ANTICOAGULATION IN CONTINUOUS RENAL REPLACEMENT THERAPY Dawn M Eding RN BSN CCRN Pediatric Critical Care Helen DeVos Children's Hospital

Goal of Anticoagulation  Maintain patency of CRRT circuit.  Minimize patient complications of anticoagulation therapies.

Sites of Clot Formation  Hemofilter  Bubble trap, dearation chamber  Catheter  Leurlock and 3 way stopcock connections

Factors Influencing Circuit Clotting and Filter Life  Vascular access  Blood flow  Circuit alarms  Anticoagulant

Vascular access  Site  Jugular  Subclavian  Femoral  Catheter size  Catheter connections

Vascular access needs to provide adequate flow to provide optimal therapy with minimal interruptions.

Properly functioning access is the key to successful CRRT therapy.

Blood Flow  Ideal flow rates 3-5ml/kg/minute  Access will ultimately determine blood flow

Circuit Alarms  Ideal circuit pressures

Anticoagulation Options  Citrate  Heparin  Citrate and low dose heparin  No anticoagulation

Citrate Anticoagulation  Regional anticoagulation of the CRRT system  Coagulation is a calcium dependent process  Citrate acts by binding calcium  Less risk of bleeding  Commercially available solutions exist

Citrate Protocol  Infused pre filter  Start infusion at 1.5 times blood flow rate  Requires monitoring of circuit and patient ionized calcium levels  Adjust infusion based on post filter ionized calcium levels Aim for post-filter ionized calcium level between 0.25 and 0.4 mmols/L  Requires calcium free dialysate and replacement solutions

Citrate Infusion Titration Scale Circuit Ionized CalciumCitrate infusion adjustment <.25 rate by 10 mL/hour 0.25 – 0.39 (optimum range) No adjustment 0.4 – 0.5 rate by 10 mL/hour > 0.5 rate by 20 mL/hour

Potential Complication of Citrate: Hypocalcemia  Infusion of calcium chloride solution to patient via a central venous access is necessary to avoid hypocalcemia.  Solution consists of 8gm Calcium Chloride in 1L NS  Start infusion at 40% of citrate flow rate  Adjust calcium chloride infusion based on patient ionized calcium levels  Aim for patient ionized calcium level of 1.1 to 1.3 mmols/L

Calcium Chloride Titration Scale Patient ionized calcium (mmol/L) Calcium Infusion Adjustment > 1.3 rate by 10 mL/hour 1.1 – 1.3 (optimum range) No adjustment 0.9 – 1.1 rate by 10 mL/hour <.9 rate by 20 mL/hour

Potential Complication of Citrate: Metabolic Alkalosis  Related to rate of citrate metabolism in liver  Citrate converts to HCO3 (1 mmol of citrate converts to 3 mmols of HCO3)  Correction of alkalosis can be done by adjusting the bicarbonate concentration in replacement and dialysate solutions, decreasing the citrate rate, or by infusing 0.9% normal saline (pH 5.4) as a replacement or dialysate solution.

Potential Complication of Citrate: Hyperglycemia  ACDA solution contains 2.45gm/dl of dextrose  Adjustments in other dextrose sources (TPN etc.) and/or insulin infusions may become necessary.

Potential Complication of Citrate: Citrate Lock  Seen with rising patient total calcium while patient’s ionized calcium is in normal range or dropping  Essentially the delivery of citrate exceeds the hepatic metabolism and CRRT clearance

Treatment of Citrate Lock  Decrease citrate rate  Adjust scale of acceptable post filter ionized calcium range  Stop citrate infusion for minutes and restart at a lower rate  Increase clearance by adjusting Replacement and/or Dialysate flow rates

Heparin Anticoagulation  Systemic anticoagulation  Requires monitoring of patient clotting times

Heparin Protocol  Continuous infusion of units/kg/hour  Infused prefilter  Loading dose may be needed  Monitor postfilter activated clotting time (ACT)  Titrate heparin infusion to maintain ACT range of seconds

Potential Complications of Heparin  Patient bleeding  Heparin induced thrombocytopenia (HIT)

Citrate and Low Dose Heparin Anticoagulation  Continuous prefilter infusion of citrate and heparin  Maintain citrate per protocol  Heparin infusion of 5 units/kg/hour

No Anticoagulation  Typically results in short filter life

Conclusions:  Wide range of practice exists.  Despite all best measures filters last from hours to days.  Individual circumstances of the patient dictate the anticoagulation regimen that is best for the patient.