CRRT. Principles and Methods Of Anticoagulation in CRRT Ravindra L Mehta MD. FACP. Citrate Anticoagulation. Overview Practical Issues Sample Orders

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1 Principles and Methods Of Anticoagulation in CRRT Ravindra L Mehta MD. FACP. Educational Objectives: 1. Define the goals of anticoagulation in CRRT and identify the factors which affect anticoagulant choice and dose. 2. Describe the methods of anticoagulation which are currently available and provide an overview of practical methods and comparison of results of different techniques. 3. Discuss the requirements for monitoring adequacy of anticoagulation and maintenance of circuit integrity. Content Description: Continuous renal replacement therapies are increasingly used to treat acute renal failure (ARF) in the ICU setting. The slow and steady removal of plasma water and/or uremic toxins is an inherent advantage for both continuous hemofiltration and hemodialysis (CAVH, CAVHD) over intermittent dialysis. However, as in other extracorporeal circuits, anticoagulation is essential to prevent activation of the clotting mechanisms within the circuit [1]. The adequacy of anticoagulation plays a key role in the efficacy of the filter in fluid and solute removal, overall filter longevity and optimum patient management. If anticoagulation is insufficient, filtration performance deteriorates and the filter may eventually clot [2], contributing to blood loss. Excessive anticoagulation, on the other hand, may result in bleeding complications reported to occur in 5 to 26% of treatments [1,3]. Several methods of anticoagulation are now available and the key features of the most common methods are summarized in Table 1. Heparin continues to be the most commonly used anticoagulant, however its use is associated with a high incidence of bleeding and in some instances heparin induced thrombocytopenia [4-6]. Regional citrate anticoagulation eliminates the bleeding risk, however requires the use of a specialized dialysis solution and monitoring of ionized calcium [7-9]. Low molecular weight heparin [10-11], prostacyclin analogues [12-13] and other anticoagulants such as orgaran [14] and high molecular weight dextrans [15] have had limited experience. While some patients may

2 not require any anticoagulation, in general filter patency is limited to hours in most instances. Filter efficacy usually declines before filters clot and should be monitored routinely. Filter longevity in excess of 96 hours is fairly common with citrate anticoagulation while hours patency is usually the norm with heparin [16-18]. The efficacy of these techniques and their relative advantages and disadvantages have been previously reviewed [19]. At the current time none of these methods is ideal and selection is usually influenced by several factors (Table 2). It is to be emphasized that technical factors and experience with anticoagulants are important PREVIOUS

3 determinants of the success of any anticoagulant regimen. This presentation discusses the currently available methods of anticoagulation for continuous renal replacement therapy and discusses factors influencing selection of an appropriate anticoagulant. Table 2: Factors affecting anticoagulant requirement in CRRT PREVIOUS

4 Suggested Reading: 1. Webb AR, Mythen MG, Jacobson D and Mackie IJ: Maintaining blood flow in the extracorporeal circuit. Intensiv Care Med 21:84-93, Martin PY, Chevrolet, JC, Suter P and Favre H: Anticoagulation in patients treated by continuous venovenous hemofiltration: A retrospective study. Am J Kid Dis 24: , Langenecker SA, Felfernig M, Werba A, Mueller CM, Chiari A and Zempfer M: Anticoagulation with prostacyclin and heparin during continuous venovenous hemofiltration. Crit Care Med 22: , Mehta RL, Dobos GJ and Ward DM: Anticoagulation in continuous renal replacement procedures. Sem in Dial1992, 5: van de Wetering J; Westendorp RG; van der Hoeven JG; Stolk B; Feuth JD; Chang PC. Heparin use in continuous renal replacement procedures: the struggle between filter coagulation and patient hemorrhage. Journal of the American Society of Nephrology, 1996 Jan, 7(1): G; Lucchese F. Heparin-associated thrombocytopenia during continuous venovenous hemofiltration [letter]. Nephron, 1996, 74(1): Mehta RL, McDonald BR, Aguilar MM and Ward DM: Regional citrate anticoagulation for continuous arteriovenous hemodialysis in critically ill patients. Kidney Int 1990, 38: Pahl MV, Lee H, Pascual M, Scannell G, Tominaga G, Waxman K: Citrate anticoagulation in continuous renal replacement therapy. Blood Purification; 1995; 13: Griswold WR, Reznik V, Lemire J, Petersen B, Mehta RL: Continuous renal replacement therapy with regional citrate anticoagulation in critically ill children. Blood Purification 1995; 13: Hory B, Cachoux A, Toulemonde F: Continuous arteriovenous hemofiltration with low-molecular-weight heparin. Nephron 1985, 42: Wynckel A, Bernieh B, Toupance O, N Guyen Ph. Wong T, Lavaud s, Chanard J: Guidelines in using enoxaparin in slow continuous hemodialysis. In Sieberth HG, Mann H, Stummvoll HK (eds): Continuous Hemofiltration. Contrib Nephrol. Basel, Karger,1991, 93: PREVIOUS

5 12. Davenport A, Will EJ, and Davison AM: Comparison of the use of standard heparin and prostacyclin anticoagulation in spontaneous and pump driven extracorporeal circuits in patient with combined acute renal and hepatic failure. Nephron, 66: , Klotz KF,Gellersen H, Brzelinski T, Sedemund-Adib B, Gehring H: Use of prostacyclin in patients with continuous hemofiltration after open heart surgery in Sieberth HG, Stummvoll HK, Kierdorf H Editors: Continuous extracorporeal treatment in multiple organ dysfunction syndrome. Contrib Nephrol. Basel, Karger, : Chong BH, Magnani: Orgaran in heparin induced thrombocytopenia.hemostasis 1992; 22: Palevsky PM, Burr R, Moreland L, Tokiwa Y, Greenberg A: Failure of low molecular weight dextran to prevent clotting during continuous renal replacement therapy. ASAIO J; 1995; 24: Bellomo R, Teede H and Boyce N: Anticoagulant regimens in acute continuous hemodiafiltration: a comparative study. Intensiv Care Med 19: , Martin PY, Chevrolet, JC, Suter P and Favre H: Anticoagulation in patients treated by continuous venovenous hemofiltration: A retrospective study. Am J Kid Dis 24: , Stefanidis I; Hagel J; Frank D; Maurin N. Hemostatic alterations during continuous venovenous hemofiltration in acute renal failure. Clinical Nephrology, 1996 Sep, 46(3): Favre H, Martin PY, Stoermann C: Anticoagulation in continuous extracorporeal renal replacement therapy. Sem In Dial 1996, 9: PREVIOUS