Regional Citrate Anticoagulation

during CVVH in the

Pediatric Intensive Care Unit

T Gaillot, V Phan, P Jouvet, F Gauvin, C Litalien

Introduction

• CVVH is being increasingly utilized for the care of PICU patients

• Imperative need :Effective anticoagulation to prevent recurrent clotting of the extracorporeal circuit and to achieve efficient and uninterrupted therapy

• Historically, systemic anticoagulation with heparin mainstay of anticoagulation for CVVH

• Limits/contraindications :• High risk for bleeding• Active bleeding• Heparin-induced thrombocytopenia• Use of activated Protein C

Regional citrate anticoagulation (RCA):

• Attractive alternative to systemic heparinization with less risk of bleeding

• Citrate chelates ionized Ca2+, an essential cofactor in the clotting cascade

• Anticoagulation is limited to the extracorporeal circuit by infusing citrate solution into the arterial limb of the circuit

• Systemic anticoagulation is avoided by restoring ionized Ca2+ in the systemic circulation by infusing Ca2+ solution through a separate central line

Introduction

Introduction

RCA and mean circuit lifetime:

• Adult studiesMonchi et al, 2004: RCA vs heparin: 70 h vs 40 h Dorval et al, 2003: 44 24 h

• Pediatric studiesChadha et al, 2002: 51 8 hElhanan et al, 2004: 56 22 hBunchman et al, 2002: 71 7 h

Introduction

RCA and complications:

• Citrate is metabolized in the liver and produces HCO3-

and citric acid can result in metabolic alkalosis

• Accumulation of citrate may occur if liver metabolism is impaired can result in citrate toxicity or "citrate gap"

Objective

To evaluate the mean circuit lifetime and

metabolic complications of RCA in critically ill

children after the introduction of this

anticoagulation technique in our PICU

Material and methods

• Retrospective chart review • Children who underwent hemofiltration with RCA from

March 2003 to December 2003 were included

• Mean circuit lifetime (MCL) and reasons for circuit discontinuation were determined

• Metabolic alkalosis : pH 7.45 and HCO3- 30 mmol/L

• Citrate gap : total to ionized Ca2+ ratio > 2.5

Material and methods

DIALIZERPrisma

M-10, M-60 or M-100(AN-69)

From patient To patient

Ultrafiltrate

ACD-A

Rate: 1.5 X BFR

Normocarb

Rate: 2 L/1.73 m2/h

BFR: 2-8 ml/kg/min

Normocarb

Rate: 2 L/1.73 m2/h Systemic infusion

Calcium chloride (8g/1L NS)

Rate: 0.4 X ACD-A rate

Bunchman et al , 2002

27 involuntary discontinuations (73%) MCL= 28 35 h

Circuit failure (n=23, 85%)  10 Catheter dysfunction 13 High transmembrane

pressure and/or clotting

Technical failure (n=3, 11%) 1 impossible auto-test 1 screen failure 1 unknown failure

5 patientsmean age 5.5 6.8 y and weight 28.1 33 kg

37 circuitsMean circuit lifetime (MCL) = 29 36 h

10 elective discontinuations (27%) MCL= 29 32 h

Medical cause (n=1, 4%)1 bleeding

Results Kaplan-Meier curve of time to circuit discontinuation

Results

•Post filter ionized Ca2+ : 0.40 0.10 mmol/L

•Patient ionized Ca2+ : 1.14 0.13 mmol/L

•13 episodes (35 %) of metabolic alkalosis in 4 patients

•9 episodes (24 %) of citrate gap in 2 patients

Conclusion

• In our PICU, the mean circuit lifetime using RCA was much shorter than those reported despite post-filter ionized Ca2+ within the optimum range

• Metabolic alkalosis was frequently encountered

• Citrate toxicity occurred in 2 patients out of 5

• The use of RCA may be somewhat problematic in some critically ill children

Perspectives

• RCA remains an attractive option to provide anticoagulation in those patients with heparin contraindications

• Prospective, randomized controlled trials comparing RCA and systemic heparinization are needed before RCA replaces heparin in all critically ill children