PRINCIPLES OF DIALYSIS
Dr. Arun Varghese T
Nephrologist
Siva Hospital
• Principles?
Categorization of molecules
• High efficiency vs low efficiency
• High flux vs low flux
• KoA, Kuf
• Isolated ultrafiltration/Sequential dialysis
• Hemodiafiltration
• Hemofiltration
Functions of the Kidneys
• Excretory
– Excretion of waste products
• Regulatory
– Fluid
– Electrolytes
– Acid base
• Hormonal
– Rennin
– Erythropoietin
– 1,25 OH D3
• Metabolic
Functions of the Kidneys
• Excretory
• Regulatory
– Electrolytes
– Acid base
– Fluid
• Hormonal
– Renin
– Erythropoiten
– 1,25 OH D3
• Metabolic
Solute removal or solute shift
Water removal
Kidney Dialyzer
Urine Dialysate
Functions of the Kidneys
• Excretory
• Regulatory
– Electrolytes
– Acid base
– Fluid
• Hormonal
– Renin
– Erythropoiten
– 1,25 OH D3
• Metabolic
Solute removal or solute shift
Water removal
Functions of the Kidneys
• Excretory
• Regulatory
– Electrolytes
– Acid base
– Fluid
• Hormonal
– Renin
– Erythropoiten
– 1,25 OH D3
• Metabolic
Solute removal or solute shift
Water removal
diffusion
ultrafiltration
• Solution
• Semipermeable membrane
• Solution –mixture of solvent and solute
In dialysis
• Treated water- solvent
• Electrolytes and glucose – solute
• Solubility
• Membrane – thin layer of tissue
What is Diffusion ?
• Movement of the solute through semi
permeable membrane from one side to the
other on the basis of concentration gradient
Diffusion – Random Molecule Movement
`
Diffusion – Random Molecule Movement
`
Diffusion – Random Molecule Movement
`
Diffusion – Random Molecule Movement
`
• example
• Tea bag
Functions of the Kidneys
• Excretory
• Regulatory
– Electrolytes
– Acid base
– Fluid
• Hormonal
– Renin
– Erythropoiten
– 1,25 OH D3
• Metabolic
Solute removal or solute shift
Water removal
diffusion
ultrafiltration
• Movement of fluid (solvent) across the
membrane
• Controlled fluid removal by manipulation
of pressure
• Filtration occure when fluid is pushed through
hydraulic pressure
• Fluid always moves from higher pressure to a
lower one
Ultrafiltration
A B
Ultrafiltration
A B
Basic Principals of Dialysis
• Principles related to solute removal
– Diffusion
– Convection
– ( KoA)
• Principles related to water removal
– Ultrafiltration
– Osmosis
– (Ultrafiltration coefficient-KUF)
• Convection is transfer of solutes by physical
circulation of a liquid
• Example
Ultrafiltration & Convection
Movement of FLUID across a
semipermeable from an area of LOWER
solute concentration to an area of HIGHER
solute concentration.
• In diffusion- solutes move
• In osmosis – solvent moves
• Application in Dialysis
• How to measure diffusion?
• KoA
• What are the factors determining diffusion?
MW of solute
Pore size
Pore number & distribution
Membrane thickness
Membrane surface area
Temperature on either side
Concentration gradient
Diffusion in dialysis
MW of solute
Pore size
Pore number & distribution
Membrane thickness
Membrane surface area – A
Temperature on either side
Concentration gradient
Ko
KoA
• The theoretical maximum clearance of the
dialyzer at infinite dialysate and blood flow
• Ko- permeability coefficient of the dialyzer
• A - surface area
• Expressed in ml/min
Mass transfer area coefficient KoA
Diffusive resistance
`
• Efficacy
• Related to urea clearance of dialyzer urea
clearance – KoAurea
– Low efficacy – KoAurea < 500 ml/min
– High efficacy – KoAurea > 600 ml/min
Diffusion in Dialyzer
For adequate diffusion
Dialysate flow 2-2.5 time blood flow
Effect of Blood Flow on Clearance
Distribution of pore size
A
B
Categorization of molecules
• What are the factors determining
ultrafiltration?
