MAINTAINING BLOOD-FLOW IN THE EXTRACORPOREAL CIRCUIT - HEMOSTASIS ANDANTICOAGULATION

Objectives: To review the methods and developments in maintaining extr acorporeal circuits in critically ill patients. Design: The review inc ludes details of the pathophysiological processes of haemostasis and c oagulation in critically ill patients, methods of maintaining blood fl ow in the extracorporeal circuit and methods of monitoring anticoagula tion agents used. Setting: Information is relevant to the management o f critically ill patients requiring extracorporeal renal and respirato ry support and cardiopulmonary bypass. Conclusions: Heparin is the mai nstay of anticoagulation for the extracorporeal circuit although the c omplex abnormalities of the coagulation system in critically ill patie nts are associated with a considerable risk of bleeding. Alternative t herapeutic agents and physical strategies (prostacyclin, low molecular weight heparin, sodium citrate, regional anticoagulation, heparin bon ding and attention to circuit design) may reduce the risk of bleeding but expense and difficulty in monitoring are disadvantages.