Anticoagulation in CRRT

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Anticoagulation in CRRT
Timothy E. BunchmanProfessorPediatric
Nephrology Transplantation
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Anti-Coagulation

• What is best?
• Can you run anticoagulation free?
• Having no anticoagulation shortens circuit life
• Will you use Heparin?
• Patient bleeding
• Platelet count (HIT)
• Will you use Citrate?
• Citrate lock
• Metabolic alkalosis

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Anticoagulation free Protocols

• Classically occur in patients with MODS with
  abnormal clotting parameters
• Usually these patient are given ample amount of
  platelet infusions and coagulation factors
• This excessive amount of volume adds to greater
  need for ultrafiltration
• Final affect is clotting

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Heparin or Citrate (Mehta data)
Saline Flushes
Filter Life (hours)
Citrate
Heparin
Mehta,RL. Regional Citrate anticoagulation for
CAVHD in critically ill patients . Kidney Int,
38 976-978, 1990.
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Heparin ProtocolsBenefit and Risks

• Benefits
• Heparin infusion prior to filter with post filter
  ACT measurement
• Bolus with 10-20 units/kg Infuse at 10-20
  units/kg/hr
• Adjust post filter ACT 180-200 secs

• Risks
• Patient Bleeding
• Unable to inhibit clot bound thrombin
• Ongoing thrombin generation
• Activates - damages platelets / thrombocytopenia

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Citrate How does it work

• Clotting is a calcium dependent mechanism
  chelating calcium within blood will inhibit
  clotting
• Adding citrate to blood will bind the free
  calcium (ionized) calcium in the blood thus
  inhibiting clotting
• Common example of this is blood banked blood

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Citrate Mechanism of Action

• (Thanks to Peter Skippen)

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Citrate Advantages

• No need for heparin
• Commercially available solutions exist
  (ACD-citrate-Baxter)
• Less bleeding risk
• Simple to monitor
• Many protocols exist

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(Ca 0.4 x citrate rate 60 mls/hr)
(Citrate 1.5 x BFR 150 mls/hr)
Pediatr Neph 2002, 17150-154
(BFR 100 mls/min)
Normal Saline Replacement Fluid
Calcium can be infused in 3rd lumen of triple
lumen access if available.
Normocarb Dialysate

• ACD-A/Normocarb Wt range 2.8 kg 115 kg
• Average life of circuit on citrate 72 hrs (range
  24-143 hrs)

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Complications of CitrateMetabolic alkalosis

• Metabolic alkalosis due to
• citrate converts to HCO3 (1 mmol of citrate
  converts to 3 mmols of HCO3)-major cause
• Solutions contain 35 meq/l HCO3-minor cause
• NG losses-minor cause
• TPN with acetate component-minor cause
• Rx metabolic alkalosis by addition of an acid
  load Normal Saline (pH 5.4)

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Complications of CitrateCitrate Lock

• Seen with rising total calcium with either a
  sustained or dropping patient ionized calcium
• Essentially delivery of citrate exceeds hepatic
  metabolism and CRRT clearance
• Rx of citrate lock
• Decrease or stop citrate for 10-30 minutes then
  restart at 70 of prior rate
• Patients receiving multiple blood products
  receive additional citrate that may not be
  accounted for!

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What is the best anticoagulant

• None
• Heparin
• Standard
• Low molecular weight
• Citrate

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Citrate Heparin LM Hep
Hoffbauer R et al. Kidney Int. 1999561578-1583.
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Heparin or Citrate?(M Golberg RN et al, Edmonton
PCRRT 2002)

• Heparin circuits
• 13 patients with 45 filters
• 29.4 23 hrs average length of circuit
• Citrate circuits
• 16 patients with 51 filters
• 49.1 26 hrs average length of circuit
• (p lt 0.001)

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Filter clot free survival at fixed time intervals
according to method of anticoagulation
citrate
heparin
(data from Sheldon Tobe)
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ppCRRT- Anticoagulation

• Center, Patient and Circuit Demographics
• Data collected from 1/1/01 through 10/31/03
• HepACG only 3 centers (1 CVVH, 2 CVVHD)
• CitACG only 2 centers
• HepACG changed to CitACG 2 centers
• 138 patients total
• 18208 hours of CRRT circuit time
• 230 hepACG circuits (52) (9468.hrs)
• 158 citACG circuits (36) (6545 hrs)
• 54 noACGcircuits (12) (2185 hrs)

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ppCRRT Anticoagulation
(Brophy et al, submitted)
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ppCRRT Anticoagulation

• 43/158 citACG vs 58/230 hepACG clotted (NS)
• 9 pts (hepACG) had systemic bleeding 4 led to
  hepACG discontinuation
• 1 pt (hepACG) developed Thrombocytopenia leading
  to hepACG discontinuation
• No systemic bleeding side effects were reported
  with citACG 4 pts developed alkalosis and 2 pts
  with hepatic failure developed citrate lock.
• No correlation between circuit survival and (1)
  mean hepACG rate (2) ACT/hour or (3) ACTs
  less 180 seconds

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Summary

• Many protocols exist for anticoagulation
• All have risk and benefit
• Heparin with protamine has been used but adds to
  potential complications and work at bedside

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Conclusion

• Choice of anticoagulation is best decided locally
• For the benefit of the bedside staff who do the
  work come to consensus and use just one protocol
• Having the protocol changed per whim of the
  physician does not add to the the care of the
  child but subtracts due to additional confusion
  and work at bedside