1. Treatment Related Factors
Catheter performance
QB tends be roughly comparable for FE and R) sided SC and IJ lines
Maximum achievable QB tends to be lower by ~100 mL/min in L) sided SC and IJ lines
AR tends to be highest in short FE lines, intermediate in long FE lines, and lowest in SC and IJ lines
Dialyzer and filter performance
Oliver et al, Semin Dial, Vol 14, pp , 2001
Little et al, AJKD, Vol 36, pp , 2000
Margetts et al, JASN, Vol 10, pp 211A, 1999

2. Little et al, AJKD, Vol 36, pp 1135-1139, 2000

3. A- IJ catheter with no recirculation; B- 20 cm FE catheter assumed to have AR of 0% at 150 mL/min, 8.5% at 250 mL/min and 17% at 350 mL/min; C- 15 cm FE catheter assumed to have AR of 5% at 150 mL/min, 20% at 250 mL/min and 30% at 350 mL/min (iHD treatments are modelled under the following conditions; duration 240 mins, dialysate flow 500 mL/min, hemodialyzer mass transfer coefficient 911 mL/min, V 40 L, nPCR 0.8 g/kg/day)

4. Treatment Related Factors
Catheter performance
Dialyzer (iHD and Hybrid) performance
Heparin-free iHD is associated with significant fibre bundle clotting, and also with reduced delivered iHD dose
K decreases by 10-20% during in the hour before dialyzer clotting during Hybrid Therapy
Low-flux dialyzers are associated with lower iHD dose (KoA, QD)
Sakiewicz et al,JASN, Vol 10, pp 196A, 1999
Evanson et al, AJKD, Vol 32, pp , 1998
Marshall et al, UpToDate, “Sustained Low-Efficiency Dialysis”
Paganini et al, Am J Kidney Dis, Vol 28 (Suppl), ppS81-S89, 1996

5. Marshall and Golper, UpToDate, “Sustained Low-Efficiency Dialysis”

6. Treatment Related Factors
Catheter performance
Filter (CRRT) performance
Down time due to filter clotting is the major reason for reduced CRRT dose

8. Treatment Related Factors
Catheter performance
Filter (CRRT) performance
Down time due to filter clotting is the major reason for reduced CRRT dose
Concentration polarization reduces filtration rate and the filtrate concentrations of various medium / large sized proteins
High filtration fraction (high UF + low QB or post dilution) is associated with both of above
Pre-dilution versus post-dilution

9. Treatment Related Factors

10. Treatment Related Factors
For iHD, long catheters should be used for femoral angioaccess, and adjust dose prescription in anticipation of increased AR
For iHD, can adjust for solute compartmentalization using the Daugirdas, Garred, or Tattersall rate equations
For both iHD and CRRT, optimize anticoagulation and adjust dose prescription in the advent of dialyzer and filter clotting

11. Treatment Related Factors
For CRRT, avoid high filtration fraction by higher blood flow rates and pre-dilution to minimize concentration polarization and hemoconcentration
Except using Regional Citrate Anticoagulation with post-dilution replacement
For CRRT, adjust prescription for predilution with either a FUN/BUN ratio or an empirical 15% for lower-dose prescriptions (~2L/hr) and 30-40% for higher-dose prescriptions (>4L/hr)

12. Overview Revisiting of dose and outcomes
Patient and treatment related factors affecting dose prescription and delivery
Therapy-specific dose-outcome data
Approach to prescription and quantification of acute RRT dose

13. Dose-Outcome Data CRRT

15. Table I – Clinical Diagnosis of study patients
No of Patients
Multiple injury 12
Aortic rupture 2
Osteomyelitis 1
Abdominal aortic aneurysm repair
22*
Thoracic aortic aneurysm repair 4
Other vascular procedures 11
Bronchial carcinoma 3
Other thoracic procedures
Necrotising pancreatitis 10
Gastric cancer 9
Peritonitis / intestinal perforation 7
Diseases of gallbladder 6
Ileus 5
Perforated ulcer
Other abdominal operations 17
*Emergency in 18, elective in 4

16. * Not Randomized

24. Dose-Outcome Data (CRRT)
Dose is quantified as effluent (filtration) rate indexed to body size
A dose of 35 mL/kg/hr in post-dilution mode is reported as giving the best results
Starting acute RRT earlier rather than later is suggested as giving the best results

