PCRRT PRESCRIPTIONS in ARF

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PCRRT PRESCRIPTIONSin ARF

• Patrick D. Brophy MD University of Michigan
  Pediatric Nephrology

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Objectives

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

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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

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ARF-- Etiology

• Developing Countries
• Hemolytic-Uremic Syndrome (31)
• Glomerulonephritis (23)
• Post-Op Sepsis/Prerenal ischemia
• Chan et.al. PIR, 232002

• Industrialized Countries
• Intrinsic Renal Disease (44)
• Post-Op Septic Shock (34)
• Organ/Bone Marrow Transplant (13)

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ARFTreatment 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

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PEDIATRIC PRESCRIPTION for CRRT

• Classic Case
• 10kg infant (75 cm) BSA0.45m2, 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,
  iCa1.0, K5.8

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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

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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

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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)

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Werner et al.,1994, Critical Care Medicine, 22,
320-325
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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 didnt increase urea clearance
  (animals not uremic though)

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Bunchman et al 1995, AJKD, 25,17-21
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Bunchman et al 1995, AJKD, 25,17-21
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Bunchman et al 1995, AJKD, 25,17-21
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Bunchman et al 1995, AJKD, 25,17-21
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Zobel et al,1991 in Contiuous Hemofiltration.
Contrib Nephrol. V93 pp257-260
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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
  8103-106,1994)-This extrapolates out to 1 ml/kg/
  hr (NET UF) over 48 hr of continuous
  hemofiltration.

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Dialysate/ Ultrafiltration Rates

• The UF rate/plasma flow rate BFRx(1-HCT) ratio
  should lt 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)

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Ronco et al. Lancet 2000 351 26-30
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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

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Access Machinery

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

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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

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Anticoagulation

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

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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 282000

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Recommendations for Pediatric Prescription

• CVVH/CVVHD/CVVHDFD useful when limited by
  membrane UF capacity
• Pre/Post FRF or Dialysate
• Combined UFdialysate 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

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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)

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• ACKNOWLEDGEMENTS
• MELISSA GREGORY
• ANDREE GARDNER
• JOHN GARDNER
• THERESA MOTTES
• TIM KUDELKA
• LAURA DORSEY BETSY ADAMS