Anticoagulation in CRRT Timothy E Bunchman Professor Pediatric

Anticoagulation in CRRT Timothy E. Bunchman Professor Pediatric Nephrology & Transplantation

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

Anticoagulation free Protocols n n 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

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

Heparin Protocols Benefit and Risks n n Benefits Heparin infusion prior to filter with post filter ACT measurement Bolus with 10 -20 units/kg Infuse at 1020 units/kg/hr Adjust post filter ACT 180 -200 secs n n n Risks Patient Bleeding Unable to inhibit clot bound thrombin Ongoing thrombin generation Activates - damages platelets / thrombocytopenia

Citrate: How does it work n n n 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

Citrate: Mechanism of Action n (Thanks to Peter Skippen)

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

(Ca = 0. 4 x citrate 60 mls/hr) (Citrate = 1. 5 x BFR 150 mls/hr) Pediatr Neph 2002, 17: 150 -154 (BFR = 100 mls/min) Normocarb Dialysate Normal Saline Replacement Fluid Calcium can be infused in 3 rd lumen of triple lumen access if available. ACD-A/Normocarb Wt range 2. 8 kg – 115 kg n. Average life of circuit on citrate 72 hrs (range 24 -143 hrs)

Complications of Citrate: Metabolic alkalosis n Metabolic alkalosis due to n n n citrate converts to HCO 3 (1 mmol of citrate converts to 3 mmols of HCO 3)-major cause Solutions contain 35 meq/l HCO 3 -minor cause NG losses-minor cause TPN with acetate component-minor cause Rx metabolic alkalosis by addition of an acid load = Normal Saline (p. H 5. 4)

Complications of Citrate: “Citrate Lock” n Seen with rising total calcium with either a sustained or dropping patient ionized calcium n n Rx of “citrate lock” n n Essentially delivery of citrate exceeds hepatic metabolism and CRRT clearance 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!

What is the best anticoagulant n n None Heparin n Standard Low molecular weight Citrate

Citrate Heparin LM Hep Hoffbauer R et al. Kidney Int. 1999; 56: 1578 -1583.

Heparin or Citrate? (M Golberg RN et al, Edmonton PCRRT 2002) n Heparin circuits n n n 13 patients with 45 filters 29. 4 + 23 hrs average length of circuit Citrate circuits n n 16 patients with 51 filters 49. 1 + 26 hrs average length of circuit n (p < 0. 001)

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

pp. CRRT- Anticoagulation Center, Patient and Circuit Demographics · Data collected from 1/1/01 through 10/31/03 · Hep. ACG only: 3 centers (1 CVVH, 2 CVVHD) · Cit. ACG only: 2 centers · Hep. ACG changed to Cit. ACG: 2 centers · · 138 patients total 18208 hours of CRRT circuit time Ø 230 hep. ACG circuits (52%) (9468. hrs) Ø 158 cit. ACG circuits (36%) (6545 hrs) Ø 54 no. ACGcircuits (12%) (2185 hrs)

pp. CRRT: Anticoagulation (Brophy et al, submitted)

pp. CRRT: Anticoagulation · · · 43/158 cit. ACG vs 58/230 hep. ACG clotted (NS) 9 pts (hep. ACG) had systemic bleeding; 4 led to hep. ACG discontinuation 1 pt (hep. ACG) developed Thrombocytopenia leading to hep. ACG discontinuation No systemic bleeding side effects were reported with cit. ACG; 4 pts developed alkalosis and 2 pts with hepatic failure developed citrate lock. No correlation between circuit survival and (1) mean hep. ACG rate (2) #ACT/hour or (3) # ACT’s less 180 seconds

Summary n n n 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

Conclusion n 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 care of the child but subtracts due to additional confusion and work at bedside