• Trans membrane pressure
• Hydraulic permeability of the membrane
ULTRAFILTRATION
Controlled fluid removal by manipulation of
hydrostatic pressure.
• Ultrafiltration uses both positive and negative pressure:
o Positive pressure
• pressure exerted by the blood flowing through the
dialyzer, Results from blood being pushed by blood
pump
o Negative pressure
• pressure applied to the dialysate side by the machine
• Pulls excess fluid from blood compartment to dialysate
compartment drain
Ultrafiltration
A B
Ultrafiltration
A B
Ultrafiltration
Transmembrane pressure
(TMP)
=
Positive pressure A - Negative pressure B
A B
• Hydraulic permeability
• Surface area
• Number and size of por
Ultrafiltration Coefficient (KUF)
• Milliliter of fluid per hour per mm Hg pressure
difference across the membrane
• Expressed in ml/hr/mmHg
• Flux
– Measure of ultrfiltration capacity
– Low or high flux dialyzers based on KUF
Low flux vs high flux
– Low flux - KUF < 10 ml/hr/mmHg
– High flux - KUF > 20 ml/hr/mmHg
– Low flux - B2 microglobulin clearance < 10 ml/min
– High flux - B2 microglobulin clearance > 20 ml/min
• Summarise
• High efficiency vs low efficiency
• High flux vs low flux
• KoA, Kuf
• Isolated ultrafiltration/Sequential dialysis
• Hemodiafiltration
• Hemofiltration
RRTs – Principles of Dialysis
Diffusion Convection Ultrafiltration
Conventional
Hemodialtsis
+++ + +
Hemofiltration - ++++ ++++
Hemodialfiltration +++ ++++ ++++
RRTs – Principles of Dialysis
Diffusion Convection Ultrafiltration
Conventional
Hemodialtsis
+++ + +
High Efficiency HD ++++ + +
High Flux Dialysis +++ +++ +++
Hemofiltration - ++++ ++++
Hemodialfiltration +++ ++++ ++++
1
• The blood dialysate flow configuration that
maintains the optimum blood dialysate
concentration gradient
A. Concurrent flow
B. Countercurrent flow
C. Crosscurrent flow
D. Recirculation flow
2
• Ultrafiltration during hemodialysis is due to
A. Dialysate flow rate
B. Blood flow rate
C. Osmotic pressure gradient between blood and
dialysate
D. Hydrostatic pressure gradient between blood
and dialysate
E. None of above
3
• Ultrafiltration coefficient (KUF) refers to
A. The resistance to water removal
B. Amount of water removed from blood per unit
time as a function of pressure difference
C. The amount of water removed per unit time
D. The resistance of dialyzer to solute removal
4
• Mass transfer coefficient refers to
A. Amount of fluid removed per unit time
B. Amount of solute removed per unit time
C. The resistance offered to solute removal
D. The resistance offered to fluid removal
E. None of them
• Thank you
5
• Sieving coefficient depends on all of following
EXEPT
A. Molecular weight cutoff the membrane
B. Ultrafiltration rate
C. Surface area
D. Diffusion
Sieving coefficient
Body water distribution
• In dialysis water and solutes can be removed
only from bloodstream
Fluid compartments
• Diffusion is greater for small molecules as
compared to larger molecules
• Low flux: molecular wt cut off = 10000
daltons
• High flux: molecular weight cut off = 30000
daltons
RRTs – Principles of Dialysis
Diffusion Convection Ultrafiltration
Conventional
Hemodialtsis
+++ + +
High Efficiency
HD
++++ + +
High Flux
Dialysis
+++ +++ +++
Hemofiltration - ++++ ++++
Hemodialfiltrat
ion
+++ ++++ ++++
Peritoneal
Dialysis
+++ - -
Urea kinetic modelling
Measuring dialysis adequacy
• Urea reduction ratio
• Kt/V

principles of dialysis 2019.pptx

  • 1.
