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 Calcium

Citrate 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 10-30 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 10-20

units/kg/hour Infused prefilter Loading dose may be needed Monitor postfilter activated clotting time

(ACT) Titrate heparin infusion to maintain ACT range of 180-220 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.