PCRRT PRESCRIPTIONS in ARF

1. PCRRT PRESCRIPTIONSin ARF Patrick D. Brophy MD University of Michigan Pediatric Nephrology

2. Objectives • Define ARF • Prescriptions: Based on What? • Case Format • Modality • BFR • UF rate • Dialysate/FRF rates • Other issues – anticoagulation, access

3. Acute Renal failure • Definition: A life threatening abrupt cessation/reduction of urinary output to less than 300ml/m2 caused by prolonged renal ischemia in most cases (may occasionally present as high output renal failure- high urinary output with increasing BUN and Creatinine) • Can lead to severe hypertension (fluid overload) metabolic abnormalities (acidosis, hyperkalemia) requiring emergent therapy

4. Developing Countries Hemolytic-Uremic Syndrome (31%) Glomerulonephritis (23%) Post-Op Sepsis/Prerenal ischemia Chan et.al. PIR, 23:2002 Industrialized Countries Intrinsic Renal Disease (44%) Post-Op Septic Shock (34%) Organ/Bone Marrow Transplant (13%) ARF-- Etiology

5. ARF—Treatment Options • Conservative- fluid management and nutrition • Renal Replacement Options: • Hemodialysis- Hemodynamic Instability • Peritoneal Dialysis- efficiency • CVVH(D)/(DF)- Hemodynamically less volatile than HD, Can provide optimal fluid and nutritional management & Clearance

6. PEDIATRIC PRESCRIPTION for CRRT • Classic Case • 10kg infant (75 cm) BSA=0.45m2, high vent settings-lungs wet, ? sepsis • up 2 kg from dry weight, no urine for 12 hr • HR 160, BP 80/40 on pressors, pH 7.2 • Creatinine= 1.0 mg/dl BUN 40, lactate 4.0, iCa=1.0, K=5.8

7. Approach • This patient clearly is in need of Hemofiltration • ISSUES: Determining the prescription • CAVH(D)/(DF) vs CVVH(D)/(DF) • Blood Flow Rate • Ultrafiltrate (dialysate/FRF rate) • Access & Machinery • Fluids for dialysate/Filter Replacement • Anticoagulation

8. CAVH(D) vs CVVH(D) • CAVH(D) • Initial form of therapy, Dependent on BP of patient (difficult to control UF), Technologically easier (require 2 catheters) • CVVH(D) • Newer machines, 1 catheter, improved solute clearance, increased extracorporeal volume, standard of care

9. Werner et al.,1994, Critical Care Medicine, 22, 320-325 • Goals: Evaluation of CVVH using 4 week old lambs (pediatric size ~ 12.2 kg) • Compared 3 systems postdilution, predilution and hemofiltration (post-filter replacement) with counter-current dialysis (standardized UF, BFR and hemofilter)

10. Werner et al.,1994, Critical Care Medicine, 22, 320-325

11. Werner et al.,1994, Critical Care Medicine, 22, 320-325 • Conclusions • 1) CVVH(D) feasible in this size group • 2) Stable blood flow rates from 5-10 ml/kg/min • 3) BFR in this range with UF rates of 1ml/kg/ min can produce urea clearance of 1 ml/kg/min (without causing to large a negative intrafilter pressure) • 4) dialysis didn’t increase urea clearance (animals not uremic though)

12. Bunchman et al 1995, AJKD, 25,17-21

13. Bunchman et al 1995, AJKD, 25,17-21

14. Bunchman et al 1995, AJKD, 25,17-21

15. Bunchman et al 1995, AJKD, 25,17-21

16. Zobel et al,1991 in Contiuous Hemofiltration. Contrib Nephrol. V93 pp257-260

17. Dialysate/ Ultrafiltration Rates • No Study has identified effective, safe UF or dialysate flow rates in Children. • For HEMODIALYSIS– NET UF rate of 0.2ml/kg/min is tolerated (Donckerwolke –Ped Neph 8:103-106,1994)-This extrapolates out to 1 ml/kg/ hr (NET UF) over 48 hr of continuous hemofiltration.

18. Dialysate/ Ultrafiltration Rates • The UF rate/plasma flow rate [=BFRx(1-HCT)] ratio should < 0.35-0.4 in order to avoid filter clotting (Golper AJKD 6: 373-386,1985) • Dialysate flow rates ranging from 10-20 ml/min/m2 (~2000ml/1.72m2/hr) are usually adequate (experiential but consistent with adult data)

19. Ronco et al. Lancet 2000; 351: 26-30

20. Ronco et al. Lancet 2000; 351: 26-30 • Conclusions: • Minimum UF rates should reach at least 35 ml/kg/hr • Survivors in all their groups had lower BUNs than non-survivors prior to commencement of hemofiltration

21. Access & Machinery • Machinery: • PRISMA, DIAPACT, BAXTER, EDWARDS, FRESENIUS • Access: • If poor blood flow- no point in continuing! • Generally want to keep Venous pressure no > 200 mm Hg • IJ placement preferable (triple lumen ideal!) • Size based on Patient’s size

22. Bicarbonate Vs Lactate Fluid • Commercial vs Custom Solutions For FRF or Dialysate • Generally Bicarbonate based solutions preferable (no definitive study to support this- but easier to interpret lactic acidosis) • FDA approved: ie. Normocarb (D –only) • Cost effectiveness: pharmacy/nursing costs

23. Anticoagulation • Heparin • Citrate • None • No good head to head studies comparing Heparin vs. Citrate in Pediatrics • Center specific and Comfort level

24. Other Considerations • Nutrition: • CRRT allows optimization of nutritional supplementation (esp in high catabolic states- such as ARF)- but it also contributes to a negative nitrogen balance • Aim for anabolic state- 1.5 g/kg/day protein is inadequate – 2-3 g/kg/day better, with 20-30% increase in caloric intake over resting energy expenditure • Maxvold et.al. Crit Care Med 28:2000

25. Recommendations for Pediatric Prescription • CVVH/CVVHD/CVVHDF—D useful when limited by membrane UF capacity • Pre/Post FRF or Dialysate • Combined UF+dialysate flow rates 10-20 ml/min/m2 (~2000ml/1.72m2/hr) {INCREASE WITH TOXINS) • At 0.45m2 = 540ml/hr (exceeds adult recommendations) • Net UF rate 1 ml/kg/hr • BFR (4-10 ml/kg/min)-Huge blood flow circulations in small infants

26. Recommendations Continued • Access-Dual lumen 8 Fr (triple Lumen if available) • Bicarbonate based Dialysate or FRF • Anticoagulation- based on patient circumstance and center experience • Maximize Nutrition (good communication among caregivers imperative)

27. ACKNOWLEDGEMENTS MELISSA GREGORY ANDREE GARDNER JOHN GARDNER THERESA MOTTES TIM KUDELKA LAURA DORSEY & BETSY ADAMS