    PRINCIPLES OF DIALYSIS Dr.Arun Varghese T Nephrologist Siva Hospital
  • 2.
  • 3.
  • 4.
    • High efficiencyvs low efficiency • High flux vs low flux • KoA, Kuf • Isolated ultrafiltration/Sequential dialysis • Hemodiafiltration • Hemofiltration
  • 5.
    Functions of theKidneys • Excretory – Excretion of waste products • Regulatory – Fluid – Electrolytes – Acid base • Hormonal – Rennin – Erythropoietin – 1,25 OH D3 • Metabolic
  • 6.
    Functions of theKidneys • Excretory • Regulatory – Electrolytes – Acid base – Fluid • Hormonal – Renin – Erythropoiten – 1,25 OH D3 • Metabolic Solute removal or solute shift Water removal
  • 9.
  • 10.
    Functions of theKidneys • Excretory • Regulatory – Electrolytes – Acid base – Fluid • Hormonal – Renin – Erythropoiten – 1,25 OH D3 • Metabolic Solute removal or solute shift Water removal
  • 11.
    Functions of theKidneys • Excretory • Regulatory – Electrolytes – Acid base – Fluid • Hormonal – Renin – Erythropoiten – 1,25 OH D3 • Metabolic Solute removal or solute shift Water removal diffusion ultrafiltration
  • 12.
  • 13.
    • Solution –mixtureof solvent and solute In dialysis • Treated water- solvent • Electrolytes and glucose – solute • Solubility
  • 14.
    • Membrane –thin layer of tissue
  • 16.
    What is Diffusion? • Movement of the solute through semi permeable membrane from one side to the other on the basis of concentration gradient
  • 17.
    Diffusion – RandomMolecule Movement `
  • 18.
    Diffusion – RandomMolecule Movement `
  • 19.
    Diffusion – RandomMolecule Movement `
  • 20.
    Diffusion – RandomMolecule Movement `
  • 21.
  • 22.
  • 23.
    Functions of theKidneys • Excretory • Regulatory – Electrolytes – Acid base – Fluid • Hormonal – Renin – Erythropoiten – 1,25 OH D3 • Metabolic Solute removal or solute shift Water removal diffusion ultrafiltration
  • 25.
    • Movement offluid (solvent) across the membrane • Controlled fluid removal by manipulation of pressure
  • 26.
    • Filtration occurewhen fluid is pushed through hydraulic pressure • Fluid always moves from higher pressure to a lower one
  • 27.
  • 28.
  • 29.
    Basic Principals ofDialysis • Principles related to solute removal – Diffusion – Convection – ( KoA) • Principles related to water removal – Ultrafiltration – Osmosis – (Ultrafiltration coefficient-KUF)
  • 31.
    • Convection istransfer of solutes by physical circulation of a liquid
  • 32.
  • 33.
  • 35.
    Movement of FLUIDacross a semipermeable from an area of LOWER solute concentration to an area of HIGHER solute concentration.
  • 36.
    • In diffusion-solutes move • In osmosis – solvent moves
  • 37.
  • 39.
    • How tomeasure diffusion? • KoA
  • 40.
    • What arethe factors determining diffusion?
  • 41.
    MW of solute Poresize Pore number & distribution Membrane thickness Membrane surface area Temperature on either side Concentration gradient
  • 42.
    Diffusion in dialysis MWof solute Pore size Pore number & distribution Membrane thickness Membrane surface area – A Temperature on either side Concentration gradient Ko
  • 43.
    KoA • The theoreticalmaximum clearance of the dialyzer at infinite dialysate and blood flow • Ko- permeability coefficient of the dialyzer • A - surface area • Expressed in ml/min
  • 44.
    Mass transfer areacoefficient KoA Diffusive resistance `
  • 45.
    • Efficacy • Relatedto urea clearance of dialyzer urea clearance – KoAurea – Low efficacy – KoAurea < 500 ml/min – High efficacy – KoAurea > 600 ml/min
  • 46.
