1. Hemodialysis Adequacy
Lutfi Alkorbi MD
King Faisal Specialist Hospital
Riyadh Saudi Arabia

2. Global dialysis population

3. Cardiovascular mortality in general population VS ESRD patients

4. Mortality in Hemodialysis Patients in Europe, Japan, and the United States
DOPPS 2006

5. Dialysis adequacy and death
The effect of dialysis dose on survival

6. First Randomised Controlled Trial In Dialysis
The National Cooperative Dialysis Study (NCDS) was the first multicentric, randomized and controlled trial to investigate the impact of dialysis dose on patients' outcome patients were randomized to two different urea time‐averaged concentrations (TAC; 100 vs 50 mg/dl) and to two different treatment times (2.5–3.5 vs 4.5–5.5 h) and followed‐up for 6 months.
NCDS 1980

7. First Randomised Controlled Trial In Dialysis
Predialysis urea 38 vs 26 mmol. Dialysis h vs h
high kt/v and long dialysis
high kt/v and short dialysis
low kt/v and long dialysis
low kt/v and short dialysis
NCDS 1980

8. Secondary analysis of NCDS
A 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.

9. Higher Kt/V has better outcome
Gotch FA,Sargent Kidney Int 1985;28:526

10. NCDS Conclusion
Thus, according to NCDS patient morbidity and treatment failure are related to the dialysis dose

11. Why Should We Measure Dialysis Dose?
There is a correlation between delivered dose of hemodialysis and patient morbidity and mortality
Clinical symptoms are not reliable

12. Increasing dialysis dose improved survival
Kidney Int 1996; 50:550

13. Measures of dialysis adequacy
SpKt/V
eKt/V
StdKt/V
URR

14. Hemodialysis Dose Measurement
Kt/V
K= dialyzer urea clearance L/h
t = dialysis session length hr
v = distribution volume of urea L
URR

15. Urea reduction Ratio (URR)
URR = 100 x (1-Ct/Co)
Ct = postdialysis BUN
Co = predialysis BUN

16. Urea Reduction Volume (URR)
Simple
Prediction 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

17. URR & Kt/V

18. Hemodialysis Dose Measurement
The preferred method is by formal kinetic urea modeling
K/DOQI 2006

19. Kt/V Computerized software Mathematical logarithm
Kt/v = -Ln (R-0.008t)+(4-3.5xR) x UF W
Ln = natural logarithm
R = postdialysis BUN
predialysis BUN
UF = Ultrafiltration volume in liters
W = Postdialysis weight in kg

20. BUN Sampling Predialysis Postdialysis Immediate predialysis
Slow flow/stop pump

21. 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 CO
So: during HD, there is loss of urea from well perfused areas, this result in  in BUN over 60 minutes post dialysis.

22. Post Dialysis BUN Sampling
Avoid 2 rebound:
Early (<3min post dialysis)
Access recirculation,begin immediately post hemodialysis and rebound in 20 seconds
Cardiopulmonary recirculation, begin 20 seconds post hemodialysis and is completed in 2-3 minutes after slowing or stopping the blood pump.
Late (>3 min)
Completed within minutes due to flow-volume disequilibrium.

23. 65% rebound ( >50% is AR,15%CP,31% D)
Urea Rebound
65% rebound ( >50% is AR,15%CP,31% D)

24. Single-Compartment Fixed Volume Solute Kinetic Mode

25. Single-Pool vs Double-Pool
Does not account for urea transfer between fluid compartments
With  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)

26. Two-Compartment Variable Volume Solute Kinetic Model

27. Equilibrated Kt/V
eKt/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 minutes
The degree of rebound is high in small patient
eKt/V= spKt/V x (spKt/V) / t (for arterial access)
eKt/V= spKt/V x (spKt/V) / t (for venous access)

28. Minimum dialysis dose SpKt/V > 1.2 US eKt/V > 1.2 Europe
StdKt/V

29. Daugirdas Formula

30. Daugirdas Formula

31. Prescribed vs. delivered Kt/V
Prescribed 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 on
how the patient really dialyzed the day the
kinetic labs were drawn

33. Discrepancies Between Delivered and Prescribed Dialysis Dose
Delivered less than the prescribed:
Low blood flow
Inadequate dialyzer performance
Low dialysate flow
Dialysis machine programmed incorrectly
Hemodialysis ended prematurely
The predialysis BUN was drained after initiation of hemodialysis
Access recirculation

34. Discrepancies Between Delivered and Prescribed Dialysis Dose
Delivered Dose More than the Prescribed:
Postdialysis BUN was drained from venous bloodline
The post dialysis BUN was diluted with saline
Small (V)

35. Low kt/v

36. How to improve clearance
Blood flow
Dialysate flow
Dialyzer
Duration
frequency

37. Blood flow and Clearance

38. Blood flow and Clearance

39. Dialysate flow and clearance

40. The HEMO Study (2002)

41. The HEMO Study (2002) Standard dose group High dose group SpKt/V 1.7
eKt/V
URR
Dialysis T min
SpKt/V
eKt/V
URR
Dialysis T min

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

43. Fluid and electrolytes hemostasis
Optimal Dialysis
Anemia management
BP control
Good nutrition
Dialysis
adequacy
Fluid and electrolytes hemostasis
Adequate solute removal
BMD
management

44. Fluid and electrolytes hemostasis
Optimal Dialysis
Anemia management
BP control
Good nutrition
Dialysis
adequacy
Kt/v
Fluid and electrolytes hemostasis
Adequate solute removal
BMD
management

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

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

47. The MPO Study (2009)

48. Standard Kt/V

49. Standard Kt/V why Hemo study is negative ?

51. FHN

54. Better survival with long dialysis
UpToDate

55. Residual renal function

56. Residual renal function

57. Time is important

60. What about hemodiafiltration ?