Anticoagulation options for intermittent haemodialysis

Anticoagulation of the extracorporeal circuit, once a major technical problem that delayed the development of chronic intermittent haemodialysis, is today largely taken for granted as part of normal routine practice. The initiation of coagulation in the extracorporeal hemodialysis circuit is a manifestation of bioincompatibility, due to the activation of leukocytes, platelets and the coagulation cascades, rather than simple contact of intrinsic system coagulation proteins which the dialyser surface and plastic tubing leading to activation of the contact coagulation cascade. Although unfractionated heparin remains the most commonly used anticoagulant world wide, low molecular weight heparin offers the advantage of more reliable pharmacokinetics, allowing the use of a simple single bolus, with less dialyser fouling, and perhaps more importantly, less osteoporosis, hyperkalemia and abnormal lipoprotein profile. Although regional anticoagulants are available and offer the advantage of reducing the risk of haemorrhage, these tend to be prohibitively expensive, or require increased complexity such as citrate. Unfortunately the incidence of immune mediated heparin induced thrombocytopenia appears to be increasing, and these patients require systemic anticoagulation with the direct thrombin inhibitors and/or heparinoids to prevent thrombosis.