicallysystemically

Water Soluble vitamins, replaced Water Soluble vitamins, replaced systemicallysystemically

Proteins esp glutamateProteins esp glutamate

Dialysate fluids …the Dialysate fluids …the EvidenceEvidence

Cole et al The Impact of lactate buffered Cole et al The Impact of lactate buffered high volume hemofiltration on acid base high volume hemofiltration on acid base balance Intensive Care Medicine balance Intensive Care Medicine 2003:29:1113-202003:29:1113-20

Barenbrock Effects of Bicarb and lactate Barenbrock Effects of Bicarb and lactate buffered replacement fluids on CVS buffered replacement fluids on CVS outcome in CVVH patients Kidney Int outcome in CVVH patients Kidney Int 2000;58(4) 1751-72000;58(4) 1751-7

How long should a filter How long should a filter last?last?

ADVANTAGES & ADVANTAGES & DISADVANTAGESDISADVANTAGES

Thank youThank you