    Diffusion in Dialyzer Foradequate diffusion Dialysate flow 2-2.5 time blood flow
  • 47.
    Effect of BloodFlow on Clearance
  • 49.
  • 50.
  • 52.
    • What arethe factors determining ultrafiltration?
  • 53.
    • Trans membranepressure • Hydraulic permeability of the membrane
  • 54.
    ULTRAFILTRATION Controlled fluid removalby manipulation of hydrostatic pressure. • Ultrafiltration uses both positive and negative pressure: o Positive pressure • pressure exerted by the blood flowing through the dialyzer, Results from blood being pushed by blood pump o Negative pressure • pressure applied to the dialysate side by the machine • Pulls excess fluid from blood compartment to dialysate compartment drain
  • 55.
  • 56.
  • 57.
  • 58.
    • Hydraulic permeability •Surface area • Number and size of por
  • 59.
    Ultrafiltration Coefficient (KUF) •Milliliter of fluid per hour per mm Hg pressure difference across the membrane • Expressed in ml/hr/mmHg
  • 60.
    • Flux – Measureof ultrfiltration capacity – Low or high flux dialyzers based on KUF
  • 61.
    Low flux vshigh flux – Low flux - KUF < 10 ml/hr/mmHg – High flux - KUF > 20 ml/hr/mmHg – Low flux - B2 microglobulin clearance < 10 ml/min – High flux - B2 microglobulin clearance > 20 ml/min
  • 62.
  • 63.
    • High efficiencyvs low efficiency • High flux vs low flux • KoA, Kuf • Isolated ultrafiltration/Sequential dialysis • Hemodiafiltration • Hemofiltration
  • 64.
    RRTs – Principlesof Dialysis Diffusion Convection Ultrafiltration Conventional Hemodialtsis +++ + + Hemofiltration - ++++ ++++ Hemodialfiltration +++ ++++ ++++
  • 65.
    RRTs – Principlesof Dialysis Diffusion Convection Ultrafiltration Conventional Hemodialtsis +++ + + High Efficiency HD ++++ + + High Flux Dialysis +++ +++ +++ Hemofiltration - ++++ ++++ Hemodialfiltration +++ ++++ ++++
  • 66.
    1 • The blooddialysate flow configuration that maintains the optimum blood dialysate concentration gradient A. Concurrent flow B. Countercurrent flow C. Crosscurrent flow D. Recirculation flow
  • 67.
    2 • Ultrafiltration duringhemodialysis is due to A. Dialysate flow rate B. Blood flow rate C. Osmotic pressure gradient between blood and dialysate D. Hydrostatic pressure gradient between blood and dialysate E. None of above
  • 68.
    3 • Ultrafiltration coefficient(KUF) refers to A. The resistance to water removal B. Amount of water removed from blood per unit time as a function of pressure difference C. The amount of water removed per unit time D. The resistance of dialyzer to solute removal
  • 69.
    4 • Mass transfercoefficient refers to A. Amount of fluid removed per unit time B. Amount of solute removed per unit time C. The resistance offered to solute removal D. The resistance offered to fluid removal E. None of them
  • 70.
  • 71.
    5 • Sieving coefficientdepends on all of following EXEPT A. Molecular weight cutoff the membrane B. Ultrafiltration rate C. Surface area D. Diffusion
  • 72.
  • 73.
    Body water distribution •In dialysis water and solutes can be removed only from bloodstream
  • 74.
  • 76.
    • Diffusion isgreater for small molecules as compared to larger molecules • Low flux: molecular wt cut off = 10000 daltons • High flux: molecular weight cut off = 30000 daltons
  • 77.
    RRTs – Principlesof Dialysis Diffusion Convection Ultrafiltration Conventional Hemodialtsis +++ + + High Efficiency HD ++++ + + High Flux Dialysis +++ +++ +++ Hemofiltration - ++++ ++++ Hemodialfiltrat ion +++ ++++ ++++ Peritoneal Dialysis +++ - -
  • 78.
  • 79.
    Measuring dialysis adequacy •Urea reduction ratio • Kt/V