1. Compare and Contrast 3
Modalities of Renal
Replacement Therapy
CRRT/SLED/IHD

2. Explain the Acronym
 IHD
– Intermittent Haemodialysis
 SLEDD
– Slow Low Efficiency Daily Dialysis
 CRRT
– Continuous Renal Replacement Therapy

3. Haemodialysis vs Haemofiltration

4. Dialysis
 Electrochemical
gradient across the
membrane
 DIFFUSION across
the membrane
 Eg, IHD, CAPD
 Good for small
molecules eg Urea

5. Filtration
 “Solvent drag” driven
by transmembrane
pressure (solute
carried in solution)
 Solute and solvent
move across porous
membrane
(CONVECTION)
 Good for fluid and
middle sized
molecules

6. Convection of a Solute
 Depends on
– Hydraulic permeability coefficient (sieving
Coefficient)
– Membrane Surface area
– Transmembrane pressure

7. Patient Type- IHD

8. Patient Type- CRRT

9. Outline the differences in
membranes between IHD and
CRRT

10. IHD membranes
 Low flux
 Cellulose based
(cuprophane)
 Unable to remove middle
molecules >500kD
 Haemodynamic instability
and SIRS response…
 Need large SA if high
volume…1.6-2m2

11. CRRT membranes
 High flux
 Synthetic
 Remove up to 20-30kD
 Convection superior to
diffusion
 Membrane size not
standard. 1.2m2
 AN69, polyamide, polysulphone, cellulose triacetate

12. Time for some evidence:
 HEMO study: no impact on morbidity with
high or low flux filters Eknoyan G et al, Effect of dialysis
dose and membrane flux in maintenance hemodialysis NEJM, 2002
347:2010-9
 Cochrane data base review: no benefit in
terms of mortality or dialysis related
adverse events
 MPO study: mortality benefit in Alb<40 or
B2M. Locatelli F et al, Membrane permiability outcome group:
Effect of membrane permiability on survival of haemodialysis
patients. J Am Soc Nephrol 2009; 20: 645-654

13. Blood flow rate

14. 3 Modalities and Clotting

15. 3 Modalities and Access
devices

16. Dialysis Rate

18. TYPES of Buffer
• LACTATE-> bicarb  BICARB-> expensive,
1:1 by liver reserved for those
unable process
lactate or high lactate
producing…..(7) short
shelf life

19. Other Additives
 K+
 No K added for use in hyperkalaemic states
 PO4
– Would precipitate out with Ca++ so is replaced
systemically
 Water Soluble vitamins, replaced systemically
 Proteins esp glutamate

20. Dialysate fluids …the Evidence
 Cole et al The Impact of lactate buffered high
volume hemofiltration on acid base balance
Intensive Care Medicine 2003:29:1113-20
 Barenbrock Effects of Bicarb and lactate
buffered replacement fluids on CVS outcome in
CVVH patients Kidney Int 2000;58(4) 1751-7

21. How long should a filter last?

22. ADVANTAGES &
DISADVANTAGES

23. Thank you