25. Dose-Outcome Data iHD

38. Dose-Outcome Data (iHD)
Dose is quantified as clearance indexed to solute pool size (single pool Kt/V)
A dose of >1.0 is reported as giving the best results
Daily iHD is reported as giving better results that alternate day iHD

40. Phu et al. 70 patients with sepsis randomized to CVVH or CAPD
Average weight 53 kg
Most common diagnosis falciparum malaria
CVVH 25L/day pre-dilution lactate based substitution fluid rate, Ku 25L/day
CAPD 70L/day dialysate exchanged, Ku 28L/day

41. CAPD provided unsatisfactory control of cidosis, longer duration of ARF, poorer survival

42. Overview Revisiting of dose and outcomes
Patient and treatment related factors affecting dose prescription and delivery
Therapy-specific dose-outcome data
Approach to prescription and quantification of acute RRT dose

43. CRRT Prescription
For all CRRT, aim for >85% delivery of prescribed dose
For all CRRT, aim for effluent rate of >35 mL/kg/hr, with appropriate adjustments for the effect of pre-dilution, and accounting for patient and treatment related barriers

44. CRRT Prescription
It is unlikely CVVH can achieve an effluent rate of 35mL/kg/hr without high blood flow rate +/- pre-dilution
Except the patient is small/pediatric, or not particularly sick or
Using Regional Citrate Anticoagulation + post-dilution
The adequacy of an effluent rate of 35mL/kg/hr is unclear for CVVHD(F) since this dose applies to dialysate generated by diffusion rather than filtrate generated by convection

45. iHD Prescription
It is unlikely that iHD can deliver an adequate dose outside of a daily or near –daily regimen unless the patient is unless the patient is small/pediatric, or not particularly sick
For daily iHD, aim for a delivered single pool Kt/V of at least >1.0, accounting for patient and treatment related barriers (? prescribe 1.3)

46. iHD Prescription
The most practical expression of iHD dose is single pool Kt/V, and is most accurately achieved by formal UKM
The most realistic expression iHD dose is equilibrated Kt/V, and is most accurately achieved by adjusting single pool Kt/V using the Daugirdas, Garred, or Tattersall rate equations

47. PD Prescription
It is even less likely that PD can deliver an adequate dose outside of continuous flow PD unless the patient is small/pediatric, or not particularly sick

48. Dose and Therapy Choice
If iHD is not delivering adequate dose despite optimizing all factors, try Hybrid Therapy or CRRT
If CRRT is not delivering adequate dose despite optimizing all factors, try Hybrid Therapy or iHD
There are increasing data suggesting that delaying acute renal replacement therapy in critically ill patients is unwise

49. Is there an expression of acute RRT dose that will allow us to reconcile these different recommendations for iHD and CRRT?

50. Standard Kt/V (stdKt/V) Units: week-1

53. stdKt/V Requires a solute steady state for calculation
Expresses acute RRT dose as a new less intuitive parameter
Based on peak-concentration hypothesis, which can reconcile Kt/V standards forCAPD and iHD dose in the outpatient setting, but is arbitrary and difficult to define in the critically ill

54. Corrected Equivalent Renal Urea Clearance (EKRc) Units: mL/min

55. = G/TAC or J/TAC

56. A comparison of BUN time-concentration profiles between two intermittent hemodialysis regimens delivering a cEKR of 24 ml/min. The solid line reflects solute removal over 3 treatments per week, the dotted solute removal over 7 treatments per week.

57. EKRc (1st Generation)
Analogous to GFR, conceptually simple since it expresses acute RRT dose as mL/min
Is corrected for body size (a 70 kg person with a V of 40L or BSA of 1.73m2)
Is based on time-averaged BUN, which is
easier to define and less arbitrary than peak BUN

62. EKRjc (2nd Generation)

63. EKRjc (2nd Generation)
Is valid during solute non-steady state, and is insensitive to variation in V and G
Does not require precise knowledge of V, G of Kd
Can be calculated on a simple Excel spreadsheet with input of patients’ estimated V and BUN both pre and post iHD for sequential dialysis cycles
Can use post-iHD Ceq (Tattersall)

67. Dialysis Dose and Prescription

71. Augmented vs Normal Renal Replacement Therapy in Acute Renal Failure
Augmented vs Normal Renal Replacement Therapy in Acute Renal Failure

73. How should one prescribe and dose acute RRT to optimize patient outcomes?
Individually, according to the requirements of the patient