Management of Heparin-Induced Thrombocytopenia During Renal Replacement Therapy

Citrate anticoagulation for continuous renal replacement therapy (CRRT) in patients with acute kidney injury admitted to the intensive care unit

Continuous forms of renal replacement therapy (CRRT) have become established as the treatment of choice for supporting critically ill patients with acute kidney injury. Typically, these patients have activation of the coagulation cascades, peripheral mononuclear cells and platelets, but also a reduction in natural anticoagulants, and are therefore prothrombotic. For continuous modes of renal replacement therapy to be effective, in terms of both effective solute clearance and also fluid removal, the extracorporeal circuits must operate continuously. Thus, preventing clotting in the CRRT circuit is a key goal to effective patient management. As these patients may also be at increased risk of bleeding, regional anticoagulation with citrate is increasing in popularity, particularly following the introduction of commercially available CRRT machines and fluids specifically designed for citrate anticoagulation. Although regional anticoagulation with citrate provides many advantages over other systemic anticoagulants, excess citrate may lead to both metabolic complications, ranging from acidosis to alkalosis and may also potentially expose patients to electrolyte disturbances due to hyper- and hyponatraemia and hyper- and hypocalcaemia.

Heparin-induced thrombocytopenia: An uncommon but serious complication of heparin use in renal replacement therapy

Heparin-induced thrombocytopenia (HIT) is an uncommon but potentially life-threatening complication of heparin therapy. Hemodialysis and hemofiltration patients are regularly exposed to heparin, which is used for extracorporeal anticoagulation. Type II HIT (HIT-II) is the rarer immune-mediated form and is of huge clinical significance. The clinical manifestation of HIT-II is characteristically with venous and arterial thrombotic events. However, systemic and pulmonary reactions have been reported. Type II HIT is due to antibodies to the heparin-platelet factor 4 complex, which induce a cascade of events leading to thrombocytopenia and thrombosis. Nowadays, with increasing availability of functional and immunoassay tests for HIT-associated antibodies, HIT diagnosis can be confirmed more readily. Hence, it is important to rapidly recognize, diagnose, and manage this syndrome early in hemodialysis patients with thrombocytopenia to avoid serious consequences resulting in morbidity and mortality. We report a case of HIT-II manifesting atypically as a "pseudopulmonary embolus" in a hemodialysis patient and discuss the clinical management of HIT.